WO2017094030A2

WO2017094030A2 - Active support metal catalyst and its method of preparation thereof

Info

Publication number: WO2017094030A2
Application number: PCT/IN2016/050432
Authority: WO
Inventors: Snehesh SHIVANANDA AIL; S Dasappa
Original assignee: Indian Institute of Science IISC
Current assignee: Indian Institute of Science IISC
Priority date: 2015-12-03
Filing date: 2016-12-02
Publication date: 2017-06-08
Anticipated expiration: 2018-06-03
Also published as: WO2017094030A3

Abstract

In accordance with the present subject matter there is provided an active support metal catalyst, and especially a high dispersion cobalt catalyst, with enhanced active metal sites having desired structural integrity. The present invention also provides a method for the preparation of the metal catalyst, preferably, cobalt catalyst, under combustion.

Description

ACTIVE SUPPORT METAL CATALYST AND ITS METHOD OF

PREPARATION THEREOF.

FIELD OF INVENTION

[0001] The present disclosure relates to a process of conversion of a mixture of carbon-monoxide and hydrogen ("syngas" or "synthesis gas") to higher hydrocarbons using novel metal catalysts. In particular, the disclosure relates to the synthesis of supported metallic catalysts dispersed over high surface area support extrudes or spheres using vacuum assisted solution-combustion-synthesis (CS) method, and the use of combustion synthesized catalysts for generating higher hydrocarbons, such as gasoline, diesel, waxes, etc. via Fischer-Tropsch (FT) reaction.

BACKGROUND OF INVENTION

[0002] Catalysts play an integral role in several industrial reactions. Catalysts in general promote reaction rates, thereby directly influencing the process and the resultant product yield. Catalysts are also essential for most modern, cost and energy efficient means, for the production of a broad range of petroleum refining, chemical products, pharmaceuticals and for environmental protection.

[0003] Amongst the alternative energy sources, biomass plays a major role in the energy sector. A wide range of biomass based materials, such as crop residues, agro- crops, and several tree species can be burnt directly for energy or can be processed further for conversion to liquid fuels like ethanol and diesel.

[0004] Wood constitutes 80 percent or more of volatile matter and nearly 20% char can be converted to gaseous fuels. Biomass to liquid (BTL) is suggested to be a positive route to reduce the inclination towards fossil transportation fuels and is also a key to keep the environment clean. Processes that have been positively tested for BTL fuels include fast pyrolysis, direct liquefaction, transesterification of vegetable oils, production of bio-ethanol from agricultural crops, and Fischer Tropsch (FT) reaction for the conversion of biomass derived syngas to liquid transportation fuels. Compared to the other processes, the FT process is easily scalable (throughput of 100 kg/day to 1500 kg/day). Moreover, the diesel fractions obtained from the FT process have high cetane number and are devoid of sulphur, asphaltenes, and aromatics. FT process is a catalyst driven reaction, catalyzed by either iron or cobalt catalysts, carried out in a fixed bed, fluidized bed, or a slurry bed reactor. The product of FT reaction, synthetic crude oil, often referred to as 'syncrude', comprises of gaseous hydrocarbons, organic liquids, water, and organic solids. These products are subjected to an upgradation step that transforms the syncrude into more useful products - liquid transportation fuels or chemicals.

[0005] FT reactions are operated effectively at pressures ranging from 1 MPa to 6 MPa and temperatures ranging from 463 K to 623 K. The formation of primary FT products, viz., paraffins and olefins are described in Eqn.l and Eqn.2. In case of both the reactions, H₂0 is the prevailing oxygenated FT product. The water-gas shift (WGS) reaction which has a major effect on the FT stoichiometry, directly affects its reaction rates. With the cobalt catalyzed FT reaction, the WGS activity is negligible, and this reaction can be considered as a non-reversible reaction resulting in the formation of minimum concentration of C0₂. However, in case of Fe catalyzed FT reactions, the WGS reaction approaches equilibrium at temperatures in the range of 523-573 K, and under these reaction conditions, C0₂ is treated as a reactant along with H₂ and CO. Alcohols are also produced in small quantities as side reactions, during the FT process, as described in Eqn.3.

[0006] ( 2/; 1 )// . nCO > („//■„. - nll . O (1)

[0007] 2nH₂ + nCO→ C_nH_2n + nH₂0 (2)

[0008] 2nH₂ + nCO→C„H_2n+20 + (n - i)H₂0 (3) [0009] The role of catalysts with regards to FT reaction has been a matter of extensive studies for quite some time. The FT catalysts must possess high activity, selectivity, stability, and regeneration properties. For these reasons, iron and cobalt are the most widely used Fischer Tropsch catalysts, particularly for its high CO hydrogenation activity and high selectivity to higher hydrocarbons. Both Fe and Co catalysts are used in their metallic form, rather than their native oxide states. Therefore, the metal oxide catalysts are subjected to a reduction process for use in FT reaction.

[0010] Cobalt catalysts, though expensive compared to iron catalysts, are more resistant to deactivation by sintering and oxidation. At low CO conversions (Xco=30 - 40%), the activity of both the metals is comparable. However, at high CO conversions (Xco=60 - 70%), the productivity of higher hydrocarbons is more significant in cobalt catalysts. This is attributed to reduced reaction rates of Fe catalysts, due to high water concentrations. The water gas shift reaction is more significant on Fe catalysts than on Co catalysts. The hydrocarbon products with Fe catalysts primarily include branched compounds (a-olefins) and oxygenates, while Co catalysts chiefly yield n-paraffins.

[0011] A striking feature of Fe catalysts is its use under wide range of process conditions (temperature, pressure and space velocities). Fe catalysts yield FT products under varying pressure ranges (1.0 - 6.0 MPa), low temperature Fischer Tropsch (LTFT) and high temperature Fischer Tropsch (HTFT) reactors, and varying H₂/CO ratios (0.5 - 2.5). HTFT reactors utilize iron catalysts with product spectrum largely comprising of middle distillates and gasoline fractions, while LTFT reactors utilize mostly cobalt catalysts, yielding longer chain hydrocarbons and waxes.

[0012] Contrastingly, Co catalysts can be used only under narrow operating ranges - H₂/CO feed ratio in the range of 2.0 to 2.2 and low operating temperature (453 - 503 K), since high temperature leads to drastic increase in the CH₄ concentrations and also causes fouling of catalysts by carbide formation. [0013] Unlike iron carbide in iron based catalysts, in case of cobalt the metallic form of cobalt is desirable for FT reaction. The supported C0₃O₄ precursors are reduced to Co⁰ by reduction with ¾, at elevated temperatures (773 K - 873 K). The reducibility of cobalt catalysts is dependent on several factors such as the C0₃O₄ crystallite size, temperature of reduction and the extent of metal support interaction. It is observed that for large cobalt metal particles the rate of FT reaction is directly proportional to the fraction of active cobalt metal sites present on the catalyst surface. However, in case of smaller cobalt crystallite sizes (< 7 nm), it has been observed that this relation is not valid since smaller crystallite sizes form different cobalt metal phases, which are not active for FT reaction.

[0014] The synthesis method has a direct impact on the catalyst properties and hence the choice of the synthesis procedure has been extensively explored for the FT catalysts. The incipient wetness impregnation (IWI) is the simplest and most commonly used technique for depositing cobalt metal or metal oxides on the high surface area supports. Incipient wetness occurs when the support pores are saturated with the aqueous solution containing metal precursors, and no moisture exists over and above the liquid for filling the support pores. The impregnated mixture is then dried and calcined at 623 K to decompose the metal nitrate resulting in the formation of residual cobalt oxides. In general, the time required for calcining of IWI catalysts results in the agglomeration of cobalt particles and reduced metal dispersion.

[0015] This can be overcome, only to a certain extent, by impregnating the metal precursor in a rotating vessel, maintained under vacuum. More recently, the combustion synthesis (CS) method of metal oxides has been utilized for synthesizing cobalt oxides for Fischer Tropsch synthesis. The combustion synthesis technique, also known as self-propagating high-temperature synthesis (SHS) is an efficient energy compensating method for developing nano-materials, mostly metal-oxides.

[0016] Though combustion-synthesized catalysts have been extensively studied for various applications, one of the major limitations for this process is the large heat release and temperature rise rates, resulting in the formation of combustion products with uncontrolled explosion.

[0017] In known catalysts developed under solution combustion method, the inherent explosive nature of the processes has restricted the metal loading to 5-10 wt.%, since at higher metal loadings, the large rates of gas release and large rates of temperature increase (>200-350 K/min), powders the support material, resulting in the formation of fine powders. These powders are not fit to be used without pelletization in fixed bed reactors. For use of these powdered catalysts in a fixed bed reactor, re-pelletization of these powdered catalysts is adapted, which is a disadvantageous recourse.

[0018] A large number of reactions for the synthesis of catalysts are conducted in the industries through the catalytic route. Every reaction requires specific catalytic properties, such as metal loading, crystallite size, dispersion, catalyst in zero valent state or oxide form, catalyst particle size and so on.

[0019] Therefore, there is a need to develop effective catalysts for wide class of industrial reactions, having a high metal loading and uniform deposition across the support framework of varying sizes.

SUMMARY OF THE INVENTION

[0020] In an aspect of present disclosure, there is provided a method for preparing an active support metal-containing catalyst, the method comprising: (a) obtaining at least one metal salt precursor; (b) obtaining an active support; (c) preparing a solution by contacting a redox mixture of at least one metal salt precursor and a reducing fuel with water; (d) contacting the solution of redox mixture with the active support to obtain an intermediate material; and (e) removing water and calcining the intermediate material to obtain an active support metal-containing catalyst, wherein the active support metal-containing catalyst has 10-40% of metal loading. [0021] In an aspect of present disclosure, there is provided an active support metal- containing catalyst for the conversion of hydrogen and carbon monoxide gases, said catalyst consisting of: about 20 weight percent active metal oxide; about 80 weight percent active support, wherein the metal oxide deposited on active support is reduced to metal when used in the applications.

[0022] In an aspect of present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, said process comprising the steps of: contacting the catalyst with a mixture of carbon monoxide and hydrogen at a temperature in the range of 450 K to 550 K at 1 to 5 MPa, to obtain higher hydrocarbon.

[0023] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0025] Figure 1 illustrates the description of the temperature - time profile of the CS redox mixture i.e., HMT (hexamethylenetetramine) and cobalt nitrate hexahydrate, in accordance with an embodiment of the present disclosure.

[0026] Figure 2 illustrates the description of TGA-DTA curve of the redox reaction as measured in the Perkin Elmer STA-6000, in accordance with an embodiment of the present disclosure. [0027] Figure 3 illustrates the XRD analysis of the calcined and the reduced cobalt catalysts synthesized by IWI method and CS method, in accordance with an embodiment of the present disclosure.

[0028] Figure 4 illustrates the temperature programmed reduction (TPR) profiles and the H₂ chemisorption profiles of the synthesized catalysts, in accordance with an embodiment of the present disclosure.

[0029] Figure 5 illustrates the XPS spectra of the calcined cobalt catalysts indicating the reduction in the metal support interaction by CS method as compared to incipient wetness impregnation (IWI method), in accordance with an embodiment of the present disclosure.

[0030] Figure 6 illustrates the GC-MS spectra of the liquid phase hydrocarbon for the synthesized catalyst, in accordance with an embodiment of the present disclosure.

[0031] Figure 7 illustrates the CO conversion and the hydrocarbon selectivity for the synthesized catalysts, in accordance with an embodiment of the present disclosure.

[0032] Figure 8 illustrates the variation in the product spectrum for the synthesized catalysts, in accordance with an embodiment of the present disclosure.

[0033] Figure 9 illustrates the comparative data of the activity and selectivity of the catalysts of the instant disclosure with that of the catalysts synthesized in the prior arts, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.

Definitions [0035] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

[0036] The articles "a", "an" and "the" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

[0037] The terms "comprise" and "comprising" are used in the inclusive, open sense, meaning that additional elements may be included. Throughout this specification, unless the context requires otherwise the word "comprise", and variations, such as "comprises" and "comprising", will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

[0038] The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.

[0039] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a weight range of about 0.01 wt % to about 30 wt % should be interpreted to include not only the explicitly recited limits of about 0.01 wt% to about 30 wt%, but also to include sub-ranges, such as 0.05 wt % to 1 wt %, 7 wt % to 15 wt %, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 0.5 wt %, 1.1 wt %, and 12.9 wt %, for example. [0040] The synthesis method has a direct impact on the catalyst properties and hence the choice of the synthesis procedure has been extensively explored for the FT catalysts. The incipient wetness impregnation (IWI) is the simplest and most commonly used technique for depositing cobalt metal or metal oxides on the high surface area supports. Incipient wetness occurs when the support pores are saturated with the aqueous solution containing metal precursors, and no moisture exists over and above the liquid for filling the support pores. The impregnated mixture is then dried and calcined at 623 K to decompose the metal nitrate resulting in the formation of residual cobalt oxides. In general, the time required for calcining of IWI catalysts results in the agglomeration of cobalt particles and reduced metal dispersion. This can be overcome, only to a certain limit, by impregnating the metal precursor in a rotating vessel, maintained under vacuum.

[0041] More recently, the combustion synthesis (CS) method of metal oxides have been utilized for synthesizing cobalt oxides for Fischer Tropsch synthesis. The combustion synthesis technique, also known as self-propagating high-temperature synthesis (SHS) is an efficient energy compensating method for developing nano- materials, mostly metal-oxides. In the CS method, once the initial exothermic mixture comprising of a fuel and an oxidizer is ignited by an external thermal source, a swift (1 - 100 mm/s) high temperature reaction wave (1000 K - 3000 K) travels across the reaction mixture in a self-sustained fashion. The inherent heat generated can be favourably utilized to generate cobalt oxides over the support surface. The redox reaction between the fuel (urea, glycine, hexamethylenetetramine) and the oxidizing metal precursor (cobalt nitrate), after preheating to a moderate temperature (423 K - 473 K), self-ignites the entire volume resulting in the formation of nano sized cobalt oxides.

[0042] The most striking feature of CS includes homogeneous distribution of the metal oxide in a desired composition, since the initial reaction media being in liquid state (aqueous solution of the redox mixture), molecular level mixing of reactants is enabled. Above all the high reaction temperature can volatilize low boiling point impurities, ensuring high product purity.

[0043] In particular, the CS reactions are identified by large rates of heat release, high temperature rise rates (~ 200 - 500 K/min), and rapid rates of product formation. These extreme reaction dynamics limit the synthesis of catalysts with metal loading greater than 7% - 8%.

[0044] For higher metal loadings, the combustion products form with uncontrolled explosion, resulting in powdering of the catalysts and in most cases, mass loss of the active material. This particular constraint prevented the use of combustion synthesized catalysts for use in FT reactions, where the metal loading is generally preferred to be >15%. Also, the use of these catalysts in fixed bed reactors necessitates the re-pelletization of the powdered catalysts, which is an unpropitious route. Majority of the CS catalysts reported in the literature with high metal loading exist in powdered form that can only be used in a fluidized bed or a slurry phase reactor.

[0045] Thus there is a need for a combustion synthesized catalyst that can be used exclusively for fixed bed Fischer Tropsch reaction, and also for reactions that demand metal loading greater than 15 wt%, for direct use in fixed bed reactors. The present study demonstrates the synthesis of cobalt catalysts supported on silica doped alumina spheres with cobalt loading greater than 10%, using combustion synthesis (CS) procedure. The method of preparation of catalyst as described in the present disclosure can be extended for any metal-support framework, with any metal loading (up to 40 %) and over support extrudes of whatever size (powders, pellets, monoliths). Though CS synthesized catalysts have been extensively studied for various applications, the major drawback for this process is the large heat release and temperature rise rates resulting in formation of combustion products with uncontrolled explosion. This occurrence is evident for metal loadings above 5% and causes formation of fine powders. For use of these powdered catalysts in a fixed bed reactor, re-pelletization of these powdered catalysts is adapted, which is a disadvantageous recourse. In the present disclosure, supported combustion synthesized cobalt catalysts have been developed with metal loading greater than 15 %, deposited over active supports, without affecting the structural integrity of the support material and in turn, increases the feasibility of conversion of CO + H₂ to liquid higher hydrocarbons.

[0046] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, the method comprising: (a) obtaining at least one metal salt precursor; (b) obtaining an active support; (c) preparing a solution by contacting a redox mixture of at least one metal salt precursor and a reducing fuel with water; (d) contacting the solution of redox mixture with the active support to obtain an intermediate material; and (e) removing water and calcining the intermediate material to obtain an active support metal- containing catalyst, wherein the active support metal-containing catalyst has 10-40% of metal loading.

[0047] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the metal salt precursor is selected from the group consisting of cobalt nitrate hexahydrate, iron nitrate nonahydrate, copper nitrate trihydrate, copper nitrate hexahydrate, nickel nitrate hexahydrate, strontium nitrate, manganese nitrate tetrahydrate, and combinations thereof.

[0048] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the metal salt precursor is cobalt nitrate hexahydrate.

[0049] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the metal salt precursor can comprise of metal acetates or carbonates. [0050] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the active support is selected from the group consisting of silica doped alumina, silica, alumina, and combinations thereof.

[0051] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the active support is silica doped alumina support.

[0052] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the active support is taken in a specific mass 0.8 grams per gram of the catalyst of high specific surface area of 425 m /g.

[0053] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the active support is taken in a specific mass of the catalyst of high specific surface area of 384 m7e.

[0054] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the reducing fuel is selected from the group consisting of urea, glycine, glycerine, citric acid, hexamethylenetetramine, oxalic dihydrazide, and combinations thereof.

[0055] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the reducing fuel is hexamethylenetetramine.

[0056] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the redox mixture is prepared by contacting stoichiometric quantities of the at least one metal salt precursor and the reducing fuel.

[0057] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the intermediate material in step (d) is obtained by mixing the active support with the solution in a rotating vessel under sub-atmospheric conditions with the pressure ranging from 0.03 - 0.05 bar.

[0058] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the intermediate material is calcined in step (e) by combustion of redox mixture.

[0059] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the combustion of the redox mixture is initiated by the precise ignition temperature in the range of 550-575

K.

[0060] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the combustion of the redox mixture is initiated by the precise ignition temperature of 571 K.

[0061] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, said catalyst consisting of: about 20 weight percent active metal oxide; about 80 weight percent active support, wherein the metal oxide deposited on active support is reduced to metal when used in the applications.

[0062] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the catalyst has BET surface area in the range of 300 to 400 m²/g.

[0063] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the catalyst has BET surface area in the range of 300 to 350 m²/g.

[0064] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the catalyst has BET surface area in the range of 300 to 325 m²/g.

[0065] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the catalyst has BET surface area in the range of 300 to 315 m²/g.

[0066] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the metal oxide is selected from the group consisting of oxides of cobalt, iron, manganese, strontium, nickel, and combinations thereof.

[0067] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, wherein the active support is selected from the group consisting of alumina and silica.

[0068] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, comprising the steps of: contacting the catalyst with a mixture of carbon monoxide and hydrogen at a temperature in the range of 450 K to 550 K at 1 to 5 MPa, to obtain higher hydrocarbon.

[0069] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein higher hydrocarbon comprises of straight chain hydrocarbons with the fractions of gasoline (Cn - Cu), diesel (C₁₄ - C₂₄), waxes (C₂₄₊), and combinations thereof.

[0070] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein the catalyst is contacted with the mixture at a weight hourly space velocity of 2000-3000 ml/(h.g_cat). [0071] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein the catalyst is contacted with the mixture at a weight hourly space velocity of 2610 ml/(h.g_cat).

[0072] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein the catalyst includes about 10-40% metal and about 60 - 90 % silica doped alumina by weight.

[0073] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein the higher hydrocarbon is a liquid having a boiling point range of 423.15 - 643.15 K and lower at atmospheric pressure.

[0074] In an embodiment of the present disclosure, there is provided a process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, wherein the higher hydrocarbon is a liquid having a boiling point range of 413.15 - 623.15 K and lower at atmospheric pressure.

[0075] In an embodiment of the present disclosure, there is provided an active support metal-containing catalyst.

[0076] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, preferably a cobalt catalyst for a wide class of industrial reactions, the catalyst is provided with a high metal loading and uniform deposition across the support framework of varying size.

[0077] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the method adopts a solution combustion method, to synthesize high activity cobalt catalyst.

[0078] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the method can be extended for any metal-support framework, including Co, Fe, Ni, Cu, Ru, Pt, Pd, Ce and other metals, on oxide support structures like AI2O3, Si0₂, Ti0₂, Zr0₂, zeolites and alumino-silicates.

[0079] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the method steps can also be used for a wide class of industrial reactions such as Fischer Tropsch, hydrogenation, dehydrogenation, oxidation, photocatalysis, etc.

[0080] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal -containing catalyst, wherein the method provides a cobalt catalyst with a uniform deposition and varying metal loading.

[0081] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the variable speed facility as adopted in the process steps helps in eliminating the possibility of thermal shocks and powdering of the support material.

[0082] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the deposition of metal into the support framework is performed in multiple stages due to the excessive heat release from the combustion reaction.

[0083] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal -containing catalyst, wherein the infused catalysts are calcined in a muffle furnace at a temperature of about 500 K after each loading.

[0084] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the identification of the redox mixture ignition temperature by placing the known mass of the impregnated redox mixture in the muffle furnace and measuring the mixture temperature using a 1 mm diameter R-type thermocouple as the furnace temperature is ramped from ambient temperature to 673 K.

[0085] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the known volume of redox mixture is impregnated into the support matrix and calcined at the ignition temperature, followed by weighing of the synthesized catalyst for determination of the metal loading.

[0086] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the impregnation and calcination of the redox mixture is repeated until desired reaction specific metal loading is achieved thereof.

[0087] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the catalysts synthesized in various stages, result in deposition of metal loading ranges from 0.01 to 40 % .

[0088] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the catalysts synthesized in various stages, result in deposition of metal loading ranges from 10 to 40 % .

[0089] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the catalysts synthesized in various stages, result in deposition of metal loading of 20% on the support extrudes or structures.

[0090] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein cobalt oxides are deposited on silica doped alumina supports and further reduced to metallic cobalt for used in Fischer Tropsch reaction.

[0091] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein supports particle size ranging from powders to pellets and spheres, as well as supports as large as monolith structures. [0092] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal -containing catalyst, wherein the determination of the precise ignition temperature for the initiation of combustion reaction and the calcination time is performed in a thermogravimetry and differential thermal analyzer, and the desired temperature is maintained during the process.

[0093] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the catalyst is placed in a quartz reduction tube and further in a tubular furnace. An ultra-high pure hydrogen is passed over the synthesized metal oxides. The furnace temperature is increased to predetermined metal-oxide reduction temperature at a ramp rate ranging from 5 K/min to 10 K/min, to reduce the synthesized metal oxides to its corresponding zero valent metal state.

[0094] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the preparation of catalysts of high metal loading using support extrudes or spheres or honeycombs of various sizes.

[0095] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein an aqueous solution of redox mixture and support extrudes is mixed in a rotary stirrer under vacuum conditions of about 25 in Hg, within the rotating vessel for enabling faster evaporation. The rotating vessel is rotated in cyclic clockwise and counter-clockwise rotation to prevent sticking of catalyst particles on the evaporator surface. The vessel is rotated at about 150 rpm during the impregnation process and at 200 rpm during the close to complete drying process. In a step-wise or in a multi-stage the impregnation of metal salts in the range of 5 wt% - 7 wt% is performed.

[0096] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the volume of redox mixture is impregnated into the support matrix and calcined at the ignition temperature, followed by weighing of the synthesized catalyst for determination of the metal loading.

[0097] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the impregnation and calcination of the redox mixture is repeated until desired reaction specific metal loading is achieved thereof.

[0098] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the method for the fixed bed Fischer Tropsch (FT) reaction is described. Initially, the reaction comprising about 20 wt % of cobalt supported on silica doped alumina spheres is selected. The metal precursor for this process is preferably Co(N0₃)2.6H₂0, which is dissolved in water. The stoichiometric quantity of hexamethylenetetramine (C6H12N4) is added to the solution prepared in the above step with the metal precursor and the fuel in molar ratio of 3.87. The aqueous solution of cobalt nitrate as an oxidizer and the hexamethylenetetramine as a fuel is impregnated into the silica doped alumina spheres with surface area of 384 m /g. Calcination of the impregnated mixture at temperature of 421 K is performed for the synthesis of the metal oxides. The process steps are repeated until 20 wt % metal loading is achieved, which includes each stage-wise impregnation of 5 weight %. The synthesized oxide catalysts is reduced by flowing ultrahigh pure hydrogen at 1200 K for 16 hours, with a ramp rate of 10 K/min.

[0099] In an embodiment of the present disclosure, there is provided a method of synthesizing active cobalt catalysts for fixed bed Fischer Tropsch (FT) reaction comprising of 20 weight percent cobalt supported on silica doped alumina (SDA) spherical particles with diameters varying from 0.8 - 1.2 mm: the catalyst, wherein the metal precursor containing Co(N0₃)2.6H₂0 is dissolved in water; stoichiometric quantity of hexamethylenetetramine (C6H12N4) is added to the solution prepared in the above step with, metal precursor and the fuel in molar ratio of 3.87; the aqueous solution of cobalt nitrate as an oxidizer and the hexamethylenetetramine as a fuel is impregnated into the silica doped alumina spheres with surface area of 384 m g; calcination of the impregnated mixture at 421 K for the synthesis of metal oxides; repetition of impregnation and calcination steps occurred until 20 weight percent metal loading is achieved, which includes each impregnation of 5 - 8 weight percent; reducing of the synthesized oxide catalysts in flowing ultrahigh pure hydrogen at 1200 K for 16 hours, with a ramp rate of 10 K/min.

[00100] In an embodiment of the present disclosure, there is provided a method for synthesizing active supported oxide and metallic catalysts, comprising: weighing calculated stoichiometric quantities of metal salt precursors, comprising of metal hydroxide cations and N0₃ ^" anions; weighing calculated stoichiometric concentration of a water soluble fuel that serves as a reducing agent; weighing reaction specific mass of high specific surface area oxide supports or catalyst carriers; synthesizing aqueous solution of the metal salt precursor and the reducing fuel, to form a solution of the redox mixture; immersion of oxide supports in the aqueous solution containing the redox mixture; mixing of oxide supports with the aqueous solution in a prefabricated rotating vessel, maintained under sub- atmospheric pressures; evaporation of the water from the aqueous media; impregnation of the redox mixture into the support matrix; combustion of the redox mixture leading to calcination of the metal precursor and yielding metal oxide.

[00101] In an embodiment of the present disclosure, there is provided a method for synthesizing active supported oxide and metallic catalysts, wherein the method additionally including: placing of synthesized metal oxide catalyst in a quartz reduction tube and further in a tubular furnace; flowing of ultra-high pure hydrogen over the synthesized metal oxides; increasing the furnace temperature to predetermined metal-oxide reduction temperature at a ramp rate ranging from 5 K/min to 10 K/min; consequent reduction of the synthesized metal oxides to its corresponding zero valent metal state. [00102] In an embodiment of the present disclosure, there is provided a method of synthesizing catalysts of high metal loading using the combustion process over support extrudes or spheres or honeycombs of various sizes, comprising: use of wide range of porous, high surface area oxide supports - Si0₂, AI2O3, Ti0₂, mixed metal oxide supports, monoliths or honeycomb supports (-500 cpsi); mixing of aqueous solution of redox mixture and support extrudes in a rotary stirrer; creating vacuum of 25 in Hg, within the rotating vessel for enabling faster evaporation; cyclic clockwise and counter-clockwise rotation of the rotary vessel to prevent sticking of catalyst particles on the evaporator surface; rotation of vessel at 150 rpm during the impregnation process and at 200 rpm during the close to complete drying process; step wise impregnation of the metal salts with 5 wt.% - 8 wt.% metal loading at every impregnation step; for 20 wt.% loading, as desired for the Fischer-Tropsch reaction, the desired metal loading over the support extrudes are obtained in 3 metal loadings; consequently, for higher metal loadings (~ 40 wt.%), as required in reactions such as the water gas shift activity, and tar catalytic cracking, the desired metal loadings are achieved in 5 to 6 impregnations.

[00103] In an embodiment of the present disclosure, there is provided a method for preparing an active support metal-containing catalyst, wherein the syngas with H₂/Co ratio of 2.3: 1 is circulated over the synthesized catalyst, placed in a fixed bed reactor at reaction temperature of 503 K and 3 MPa, with a weight hourly space velocity of 2610 ml/(h.gcat).

[00104] The process steps of the present invention for the preparation of active supported oxide and metallic catalysts are now described. Initially, calculated stoichiometric quantities of metal salt precursors, preferably metal hydroxide cations and NO ^" anions are obtained. Then, the reaction specific mass of high specific surface area oxide supports or catalyst carriers is measured. Aqueous solution of the metal salt precursor and the reducing fuel, is prepared to form a solution of the redox mixture and oxide supports are immersed in the aqueous solution containing the redox mixture. The mixing of oxide supports with the aqueous solution is performed in a prefabricated rotating vessel that is maintained under sub-atmospheric pressures. The water from the aqueous media is evaporated and the impregnation of the redox mixture into the support matrix is performed. The combustion of redox mixture leading to calcination of the metal precursor and metal oxide.

[00105] The structural properties of the synthesized catalysts were characterized using BET, XRD, TPD-TPR and XPS. The synthesized catalysts were further tested for its performance in a fixed bed Fischer Tropsch (FT) reaction facility, used for converting syngas into higher hydrocarbons. FT reaction exclusively requires catalysts with metal loading greater than 15%. The characteristics of CS catalysts are compared to the catalysts prepared by conventional incipient wetness impregnation (IWI) method. The characterization results reveal higher degree of metal reduction, larger fraction of active metal sites and lower metal support interaction for CS catalysts, compared to rWI synthesized catalysts. Moreover, the FT reaction results show remarkable results for CS catalysts with increased CO conversion, higher Cs₊ selectivity and higher product yield. Further, the hydrocarbon product spectrum for CS catalysts showed higher hydrocarbon chain growth probability over CS catalysts leading to formation of waxes at 503 K and 3 MPa. The improved performance of combustion synthesized catalysts evidences potential applicability for industrial XTL (X = Biomass, Coal, CH₄) systems via Fischer Tropsch reactions.

[00106] The silica doped alumina supported cobalt catalysts that are prepared with potassium for fixed bed Fischer Tropsch reaction. In this aspect, 20 weight percent cobalt catalysts are prepared over silica doped alumina spheres and impregnated with potassium nitrate such that the potassium loading in the synthesized catalysts is varied from 1% to 3%. The calcination of the impregnated support extruded in an inert atmosphere like Ar or He, to yield active zero valent metal catalysts is performed without the requirement of an additional hydrogen reduction.

EXAMPLES

[00107] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and material similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may vary.

Example 1

Method of catalyst synthesis:

[00108] The present disclosure provides the method of the preparation of catalyst by mixing of aqueous solution of redox mixture and support extrudes in a rotary stirrer with a vacuum of 25 in Hg within the rotating vessel resulting in enhanced evaporation of the water. The vessel was rotated in a cyclic clockwise and counter-clockwise direction in order to prevent sticking of catalyst particles on the evaporator surface. Consequently, the vessel was rotated at 150 rpm during the impregnation process and at 200 rpm at a stage when the drying process was in "nearly dried" stage. To prevent the powdering of the synthesized catalysts, the redox mixture was impregnated with 5 wt% - 8 wt% metal loading at every impregnation step. For 20 wt% loading, as desired for the Fischer-Tropsch reaction, the desired metal loading over the support extrudes were obtained in 3 metal loadings.

Example 2 Surface area measurements for the catalysts:

[00109] The surface area measurements for the cobalt catalysts of the present invention are performed using Brunauer-Emmett-Teller (BET) method and there results are tabulated in Table- 1. The Table- 1 lists the surface area of the support structure and the catalyst of the present invention.

[00110] Table 1: BET surface area of catalysts

Example 3

Temperature - time profile of the CS Redox mixture:

[00111] The maximum temperature reached during the redox reaction and the overall time of the reaction is displayed in Figure 1. Experimental determination of the maximum combustion temperature attained by the redox reaction resulted in 571 K, which is sufficient for complete decomposition of the metal precursor. The temperature-time profile for the hexamethylenetetramine (HMTA) and cobalt-nitrate hexahydrate redox reaction with an oxidizer to fuel molar ratio of 3.86 is shown in Figure 1. Clearly, two stages of combustion are observed. The first stage, observed from the reaction initiation at 421 K to 480 K, with a slope of 15 K/min, is due to the initiation of surface combustion reaction. The second stage, as observed from 480 K to a maximum temperature of 571 K, is accounted for the redox reaction of bulk NO and the fuel. The temperature rises in this stage at a rate of 180 - 200 K/min. The entire combustion reaction resulting in the formation of cobalt oxides is completed in a short span of 10 minutes.

Example 4

TGA-DTA curve of the redox reaction:

[00112] The thermal events occurring in the course of the combustion reaction were recorded using a differential thermal and thermogravimetry analyser (DTA- TGA), at a heating rate of 5 K/min in a static air, using alumina crucibles. Initial temperature for the analysis is about 313 K, and the maximum temperature is selected until a stable specimen weight is observed (i.e., dm/dt = 0), indicating completion of all chemical reactions, leaving behind cobalt oxide. The corresponding DTA-TGA plots for IWI and CS impregnated supports are shown in Figure 2.

[00113] The redox reactions occur in the temperature range of 430 K - 520 K, where a total weight loss of 25% was observed. Region I for CS catalysts, as seen from 430 K to 455 K, showed 4.5% sample weight loss. The exothermic reactions that occur in this region correspond to the surface combustion of NO and HMTA. In region II, observed from 455 K - 475 K, the sharp exothermic peak corresponds to the redox reaction of bulk NO and HMTA. A maximum weight loss of 16% is observed in this region. The weight loss observed in region III was due to the redox reaction of residual fuel-oxidizer mixture, as observed from 476 K to 521 K, accounting for 5% sample weight loss. The thermal behaviour observed for IWI catalysts shows a broad weight loss region with an endothermic decomposition of Co(N03)₂-6H₂0, resulting in the formation of C0₃O₄ . The weight loss curve for CS catalysts disclosed clearly that the selected stoichiometry produces enough heat for decomposition of cobalt nitrate resulting in the formation of supported C0₃O₄.

Example 5

XRD analysis of the calcined and the reduced cobalt catalysts synthesized by IWI method and CS method:

[00114] X-ray diffraction studies of the catalysts conducted in a Rigaku

Smartlab X-ray spectrometer, showed that 2-Θ values varied from 300-700 at the rate of 0.20/min with Cu-Κα radiation (λ = 1.54). Figure 3 showed XRD spectra for calcined and reduced catalysts.

[00115] The calcined catalysts showed distinct peaks for C0₃O₄. For the calcined catalysts, the 2- Θ peaks occurred at 31.2°, 36.94°, 44.86°, 55.72°, 59.36° and 65.24°, which were consistent with the diffraction pattern for C0₃O₄. The XRD spectra of the catalysts reduced with H₂, at the reduction temperature, revealed sharp 2-Θ peaks at 44.1° and 51.5°, which corresponded to the diffraction spectrum for metallic cobalt. The crystallite size of the catalysts, dc₀304 (cobalt oxide crystallite size) and dc₀ (metallic cobalt crystallite size), calculated using the modified Schrerrer equation and tabulated in the Table 1 :

[00116] Table 1:

[00117] The cobalt crystallite sizes as shown in Table- 1, resulted in the cobalt average crystallite size of 26 nm and 18 nm for IWI and SCM catalysts respectively, clearly indicating higher metal dispersion for combustion synthesized catalysts. Example 6

Temperature programmed reduction (TPR) profiles and the H₂ chemisorption profiles of the synthesized catalysts:

[00118] Temperature programmed reduction (TPR) experiments were conducted in a Micrometrics Autochem 2920 TPR-TPD system to determine the reduction temperature of synthesized catalysts and are depicted in Figure 4. The degree of reduction and metal dispersion were evaluated using H₂ chemisorption techniques as described in Equation No.4 and Equation No.5, respectively.

EotEitsssi'.No.S

[00119] The SDA supported cobalt catalysts reduced over wide temperature ranges. For the SDA-IWI catalysts the reduction temperatures extended upto 1080 K. Whereas for CS catalysts, the reduction temperatures extended to 1200 K. The varying reduction temperatures were due to the different phases of cobalt oxides present on the supported catalyst. Three distinct reduction temperature ranges were observed. The first H₂ consumption peak at Tl = 550 K, corresponded to the reduction of C0₃O₄ to CoO. A broad hydrogen consumption plateau was observed starting from 610 K (T2 ) to 910 K (T3). This wide reduction regime is attributed to the reduction of Co³⁺ ions in C0₃ A10₆ crystallites and also due to the reduction of surface or subsurface Co²⁺ ions in the Co²⁺-Al³⁺ spinel framework. Normally, the AI₂O₃ supported IWI catalysts do not display reduction of cobalt-alumina compounds at these temperatures. The doping of silica into the alumina reduces the formation of aluminates, resulting in the formation of relatively weakly bound cobalt-support species which are easily reduced below 1200 K. For SDA-CS catalysts, only marginal H₂ consumption was observed in the temperature range of 600 - 700 K, unlike SDA-IWI catalysts, indicating the absence of the corresponding cobalt surface species. However, the CS catalysts showed H₂ consumption upto 1200 K, implying continued reduction of the cobalt alumina spinel structures. The degree of cobalt reduction (DOR) obtained from the H₂ TPR curves and the average metal dispersion (D) evaluated from the H₂ -TPD curves are shown in Table 2 below.

Table 2: TPR and TPD summary of SDA-IWI and SDA-CS catalysts

[00120] It can be seen that the degree of reduction obtained from the TPR spectra increases by 14% for the SCM catalyst.

Example 7

X-ray Photoelectron spectroscopy spectra of the catalyst: [00121] XPS analysis was performed on AXIS ULTRA system using Al Ka radiation (hv=1486.6 eV) operated at 15kV and 10 mA with spectral measurements at room temperature and 10-8 Torr, and are illustrated in Figure 5. XPS results provided information of the cobalt oxidation state and the nature of metal support interaction in the synthesized catalysts.

[00122] The XPS spectra of the SDA supported Co catalysts revealed C0₃O₄ as the dominating cobalt oxide phase on the catalyst surface. The deconvoluted XPS spectra of the SDA supported catalysts, showed peak at 779.9 eV for the SDA-rWI catalyst, which is assigned to the Co³⁺ oxidation state and the peak at 781.8 eV, assigned to the Co⁺² oxidation state. The satellite peaks for the 2p_3/2 orbital was observed at 787.6 eV. For the SDA-CS catalysts, the binding energy associated with the Co³⁺ oxidation state was observed at 779.7 eV, implying that the electron density of surface Co³⁺ was higher than that of rWI catalysts and therefore signifying a weaker metal support interaction in the case of CS catalysts. The binding energy of Co³⁺ in the 2p_3/2 orbital and the spin orbital splitting are tabulated in the Table 3. The ratio of the intensities of Co2p_3/2 peak at 779.9 eV to the intensity of the shake-up satellite peak provides the relative formation of CoAl₂0₄ in the synthesized catalysts. From Table-3, it is evident that the silica doping in the A1₂0₃ drastically reduced the formation of cobalt aluminates. Moreover, the CS catalysts too revealed decreased production of cobalt aluminates, indicating lower metal support interaction. The measure of the cobalt dispersion, evaluated from the Al and Co peak intensity ratios, indicated a higher cobalt dispersion for the SDA-CS catalysts. The percentage metal dispersion obtained from the H₂ TPR-TPD experiments supported the values obtained from XPS spectrum analysis. The metal dispersion as observed from the XPS spectral analysis showed that higher dispersion was observed for catalysts synthesized by the CS method.

Table 3: XPS comparison for SDA-IWI and SDA-CS catalysts Catalyst B.E. Co2p₃/2 Spin orbital I-Co2p_3/2/I- 1

(eV) splitting r (eV) shake-up

SDA-IWI 779.9 15.3 0.9 1 0.6

SDA-CS 779.7 15.2 1.1 1 1.6

Example 8

GC-MS spectra of the liquid phase hydrocarbon for the synthesized catalyst:

[00123] The GC-MS spectra as provided in Figure 6 illustrated that the fractions of liquid hydrocarbons as obtained in the FT reactions using the silica doped alumina supported CS catalysts. The spectra showed distinctly paraffinic hydrocarbons in the range from CIO (at retention time of 11.14 min) to C36 (at retention time of 58.86 min). The individual weight fractions were calibrated and quantified using the Supelco standards obtained from sigma aldrich.

Example 9

CO conversion and the hydrocarbon selectivity for the synthesized catalysts:

[00124] It was perceived from Figure 7 that the CO conversion observed for

SCM catalysts was 30% higher than IWI catalysts at a WHSV 2610 ml/(h*gcat). At the same WHSV, C₅₊ selectivity of 73% is observed for IWI catalysts compared to 77% for SCM catalysts. Higher CO conversion and hydrocarbon yields over SCM catalysts are attributed to higher degree of reduction, smaller crystallites' sizes and higher metal dispersion. The decreasing space velocity was also observed to increase the CO conversion. For Cs₊ selectivity only marginal variation was observed with reducing bed residence times. A 70% increase in the CO conversion for SCM catalyst was recorded by reducing the WHSV from 2610 ml/(h*gcat) to 873.3 ml/(h*gcat). For the same reduction in space velocities, the Cs₊ selectivity increased only by 8.5% for SCM catalysts.

Example 10 Variation in the product spectrum for the synthesized catalysts:

[00125] As seen from the product spectrum analysis (Figure 8), the nature of

FT products is a strong function of the synthesis method. The Cs₊ product spectrum is categorized into liquid fractions (C10-C24) and waxes (C₂₄₊). The hydrocarbons are majorly straight chain paraffins. Higher wax production was observed for SDA-CS catalysts compared to SDA-IWI catalysts.

[00126] Remarkably, for combustion synthesized catalysts, the higher hydrocarbon weight fractions yield primarily C24₊ straight chain compounds, consistent to paraffin waxes. The higher hydrocarbon weight fraction distributions are evident in Figure 8. Higher concentration of paraffin waxes over SCM catalysts revealed formation of longer chain hydrocarbons on the catalyst surface.

Example 11

Comparative data of the activity and selectivity of the catalysts of the instant disclosure with that of the catalysts synthesized in the prior arts:

[00127] In comparison with catalysts that are synthesized by conventional incipient wetness impregnation (IWI) method, it was observed that the characteristics of CS catalyst of the present invention, reveals higher degree of metal reduction, larger fraction of active metal sites and lower metal support interaction for CS catalysts. Moreover, it was also observed that the FT reaction results showed advantageous results for the CS catalyst with an increased CO conversion, a higher C5+ selectivity and a higher product yield. As particularly shown in Figure 9, which is a comparative account of the yield for the catalysts prepared in accordance with the present invention with other known catalysts. The SCM process for synthesizing supported cobalt catalysts and the silica doped alumina support have a substantial effect on the catalyst structure resulting in improved extent of reduction, reduced crystallite size and higher metal dispersion.

[00128] Overall, the present disclosure demonstrates the synthesis of cobalt catalysts supported on silica doped alumina spheres with cobalt loading greater than 10%, using combustion synthesis (CS) procedure. The synthesis method described in this study can be extended for any metal-support framework, with any metal loading (up to 40 %) and over support extrudes of whatever size (powders, pellets, monoliths). Though, CS synthesized catalysts have been extensively studied for various applications, the major drawback for this process is the large heat release and temperature rise rates resulting in formation of combustion products that can only be used in a fluidized bed or a slurry phase reactor, with uncontrolled explosion. In contrast, in the current work, supported combustion synthesized cobalt catalysts have been developed with metal loading of 20%, deposited over support spheres, without affecting the structural integrity of the support material.

[00129] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred examples and implementations contained therein.

References:

A. Carlo Giorgio Visconti, Enrico Tronconi, Luca Lietti, Pio Forzatti, Stefano Rossini, and Roberto Zennaro. Detailed kinetics of the Fischer-Tropsch synthesis on cobalt catalysts based on h-assisted co activation.Topics in Catalysis, 54(13-15):786-800, 2011

B. Alan Jean-Marie, Anne Griboval-Constant, Andrei Y Khodakov, and Fabrice Diehl. Cobalt supported on alumina and silica-doped alumina: Catalyst structure and catalytic performance in Fischer-Tropsch synthesis. Comptes Rendus Chimie, 12(6):660-667, 2009.

C. Estephania Lira, Carmen M Lopez, Freddy Oropeza, M_onica Bartolini, Juan Alvarez, Mireya Goldwasser, Francisco L_opez Linares, Jean-Francois Lamonier, and M Joseina Perez Zurita. HMS mesoporous silica as cobalt support for the Fischer-Tropsch synthesis: Pretreatment, cobalt loading and particle size effects. Journal of Molecular Catalysis A: Chemical, 281(1): 146- 153, 2008.

D. Rungravee Phienluphon, Lei Shi, Jian Sun,Wenqi Niu, Peng Lu, Pengfei Zhu, Tharapong Vitidsant, Yoshiharu Yoneyama, Qingjun Chen, and Noritatsu Tsubaki. Ruthenium promoted cobalt catalysts prepared by an autocombustion method directly used for Fischer-Tropsch synthesis without further reduction. Catalysis Science & Technology, 4(9):3099-3107, 2014.

E. Lei Shi, Kai Tao, Tokimasa Kawabata, Takeshi Shimamura, Xue Jun Zhang, and Noritatsu Tsubaki. Surface impregnation combustion method to prepare nanostructured metallic catalysts without further reduction: As-burnt Co/Si0₂ catalysts for _scher{tropsch synthesis. ACS Catalysis, 1(10): 1225-1233, 2011.

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Claims

I/We Claim:

1. A method for preparing an active support metal-containing catalyst, the method comprising:

a. obtaining at least one metal salt precursor;

b. obtaining an active support;

c. preparing a solution by contacting a redox mixture of at least one metal salt precursor and a reducing fuel with water;

d. contacting the solution of redox mixture with the active support to obtain an intermediate material; and

e. removing water and calcining the intermediate material to obtain an active support metal-containing catalyst,

wherein the active support metal-containing catalyst has 10-40% of metal loading.

2. The method as claimed in claim 1, wherein the metal salt precursor is selected from the group consisting of cobalt nitrate hexahydrate, iron nitrate nonahydrate, copper nitrate trihydrate, copper nitrate hexahydrate, nickel nitrate hexahydrate, strontium nitrate, manganese nitrate tetrahydrate, and combinations thereof.

3. The method as claimed in claim 2, wherein the metal salt precursor is cobalt nitrate hexahydrate.

4. The method as claimed in claim 1, wherein the active support is selected from the group consisting of alumina, silica, and combinations thereof.

5. The method as claimed in claim 4, wherein the active support is silica doped alumina support.

6. The method as claimed in claim 4, wherein the active support is taken with a high specific surface area of 425 m7e.

7. The method as claimed in claim 1 , wherein the reducing fuel is selected from the group consisting of urea, glycine, glycerine, citric acid, hexamethylenetetramine, oxalic dihydrazide, and combinations thereof.

8. The method as claimed in claim 7, wherein the reducing fuel is hexamethylenetetramine.

9. The method as claimed in claim 1 , wherein the redox mixture is prepared by contacting stoichiometric quantities of the at least one metal salt precursor and the reducing fuel.

10. The method as claimed in claim 1, wherein the intermediate material in step (d) is obtained by mixing the active support with the solution in a rotating vessel under sub- atmospheric pressure ranging from 0.03 - 0.05 bar.

11. The method as claimed in claim 1, wherein the intermediate material is calcined in step (e) by combustion of redox mixture.

12. The method as claimed in claim 11, wherein the combustion of the redox mixture is initiated by the ignition temperature ranging from 550 - 570 K.

13. An active support metal-containing catalyst for the conversion of hydrogen and carbon monoxide gases, said catalyst consisting of:

a metal oxide; and

about 80 weight percent active support,

wherein the metal oxide deposited on active support is reduced to metal when used in the applications.

14. The catalyst as claimed in claim 13, wherein the catalyst has BET surface area in the range of 300 to 400 m /g.

15. The catalyst as claimed in claim 13, wherein the metal oxide is selected from the group consisting of oxides of cobalt, iron, manganese, strontium, nickel, and combinations thereof.

16. The catalyst as claimed in claim 13, wherein the active support is selected from the group consisting of silica doped alumina, alumina, silica, and combinations thereof.

17. A process for the conversion of mixture of carbon monoxide and hydrogen to produce higher hydrocarbon, said process comprising the steps of:

contacting the catalyst as claimed in claim 13 with a mixture of carbon monoxide and hydrogen at a temperature in the range of 450 K to 550 K at 1 to 5 MPa, to obtain higher hydrocarbon.

18. The process as claimed in claim 17, higher hydrocarbon is selected from the group consisting of diesel, gasoline, waxes, and combinations thereof.

19. The process as claimed in claim 17, wherein the catalyst is contacted with the mixture at a weight hourly space velocity of 2000-3000 ml/(h.g_cat).

20. The process as claimed in claim 17, wherein the catalyst includes about 10- 40% metal and about 90 - 60 wt % silica doped alumina by weight.

21. The method as claimed in claim 17, wherein the higher hydrocarbon is a liquid having a boiling point range of 150 - 370 °C and lower at atmospheric pressure.

22. An active support metal-containing catalyst prepared by a process as claimed in claim 1.

23. The active support metal-containing catalyst as claimed in claim 22 is used for converting the mixture of carbon monoxide and hydrogen to higher hydrocarbons.