WO2012174284A1

WO2012174284A1 - Reactors containing liquid metal

Info

Publication number: WO2012174284A1
Application number: PCT/US2012/042521
Authority: WO
Inventors: Irving B. Morrow, Jr.; Mark Wilkinson; David STECKLER; Shawn ROY; William H. Davis; Roderick SIDWELL; Frank MEDROS; Terumi OKANO; Jonathan LEBEAUX; Alejandro RIVERA; Shawn CAHILL; David Robertson
Original assignee: ZE-GEN Inc; Ze Gen Inc
Current assignee: ZE-GEN Inc; Ze Gen Inc
Priority date: 2011-06-17
Filing date: 2012-06-14
Publication date: 2012-12-20
Anticipated expiration: 2013-12-17

Abstract

The present invention generally relates to reactors containing one or more metals in a liquid state for at least partially oxidizing feed materials, e.g., to produce syngas or other products, for example, gases such as fuel gases. The metals within the reactor may include, for example, one or more of copper, iron, tin, zinc, silver, palladium, gold, and/or other metals and alloys thereof. In some cases, the reactor may be operated such that substantially no oxide of the metals accumulate within the reactor, and/or such that substantially all of the oxygen entering the reactor is utilized by the feed material or char within the reactor. In some embodiments, a carbon-containing material may be fed to the reactor to chemically reduce any metal oxides that are present. The reactor may also be operated such that substantially no carbon boils occur within the reactor. In addition, the reactor can be operated autothermally in some cases, i.e., essentially all of the heat necessary to keep the metal within the reactor in a liquid state comes exclusively from exothermic partial oxidation of one or more feed materials supplied to the reactor. Moreover, the heat generation may be adjusted by the degree of oxidation of the feed material without oxidizing the metal bath. Still other aspects of the invention are generally directed to methods of using such reactors, methods of producing such reactors, or the like.

Description

REACTORS CONTAINING LIQUID METAL

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Serial No. 61/498, 183, filed June 17, 2011 , entitled "Reactors Containing Liquid Metal," incorporated herein by reference in its entirety.

FIELD OF INVENTION

The present invention generally relates to reactors containing one or more metals in a liquid state for at least partially oxidizing feed materials, e.g., to produce syngas or other products, for example, gases such as fuel gases.

BACKGROUND

Feed materials such as organic materials can be reacted to produce synthesis gas (typically a mixture of CO and H₂, sometimes referred to as syngas) by various techniques. In some cases, the feed materials desired to be converted into syngas may include bulk feed materials such as municipal solid waste, construction and demolition waste, wastewater sludge, or the like. Examples of suitable known production techniques include plasma technologies, reactions involving steam, or reactors containing liquid iron. However, with respect to reactors containing liquid iron, many challenges remain before such reactors can be reliably used commercially, especially with bulk feed materials. For example, such reactors may produce relatively large amounts of carbon dioxide (which often cannot be further processed into useful products and/or energy), irreversibly create iron oxides (with a reduction in the amount of liquid iron available for continued reaction), and/or heterogeneously or non-uniformly react with the feed materials (e.g., due to poor mixing and/or reaction within the liquid iron), resulting in the formation of carbon boils (a sudden, violent production of carbon monoxide and/or carbon dioxide from within the liquid iron). Accordingly, improvements in systems and methods for reacting feed materials to produce syngas or other gases are needed.

SUMMARY OF THE INVENTION

The present invention generally relates to reactors containing one or more metals in a liquid state for at least partially oxidizing feed materials, e.g., to produce syngas or other products, for example, gases such as fuel gases. The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.

In one aspect, the present invention is generally directed to a method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor. In one set of embodiments, the method includes acts of providing a reactor containing a liquid metal comprising copper, feeding one or more materials to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1, and reacting the one or more materials within the reactor to produce synthesis gas comprising carbon monoxide. In some cases, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen. In certain embodiments, reaction occurs within the reactor such that substantially no copper oxide accumulates within the reactor over a period of at least one day.

In another set of embodiments, the method includes acts of providing a reactor containing a liquid metal comprising copper, feeding one or more materials to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1, and reacting the one or more materials within the reactor to produce synthesis gas. In some cases, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen. In certain embodiments, at least about 80% of the oxygen in the one or more materials fed to the reactor is reacted within the reactor.

In accordance with yet another set of embodiments, the method includes acts of providing a reactor containing a metal in a liquid state, feeding one or more materials to the reactor, and reacting the one or more materials within the reactor to produce carbon monoxide under conditions selected such that substantially no oxide of the metal accumulates within the reactor. In certain instances, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1.

In still another set of embodiments, the method comprises acts of providing a reactor containing a metal in a liquid state, feeding one or more materials to the reactor, and reacting the one or more materials within the reactor such that at least about 80% of the oxygen in the one or more materials is reacted within the reactor. In some embodiments, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1.

In yet another set of embodiments, the method includes acts of providing a reactor containing at least 10 tons of metal in a liquid state, feeding one or more materials containing carbon and oxygen to the reactor, and reacting the one or more materials within the reactor to produce a synthesis gas comprising carbon monoxide under conditions without active stirring of the metal in the liquid state in the reactor. In certain instances, essentially all stirring of the metal in the liquid state within the reactor is driven by heat convection. In one set of embodiments, the method includes acts of providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V, feeding one or more materials to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1, and reacting the one or more materials within the reactor to produce synthesis gas comprising carbon monoxide. In some cases, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen. In certain embodiments, reaction occurs within the reactor such that substantially no metal oxide accumulates within the reactor over a period of at least one day.

In another set of embodiments, the method includes acts of providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V, feeding one or more materials to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1, and reacting the one or more materials within the reactor to produce synthesis gas. In some cases, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen. In certain embodiments, at least about 80% of the oxygen in the one or more materials fed to the reactor is reacted within the reactor.

In accordance with yet another set of embodiments, the method includes acts of providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V, feeding one or more materials to the reactor, and reacting the one or more materials within the reactor to produce carbon monoxide under conditions selected such that substantially no oxide of the metal accumulates within the reactor. In certain instances, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1.

In still another set of embodiments, the method comprises acts of providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V, feeding one or more materials to the reactor, and reacting the one or more materials within the reactor such that at least about 80% of the oxygen in the one or more materials is reacted within the reactor. In some embodiments, at least one of the materials fed to the reactor is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1.

In yet another set of embodiments, the method includes acts of providing a reactor containing at least 10 tons of one or more liquid metals having an overall standard oxidation potential of at least 0 V, feeding one or more materials containing carbon and oxygen to the reactor, and reacting the one or more materials within the reactor to produce a synthesis gas comprising carbon monoxide under conditions without active stirring of the metal in the liquid state in the reactor. In certain instances, essentially all stirring of the metal in the liquid state within the reactor is driven by heat convection.

The present invention, in another aspect, is generally directed to a method of operating a liquid metal gasifier reactor. In accordance with one set of embodiments, the method includes acts of providing a reactor containing (a) a liquid metal comprising copper and (b) copper oxide, and feeding a carbon-containing material to the reactor under conditions selected to chemically reduce the copper oxide to form copper.

According to another set of embodiments, the method includes acts of providing a reactor containing: (a) a metal in a liquid state and (b) an oxide of the metal, and feeding a carbon-containing material to the reactor under conditions selected to chemically reduce the oxide of the metal.

In yet another set of embodiments, the method includes acts of providing a reactor containing a metal in a liquid state, feeding one or more materials containing carbon and oxygen to the reactor, and reacting the one or more materials within the reactor to produce heat at least sufficient to maintain the metal in the liquid state within the reactor over a period of at least one day.

The method, in still another set of embodiments, includes acts of providing a reactor containing a metal in a liquid state; at a first time, feeding a carbon-containing material to the reactor under conditions selected to facilitate reacting the material with oxygen or an oxygen containing material to produce carbon monoxide, where some of the metal is oxidized to produce a metal oxide; and at a second time, feeding a carbon-containing material to the reactor under conditions selected to facilitate reacting the material with the metal oxide to chemically reduce the metal oxide within the reactor to the metal.

In another aspect, the present invention encompasses methods of making one or more of the embodiments described herein, for example, a reactor containing a metal in a liquid state. In still another aspect, the present invention encompasses methods of using one or more of the embodiments described herein, for example, a reactor containing a metal in a liquid state.

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and/or inconsistent disclosure with respect to each other, then the document having the later effective date shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:

Fig. 1 is a process flow diagram illustrating a reactor containing a liquid metal, according to certain embodiments of the invention;

Fig. 2 is a schematic cross-sectional diagram that illustrates a reactor in accordance with one embodiment of the invention;

Figs. 3A-3C illustrate additional views of the reactor shown in Fig. 2;

Figs. 4A-4B are graphs that show data illustrating the production of syngas from a reactor as is shown in Fig. 2;

Fig. 5 shows experiments using various C:0 ratios in a reactor in certain embodiments of the invention; and

Figs. 6A-6B show various experiments illustrating autothermal operation of a reactor, in accordance with certain embodiments of the invention.

DETAILED DESCRIPTION

In one aspect, the present invention is generally directed to reactors containing at least one metal in a liquid or molten state. One non-limiting illustrative example is now discussed with reference to the schematic diagram shown in Fig. 1. In this figure, reactor 10 contains at least one metal 15 in a liquid state. The liquid metal may include, for example, copper or iron, or other metals as discussed below. Feed materials are fed into the reactor, e.g., into the liquid metal and/or into the "headspace" or gas space above the liquid metal. In Fig. 1, for instance, feed materials are illustrated as entering headspace 18 above liquid metal 15 through inlet 20 from conduit 22.

Within reactor 10, the feed materials are oxidized (or pyrolyzed), e.g., reacted with oxygen to produce products such as syngas. For example, a carbon-containing material may be oxidized to produce carbon oxides, typically carbon monoxide (CO) and/or carbon dioxide (C0₂). The amount of carbon monoxide and/or carbon dioxide produced is a function of various factors, including the amount of oxygen (0₂) present within the reactor, which may be supplied to the reactor as, e.g., air, enriched air (i.e., enriched in oxygen over atmospheric levels), a purified oxygen stream, or as another oxygen-containing material. In Fig. 1, this is illustrated by conduit 27 entering headspace 18 via inlet 25; in other embodiments, however, the oxygen- containing material may enter the reactor from beneath the surface of the liquid metal, e.g., via one or more lances or tuyeres, instead of and/or in addition to being supplied to the headspace. Other materials present within one or more of the feed materials may be oxidized as well. For example, if a feed material also contains hydrogen (as would be the case, for instance, with organic or hydrocarbon feed materials), such materials may be oxidized or pyrolyzed to produce hydrogen gas (H₂) and/or water (H₂0). The amount of hydrogen gas and/or water that is produced may be a function of various factors, including the amount of oxygen present within the reactor. Other elements present within one or more of the feed materials may also be at least partially oxidized, depending on the partial pressure of oxygen within the reactor; for example, sulfur may be partially or fully oxidized or otherwise reacted to produce sulfur oxides (SO_x) or H₂S, nitrogen may be partially or fully oxidized to produce nitrogen oxides (NO_x), calcium may be partially or fully oxidized to produce calcium oxide (CaO), silicon may be partially or fully oxidized to produce silicon dioxide (Si0₂), etc. In some embodiments, it may be possible to produce oxides within a reducing atmosphere, e.g., within an atmosphere having a relatively low oxygen partial pressure

When the reactor only partially oxidizes a feed material, a greater amount of CO and/or H₂ may be produced (relative to C0₂ and/or H₂0), thereby forming syngas. Some amount of H₂0 and/or C0₂ may be present within the syngas as well. The syngas produced within the reactor may then be captured from the reactor, and subsequently used as a fuel and/or as a reactant for further chemical reactions. For example, as is shown in Fig. 1, some of the gas within headspace 18, e.g., syngas, may exit reactor 10 through outlet 30 into conduit 33, e.g., for purification, separation, collection, further reaction, etc.

Metal 15 within reactor 10 may be heated to cause the metal to melt or liquefy using one or more sources of heat; for example, electrical or resistive heating may be used, or other sources of heat as discussed below. The metal may be heated within the reactor and/or prior to entering the reactor. In addition, in some embodiments, the reactor may be operated, at least at certain times, under "autothermal" conditions, i.e., such that essentially all of the heat necessary to keep the metal within the reactor in a liquid state comes exclusively from the reaction of one or more feed materials supplied to the reactor. For example, the oxidation reaction to convert one or more of the feed materials to produce syngas is an exothermic reaction, i.e., some heat is produced in the process, which may be harnessed under certain conditions to control the temperature of the reactor, e.g., such that the metal within the reactor remains liquid.

Accordingly, certain aspects of the present invention are generally directed to reactors containing one or more metals in a liquid state for oxidizing feed materials, e.g., to produce syngas or other products, such as gases or liquids. Any material fed into the reactor may be considered a "feed material," including solid materials, liquid materials, gaseous materials (e.g., gaseous hydrocarbons such as methane, air, oxygen, etc.), and the like, as well as any combinations thereof. The feed materials may be added to the reactor using any suitable technique. For instance, feed materials may be actively fed into the reactor, e.g., using conveyor belts, bucket elevators, hopper tubes, pipes, tubes, lances, tuyeres, etc. Non-limiting examples of such systems may be seen, for example, in U.S. Pat. Apl. Pub. No. 2009/0188844. In some cases, feed materials may be physically "pushed" or pressurized to flow into the reactor. In some embodiments, gravity or passive techniques may be used to deliver feed materials into the reactor, alone or in combination with other delivery techniques. If more than one feed material is fed to the reactor, the feed materials may enter the reactor as one stream (e.g., through a single inlet) or as multiple streams (e.g., through multiple inlets), for example, using any suitable combination of these and/or other techniques as described herein.

In certain embodiments, the feed material includes a carbon-containing material. A carbon-containing material may be any material containing carbon, e.g., in a relatively pure or carbon-rich form (for example, coal, coke, etc.), and/or as compounds that include carbon atoms (for example, organic compounds, hydrocarbons, etc.). Examples of carbon-containing materials include, but are not limited to, biomass (e.g., produced from plants such as switchgrass, corn, sugar cane, sugar beets, trees, straw, rice, cotton, etc.), wood, polymers such as rubber or plastics, hydrocarbons such as gasoline, diesel, kerosene, methane, propane, butane, petroleum oil, or the like. Other suitable feed materials include, but are not limited to, waste materials such as garbage, municipal solid waste (MSW), refuse derived fuels (RDF), including RDF based upon MSW, construction and demolition wastes (C&D), wastewater sludge, scrap tires, plastic wastes, medical waste, waste oils, or the like. The carbon-containing materials can include solid feed materials and/or non-solid materials (e.g., semi-solid mixtures, liquid materials, gas materials, etc.).

In certain embodiments, the feed material may not be precisely known, and/or the feed material may be one that is compositionally heterogeneous. For example, various types of bulk feed materials may be used, such as garbage, MSW, RDF, C&D, waste oil, or the like. Such materials are typically collected "in bulk" (for instance, from different sources) and may not be typically sorted to produce a homogenous feed composition, e.g., due to the mass and/or difficulty in sorting such materials. Accordingly, such materials can be fed into a reactor as an unsorted or heterogeneous bulk feed. As specific non-limiting examples, C&D waste may include wood, nails, wallboard, cardboard, carpet remnants, metal fragments, plastic fragments, pipe, dried glue, plastic, etc., and such C&D waste may not be presorted compositionally prior to being fed into a reactor. As another example, waste oil from different cars, other vehicles, and/or other sources (e.g., having different grades of oil, additives, contaminants, etc.) can be pooled together and fed into a reactor, although the specific composition, or even the grade, of oil within the waste oil may not be accurately known. In addition, in some embodiments, different types of waste may be mixed within the reactor and/or prior to being fed to the reactor, for instance, MSW and waste oil may be mixed together as a feed material.

In some embodiments, however, some processing or sorting of a feed material may occur prior to feeding the material to the reactor. For example, a solid feed material may be processed (e.g., cut, chopped, shredded, etc.) to produce particles (e.g., forming "chips" or "pellets") of a certain size before being fed into the reactor. In some cases, this may be performed without any sorting of the feed material, although in other cases, some sorting of the feed material may occur. For example, a solid feed material may be processed to produce particles having a maximum size of less than about 5 inches (about 12.7 cm), less than about 4 inches (about 10.2 cm), less than about 3 inches (7.6 cm), less than about 2 inches (about 5.1 cm), less than about 1.5 inches (about 3.8 cm), or less than about 1 inch (about 2.5 cm). As a specific non-limiting example, a feed material comprising wood may be broken down or chopped into wood pellets, although there may be no attempt to separate different types of wood and/or contaminants that are present within the wood. The wood may include fresh wood (e.g., from cut trees, bushes, etc.), and/or "waste wood" (e.g., railroad ties, utility poles, wooden pallets or skids, wood panels, etc. which have been previously used for other applications). Other examples may be seen, for instance, in U.S. Pat. Apl. Pub. No. 2009/0188844.

In certain embodiments, a feed material can include moisture (i.e., water). For example, the moisture within a feed material may be at least about 5% by weight, and in some instances, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% by weight of moisture. In some embodiments, the liquid metal within the reactor may be chosen to be one that does not react, or does not irreversibly react, with water, e.g., to produce oxides. For example, a liquid metal including copper does not typically react irreversibly with water to produce copper oxides. Non-limiting examples of such liquid metals are discussed below.

However, lower moisture contents may be desirable in some embodiments, as the water fed into the reactor may be heated within the reactor to produce steam without any substantive chemical reaction, which may in certain instances incur an energy consumption penalty (latent heat of the water) and/or produce a safety hazard. For instance, the moisture may be no more than about 60%, no more than about 50%, no more than about 40%, no more than about 30%, no more than about 20%, or no more than about 10% by weight in certain embodiments. Accordingly, in some embodiments, a feed material is treated, physically and/or chemically, to at least partially remove water (for example, through drying) before being fed to the reactor.

As mentioned, the feed materials can be fed into a reactor containing one or more metals in a liquid state. It should be understood that references herein to a "metal" in a reactor is for ease of convenience and presentation only, and in other embodiments of the invention, there may be more than one metal present within the reactor, e.g., in a liquid state. For example, a "metal" within a reactor as discussed herein may include a mixture or an alloy of two, three, four, or more metals. As specific non-limiting examples, the metal within the reactor may be brass (e.g., an alloy of copper or zinc), bronze (an alloy of copper and tin), or the like. In other embodiments, however, the reactor may consist essentially of a single metal that is in a liquid state.

As specific non-limiting examples, a reactor as discussed herein may comprise or consist essentially of a liquid metal such as copper, iron, nickel, chromium, tin, nickel, zinc, lead, silver, palladium, and/or gold, and/or a combination of any of these and/or other metals or materials, e.g., as in a liquid metal alloy. For example, the liquid metal within a reactor may be copper, iron, or an alloy such as brass or bronze. The alloy may be eutectic in some embodiments. In some cases, the reactor may include a noble metal in a liquid state, such as copper, silver, gold, palladium, platinum, or the like. If two or more liquid metals are present within the reactor, e.g., as an alloy or other mixture, the metals may be present in any suitable ratio. For example, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99% by volume or mass of the liquid metal within the reactor may be a first metal, and with the remainder being one or more other metals. For example, in one set of embodiments, a reactor may include a liquid metal comprising or consisting essentially of copper. In some cases, the reactor may contain a liquid metal comprising at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99% copper, with the remainder of liquid metal being other materials, e.g., other metals and/or other materials.

In some embodiments, other compounds are present within the liquid metal as well, for example, dissolved, suspended, or trapped therein. For example, the liquid metal may include one or more gases (e.g., air, oxygen, syngas, feed gases, inert gases, etc.), carbon-containing materials, other solids, other liquids, etc. As examples, one or more fluxes may be present within the liquid metal (for example, AI₂O₃, lime, silica, CaO or quicklime, CaC0₃, Ca(OH)₂, CaS0₄, etc.), or the liquid metal may contain slag materials (e.g., Fe₃0₄, Fe₂0₃, CaSi0₃, A1₂0₃, PbO, Pb0₂, Pb 0₄, Pb₂0₃, Ρ₂0₅, CuO, etc.), oxides (e.g., of one or more of the liquid metals within the reactor), or the like.

Any suitable method can be used to heat the metal within the reactor to a temperature greater than the melting point of the metal to melt some or all of the metal. If more than one metal is present, then the metal mixture or alloy may have a single melting point, e.g., as in a eutectic mixture, and/or the metal mixture may have two or more melting points when various components of the mixture reach their respective melting points. Non-limiting examples of techniques for heating the metal include supplying heat to the reactor from an external source (e.g., to heat the reactor and/or the metal within the reactor), heating one or more materials entering the reactor, causing a chemical reaction within the reactor that produces heat, supplying electrical current to the reactor and/or to a metal within the reactor to cause resistive heating to occur, or the like. Combinations of these and/or other techniques may be used in certain cases.

As various examples, if external heating of the reactor and/or one or more feed materials entering the reactor is used, then the heat may arise from any suitable source. For example, a fuel can be oxidized or burned to produce heat energy, the heat may be produced using an electrical or induction heater, an external source of heat (e.g., a municipal source or heat from another process or another factory) can be used, or a reactant may be fed into the reactor that can be reacted (for instance, oxidized or pyrolyzed) to produce heat. The reactant may also be reacted, e.g., to produce syngas and/or other products, for example, if the reactant is a feed material or contains a carbon-containing material. In some cases, e.g. as discussed below, the heat produced from such reactions can be used to at least partially maintain the temperature within the reactor, for instance, such that the reactor is running under autothermal conditions at least for certain periods of time, such that the heat necessary to keep the metal within the reactor in a liquid state comes essentially exclusively from one or more feed materials supplied to the reactor.

As still other non-limiting examples, if electrical heating is used, electric power for use in heating can be supplied in such a manner that causes electrical current to flow through the reactor and/or through the liquid metal, e.g., via one or more induction channels located at the bottom, top, and/or sides of the reactor. The reactor may be electrically heated, for instance, by induction currents induced by alternating current flowing through coils or loops. As a specific non-limiting example, a high-frequency alternating current (AC) can be provided, e.g., using an electromagnet, and/or heat may be generated by magnetic hysteresis losses in materials that have significant relative permeability. The frequency of AC used may depend on factors such as the reactor size, the composition of the reactor and/or materials within the reactor, coupling (e.g., between a coil and the reactor), the penetration depth, etc. As yet another example, a standalone induction furnace can be used to heat a metal, which is then fed to the reactor. Induction heaters can be readily obtained from various commercial sources, for example, from Ajax Tocco Magnetothemic, Inc., Warren, OH.

The metal within the reactor may be heated to a temperature at least sufficient to melt at least a portion of the metal within the reactor, i.e., to a temperature that is the same or greater than the melting point of the metal within the reactor. In some embodiments, relatively high temperatures are used within the reactor. For instance, the metal within the reactor may be heated to at least the melting point of copper, the melting point of iron, the melting point of nickel, etc., or to the melting point of any other metals disclosed herein. As other examples, the metal within the reactor can be heated to a temperature of at least about 1000 °C, at least about 1200 °C, at least about 1500 °C, at least about 1700 °C, at least about 2000 °C, etc.

Metals may be added prior to operation of the reactor and/or during operation of the reactor, e.g., as a "make up" volume to replace metal that is lost during operation of the reactor. The metal may be added in liquid form (e.g., heated separately prior to being added to the reactor) and/or in solid form (e.g., to be heated, at least partially, within the reactor).

The feed materials fed to the reactor can be reacted within the reactor to produce carbon monoxide (CO) and/or carbon dioxide (C0₂), and/or other products such as hydrogen (H₂) or water (H₂0), in accordance with certain aspects of the invention. For example, a carbon- containing material can be at least partially oxidized upon reaction with oxygen (e.g., from air, oxygen, enriched air, etc.) to produce carbon oxides, typically carbon monoxide (CO) and/or carbon dioxide (C0₂). Many carbon-containing materials also contain hydrogen (for example, such as organic materials, biomaterials, hydrocarbons, etc.), which materials may be reacted to form hydrogen (H₂) or water (H₂0). In certain cases, the reaction is performed under partial oxidation conditions (as discussed below) to encourage the production of at least some carbon monoxide and hydrogen gas with respect to carbon dioxide and water. A gas containing at least about 8% carbon monoxide and at least about 8% hydrogen gas by volume may be considered to be a syngas. In some cases, the syngas is mixed with other gases (e.g., nitrogen, water, carbon dioxide, etc.), although the syngas may also be purified from such gases using techniques such as those known to those of ordinary skill in the art, e.g., after exiting the reactor.

The feed materials may be fed to the liquid metal and/or the headspace above the liquid metal. For example, in some embodiments, some reactions can occur within the headspace, especially when certain liquid metals such as copper or copper alloys are used within the reactor. Without wishing to be bound by any theory, it is believed that in certain cases, the heat generated using certain liquid metals within the reactor heats gases within the headspace above the liquid metal such that at least some of the reactions involving the feed material can occur in the headspace, e.g., due to exposure of those feed materials to relatively high temperatures and/or because there may be a large area of contact between the feed materials and reactive gases within the headspace. For example, carbon-containing materials entering the reactor may pass through the headspace (e.g., due to action of gravity), and such materials are exposed to such relatively high temperatures and/or are separated or dispersed as they pass through the headspace, thereby allowing such reactions to occur.

Accordingly, in some embodiments, a reactor is operated to have a suitable volume of headspace in which such reactions may at least partially occur. For example, in certain instances, a relatively large headspace volume may be desirable to facilitate such reactions within the reactor, although in other embodiments, the headspace volume is smaller, e.g., to encourage more reaction within the liquid metal within the reactor. In some embodiments, the volume of headspace may depend on whether feed materials (e.g., carbon-containing materials and/or oxygen-containing materials) are fed into the headspace above the liquid metal, and/or into the liquid metal itself). As specific non-limiting examples, the volume of the headspace may be at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 75%, at least about 100%, at least about 150%, at least about 200%, at least about 300%, at least about 400%, at least about 500%, at least about 700%, or at least about 1000% of the volume of the liquid metal contained within the reactor. It should also be understood that there may be dozens or hundreds of reactions occurring within the headspace within the reactor, and in some cases, the reactions may not be completely understood.

Non-limiting examples of decomposition reactions that can occur within the reactor, e.g., within the liquid metal and/or within the headspace above the liquid metal, include oxidation and pyrolysis. In some embodiments, both types of reaction may be occurring simultaneously, and in certain instances, other reactions may also be occurring as well as, instead of or in addition to, oxidation and/or pyrolysis reactions. In some instances, the specific reactions occurring within the reactor may not be easy to determine or quantify. Typically, in a partial oxidation reaction, a carbon-containing material reacts with oxygen (e.g., in air, enriched air, oxygen, etc.) to produce smaller compounds containing oxygen; if time and reaction conditions permit, the compounds can be oxidized fully to from carbon oxide products (carbon monoxide and/or carbon dioxide). In a pyrolysis reaction, a hydrocarbon-containing material is reacted to produce smaller or simpler compounds (e.g., H₂), but oxygen is not used as part of this reaction. Partial oxidation and pyrolysis reactions may occur within the reactor at relatively elevated temperatures, e.g., at temperatures at least sufficient to cause at least a portion of the metal within the reactor to be in a liquid state, as previously discussed.

As mentioned, in some embodiments, such reactions may not be particularly well- defined or well-characterized. For instance, certain feed materials, for example, complex or compositionally heterogeneous bulk feed materials, may be oxidized and/or pyrolyzed in a complex series of oxidation, pyrolysis, and/or other decomposition reactions to ultimately produce simpler compounds, such as lower-carbon compounds or carbon oxides, although not all of these reactions may be understood or defined within the context of the overall reaction scheme. In some embodiments, a combination of oxidation and pyrolysis occurs, for example, under partial oxidation conditions. Typically, under partial oxidation conditions, a carbon- containing material may be reacted with oxygen such that at least some carbon monoxide is produced, in addition to or instead of carbon dioxide. For example, at least about 10% by volume of the carbon oxides produced under partial oxidation conditions may be carbon monoxide, and in some cases, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% by volume may be carbon monoxide.

In certain embodiments, the creation of partial oxidation conditions within the reactor can be controlled, for example, by controlling the temperature of the reactor and/or by controlling one or more of the feed materials entering the reactor, for example, controlling the amount or rate at which one or more of the feed materials enters the reactor. In some cases, the entry of the feed materials may be controlled to control the overall molar ratio of carbon to oxygen entering the reactor, e.g., such that the reaction stoichiometry and heat generation in the reactor can be controlled. In other embodiments, however, a reactor can be operated under partial oxidation conditions by other methods.

As a non-limiting example, in one set of embodiments, one or more feed materials may be fed to the reactor such that an overall molar ratio of carbon to oxygen in the feed materials is between about 0.6: 1 and about 1.2: 1. In other embodiments, the overall molar ratio of carbon to oxygen in the feed materials that are fed to the reactor may be between about 0.7: 1 and about 1.2: 1, between about 0.8: 1 and about 1.2: 1, between about 0.9: 1 and about 1.1: 1, or between about 0.95: 1 and about 1.05: 1, etc. In certain cases, the overall molar ratio of carbon to oxygen in the feed materials can be estimated, e.g., by determining or estimating the composition of the feed materials entering the reactor. For example, the overall molar ratio of a known hydrocarbon and air entering a reactor at a known flow rate may be determined using standard chemical engineering calculations and nothing more than routine skill in the art. In other cases, however, the overall molar ratio of carbon to oxygen in the feed materials is not precisely known, and/or in embodiments where compositionally heterogeneous feed materials may be used. In such embodiments, however, the overall molar ratio may still be estimated in certain cases with reasonable accuracy and without requiring undue experimentation by knowing the general composition of the incoming feed materials.

In addition, in certain embodiments, the overall molar ratio of carbon to oxygen may be controlled as discussed herein while the carbon-containing material is fed to the reactor at a high feed rate. For example, the feed material may be supplied to the reactor at a feed rate of at least about 0.001%/s, where the percentage is taken as the mass of feed material relative to the mass of liquid metal within the reactor. The feed material can be measured as the carbon-containing material that is fed to the reactor. Higher rates can be used in some embodiments, for example, feed rates of at least about 0.003%/s, at least about 0.005%/s, at least about 0.01%/s, at least about 0.03%/s, at least about 0.05%/s, at least about 0.07%/s, at least about 0.1%/s, at least about 0.2%/s, at least about 0.3%/s, at least about 0.5%/s, at least about 0.7%/s, or at least about 1%/s.

In certain embodiments, the overall molar ratio of carbon to oxygen is externally controlled, for example, by monitoring the amount of carbon monoxide and/or the ratio of carbon monoxide to carbon dioxide produced within the reactor, and adjusting the feed materials as necessary, e.g., by increasing or decreasing, as necessary, the feed rates of any carbon- containing materials and/or oxygen-containing materials, and/or by adding or removing streams of feed material to the reactor. As mentioned, such a procedure can allow for control of the overall molar ratio of carbon to oxygen even if the overall molar ratio of carbon to oxygen in the feed materials is not precisely known. As a specific example, a first stream may include a carbon-containing material (which may also include some oxygen in some cases) and a second stream may include an oxygen-containing gas such as air, oxygen, enriched air, or the like. By controlling the relative ratios of the feed rates of the first and second streams, the overall molar ratio of carbon to oxygen can be controlled, e.g., to produce ratios such as those described above. In certain embodiments, the overall molar ratio of carbon to oxygen is controlled by feeding another feed material, for example, one that is oxygen-poor or oxygen-rich, and/or one that is carbon-poor or carbon-rich. See, for example, U.S. Patent Application Serial No.

12/899,809, filed October 7, 2010, entitled "Method for Controlling Syngas Production in a System with Multiple Feed Materials," by Davis, et al. In yet other embodiments, a

combination of these and/or other techniques is used to control the overall molar ratio of carbon to oxygen.

Conventionally, reactors containing one or more metals in a liquid state, conventionally primarily liquid iron, and not typically configured to convert feed materials into syngas while employing relatively high overall molar ratios of carbon to oxygen, e.g., such that the overall molar ratio of carbon to oxygen in the feed materials is between about 0.6: 1 and about 1.2: 1, as such conditions have been understood to result in the production of iron oxide or slag within the reactor due to the relatively high amounts of oxygen present under such conditions. In many cases, iron oxides or slag that are produced are produced irreversibly, and cannot be removed from the reactor without first shutting down the reactor; and if not removed, the production of iron oxide or slag within the reactor can cause the reactor to shut down as the iron oxide or slag accumulates and eventually blocks access to any liquid iron remaining within the reactor.

Accordingly, such reactor can be prone to substantial breakdowns or loss of efficiency if operated under such conditions. Reactors containing one or more metals in a liquid state to convert feed materials into syngas have therefore typically been operated such that there were very low levels of oxygen present so as to avoid the production of iron oxides or slag.

By contrast, certain embodiments of the present invention involve reactors and reactor conditions, such that reactors containing one or more metals in a liquid state can be operated with relatively high levels of oxygen. One non-limiting example of such a reactor employs a metal with a relatively low oxidation potential, such as, e.g. copper. For example, the reactor may include any number of liquid metals (e.g., as in a mixture or an alloy), where the liquid metal(s) have an overall standard electrode (oxidation) potential of greater than 0 V, e.g., as measured against a standard hydrogen electrode. (Higher voltages indicated lower oxidation potential, or a greater tendency towards reduction.) The standard oxidation potential is measured under conditions of 25 °C and 1 atm with the metal in a pure state, and is defined relative to a standard hydrogen electrode, which is arbitrarily given a potential of 0 V. In some embodiments, the liquid metal may have a standard oxidation potential of greater than about 0.1 V, greater than about 0.2 V, greater than about 0.3 V, greater than about 0.4 V, or greater than about 0.5 V. Copper does not produce copper oxides (e.g., CuO and/or Cu₂0) as readily as iron is able to produce iron oxides (i.e., iron is more apt to be oxidized than is copper, as illustrated by their standard oxidation potentials of -0.04 V and +0.52 V respectively), and under certain inventive conditions, substantially no copper oxide may be produced while oxidizing feed materials to produce syngas or other gases. For instance, when the reactor is operated such that a relatively large amount of carbon-containing material is fed into the reactor, any copper oxides that are produced may be essentially immediately reduced back to copper; thus, under such conditions, there may be essentially no production or accumulation of copper oxide within the reactor. In addition, in some embodiments, as discussed herein, circulation within the reactor of fluids and/or metal may be used to facilitate the reduction of metal oxides such as copper oxide to metals, e.g., by causing the metal oxides to enter regions within the reactor having relatively lower oxygen partial pressures.

It should also be understood that perfect instantaneous mixing within the reactor cannot typically be practically achieved. For example, the addition of oxygen to the reactor may result in regions within the reactor having relatively higher or lower oxygen partial pressures. In some embodiments of the invention, circulation within the reactor of fluids and/or liquid metal may be used to facilitate the reduction of metal oxides to metals, e.g., by moving the metal oxides to regions having relatively lower oxygen partial pressures.

In some reactors of certain embodiments of the invention, any copper oxides that are produced are not produced irreversibly. Accordingly, even if the reactor is operated under conditions in which some copper oxide production occurs, the copper oxides can be readily reduced back to copper metal by feeding additional carbon-containing materials to the reactor and/or altering the reaction conditions within the reactor such that the copper oxides are exposed to reducing conditions. For example, circulation of metal in the bath, addition of a reducing gas such as hydrogen to the reactor, increasing the amount of feed material, and/or reduction in the amount of oxygen added to the reactor relative to the amount of feed material may be used to reduce any copper oxides that may be present.

Thus, by using a metal with a relatively low oxidation potential such as liquid copper within the reactor, the reactor can be run under a wide range of overall molar ratios of carbon to oxygen. Controll of the overall molar ratio of carbon to oxygen in the feed materials entering the reactor may be used to reduce or eliminate any metal oxides that are present or might be produced within the reactor. In other embodiments, however, the reactor can be operated under conditions in which some metal oxide is produced, but the metal oxide that is produced may be one that is not irreversibly produced and can be reduced to metal as discussed above.

Accordingly, under certain conditions, the reactor is operated by controlling the overall molar ratio of carbon to oxygen in the one or more feed materials such that substantially no metal oxide (e.g. copper oxide) accumulates within the reactor, e.g., under normal operating conditions. For example, the reactor may be operated for a period of at least about an hour, at least about a day, at least about a week, at least about 4 weeks, at least about 30 days, etc., and substantially no metal oxide (e.g. copper oxide) accumulates within the reactor. For instance, after such time, there may be no build-up or deposition of metal oxide (e.g. copper oxide) within the reactor, or some metal oxide (e.g. copper oxide) may be produced but is not sufficient to slow reaction within the reactor and/or block access to copper or other liquid metals within the reactor. In addition, in certain embodiments, high overall molar ratios of carbon to oxygen may result in substantially all of the oxygen that is fed to the reactor being reacted within the reactor, e.g., producing carbon monoxide and/or carbon dioxide, or other oxidation products (e.g., metal oxides or incompletely oxidized carbon-containing materials). In certain cases, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% by volume of the oxygen fed into the reactor may be consumed or reacted within the reactor (including the headspace above the liquid metal).

Besides copper, other metals exhibiting similar properties can be used in addition to and/or instead of copper within a reactor, in certain embodiments of the invention. For example, metals such as gold, lead, zinc, silver, tin, palladium, platinum, or the like may be used, as such metals also may be used in a liquid state within a reactor to facilitate the oxidation of feed materials to produce syngas or other gases without producing the respective metal oxides, and/or such that any metal oxides that are produced can be reduced back to the metal state, for example, upon the addition of carbon-containing materials and/or by exposing such metal oxides to suitably reducing conditions, such as those described above. In still other embodiments, mixtures or alloys of one or more of these metals and/or other metals are used. As mentioned, by controlling the overall molar ratio of carbon to oxygen in the feed materials entering the reactor, oxides of metals such as these can be reduced and/or eliminated from the reactor, and/or substantially no metal oxides may be produced within the reactor. For instance, in certain embodiments, the reactor can be operated such that any metal oxides that are produced are substantially balanced by the reaction of such metal oxides to a reduced, non-oxide metal state; thus, substantially no accumulation of any metal oxides within the reactor may occur. As previously discussed, in certain embodiments, the reactor may contain one or more liquid metals having an overall standard oxidation potential of at least about 0 V, or other potentials as described herein.

Thus, in some embodiments, a metal oxide can be reduced by reacting the metal oxide with a carbon-containing material under suitable conditions. Without wishing to be bound by any theory, it is believed that under some conditions, the metal oxide is reduced to a non- oxidized state upon exposure to a carbon-containing material, as the metal oxide is reduced while the carbon-containing material is oxidized, e.g., to produce carbon monoxide and/or carbon dioxide, or other oxidation products as discussed herein. Moreover, in certain embodiments, any metal oxides that are produced within the reactor may be reduced, for example, upon exposure to carbon-containing material, and/or upon exposure to a reducing environment. Thus, in various embodiments, any metal can be used within the reactor, where the metal oxide of that metal can be reduced in a suitable reducing environment and/or upon exposure to a suitable carbon-containing material that is oxidized while the metal oxide is reduced to the metal.

In some aspects of the invention, a reactor may be operated such that substantially no carbon boils occur in the liquid metal during the oxidation of the carbon-containing materials. Typically, in a carbon boil, there is a sudden, violent production of carbon monoxide and/or carbon dioxide from the liquid metal. In some cases, the carbon boil is disruptive and droplets of liquid metal may be violently splattered or expelled from the surface of the liquid metal within the reactor, potentially disrupting operation of the reactor or damaging the reactor itself. Without wishing to be bound by any theory, it is believed that a carbon boil occurs when a large mass of carbon-containing material contained within the bulk of the liquid metal is oxidized therein to produce carbon monoxide and/or carbon dioxide within the liquid metal. The carbon monoxide and/or carbon dioxide gases are trapped below the surface of the liquid metal. The trapped gases cannot escape the liquid metal, and instead are released after a large amount of such gases have accumulated within the liquid metal, thereby providing enough mass and/or buoyant force to be able to escape. The gases are thus able to escape the surface of the liquid metal as a violent "carbon boil." Those of ordinary skill in the art will be familiar with carbon boils within a liquid metal, including techniques for identifying carbon boils.

However, in certain embodiments of the present invention, carbon boils may be reduced or eliminated using various techniques as discussed herein. For example, in one set of embodiments, a higher overall molar ratio of carbon to oxygen in the feed materials can be used to reduce or eliminate carbon boils. For instance, the feed rate of carbon-containing material can be increased and/or the amount of oxygen fed to the reactor may be reduced. Other techniques such as those described herein may also be used. For example, by increasing the amount of carbon that is present within the reactor, relative to oxygen, more pyrolysis and less oxidation may occur for any carbon-containing material that is present within the liquid metal, thereby reducing the amount of carbon monoxide and/or carbon dioxide that is produced within the liquid metal. In addition, in certain embodiments, the carbon-containing material may be fed at a relatively high feed rate, for example, at a feed rate of at least about 0.001 /s, or other rates such as those discussed above.

In certain cases, a reactor can be operated to increase the amount of reaction that occurs in the headspace above the liquid metal, relative to the amount of reaction that occurs internally of the liquid metal, in order to decrease carbon boils within the reactor. Under such conditions, more reaction can occur in the headspace, which is of course not susceptible to carbon boils. Reaction in the headspace may be facilitated, for example, by feeding feed materials into the headspace above the liquid metal instead of into the liquid metal itself (for example, which would be the case for bottom-fed lances or tuyeres).

In addition, as previously discussed, the use of certain liquid metals within the reactor may be useful in heating the headspace above the liquid metal such that at least some reaction of the feed materials occurs in the headspace instead of within the liquid metal. For instance, metals having relatively high thermal conductivities, for example, copper, can be used to facilitate reaction within the headspace. In some embodiments, for example, the metals may be chosen such that the metals within the reactor, when in a liquid state, have an overall thermal conductivity of at least about 60 W/m K, at least about 70 W/m K, at least about 80 W/m K, at least about 90 W/m K, at least about 100 W/m K, at least about 110 W/m K, at least about 120 W/m K, at least about 130 W/m K, at least about 140 W/m K, at least about 150 W/m K, or at least about 160 W/m K. In addition, relatively high thermal conductivities can result in more even heating of the liquid metal, at least in some embodiments, which may be useful in reducing localized "hot spots" within the liquid metal and creating more uniform conditions to facilitate reaction, e.g., within or above the liquid metal, thereby reducing concentrations of localized reaction or carbon boil formation.

Certain metals, such as copper or certain alloys (e.g., eutectic alloys), may also be useful, in some embodiments, because of their relatively low melting points. Non-limiting examples of eutectic alloys involving copper include alloys including manganese, germanium, magnesium, antimony, or silicon. For example, in certain embodiments, a reactor can be operated to have an operating temperature of less than about 2800 °F (1811 K), less than about 2600 °F (1700 K), less than about 2400 °F (1589 K), less than about 2200 °F (1478 K), less than about 2000 °F (1366 K), less than about 1800 °F (1255 K), less than about 1600 °F (1144 K), less than about 1400 °F (1033 K), less than about 1200 °F (922 K), less than about 1000 °F (811 K), etc. In some embodiments, a reactor having a smaller mass or volume of liquid metal than is conventional for typical liquid metal reactors of similar overall size or syngas production capacity can be used, e.g., such that more of the reaction occurs in the headspace above the liquid metal and/or such that there is not as much mass of liquid metal in which reactions involving the carbon-containing material can occur. For example, in some cases, the volume of the headspace may be at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 75%, at least about 100%, at least about 150%, at least about 200%, at least about 300%, at least about 400%, at least about 500%, at least about 700%, or at least about 1000% of the volume of the liquid metal contained within the reactor. In certain embodiments, the reactor can be operated with a nominal height of liquid of less than about 24 inches (about 61 cm), less than about 18 inches (about 46 cm), less than about 16 inches (about 41 cm), less than about 12 inches (about 30 cm), less than about 10 inches (about 25 cm), less than about 8 inches (about 20 cm), less than about 6 inches (about 15 cm), or less than about 4 inches (about 10 cm). The nominal height can be calculated using the volume and the geometry of the reactor and the volume of metal within the reactor (for example, determined by dividing the mass of metal within the reactor that will be liquid during operation of the reactor by the density of the metal at the operating temperature of the reactor).

Combinations of any of these and/or other techniques may be used to reduce or eliminate carbon boils, in certain embodiments of the invention. For example, in one set of embodiments, a reactor can be used that contains liquid copper (and/or other metals as discussed herein) and a relatively large headspace, where a carbon-containing material is fed into the headspace at a relatively rapid rate, thereby promoting reaction within the headspace relative to the liquid copper itself, e.g., to reduce or eliminate the number of carbon boils that occur during oxidation of the carbon-containing materials.

In addition, in certain aspects of the invention, the reactor can be operated under conditions where the liquid metal within the reactor is not actively stirred, e.g., by inductive heating, porous plugs, stirrers, mixing blades, baffles, impellers, etc. (although in other embodiments, one or more of these may be used, and many of these are readily available from commercial suppliers). Instead, mixing of the liquid metal within the reactor may be driven by passive processes such as heat convection, e.g., where the heat and/or feed materials provided to the reactor may be used to heat and/or stir the liquid metal within the reactor, without requiring additional energy or material inputs to stir the liquid metal. Examples of techniques which can be used to reduce and/or eliminate active stirring of the liquid metal within the reactor during operation of the reactor include any of those described above. For instance, in certain embodiments, metals having relatively high thermal conductivities can be used, e.g., such that less stirring is required to substantially heat the liquid metal while avoiding localized "hot spots." For instance, a liquid metal may be used in which the metal has a thermal conductivity of at least about 60 W/m K, at least about 70 W/m K, etc., as discussed herein. As another example, a reactor having a smaller mass or volume of liquid metal can be used, i.e., a reactor having a relatively large headspace. Such reactors may have more exposed surface metal, relative to the bulk of the metal, and/or less stirring may be needed to bring portions of the bulk metal to the surface of the liquid. In some cases, such stirring may happen passively, e.g., due to differences in temperature, volume, etc., that are created within the liquid metal due to differences in temperature, pressure, bubble creation, etc. Accordingly, such stirring may be sufficient for operation of the reactor as discussed herein, without the addition of active stirring mechanisms. In contrast, in many prior art systems, a lack of active stirring would typically cause regions of uneven temperature or heating (e.g., due to poor heat conduction within the metal), regions of uneven reaction (e.g., of feed materials), carbon boils, or the like.

In one aspect of the invention, a reactor may be operated, at least partially, such that the heat necessary to keep the metal within the reactor in a liquid state comes essentially from one or more feed materials supplied to the reactor, i.e., the reactor is operated under "autothermal" conditions. For example, the reactor may be operated to be autothermal, i.e., without the use of any additional sources of heat, for at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the time when the reactor is operated such that a liquid metal is present within the reactor.

In some cases, certain metals such as those described herein may be useful in reactors able to operate, at least partially, under autothermal conditions. For example, in some embodiments, the reactor may include a liquid metal that does not result in the accumulation of metal oxides within the reactor (at least under certain operating conditions) while a carbon- containing material is oxidized to produce carbon monoxide and/or carbon dioxide; one non- limiting example of such a metal is copper, e.g., as previously discussed. As autothermal operation is, in part, a function of the amount of carbon-containing material fed to the reactor (which can be oxidized to produce heat as well as carbon monoxide and/or carbon dioxide), metals having such properties can allow for faster reaction and/or conversion of carbon- containing material, which may be enough to maintain the temperature of the liquid metal without requiring another source of heat, at least under certain conditions. In addition, in some embodiments, suitable amounts of an oxygen-containing material can also be fed to the reactor, for example as air, enriched air, or oxygen gas, to maintain a suitable overall molar ratio of carbon to oxygen in the feed materials, as noted above.

Such reactions can also produce metal oxides in some cases, e.g., due to the relatively high amounts of carbon and/or oxygen that are fed to the reactor in order to produce sufficient heat to operate the reactor under autothermal conditions. However, as previously discussed, the metal can be chosen such that any metal oxides that are produced may be readily eliminated from the reactor, for example, by exposing the metal oxides to a suitable reducing environment and/or a suitable carbon-containing material to reduce the metal oxides to metal. In contrast, some metals, such as iron, irreversibly form iron oxides under such conditions, and thus, reactors employing liquid iron baths would not be suitable for autothermal operation.

Thus, in certain embodiments of the invention, a reactor containing a suitable liquid metal can be operated under autothermal conditions, at least partially, by feeding a carbon- containing material at a relatively fast rate into the reactor (e.g., in combination with other feed materials to supply sufficient oxygen to the reactor to oxidize the carbon-containing material), while not supplying any external heat to the reactor. In some cases, the rate of feed of the carbon-containing material and/or the oxygen-containing material may be controlled to maintain the temperature of the liquid metal. For example, in one set of embodiments, the temperature of the liquid metal may be monitored, and the flow rate of incoming carbon-containing material and/or the flow rate of incoming oxygen-containing material can be correspondingly increased or decreased, depending on the variation in temperature of the liquid metal.

In some embodiments, the rate at which a carbon-containing material is fed to the reactor, in combination with rate at which an oxygen-containing material is fed to the reactor, may be such that metal oxides can be produced. As noted above, such high feed rates were typically avoided in the past, for example, in reactors containing liquid iron, as high amounts of oxygen fed to the reactor would cause the irreversible creation of iron oxides, thereby preventing long-term or sustained use of the reactor. In contrast, in the present invention, the use of certain metals that do not essentially irreversibly produce metal oxides may be used even when relatively high amounts of carbon-containing materials and/or oxygen-containing materials are fed to the reactor.

For instance, in one set of embodiments, a reactor can be operated such that at a first time, the reactor is used to react a carbon-containing material to produce carbon monoxide (and/or syngas), e.g., as previously discussed; some of the metal may also be oxidized to produce a metal oxide, at least in some cases. For example, the rate at which a carbon- containing material and an oxygen-containing material are supplied to the reactor (e.g., under autothermal conditions, or other conditions as discussed herein) may cause the production of at least some metal oxides within the reactor. However, at a second time, the reactor can be operated to chemically reduce the metal oxide within the reactor to metal. In some cases, such reaction may occur without the production of carbon monoxide, and/or such that a smaller amount of carbon monoxide is produced. For example, a reducing agent such as natural gas, hydrogen, additional feed material, etc. may be added to the reactor, or additional carbon- containing material may be added to the reactor that any metal oxides present within the reactor are reduced to metal, e.g., as was discussed above.

In addition, in some embodiments, any of the modes of operation previously described can be repeated any number of times (2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100, etc.) during steady operation of the reactor (i.e., while the liquid metal within the reactor is continually maintained in a liquid state). Thus, in the first mode of operation, the reactor is operated to produce carbon monoxide and/or syngas, while in the second mode of operation, the reactor is operated to reduce any metal oxides present within the reactor, and this process can be repeated indefinitely or as necessary during operation of the reactor. By operating the reactor using such conditions, any metal oxides that are produced within the reactor are also removed from the reactor; thus substantially no oxide of the metal accumulates within the reactor, i.e., under normal operating conditions.

The amount of time the reactor spends in each mode of operation can be the same or different. The time the reactor spends in each mode may be constant, or may vary, and in some cases the amount of time need not be predetermined, although in some embodiments, the time is predetermined or preset. For example, when a certain amount of metal oxide is observed to be present within the reactor, the reactor may be switched into the second mode of operation in order to reduce the metal oxides present within the reactor, before returning to the first mode of operation. In one set of embodiments, on the average, a reactor may be spend about 90% of its operating time in the first mode of operation and about 10% in the second mode of operation, about 80% in the first mode and about 20% in the second mode, about 70% in the first mode and about 30% in the second mode, about 60% in the first mode and about 40% in the second mode, about 50% in the first mode and about 50% in the second mode, about 40% in the first mode and about 60% in the second mode, about 30% in the first mode and about 70% in the second mode, about 20% in the first mode and about 80% in the second mode, or about 10% in the first mode and about 90% in the second mode.

The reactor containing the metal in the liquid state can have any size or configuration, in various aspects, and can be formed from any suitable material. In some cases, the reactor may be a refractory-lined reactor, for example, an induction furnace, an arc furnace, or any other type of high-temperature reactor able to contain a liquid metal. A refractory material typically is one that retains its strength at high temperatures, and thus, may be useful as part of a reactor. The refractory may be a non-metallic material having chemical and/or physical properties that makes the refractory applicable for reactors, or as components of reactors, that are exposed to environments above 1,000 °F (811 K). Non-limiting examples of refractory materials include aluminum oxide (AI₂O₃), silicon oxide (silica, Si0₂), magnesium oxide (magnesia, MgO), calcium oxide (quicklime, CaO), zirconia (Zr0₂), fireclays, chromia (Cr₂0₃), or the like.

The reactor can, in some embodiments, be selected to be sufficiently sized for the selected rates of feed of the feed materials, and/or be selected such that the amount of liquid metal contained therein can be controlled at any given time. The reactor may also be selected to have additional volume above the liquid metal (headspace), e.g., to allow at least some of the feed material to react therein, as previously discussed, and/or to accommodate gases exiting the liquid metal and/or foaming of material within the reactor, etc. The size of the reactor, the positioning of nozzles for feed materials such as carbon-containing materials, oxygen-containing feed materials, etc., and the form of the exhaust gas passageway, can also be selected based on factors such as product throughput, on the type or feed rate of the feed materials, etc.

As non-limiting examples, the volume of the reactor may be at least about 10 ft , at least about 25 ft³, at least about 50 ft³, at least about 100 ft³, at least about 150 ft³, at least about 200 ft³, at least about 250 ft³, at least about 300 ft³, at least about 350 ft³, at least about 400 ft³, at least about 450 ft 3 , or at least about 500 ft 3 , depending on the application (1 ft 3 is about 0.0283 m ). As other non-limiting examples, the weight of liquid metal within the reactor during operation of the reactor can be at least about 1 ton, at least about 2 tons, at least about 3 tons, at least about 5 tons, at least about 7 tons, at least about 10 tons, at least about 15 tons, at least about 20 tons, at least about 25 tons, at least about 30 tons, at least about 50 tons, at least about 75 tons, or at least about 100 tons (1 ton is about 907 kg). The reactor may have any suitable shape, for example, rectangular, cylindrical, spherical, irregular, etc.

The reactor may be operated using any suitable technique, e.g., as a continuous process, as a batch process, or as a semi-batch process. During operation, various parameters of the reactor can be monitored, e.g., periodically or continuously. Non-limiting examples include the temperature and/or pressure within the headspace and/or within the liquid metal, the level or amount of the liquid metal within the reactor, the incoming flow rates and/or compositions of one or more of the feed materials (e.g., carbon-containing materials and/or oxygen-containing materials), the outgoing flow rates and/or compositions of gases from the reactor, or the like.

As previously mentioned, one or more feed materials can be fed to any suitable location in the reactor. For example, the feed materials can be fed from the top of the reactor (e.g., into the headspace), or fed directly into the metal layer itself (e.g., using a feeding tube, a lance, a tuyere, etc.). If more than one feed material is fed to the reactor, then each of the feed materials may be co-fed or independently fed to any suitable location within the reactor. As a non- limiting example, a carbon-containing material may be fed to the headspace, and an oxygen- containing material may also be fed to the headspace and/or fed to the liquid metal. Non- limiting examples of feed mechanisms include auger extruder feeders (e.g., Model No. GPT2-2- 400-00, manufactured by Komar Industries, Columbus, Ohio), ram feeders (e.g., as

manufactured by Robson Handling Technology, Recycling Equipment Corporation and others), and the like.

If the feed materials include chlorine- or fluorine-containing compounds, lime can be added in certain embodiments to neutralize such compounds. Certain fluxes, such as but not limited to, soda ash and borax, may also be added, e.g., to lower melting temperatures for some of the oxides that are produced. Lime may also be added to achieve and/or maintain a desired pH in some embodiments.

Although some of these feed materials (e.g., MSW) may have highly variable composition and physical form, in some embodiments, the feed materials can be analyzed for their heat values prior to injection into the reactor, and the input of one or more feed materials into the reactor may be controlled, for example, so that the reactor can be used to produce syngas and/or energy at a certain target value. For example, two or more feed materials having various heat contents can be blended together to produce a final heat content, and/or the feed rate of one or more feed materials into the reactor may be sped up or slowed down to produce a substantially constant production rate of syngas in the reactor. Examples of such systems are disclosed in International Patent Application No. PCT/US2006/013407, filed April 11, 2006, entitled "Process and Apparatus Using a Molten Metal Bath," by Davis, et al., published as WO 2006/110706 on October 19, 2006; U.S. Patent Application Serial No. 12/105,325, filed April 18, 2008, entitled "Method for Controlling Syngas Production in a System with Multiple Feed Materials," by Davis, et al, published as U.S. Patent Application Publication No. 2008/0295405 on December 4, 2008; or U.S. Patent Application Serial No. 12/899,809, filed October 7, 2010, entitled "Method for Controlling Syngas Production in a System with Multiple Feed Materials," by Davis, et al.

As mentioned, oxygen can also be fed to the reactor in an oxygen-containing material, e.g., as oxygen gas (e.g., substantially pure oxygen gas), air, enriched air (i.e., enriched in oxygen over atmospheric levels), etc. The oxygen-containing material may be fed to the liquid metal and/or in the headspace above the metal. Examples of techniques to inject an oxygen- containing material into the reactor include lances to inject the material from the top of the reactor, or lances or tuyeres to inject the material from the bottom of the reactor. For example, an oxygen-containing material can be supplied using one or more supersonic gas lances (e.g., Praxair type J burners), which generate a gas stream capable of penetrating into the metal liquid (e.g., the exit of the lances are above the liquid metal, but sufficiently adjacent thereto so that that the supersonic stream penetrates the liquid metal). As another non-limiting example, lances or tuyere tubes to inject an oxygen-containing material into the liquid metal from the bottom of the reactor may also be used. Submerged lances or tuyeres can also be used in other

embodiments. One non-limiting example of a lance manufacturer is Process Technology International Inc, Tucker, Georgia.

The reactor may, in some embodiments, be equipped with a tapping mechanism, which may be of the same type which is used to tap blast furnaces and electric arc furnaces. For example, the reactor can be equipped with tapping mechanisms for removal or sampling of excess metal or vitreous materials. The vitreous materials or metals may be periodically tapped, for example, to maintain a constant level of the liquid metal in the reactor. Suitable tapping mechanisms include tapping drills, which are supplied by a number of manufacturers (e.g., Woodings Industrial Corporation, Mars, Pa.) or a mud gun to plug the drilled hole. In other embodiments, similar results can be achieved with periodic tapping of the reactor. While in operation, other materials such as vitreous material, oxides, etc. may accumulate in the reactor. The level of the liquid metal may be controlled such that if it rises above a pre-set point, the tapping mechanism for the metal and/or other materials will be activated.

In some embodiments, the reactor includes one or more steam injection ports. The ports may be positioned in any suitable location within the reactor, e.g., above the liquid metal.

Examples of suitable injection systems include, but are not limited to, stainless steel nozzles manufactured by Spraying Systems Inc. Steam injection may be used, for example, to control the temperature of the process due to the endothermic reaction of water and carbon. The reaction of steam with carbon present within the reactor is an endothermic reaction, which can rapidly and efficiently reduce the temperature in the reactor without, in certain embodiments, jeopardizing synthesis gas output.

Syngas and other materials can be removed through one or more outlets from the reactor, and the removal can be accomplished by any suitable technique. For example, syngas may exit the reactor through an opening on top of the reactor. In some cases, the reactor volume and dimensions above the metal may be designed to allow efficient production of syngas, and/or to reduce particulate load in the gas stream. Additional boilers, scrubbers, and compressors can be installed downstream, depending on the specific application.

The exiting stream containing syngas (and/or other gases) may be further treated and/or purified as necessary or desirable. One non-limiting example of treating particulate and impurities in a syngas output stream is to treat the stream with plasma discharge in a manner which treats these particulate and impurities, but does not significantly oxidize or "burn" the CO portion of the syngas. Examples of types of plasma discharge include microwave and inductive coupling plasma, which are capable of generating an appropriate type of non-equilibrium plasma electrode-less discharge.

Additional syngas cleaning may be necessary or desirable in certain embodiments of the invention. In some embodiments, to substantially clean the gas of chlorine, fluoride, or sulfur, a dry scrubber, injecting sodium hydroxide or lime, can be installed in the exhaust. In certain embodiments, ceramic filters or cyclone separators may be used to treat gases, e.g., in order to eliminate any residual particulates. Another method is to use a sodium hydroxide solution in a wet scrubber installed before the compressor.

Heat contained in the exiting gases can be recuperated in a heat exchanger, in certain embodiments. In addition, in some cases, the syngas may include water as previously discussed, which may in some embodiments be removed after the gas is compressed and cooled below its dew point.

U.S. Provisional Patent Application Serial No. 61/498,183, filed June 17, 2011, entitled "Reactors Containing Liquid Metal," is incorporated herein by reference in its entirety.

The following examples are intended to illustrate certain embodiments of the present invention, but do not exemplify the full scope of the invention.

EXAMPLE 1

This example illustrates the use of a reactor in accordance with certain embodiments of the invention to produce syngas from wooden feed, e.g., prepared from chopped wooden railroad ties. A gasifier reactor was prepared having the basic shape of a rectangular prism with two slag ports, three burner ports, a feed inlet, and a couple of auxiliary ports. Schematic diagrams of this reactor are shown in Figs. 2-3. Fig. 2 is a cutaway view while Figs. 3A-3C show various sides of the reactor. Dimensions in these figures are given in inches (1 inch = 2.54 cm). In these figures, reactor 10 includes feed inlet 15, burner ports 20, and air injection port 25. Contained within reactor 10 is liquid copper 30, which may be stirred using gas injected through one or both of porous plugs 55. In this example, liquid copper 30 fills the reactor to a depth of 16 inches, although other depths or volumes may be used. Also shown in these figures is outlet port 35, pyrometer view port 40, optional burner port 45, copper drain port 60, and burner port 70. Port 5 is used for access to the reactor, e.g., for acquiring samples therein or insertion of a thermocouple. Slag that is produced during operation of the reactor may be removed through one of slag ports 50. The outer dimensions of the reactor (L x W x H) were 184 inches x 76 inches x 78 inches (467 cm x 193 cm x 198 cm). The reactor was fabricated of an outer stainless steel shell filled with several layers of refractory and insulation. In particular, from the innermost layer to the outermost layer, the materials were: refractory (Tuffcrete 608, 13.25 inches or 33.7 cm thickness), firebrick

(Superduty Fire Brick, 2.5 inches or 6.4 cm), high density board (Fiberfrax Duraboard, 2 inches or 5.1 cm), and insulating board (Elmtherm Insulating Paper, 0.25 inches or 0.6 cm). These materials were obtained from Allied Mineral Products (Columbus, Ohio). During use, the reactor was filled with molten copper to a depth of 16 inches (41 cm).

The reactor was operated with the copper being heated to a temperature of 2300 °F (approximately 1300 °C) with a slightly negative pressure (-0.5 inH₂0, or about -124 Pa relative to ambient pressure). Ground wooden railroad ties were fed into the reactor/gasifier via the feed inlet 15 at feed rates of 200 lb/hr and 250 lb/hr (about 90 kg/hr and 113 kg/hr, respectively). In addition, natural gas was introduced concomitantly with the feed. Figs. 4A and 4B are respective graphs showing the record of syngas composition throughout the runs at these flow rates. Table 1 shows all of the inputs into the gasifier and measured outputs. In the tables, 1 lb/hr is about 0.454 kg/hr and scfm ("standard cubic feet per minute") is the molar flow rate of a gas corrected to standardized conditions of 1 atm and 25 °C (298 K) using the ideal gas law and the composition of the gas.

These results generally demonstrate that the reactor described above was effective at converting the wooden feed into syngas, i.e., formed of H₂ and CO under various conditions, including with relatively high feed rates of wood, and over sustained periods of time.

Table 1

Average Average

INPUTS

Feed Rate, lb/hr 198.83 249.02

Feed Moisture , Analyzer 19.50 20.75

Feed Bubbler Flow N₂, scfm 3.02 3.02

Center Bubbler Flow N₂, scfm 3.00 2.41

Feed Burner CH₄, scfm 4.50 4.50

Center Burner CH₄, scfm 2.50 2.50

Feed Burner 0₂, scfm 8.55 8.55

Feed Burner Air, scfm 71.64 110.46

Center Burner 0₂, scfm 4.77 4.75

OUTPUTS CO% Syngas Analyzer, % 16.65 14.86

C0₂% Syngas Analyzer, % 14.12 13.11

H₂% Syngas Analyzer, % 17.14 17.20

CH₄% Syngas Analyzer, % 0.80 2.22

Meas. Syngas Flow, scfm 98 156

EXAMPL] E 2

In this example, a reactor similar to the one used in Example 1, containing liquid copper, was used to generate syngas with varying C:0 ratios with railroad ties as a feed material. The moisture content in the railroad ties varied from 15% to 50%. The feed rate of air was altered, relative to the feed rate of the railroad ties, in order to obtain various C:0 ratios as discussed below. Natural gas flow rates for the feed side burner varied from 4.50 scfm to 10.0 scfm, and flow rates for the center burner varied from 2.5 scfm to 5.0 scfm. The burners in the reactor were run at slightly sub stoichiometric conditions with oxygen.

Data from these experiments is shown in Fig. 5, plotted as feed rate (left axis) or composition (right axis) versus the carbon:oxygen feed ratio. As can be seen in this figure for a variety of different carbon:oxygen feed ratios, syngas was consistently produced using this reactor.

EXAMPLE 3

Fig. 6 A shows data from an experiment using a reactor similar to the one discussed in Example 1, except that the inner bath width was 8 inches (20 cm) wider. The headspace temperature was measured continuously, while the bath temperature (liquid copper) was measured at the start and end of the run. In both cases, the temperature remained relatively consistent. In these experiments, railroad ties used as a feed material contained 40% moisture, and were fed at 150 lb/hr for 8 hours. The feed burner and center burner flow rates were fixed and had natural gas flows of 5.2 scfm and 3.2 scfm, respectively. Both burners were run at slightly sub stoichiometric conditions. The syngas produced in this experiment comprised 10% CO (dry) and 9% H₂ (dry), with the remainder mostly comprising nitrogen, carbon dioxide, and steam.

Fig. 6B shows another experiment using railroads with 50% moisture. The railroad ties were fed 150 lb/hr for 20 hours. The feed burner and center burner flows were fixed and had natural gas flows of 5.2 and 3.2 scfm, respectively. Both burners were run at slightly sub stoichiometric conditions. The headspace temperature was measured continuously, while the liquid metal bath temperature was measured at the start and end of the run. The syngas produced in this experiment comprised 6% CO (dry) and 6.5% H₂ (dry), with the remainder mostly comprising nitrogen, carbon dioxide, and steam.

In both of these experiments, the reactor was operated autothermally, i.e., essentially all of the heat necessary to keep the copper within the reactor liquid came from exothermic partial oxidation of the railroad ties and natural gas that were fed to the reactor.

EXAMPLE 4

In this example, a reactor was erroneously operated in a way such that a substantial amount of copper oxide was produced within the reactor. When the incorrect operation was discovered and corrected, the copper oxide disappeared. Accordingly, based on this observation, it is concluded that under normal operation, substantially no copper oxide accumulates within the reactor, and any copper oxide that is present can be chemically reduced to copper.

In a 30-day run involving a reactor similar to the one discussed in Example 1, the oxygen concentration of the gasification air fed into the reactor was increased from 20.9% (air) to 35.0% (enriched air). During these experiments, the operating conditions were maintained with an oxygen-to-feed ratio of 7: 1 and 150 lb/h feed (68 kg/h). During this period, the CO/C0₂ ratio of gas leaving the gasifier was around 1. The feed material that was used was very moist, -50% water.

However, a problem with operation of the reactor caused a slag object to form within the reactor. The slag object was about 10 inches wide (25 cm) and 6-8 inches (15 cm to 20 cm) above the bath level. The object withstood relatively high inlet gas velocities, suggesting that the object was not feed material or char. Part of the object was removed from the reactor, and its color was reddish with fine porosity. Preliminary chemical analysis of this suggested that the object was a mixture of slag and copper oxide. Further analysis of the reactor showed that the location where the object was formed had the highest oxygen partial pressure inside the gasifier, again suggesting that the object was formed from copper oxide.

The operational problems of the gasifier were then corrected. This caused the object, despite its size, to completely disappear within the reactor. Again, this suggested that the object was copper oxide, and that under normal operation of the reactor, any copper oxide that is present within the reactor, even if accidental, can be chemically reduced to copper.

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or

configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

The indefinite articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one."

The phrase "and/or," as used herein in the specification and in the claims, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and/or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and/or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" or "and/or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding,"

"composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of and "consisting essentially of shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

What is claimed is:

Claims

1. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

providing a reactor containing a liquid metal comprising copper; feeding one or more materials, wherein at least one of the materials is a carbonaceous material and at least one of the materials comprises oxygen, to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1; and

reacting the one or more materials within the reactor to produce synthesis gas comprising carbon monoxide, wherein the reaction occurs within the reactor such that substantially no copper oxide accumulates within the reactor over a period of at least one day.

2. The method of claim 1, wherein the liquid metal further comprises zinc.

3. The method of any one of claims 1 or 2, wherein the liquid metal further comprises tin.

4. The method of any one of claims 1-3, wherein the overall molar ratio of carbon to

oxygen is between about 0.9: 1 and about 1.1: 1.

5. The method of any one of claims 1-4, wherein the overall molar ratio of carbon to

oxygen is about 1: 1.

6. The method of any one of claims 1-5, wherein the reactor further comprises a headspace above the liquid metal, and wherein the one or more materials is fed to the headspace.

7. The method of any one of claims 1-6, wherein the reactor is sized so that the liquid metal contained in the reactor has a weight of at least about 10 tons.

8. The method of any one of claims 1-7, wherein one of carbonaceous materials fed to the reactor comprises wood.

9. The method of any one of claims 1-8, wherein the liquid metal comprises at least about 60% copper by mass.

10. The method of any one of claims 1-9, wherein the liquid metal comprises at least about 90% copper by mass.

11. The method of any one of claims 1-10, wherein the liquid metal comprises at least about 95% copper by mass.

12. The method of any one of claims 1-11, wherein the liquid metal comprises at least about 99% copper by mass.

13. The method of any one of claims 1-8, wherein the liquid metal consists essentially of copper.

14. The method of any one of claims 1-13, wherein the reaction occurs within the reactor such that substantially no copper oxide accumulates within the reactor over a period of at least 30 days.

15. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

reacting the one or more materials within the reactor to produce synthesis gas, wherein at least about 80% of the oxygen in the one or more materials is reacted within the reactor.

16. The method of claim 15, wherein the liquid metal further comprises zinc.

17. The method of any one of claims 15 or 16, wherein the liquid metal further comprises tin.

18. The method of any one of claims 15-17, wherein the overall molar ratio of carbon to oxygen is between about 0.9: 1 and about 1.1: 1.

19. The method of any one of claims 15-18, wherein the overall molar ratio of carbon to oxygen is about 1: 1.

20. The method of any one of claims 15-19, wherein the reactor further comprises a

headspace above the liquid metal, and wherein the one or more materials is fed to the headspace.

21. The method of any one of claims 15-20, wherein the reactor is sized so that the liquid metal contained in the reactor has a weight of at least about 10 tons.

22. The method of any one of claims 15-21, wherein one of the carbonaceous materials fed to the reactor comprises wood.

23. The method of any one of claims 15-22, wherein the liquid metal consists essentially of copper.

24. A method of operating a liquid metal gasifier reactor, the method comprising:

providing a reactor containing

(a) a liquid metal comprising copper, and

(b) copper oxide; and

feeding a carbon-containing material to the reactor under conditions selected to chemically reduce the copper oxide to form copper.

The method of claim 24, wherein the liquid metal further comprises zinc.

The method of any one of claims 24 or 25, wherein the liquid metal further comprises tin.

The method of any one of claims 24-26, wherein the reactor further comprises a headspace above the liquid metal, and wherein the carbon-containing material is fed to the headspace.

28. The method of any one of claims 24-27, wherein the reactor is sized so that the liquid metal contained in the reactor has a weight of at least about 10 tons.

29. The method of any one of claims 24-28, wherein the carbon-containing material comprises wood.

30. The method of any one of claims 24-29, wherein the liquid metal consists essentially of copper.

31. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

providing a reactor containing a metal in a liquid state;

feeding one or more materials to the reactor, wherein at least one of the materials is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about

0.8: 1 and about 1.2: 1; and

reacting the one or more materials within the reactor to produce carbon monoxide under conditions selected such that substantially no oxide of the metal accumulates within the reactor.

32. The method of claim 31, wherein the metal in the liquid state comprises copper.

33. The method of any one of claims 31 or 32, wherein the metal in the liquid state consists essentially of copper.

34. The method of any one of claims 31-33, wherein the metal in the liquid state comprises more than one metal.

35. The method of any one of claims 31-34, wherein the metal in the liquid state comprises a metal alloy.

36. The method of any one of claims 31-35, wherein the metal in the liquid state comprises zinc.

37. The method of any one of claims 31-36, wherein the metal in the liquid state comprises tin.

38 The method of any one of claims 31-37, wherein the metal in the liquid state comprises gold.

39. The method of any one of claims 31-38, wherein the metal in the liquid state comprises silver.

40. The method of any one of claims 31-39, wherein the metal in the liquid state comprises palladium.

41. The method of any one of claims 31-40, wherein the metal in the liquid state comprises lead.

42. The method of any one of claims 31-41, wherein the overall molar ratio of carbon to oxygen is between about 0.8: 1 and about 1.2: 1.

43. The method of any one of claims 31-42, wherein the overall molar ratio of carbon to oxygen is between about 0.9: 1 and about 1.1: 1.

44. The method of any one of claims 31-43, wherein the overall molar ratio of carbon to oxygen is about 1: 1.

45. The method of any one of claims 31-44, wherein the reactor further comprises a

headspace above the metal in the liquid state, and wherein the one or more materials is fed to the headspace above the metal.

46. The method of any one of claims 31-45, wherein the reactor is sized so that the liquid metal contained in the reactor has a mass of at least about 10 tons.

47. The method of any one of claims 31-46, wherein the metal in the liquid state has a temperature of at least about 1000 °C.

48. The method of any one of claims 31-47, wherein the metal in the liquid state has a temperature of at least about 1200 °C.

49. The method of any one of claims 31-48, wherein the metal in the liquid state has a temperature of at least about 1500 °C.

The method of any one of claims 31-49, wherein at least one of the carbonaceous materials fed to the reactor comprises wood.

A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

providing a reactor containing a metal in a liquid state;

feeding one or more materials to the reactor, wherein at least one of the materials is a carbonaceous material and at least one of the materials comprises oxygen, such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1; and

reacting the one or more materials within the reactor such that at least about 80% of the oxygen in the one or more materials is reacted within the reactor.

A method of operating a liquid metal gasifier reactor, comprising:

providing a reactor containing:

(a) a metal in a liquid state, and

(b) an oxide of the metal; and

feeding a carbon-containing material to the reactor under conditions selected to chemically reduce the oxide of the metal.

providing a reactor containing at least 10 tons of metal in a liquid state;

feeding one or more materials containing carbon and oxygen to the reactor; and reacting the one or more materials within the reactor to produce a synthesis gas comprising carbon monoxide under conditions without active stirring of the metal in the liquid state in the reactor, wherein essentially all stirring of the metal in the liquid state within the reactor is driven by heat convection.

54. A method of operating a liquid metal gasifier reactor, comprising:

providing a reactor containing a metal in a liquid state;

feeding one or more materials containing carbon and oxygen to the reactor; and reacting the one or more materials within the reactor to produce heat at least sufficient to maintain the metal in the liquid state within the reactor over a period of at least one day.

55. The method of claim 54, wherein substantially no oxide of the metal accumulates within the reactor.

56. The method of any one of claims 54 or 55, comprising reacting the one or more materials within the reactor to produce heat at least sufficient to maintain the metal in the liquid state within the reactor over a period of at least 30 days.

57. The method of any one of claims 54-56, wherein the metal in a liquid state has an overall standard oxidation potential of at least 0 V.

58. A method of operating a liquid metal gasifier reactor, comprising:

(a) providing a reactor containing a metal in a liquid state;

(b) at a first time, feeding a carbon-containing material to the reactor under conditions selected to facilitate reacting the material with oxygen or an oxygen containing material to produce carbon monoxide, wherein some of the metal is oxidized to produce a metal oxide; and

(c) at a second time, feeding a carbon-containing material to the reactor under conditions selected to facilitate reacting the material with the metal oxide to chemically reduce the metal oxide within the reactor to the metal.

59. The method of claim 58, comprising repeating each of (b) and (c).

60. The method of claim 59, comprising repeating each of (b) and (c) at least twice.

61. The method of any one of claims 58-60, wherein the metal in a liquid state has an overall standard oxidation potential of at least 0 V.

62. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V; feeding one or more materials, wherein at least one of the materials is a carbonaceous material and at least one of the materials comprises oxygen, to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1; and

reacting the one or more materials within the reactor to produce synthesis gas comprising carbon monoxide, wherein the reaction occurs within the reactor such that substantially no metal oxide accumulates within the reactor over a period of at least one day.

63. The method of claim 62, wherein the reaction occurs within the reactor such that

substantially no metal oxide accumulates within the reactor over a period of at least 30 days.

64. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, the method comprising:

providing a reactor containing one or more liquid metals having an overall standard oxidation potential of at least 0 V;

feeding one or more materials, wherein at least one of the materials is a carbonaceous material and at least one of the materials comprises oxygen, to the reactor such that an overall molar ratio of carbon to oxygen in the one or more materials is between about 0.8: 1 and about 1.2: 1; and

65. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, comprising:

reacting the one or more materials within the reactor to produce carbon monoxide under conditions selected such that substantially no metal oxides accumulate within the reactor.

66. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, comprising:

67. A method of producing a synthesis gas from a carbonaceous material in a liquid metal gasifier reactor, comprising:

providing a reactor containing at least 10 tons of one or more liquid metals having an overall standard oxidation potential of at least 0 V;

feeding one or more materials containing carbon and oxygen to the reactor; and reacting the one or more materials within the reactor to produce a synthesis gas comprising carbon monoxide under conditions without active stirring of the liquid metals in the reactor, wherein essentially all stirring of the liquid metals within the reactor is driven by heat convection.