US2007116A - Method of oxidizing hydrocarbons - Google Patents

Description

July 2, 1935. WALKER 2,007,116

METHOD OF OXIDIZING HYDROCARBONS Filed Jan. 29, 1930 4 Air fina s-,2 flock/$1M JOHN C. WALKER avwwtoz 33; his QUOTA t; Z

Patented July 2, 1935 PATENT OFFICE I METHOD or oxmrzmc nrnaocsanons John Charles Walker, Tallant, kla., vassignor to Empire Oil & Refining Company, Bartlesville, 0kla., a corporation of Delaware Application January 29, 1930, Serial No. 424,170

' 190laims. (01.260-138) This invention relates to the production of liquid hydrocarbon-oxygen compoundsby the partial oxidation of hydrocarbons, and more specifically to a method of producing alcohols, aldehydes, and other liquid hydrocarbon-oxygen compounds by the partial oxidation oi hydrocarbons such as are found in natural gas, with oxygen or air. 1 This invention is a continuation in part of and improvement on the invention described in my copending application Serial No. 192,077 for Method of producing hydrocarbon-oxygen'compounds, filed May 17, 1927.

- The primary object of the present invention is l to provide an improved process for manufacturing liquid hydrocarbon-oxygen compounds by the partial oxidation of hydrocarbons.

A more particular object of the invention is to provide improvements on the process described 20 in my aforementioned copending application whereby large yields of liquid hydrocarbon-oxygen compounds or high quality and commercial value are obtainable.

With these and other objects and features in 25 view, the invention consists in the improved method for producing hydrocarbon-oxygen compounds from hydrocarbons hereinafter described and more particularly defined in the claims.

The improved process will be hereinafter more 30 particularly described with reference to the accompanying drawing, in which:

The figure illustrates diagrammatically in side elevation, with parts in section, the preferred arrangement and design of apparatus employed in carrying out the process.

An illustrative example of an application of the process to the treatment of natural gas will now be described:

Natural gas of the approximate composition: 40 methane 54.2%, ethane 15.7 propane 11.8%, butane 3.7%, nitrogen 13.6%, and oxygen 1%, is conducted from a source. of such gas under high pressure through a meter ill, from which a measured volume of the gas is passed by a pressure regulating device l2 into pipe line ll at a substantially constant pressure of about 300 lbs. per square inch. The gas is conducted through the valved connection l6 at a regulated flow rate into the outer phase of the. cold end of a U-shaped horizontally disposed heat interchanger l8. The temperature of the gas at this point is normally within the range 50-100 F. In passing through the interchanger the gas is preheated to a temperature of approximately 700 F. by heat interchange with hot treated gas passed through the inner phase of the interchanger. A by-pass connection I9 is provided between the two arms of the interchanger about half-way of its length so that the fiow of gas through the outer phase of the interchanger may be short-circuited therethrough if desired. From the hot end of the outer phase of the interchanger the gas is discharged into a pipe 20 comprising an inlet connection for reaction vessel 22. Simultaneously air, in measured volume and also under a pressure of about 300 lbs. per square inch, is introduced into the pipe 20 from an air pipe 24 through a mixing device 26. Device 26 comprises a plurality of very small orifices opening from pipe 24 into a Venturi throat portion 28 01 the pipe 20, whereby small high velocity jets of air are introduced into the pipe 20 at right angles to the direction of flow of gas therethrough, so that a thorough and rapid mixing of the hydrocarbon and air is effected at this point. The mixture of hot gas and air thus formed, preferably containing less than by volume of oxygen, is

conducted through a pipe riser 29 to the top of reaction vessel 22 and is released into an annular reaction space 30, formed around riser 29 and below cone 3|. The space 30 is preferably filled with a contact substance or catalyst, such as pumice having a mixture of aluminum phosphate and copper oxide deposited thereon.

For treating hydrocarbon gas of the type forming the subject of this example, the amount of air introduced into pipe 20 through nozzles 26 is preferably controlled to maintain a maximum temperature in the reaction zone 30 in the neighborhood of 840 F. to 880 F. The temperature thus maintained in the reaction zone (by heat developed as a result of exothermic reactions between the hydrocarbon and oxygen) is dependent not only on the nature and amounts of the reacting constituents, but also on the character of the reaction vessel and the rapidity with which heat is removed therefrom by radiation and in the form of sensible heat carried out by the products of the reaction.

The hydrocarbon-air mixture enters the reacton chamber at the top of the filling of catalyst or contact material, and passes downwardly there: through and thence out through an outlet connection 32 at the bottom of the tube 22. Outlet 32 is located below a supporting grid 33 on which rests the catalyst or contact filling. From connection 32 the hot reaction mixture, containing the liquid hydrocarbon-oxygen products formed in the reaction zone in vapor form, passes through the inner phase of the heat interchanger i8 wherein it is cooled to a temperature of about 250300" F. by heat interchange with the hydrocarbon passing through the outer phase of the interchanger on its way to the reaction chamber. Some of the liquid hydrocarbon-oxygen products condense in the interchanger, and for this reason the interchanger and the connections leading from the discharge side of its inner phase are preferably constructed of corrosion resistant material such as brass and are arranged to facilitate rapid draining oil and collection of the condensed liquids. From the cold end of the interchanger the reaction gases and condensed vapors pass through a downwardly sloping valved pipe connection 34 into an inlet manifold 35 at oneend of a water cooled condenser 36, also preferably constructed of brass or other relatively noncorrodable metal. Water at normal temperatures enters the condenser at 31 and exits from the condenser at 38. The products of reaction are cooled to a temperature of approximately 90 F., by indirect heat transfer with the water in passing through pipes 39 of condenser 36 from manifold 35 into an outlet manifold 40, and a large volume of liquid hydrocarbon-oxygen condensate is recovered in a trap 4| at the bottom of manifold 40 and in a separator 42 at the outlet of the condenser. Separator 42 is equipped with internal helically arranged bafiles 43 whereby a whirling cyclone motion is imparted to gas passing therethrough and liquid particles are thrown to the outside and collected in a trap 44. It will be noted that the arrangement of the condenser and connections is such that the liquid condensate is kept in contact with the gas from which it is condensed and flows along with the gas stream to the separator and traps at the outlet of the condenser. By this arrangement more efilcient condensation is secured because the heavier prcducts of higher boiling point are contacted with the gas up to the time that it leaves the condenser, such heavier products aiding in the removal of lower boiling fractions by an absorption or scrubbing action.

From water cooled condenser 36 and separator 42 the treated gas, which still contains recoverable vapors of normally liquid hydrocarbonoxygen products, is led through a pipe 46, trap 48 and valved inlet pipe 50 into the hot end of a cold interchanger 52. The temperature of the gas entering interchanger 52 is approximately 80 F., and in passing through this interchanger the gas is precooled to a temperature of approximately F. to F. Any additional hydrocarbon-oxygen product condensed in the pipe line 46 and in the interchanger 52 is trapped in a separator 54 at the discharge end of the interchanger from which it may be passed through pipe connections 56 and 58 to storage.

From separator 54 the gas passes through a connection 60 into a cooler-scrubber 62. This cooler-scrubber comprises essentially a horizontal cylindrical tank which is kept about half filled with liquid hydrocarbon-oxygen condensate introduced through a pipe 64 from water cooled condenser 36 and separator 42. The coolerscrubber unit 62 is provided with refrigerating coils 66 and with bailies 68-10, whereby gas admitted at the end of the unit through the connection 60 is caused to enter the interior of the scrubber at high velocity below the surface H of the liquid condensate contained therein, the cooler tank and cooling surfaces and bafiles being so arranged that the entering velocity of the gas causes an active circulation of the mixed gas and liquid from end to end of the tank. Thus the gas on its way to the cooler-scrubber 62.

after admission near the point 12 at the bottom of one end of the tank flows to the opposite end of the tank through the liquid and then returns to the inlet end of the tank in the upper part thereof. The liquid condensate in the'tank 62 is cooled to a temperature of approximately 20 to 25 degrees F., whereby further light hydrocarbon-oxygen products are recovered from the .gas by condensation at the lower temperature and by absorption in the cold less volatile fraction obtained in the water cooled condenser 36, thus simultaneously enriching the water cooled condenser condensate. The cold treated gas is then passed through neck I3 at the top of the tank 62 and through helically arranged baffles 14 into an annular space 16 of a separating dome l8 overlying tank 62. In passing through baffles 14 into chamber 16 a whirling movement is given to the gas whereby substantially all liquid entrained in the gas is thrown out; the dry gas then flowing through a cylindrical fine mesh screen 19 into an outlet chamber 80 at the top of dome 18, from which it passes by a connection 82 into and through the interchanger 52 in heat interchanging relationship with the vapor carrying gas The tem-. perature of the dry gas is raised in the interchanger to within 3-5 degrees Jf that at which it enters the devaporizing system comprising interchanger 52 and cooler-scrubber 62.

In this condition the gas is either delivered to the treated gas pipe line 84 through connection 86, or may be recycled through a recompressor 81 and valved recycle connection 88, or may be passed with or without recompression, by a pipe 90 into and through another heat interchanger I8 and treating chamber 22' wherein it is subjected to another stage of partial oxidation treatment similar to that previously described, after admixture with air introduced through a pipe connection 92. raw gas from line I4 may be admixed with the treated gas passing to the reaction tube 22' through the valved connection 94. The reaction gas formed in chamber 22', carrying a new supply of liquid hydrocarbon-oxygen vapors, may be passed from the cold end of interchanger l8 through a valved connection 96 into the inlet of water cooled condenser 36, but is preferably passed to another similar water cooled condenser and to another similar gas de-vaporizing unit (not shown) through pipe 34.

If desired a certain amount of The vapor content of the gas leaving the gas devaporizing unit is normally low enough so that no condensation takes place in the exit pipe lines, even when the proportion of dry treated gas to untreated gas in such lines is in the neighborhood of 20% to 30%. This dry condition of the pipe lines on the delivery side of the devaporizing unit prevents internal corrosion of the lines. Moreover the tail gas residue of the treatment contains no oxygen, so that corrosion difficulties in the pipe lines leading off from the discharge side of the treating plant from this cause are also reduced.

There is a. continual flow of liquid condensate from water cooled condenser 36 into coolerscrubber 62, and a considerable additional volume of liquid is condensed and absorbed in the coolerscrubber. This liquid is removed by overflow pipes 98 and I00 to storage in suflicient quantity to maintain a constant level of the liquid in the cooler-scrubber 62. The tail gas from the final stage of treatment is finally discharged into the main gas discharge line 84.

As previously indicated, the invention contemplates both single and multi-stage treatment of the hydrocarbon, and either or both recycle and series operation of the treating units during multi-stage treatment. During recycle treatment the treated gas from treating chamber 22, for example, after having passed through hot interchanger l8, water-cooled condenser 36, cold interchanger 52, cooler scrubber 82, and back through the outer phase of cold interchanger 52, is passed by pipe 86 into re-compressor 81 where its pressure is again raised to approximately the. pressure of the hydrocarbon originally admitted to the treating chamber from pipes IQ and I6. From recompressor 81 the recycle gas is reconducted by connection 88 back through connection i6, heat interchanger l8, and air mixing passage 20 wherein a fresh supply of oxygen is admixed therewith, and thence again into. treating chamber 22. Tail gas is removed from the system through pipe 84 in suflicient quantity to maintain a desirable substantially uniform pressure and to keep the inert nitrogen content of the hydrocarbon gas treated suflicient- 1y low, and the hydrocarbon content sufficiently high, for the recovery of suitable yields of liquid hydrocarbon-oxygen products. A measured volume of raw untreated hydrocarbon may be added to the recycled gas from main l4 and connection i6 as make-up. The make-up? hydrocarbon may be a rich gas, such as a propanebutane mixture, in which event liquefaction of unoxidized propane and butane and other relatively high-boiling hydrocarbons occurs, at the pressures used, along with the liquid hydrocarbon-oxygen compounds in the cold de-vaporizing equipment. In order to separate thus liquefied hydrocarbons from the liquid hydrocarbon-oxygen products of the treatment, a pressure separator unit I02 is installed on the liquid condensate discharge lines. The pressure separator I02 illustrated diagrammatically in the accompanying drawing, is a fractionating bubble cap tower operating under substantially the same pressure as the other apparatus elements previously described. The liquid condensate is introduced through pipe connections I04 and I into the toweril02 at about its mid-point vertically. The tower is provided with a water cooling or refrigerating element I08 at its top and with a heating element H0 near its. base. The light hydrocarbon liquids may be taken off from the top of the tower adjacent the condensing element I08 through a pipe H2 and returned by a pump H4 and vaporizing chamber H5 to the treated gas line 86 for use as make up" hydrocarbon. The aqueous crude oxidation product which collects at the base of the tower is withdrawn through a connection 6 to storage. In case the liquid hydrocarbon which is condensed in the de-vaporizing elements of theapparatus carries substantially no liquid hydrocarbon-oxygen products in solution, a simple gravity pressure separator may be used in place of the fractionating tower I02 described. A solvent for the hydrocarbon-oxygen compounds may be used in conjunction with the pressure separator I02.

Partial oxidation treatment of natural gas of the aforementioned composition with about 10% by volume of air at the pressures and temperatures indicated has yielded a liquid hydrocarbonoxygen product of the following approximate composition: acetaldehyde 5 to 6 per cent by weight, methanol 34 to 36 per cent by weight,

formaldehyde 20 to 23 per cent by weight; together with varying amounts of water and higher 3 alcohols, aldehydes, acetals, esters, ketones and other hydrocarbon-oxygen compounds. The formaldehyde is recovered in the form of an aqueous solution having. 9. formaldehyde concentration of approximately 30 to 40% by weight. The composition of the tail gas produced by a single passage of the aforesaid natural gas with air through a single treating unit (comprising reaction tube, water cooled condenser and coolerscrubberi has approximately the following composition: methane 47.9%, ethane 14.5%, propane 11.1%, butane 3.2%, carbon monoxide 1.7%, hydrogen 0.2%, nitrogen 20.8%, oxygen 0%.

In order to obtain a maximum recovery of liquid hydrocarbon-oygen products per unit volume of natural gas treated it is necessary to react the hydrocarbon gas with a greater volume of air than can be satisfactorily added to the gas in a single treatment, because of the highly exothermic character of the reaction. For this reason the tail gas resulting from the first treatment of the raw natural gas in a treating unit comprising an individual reaction tube together with its gas de-vaporizlng train, is admixed with an additional permissible volume of air or oxygen and again subjected to partial oxidation reactions in the same or another reaction tube, followed by recovery of the liquid partial oxidation products formed in the same or preferably another devaporizing train. This step by step or stage treatment of the gas may be continued in successive stages so long as the tail gas from. the last stage of treatment has sufficient hydrocarbons present in its composition to yield a liquid hydrocarbon-oxygen product of value suflicient to pay for the treatment. As indicative of the composition of successive tail gases resulting from series treatment of the gas with approximately 10% of air in each stage, the following analyses are cited:

Composition of untreated natural gas Per Cent Methane 57.9 Ethane 14.9 Propane 10.9 Butane 3.5 Nitrogen 12.8

Tail gas #1 resulting from first stage treatment Per Cent Methane 50.4 Ethane 14.1 Propane 10.9 Butane 3.3 Nitrogen 19.8 Balance chiefly CO'and'CO Tail gas #2 resulting from treatment of tail gas #1 Per Cent Methane 4-9.7 Ethane 10.2 Propane 9.7 Butane 2.9

Nitrogen 24.6 Balance chiefly CO and CO2 Volume ratio of fresh hydrocarbon gas to total air used Volume ratio of fresh hydrocarbon gas to recycled tail gas Volume ratio of fresh hydrocarbon gas to discarded tail gas 36. 0 Untreatedpas composition Crude hydrocarbon-oxygen products formed: A. Yield-approximately 2.5 gals/M cu. ft. of fresh hydrocarbon gas used; B. Composition 5.43% by weight CHJCHO, 12.04% HCHO, 30.71% CHaOH, 51.80% H2O (by difference) One object of the present invention is the production of a liquid hydrocarbon-oxygen product having ahigh content of formaldehyde. The content of formaldehyde in the product varies considerably depending on the composition of the reaction mixture treated and on the pressure, character of catalyst, temperature and other conditions of treatment. Likewise the yield in gallons of crude organic product per 1000 cu. ft. of gas treated varies considerably with the composition of the reaction mixture and with pressure and other controlling factors. A natural gas having upwards of 20% by volume of ethane, propane and butane in its composition normally yields a much larger volume of formaldehyde than a gas containing a large percentage of methane ad a smaller percentage of higher parafiine hydrocarbons. The yield of formaldehyde is favorably affected by the use of a substantially constant pressure of approximately 200 to 350 lbs. per square inch in the reaction chamber, and also by the use of moderate reaction temperatures (preferably below 1000 F.), high velocity throughout, such that each unit volume of the reaction mixture passes through the high temperature reaction zone in a period preferably less than two seconds, and by the use in the reaction chamber of a contact material such as the aluminum phosphate-copper oxide mixture hereinafter more fully described.

A lean recycle gas which contained a large proportion of nitrogen and only relatively small amounts of hydrocarbons which, however, consisted chiefly of propane and butane, and having a unit heating value in the neighborhood of 400 B. t. u. per cubic foot, gave on treatment good yields of liquid product having a satisfactory formaldehyde content; whereas another gas containing relatively small amounts of ethane, propane and butane and large amounts of methane with little .inerts, and have a unit heating value of 1000 B. t. u., treated in exactly the same manner gave very low yields of formaldehyde, but

relatively much higher yields of methanol and 1000 F. or fall much below 600 F., and is pref- K erably maintained in the neighborhood of 800 to 900 F. in treating natural gas, though somewhat lower temperatures may be used in treating a reaction mixture having a high content of hydrocarbons having two or more carbon atoms in the molecule such as propane, butane and pentane. The control of the temperature is effected chiefly through the amount of oxygen'or air added to make up the reaction mixture, and through the degree of preheat which is imparted to the reaction mixture. The degree of preheat can be varied by varying the proportion of hydrocarbon which is passed through the heat interchanger units on the inlet side of the reaction zone, and through by-pass 19. The hydrocarbon not so preheated may be by-passed through a pipe H8 directly to the inlet tube of the reaction chamber.

The invention is not limited to the use of catalysts or contact substances. Satisfactory yields of the product are obtainable without the use of any catalyst or contact filling in the reaction chamber. However the reaction progresses more smoothly and is much more easily controlled when a contact material or filling is employed in the reaction chamber. The preferred contact filling consists of a pumice base having approximately 3.1 lbs. of aluminum phosphate and approximately one-half pound of copper oxide deposited thereon per cu. ft. of catalyst mass. This catalyst is of the mixed type, the aluminum phosphate being considered an excellent dehydration catalyst, while the copper oxide is a well known catalyst generally considered to favor oxidation. One advantageous feature resulting from the use of a catalyst of this type is that the fouling of the reaction chamber with carbon appears to be inhibited thereby. Use of a catalyst or contact filling of this preferred type has other advantages such as:

1. Tendency to stabilize the reaction and render it much less subject to adverse quick changes in other operating conditions, and to promote rapid recovery from the effects of adverse changes of long duration.

2. Actual increase in formaldehyde content of the liquid product.

3. An increase in the yield of liquid product from each unit of the treating apparatus.

4. A marked decrease in the time required to 9,007,110" brine tithe apparatus to a satisfactory producing oxide catalyst and maintenance of the reaction mixture under a substantially constant operating pressure, permits the use of a higher rate of gas flow through the reaction zone and consequently results in an increased unit plant capacity and increased efliciency. The optimum time of contact of each unit volume of the reaction mixture with the catalyst, or in the reaction zone,

has been found-to be in the neighborhood of one to one and one-half seconds. In place of Y the preferred catalyst other metals and nonmetals and their oxides may be used, either singly or in combination, reference being hereby made to my aforementioned application for examples. A mixture. of an oxide of a metal of the 1st or 2nd groups of the periodic table, such as copper, zinc or silver oxide, with a phosphorus acid salt or oxide of a metal of group 3, such as aluminum phosphate or oxide, in the relative proportions present in the preferred catalyst. makes a particularly satisfactory contact substance.

The design of the reaction chamber illustrated is such that after the reaction mixture is formed by mixing hydrocarbon gas and air, the mixture passes through, an open passage (tube 29 and space under cone 3|) of considered volume and at or near the reaction temperature before coming into contact with the catalyst. It has been determined that the partial oxidation reaction is initiated and partially completed in this open space, the reaction being thereafter completed and apparently modified in contact with the catalyst bed. Better yields and quality of liquid hydrocarbon-oxygen product are obtained when the reaction mixture passes initially through this heated free space than when no free space is provided separating the catalyst bed and the point at which the hydrocarbon and air are mixed to form the reaction mixture." Normally the proportions of the treating chamber and of the catalyst bed are such that with a total time of sojourn of the reaction mixture in the high temperature reaction chamber ofabout 2 seconds for example, the mixture is in contact with the catalyst about half that time, and is subjected I to temperature conditions favoring reaction for about second before coming in contact with the catalyst. When a catalyst filling is used in the reaction chamber, the volumes of catalyst space and of free open space preceding the catalyst should be so proportioned as to provide a time of sojourn of the reaction mixture in such open space at substantially reaction temperatures of at least 0.1 second before contact with the catalyst, out of a total time of sojourn of the reaction mixture at or near the reaction temperature of not to exceed 2 seconds.

Satisfactory operation of the plant is possible at pressures at and below 200 lbs. per square inch, although it has not. been found possible to secure commercial yields of liquid organic product when using pressures below 100 lbs. per sq. inch in the treatment of natural gas. A rich gas or vapor having a relatively high content of propane, bu-- tane, pentane or heavier hydrocarbons may be treated at low pressures much more satisfactory higher. pressures. But pressures above 400 to 500 lbs. per square inch are more favorable to alcohol rather than aldehyde production.

The higher the molecular weight of the hydrocarbon treated, the greater the proportion of air that can be satisfactorily mixed therewith without upsetting the-optimum temperature condi-' tions and other factors controlling the reaction.

For example a-residue gas from a natural gasoline recovery plant having a high percentage of propane and butane was found to require air admixed therewith in the proportions 01,25 to 30 percent by volume in order to maintain the desired normal reaction temperature in the reaction zone, whereas a leaner gas containing small percentages of ethane, propane,'and butane required only about 15% of air. However, a lean gas containing propane and butane in small proportions only, together with a large.

quantity of nitrogen or other inerts, may require large percentages of air or oxygen in order to maintain satisfactory reaction temperatures. Thus it was found in one case that a lean tail gas required oxygen in the proportions of 59% by volume of the hydrocarbon content of the gas, in order to maintain the desired reaction temperature, because of the large amount of inert gas present in the reaction mixture. The amount of oxygen employed should be less than 10 per cent by volume of the total reaction ,mixture or mass (including hydrocarbon and nitrogen, C0, C02, hydrogen and the like).

The liquid organic reaction products of the treatment, particularly formaldehyde, are rather readily decomposed and polymerized. The decomposition of formaldehyde is catalyzed by iron and is hastened by an apparatus design wherein the liquid products of the partial oxidation reaction are cooled slowly and allowed to stand in contact with iron and with hot gases. Accordingly the preferred apparatus for carrying out the present process is designed to allow rapid removal of the reaction products from the high temperature reaction zone, rapid cooling and separation of these products, and avoidance of traps for condensed liquid betweenthe reaction chamber and the hot inlet side of the water cooled condenser, wherein the liquid condensate can collect and stand. Any condensate formed in the heat interchanger on the discharge side of the reaction chamber is not allowed to collect and stand but is carried along with the gas stream'through the interchanger into the water cooled condenser and then cooled as rapidly as possible in the condenser. Removal of liquid at this point is rapidly accomplished. The cold end of the heat interchanger and the condenser and connections are also preferably constructed of material which is not a catalyst for formaldehyde decomposition, examples of such materials being copper and brass. The water cooled condenser is designed to so far as possible prevent fractional condensation, which is conductive to corrosion and to ineflicient removal ofthe lower vapor pressure ends carried in the gas. By effecting the separation of the entire condensate from the gas at the point where cooling of the gas has reached approximately normal atmospheric temperature, namely in the water cooled condensers, a more complete recovery of condens- -lble vapors is accomplished and the absorptive power of the higher boiling for the lower boiling vapor ends is utilized to the fullest extent. In the type of condenser illustrated there is a continuously downward passage of any previously formed condensate in continual contact with the gas in continuous tubes until separation takes place in the condenser traps and separator.

The use of the crude liquid condensate obtained in the condenser as the scrubbing and absorbing medium in the cooler-scrubber element of the de-vaporizing system is an important feature of the process whereby the following results are effected:

1. Further enrichment of the crude condensate recovered in the water-cooled cendenser.

2. Recovery of additional valuable liquid oxidation products from the gas, with consequent increased total production of liquid products.

3. Removal of all but small traces of irritating odors and corrosive acids and the like from the tail gases.

While the foregoing description has been limited to an illustrative example of the application of the process to the treatment of natural gas hydrocarbons, it will be understood that the invention is not limited in general principle and application to the treatment of any particular hydrocarbon but may be used in effecting the oxidation of pure hydrocarbons such as ethane, propane, butane, pentane, ethylene, propylene, butylene, as well as high boiling hydrocarbons or mixtures of any of these such as occur in coal gas, oil refinery gases and gasoline. Likewise while the process of the present invention is directed chiefly to the recovery of large yields of formaldehyde, it will be understood that by varying the composition, of the hydrocarbon treated, or by varying other factors such as the catalyst and pressures used, other valuable hydrocarbon-oxygen products may be obtained in commercial quantities. For example in the preferred method of operation above described a relatively large yield of liquid organic product is recovered by increasing the pressure employed to 750 lbs. per square inch, but the relative alcohol yield is considerably increased at the expense of a drop in the proportionate yield of formaldehyde. I 1

The invention having been thus described, what is claimed as new is:

1. In the manufacture of liquid hydrocarbonoxygen compounds by the partial oxidation of hydrocarbons, the step which comprises carrying out the partial oxidation reaction in the presence of a contact mass comprising aluminum phosphate and copper oxide.

2. In the manufacture of liquid hydrocarbonoxygen compounds by the partial oxidation of hydrocarbons, the step which comprises carrying out the partial oxidation reaction in the presence of a contact mass comprising a pumice base having deposited on each cubic foot thereof approximately three pounds of aluminum phosphate and half a pound of copper oxide.

3. In the manufacture of liquid hydrocarbonoxygen compounds by the partial oxidation of aliphatic hydrocarbons, the step which comprises carrying out the partial oxidation reaction under a pressure in the range 200-750 lbs. per square inch in the presence of a contact mass comprising a compound catalyst favoring dehydration and oxidation reactions.

4. In the manufacture of liquid hydrocarbonoxygen compounds by the partial oxidation of a,oo7,11e I aliphatic hydrocarbons. the step which comprises carrying out the partial oxidation reaction in the presence of a contact mass comprising a mixture of an oxide of a metal taken from the group consisting of copper, zinc and silver, together with a phosphorus acid salt of aluminum.

5. In a continuous process of manufacturing liquid hydrocarbon-oxygen compounds comprising chiefly alcohols and aldehydes by the partial oxidation of aliphatic hydrocarbons, the steps comprising delivering controlled volumes of the vaporized hydrocarbon and air to the partial oxidation reaction zone undera pressure in the range 200-750 lbs. per square inch and maintaining the hydrocarbon-air mixture entering the reaction zone under a substantially constant pressure.

6. In a process of manufacturing liquid hydrocarbon-oxygen compounds by the partial oxidation of gaseous and light liquid paraflinic and olefinic hydrocarbons, the step which comprises delivering measured volumes of the vaporized hydrocarbon and less than its volume of air to the partial oxidation reaction zone under a substan-- tially constant pressure within the range 200-750 pounds per square inch.

7. In the manufacture of liquid hydrocarbonoxygen compounds by the partial oxidation of a fluid aliphatic hydrocarbon, the step comprising placing the hydrocarbon to be treated under an approximately constant pressure in the range 200-750 pounds per square inch, and intimately admixing air therewith in proportions less than 50% per volume of the mixture by jetting the air at high velocity into a stream of the vaporized hydrocarbon flowing toward the reaction zone.

8. In a process of manufacturing liquid hydrocarbon-oxygen compounds by the partial oxidation of hydrocarbons, the step which comprises passing the vaporized hydrocarbon and oxygen containing reaction mixture under a pressure above 100 pounds per square inch and at substantially reaction temperature through an open space and thence through a catalyst packed space at a rate such that each unit volume of the reaction mixture soiourns in said open space for at least 0.1 second and in said catalyst space for a period of less than two seconds.

9. In a process for manufacturing liquid hydrocarbon-oxygen compounds by the partial oxidation of hydrocarbons under a pressure above 100 pounds per square inch, the step comprising separating liquid hydrocarbon-oxygen products formed from the gaseous residue of the partial oxidation reaction by condensation of their vapors under pressure, refrigerating the liquid condensate thus formed, and utilizing the refrigerated liquid condensate as a scrubbing medium for recovering additional hydrocarbon-oxygen compounds from the tail gas while holding the tail gas under a pressure above 100 pounds per square inch.

10. In the manufacture of liquid hydrocarbon-oxygen compounds by the partial oxidation of fluid aliphatic hydrocarbons, the step comprising carrying out the partial oxidation reaction at a temperature ranging from 600 to 1000 F. and under a pressure ranging from 200-750 pounds per square inch in the presence of a compound catalyst favoring dehydration and oxidation reactions.

11. The improvement in the art of manufacturing liquid hydrocarbon-oxygen compounds by partial oxidation of hydrocarbons which comprises, carrying out the partial oxidation reaction at an elevated temperature of not to exceed 1000 F., and at a pressure above 100 pounds per square inch, cooling the reaction products by passing them through a condenser and separating condensed liquid hydrocarbon-oxygen product from the unliquefied residue, then passing the said residue through a cooler-scrubber unit wherein additional liquid product is separated by scrubbing the gaseous residue with artificially refrigerated condensate recovered in the water cooled condenser while holding the said gaseous residue under a pressure above 100 pounds per square inch.

' 12. The process of recovering liquid hydrocarbon-oxygen products formed by the partial oxidation of hydrocarbons which comprises, ab' sorbing vapors of the hydrocarbon-oxygen products of the partial oxidation reaction from the residue gas in artifically cooled liquid hydrocarbon-oxygen product previously separated from the gas by condensation at approximately normal temperatures while hold the residue gas during the vapor absorption step under a pressure above 100 pounds per square inch.

13. In the manufacture of liquid hydrocarbon-oxygen compounds by the partial oxidation of hydrocarbons, the steps comprising forming an intimate vapor-phase mixture of a hydrocarbon and oxygen, passing said mixture through a heated partial oxidation reaction zone maintained at an elevated temperature below 1000 F. and at a pressure above 100 lbs. per square inch at a rate such that each unit volume of the reaction mixture passes through the reaction zone in less than two seconds, cooling the gaseous product of the reaction to a temperature below 100 F. and separating 'a liquid hydrocarbonoxygen condensate therefrom, cooling the condensate thus recovered to a temperature below F. and utilizing the thus cooled condensate as a scrubbing medium for absorbing additional hydrocarbon-oxygen vapors from the gaseous residue of the treatment.

14. The process as defined in claim 13 in which the reaction mixture comprises upwards of 10% by volume of a fluid aliphatic hydrocarbon containing at least two carbon atoms in its molecule, and less than 10% by volume of free oxygen.

15. A process as defined in claim 13 in which the hydrocarbon to be treated is preheated by heat interchange with the hot products of reaction, and in which the gaseous product of the treatment is finally devaporized by artificial cooling and is precooled by heat interchange with cold devaporized gaseous residue. I

16. The process as defined in claim 13 in which the reaction is carried out in the presence of a catalyst favoring both oxidation and dehydration reactions.

17. The process as defined in claim 13 in which the partial oxidation and the de-vaporization of the gaseous reaction products is carried out under substantially uniform pressures in the range200 to 500 pounds per square inch.

18. A process as defined in claim 13 in which the gaseous residue is preheated by heat inter change with the products of reaction, oxygen is admixed therewith, and the mixture thus formed is again subjected to a similar treatment.

19. A process as defined in claim 13 in which hydrocarbons .separated from the gaseous residue along with the liquid hydrocarbon-oxygen products are separated from said products at substantially the same pressure at which the reaction takes place and are again subjected to a similar treatment.

JOHN 'CHARLES WALKER.

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