US2042134A - Method of producing hydrocarbon oxygen compounds - Google Patents

Description

` ,May 26, 1936. J. c. WALKER 2,042J34 METHOD 0F PRODUCING HYDROCARBON OXYGEN COMPOUNDS Filed May 1v, 1927l AIR DUST SEPARATOR COMPRESSOR /Z IMETERI H EAT INTERCHANGER Mw; K

ICoN DENsE WESORBE Y 4 REACTION CHAMBER SEPARATOR To MAIN @Mum/woz c/OH/V C. WALKER m6 @www Patented May 26, 1936 UNITED STATES PATENT OFFICEr METHOD OF PRODUCING HYDROCARBON OXYGEN COMPOUNDS Application May 17, 1927, Serial No. 192,077

34 Claims.

This invention` relates to the production of hydrocarbon-oxygen compounds by the oxidation of hydrocarbons, and more particularly to a method of producing alcohols and aldehydes by the controlled partial or selectivecxidation of hydrocarbons such as are found in natural gas with oxygen, air, or other oxygen supplying material in the presence of a catalyst.

It is well known that when hydrocarbons of the type naturally occurring in natural gas, such as methane, ethane, propane and butane, are mixed with air or oxygen in proportions suicient to give anexplosive mixture, a complete or substantially complete combustion of the hydrocarbons can be made to take place. The principal products of the combustion are carbon dioxide and Water. It is also known that when gaseous hydrocarbons of the character above referred to are mixed with air or oxygen in amounts insufcient to form an explosive mixture or to cause 'complete combustion, partial combustion reactions can be made to take place under proper reaction conditions and in the presence of suitable catalysts, with the formation of intermediate hydrocarbon oxidation products such as alcohols, aldehydes, ketones andacids. It has also been observed that if certain of the reaction conditions such as temperature, proportions of reacting constituents, catalysts and the like, yielding the desired intermediate oxidation products of the partial oxidation of hydrocarbons of the type occurring in natural gas, are suiiiciently changed, the oxidation will be carried beyond the intermediate stage to the stage of complete combustion, giving the ordinary complete combustion products, that is, carbondioxide and water.

The primary object of the present invention is to provide a process for effecting the partial oxidation of hydrocarbons by an oxygen supplying material to produce commercial yields of Valuable hydrocarbon oxygen compounds such as alcohols and aldehydes.

`The method of the present invention constitutes a continuation in part of and improvement on the method of treating gas to render it noncorrosive described in my copending application, Ser. No. 165,656 led February 3, 1927, now Patent No. 1,960,212. The invention of said copending application developed from the observation that natural gas having small proportions of free oxygen associated therewith is strongly corrosivertoward the metal pipes and other equipment with which it comes in contact, and from thefurther discovery that by givingV such corrosive gas a partial oxidation treatment of the character set forth in said application, and thereby removing all traces of free oxygen therefrom, the gas can be rendered substantially non-corrosive.

Accordingly another object of the present invention is to provide a process for effecting the partial oxidation of hydrocarbons of the type occurring in natural gas with an oxygen bearing gas under conditions which will give commercial yields of valuable alcohol and aldehyde intermediate oxidation products and a gaseous residue which contains' substantially no free oxygen.

With these and other objects and features in view the invention consistsin lthe improved method for producing hydrocarbon-oxygen compounds by the partial oxidation of hydrocarbons hereinafter described and more particularly described in the claims.

The improved process will be hereinafter more particularly described with reference -to the accompanying drawing, in which the figure is a diagrammatic sketch or flow sheet of the process.

In carrying out the process the hydrocarbon body which is to be treated, preferably one of` the hydrocarbon mixtures now commercially available in the natural gas districts, is conducted from a source of supply in series through a dust separator for the removal of solid foreign impurities, and thence through a meter, compressor, and condenser whereby the gas is measured and then put under a desired pressure and any condensable yproducts removed, providing such removal is desired or necessary. The gas leaving the separator is next preferably preheated, and a definite relatively small proportion of air or other oxygen-bearing gas added thereto. The gas-air mixtureis now passed into -a reaction chamber containing a catalyst which has previously been heated to the desired reaction temperature.v In the catalyst chamber an exothermic reaction resembling combustion takes place by which the free oxygen and the combustible constituents of the gas are combined, the reaction temperature being preferably maintained thereby. The reaction'temperature may thus be controlled by controlling the proportion of air and the degree of preheat added to the' gas prior to admitting it to the reaction chamber.

The hot gaseous products of the reaction, after their removal from the catalyst chamber, are preferably passed through a heat interchanger wherein they are cooled by heat transfer with the gas mixture passing to the reaction chamber,

thus performing the preheating step above referred to. If necessary the gaseous products of the reaction are further cooled in a condenser so as to effect complete removal of any condensable intermediate oxidation products formed in the catalyst chamber. From the condenser the gaseous reaction residue may, if desired, be passed through a liquid gas separator or absorber, or both, where additional water or entrained liquid intermediate oxidation products are removed by scrubbing. The gaseous residue may then be passed to a distributing main, but if the primary object of the treatment is the production of alcohol and aldehyde intermediate oxidation products the gas is preferably treated to one or more additional stages of partial oxidation treatment similar to that above described, each stage being followed by condensation and separation of condensable and absorbable liquid intermediate oxidation products from the gaseous residue of the treatment, until such time as the desired proportion of the combustible constituents of the gas originally treated have entered into combination with one of the portions of oxygen added in each of the several stages. Care is preferably taken to so limit the proportion of freeoxygen added in each stage of the treatment and to so control the other variable conditions of the treatment that the gaseous residue of each stage contains substantially no uncombined oxygen and so that the desired reaction temperature for each stage will not be substantially exceeded due to l out the process according to a plan illustrated by the accompanying. flow sheet will now be de scribed. The gas to be treated, for the purposes of this illustration considered as a natural gas of relatively high caloric value, is drawn from a gas main and passed through a dust separator where any dust of foreign solid matter is removed. The gas is then passed through a meter to determine the rate of ow and volume of gas to be treated. From the meter the gas may be passed through a compressor to place it under suitable superatmospheric pressure and thence through a condenser or absorber to remove any readily condensed hydrocarbons such as the natural gas-gasoline hydrocarbons, or, if the gas is known to contain none of these products or if their removal is not desired and if the gas is already under the desired pressure for carrying out the process, it may be by-passed around the condenser and compressor by a conduit or by-pass line 2. To bring the reaction zone up 4to the desired temperature for starting the reaction, gas leaving the compressor may now be passed by lines-4 and 6 through a heater 8 and then by line I0 into a reaction chamber l2 until the temperature therein has been raised to the desired point, preferably 800 to 900 F. Other means than the heater 8 may be employed to bring the reaction chamber up to the desired starting temperature. After the reaction has once started the amount of preheat which is imparted to the reaction mixture and the amount of oznfgen bearing gas added to the hydrocarbon gas in making up the reaction mixture are pref- -erably both so regulated that the heat of the denite relatively small proportion of air or other oxygen supplying material conducted through a valve 22 and a pipe 24 from the compressor and meter shown in the drawing. The amount of air thus supplied may be regulated by the speed of the compressor or by the valve 22, or by both. If desired, the valve 22 in pipe line 24 may be closed and air may be passed by valved pipe 28 into the heater 8. In this case the heater 3 may serve as a premixing chamber wherein the air is mixed with gas entering the system through valve I8, valve I4 then being closed. From the chamber 8 the gas or gas-air mixture passes either by valved pipe coil l0 or by a valved pipe coil 28 through a heat interchanger 3B inte mixing chamber 20 and thence into the reaction chamber l2,-where the oxygen in the gas-air mixn ture is caused to completely unite with a part of the combustible constituents of the gas by what may be termed a catalytic partial oxidation reaction. The highly heated gaseous products of the reaction leave the reaction chamber by a pipe 32 and are preferably passed through the heat interchanger 30, wherein they give up the greater part of their heat to the incoming gas or gas-air mixture, thence through a water cooled condenser and liquid absorber or condenser where the intermediate oxidation products formed are recovered. The treated gaseous residue finally passes either to a gas distributing main by a pipe 34, or else through another set of apparatus units analogous to those just referred to, wherein the treatment is continued in one or more additional stages with the addition to the gas entering each stage of a relatively small proportion of oxygen bearing gas, the reaction mixture thus formed being preheated, then contacted with a catalyst at a suitable reaction temperature, and then treated in condensing and scrubbing equipment for the removal of the condensable intermediate oxidation products.

The reaction chamber l2, which may be of any' approved construction commonly used in catalytic gas reactions, is preferably lined inside with insulating material. The catalyst charge for the reaction chamber preferably comprises a relatively thick bed or plurality of shallow trays of porous material such as pumice, asbestos fiber or alundum, onv the surface of which a catalyst is deposited. Very good results have been obtained with a catalyst comprising ten grams of metallic platinum per cubic foot of pumice material. Excellent results have also been obtained with many other contact bodies known to favor dehydration, dehydrogenation or oxidation including palladium, chromium, manganese, iron, copper and nickel, as Well as with gold, silver and oxides of copper, manganese and other metals forming higher and lower oxides, such as iron, nickel, vanadium, chromium, molybdenum and cerium. Any mixture or alloy of' the above named catalysts may likewise be used. The invention is not limited vto the use of specic catalysts or contact substances, and while most prior processes directed to the production of intermediate oxidation products lfrom natural gas hydrocar mixture.

bons have carefully avoided the presence of iron in the reaction chamber as having an extremely detrimental effect on the reaction, it has been found that the process of the present invention can be successfully carried on with good yields of methanol, formaldehyde, acetaldehyde, and propionic aldehyde using iron oxide as the catalyst or contact medium.

In carrying on the process a certain proportion of air or other oxygen-supplying material is always necessary in the reaction mixture in order to initiate the reaction and to maintain the desired temperature in the reaction` zone. The amount of oxygen-supplying material thusrequired in the mixture is dependent not only on the character of products desired and o'n the reaction temperatures to be maintained to produce such products, but also on the thermal efficiency of the apparatus, the degree of preheat imparted to the reaction mixture before entering the reaction chamber', and on several other variable factors. For example in treating a hydrocarbon at a definite pressure without preheat it may be necessary to addseveral times the amount of air in order to maintain a desired reaction temperature that would be necessary for treating the same hydrocarbon under the same pressure carrying preheat approaching closely in degree the desired reaction temperature. Likewise the treatment may necessitate the use of relatively large amounts of air in order to maintain the desired reaction temperature with a moderate heat gradient between entering reaction constituents and catalyst bed in apparatus of low thermal eiciency, while the same conditions may be maintained in thermally eflicient apparatus with very much smaller proportions of air. Therefore, assuming that a definite mixture of natural gas and air is being treated, the temperature of the reaction chamber may be regulated by the amount of preheat given the gas-air Referring to the drawing this may be accomplished by proper regulation of valve 42 in pipe 26, valve 22 in pipe 24, valve I4 in pipe I6, valve I8 in pipe 6 and valve 36 in by-pass 38. Thus by regulation of these valves a portion or all of the gas and air may be by-passed around the heater or heat interchanger or both so as to impart a definite degree of preheat to the mixture entering the reaction chamber. The reaction chamber is preferably -so constructed that considerable heat interchange takes place therein between the entering gas-air mixture and the exit gases and the catalyst body. Cooling of the catalyst bed by heat interchange with the gas-air mixture entering the catalyst zone plays an important part in providing a moderate temperature gradient between the entering gas and the point of desired maximum reaction temperature in the catalyst bed. Likewise rapidly cooling the products of reaction by heat interchange with the gas-air mixture entering the reaction zone provides an increased temperature gradient between the pointof maximum reaction temperature in tte catalyst bed and the gas leaving the bcd, thereby retard-ing the thermal decomposition of the reaction products formed. In order to avoid undesirable reactions .which might take place in the heat-interchanger in some cases wherethe air and gas are admixed prior to being preheated, the air may be heated separately from the gas by passing it through the coils 28 of the heat interchanger, or else the air may be by-passedaround the interchanger through the pipe 24 and added directly to the gas in chamber each stage of the treatment a portion or all the` gas may be passed through the heater Ill by 'opening valve I8, while the remainder of the gas may be passed either through valve 36 and the heat-interchanger coils I or directly into mixing chamber through pipe I6. By this arrangement of valves and by-pass lines any desired preheat on the gas-air mixture may be obtained for adjusting the temperature ln the reaction zone.

When operating with certain proportions of gas and air under rather high preheat it is usually desirable to effect the mixture of the two only as they enter the reaction chamber. To accomplish this, air is taken by way of a valved branch line 40 ( valves 22, 42 and a valve 44 at the head of the coil 28 being closed) and passed in a separate circuit through the coils of the heat interchanger 30 and thenceinto chamber 20. While air is thus being preheated in an independent -circuit the gas may be passed through lines 4, 38 and interchanger coils I0 whereby it also receives preheat, and thence into reaction chamber I2 by way of mixing chamber 20.

The apparatus may advantageously include one or more mixingdevlces functioning like illustrated heater 8 and chamber 20 for effecting the complete mixing of the combustible gas and air prior to the introduction of the mixture into the chamber I2. Whether or not such mixing devices are employed it has been found advantageous to keep the air under slightly higher pressure than the combustible gas in order to preventl gas flowing back into the air mains and in order to insure a ready mixing of the two, as by jetting the air into the gas.

The reaction in the chamber I2 between the oxygen and the hydrocarbons in the reaction mixture proceeds with great rapidity, and if relatively largeproportions of air are used in making up the reaction mixture the temperature in the reaction zone will tend to rise too high. It has been found that the best yields of methanol, formaldehyde and acetaldehyde are obtained from the partial oxidation of natural gas in accordance with the present process when the reaction temperature is maintained in the neighborhood of 800 to 900 F., under the preferred conditions of pressure, catalysts and the like herein discussed. Likewise it has been found that as the reaction temperature rises much above the desired maximum of 900 F. (i. e. 1000 or above), the yield of alcohols and aldehydes becomes decidedly poorer, entirely disappearing at higher temperatures with the production of carbon monoxide, carbon dioxide, and hydrogen. It has been particularly noticed that the yield of methanol becomes decidedly and markedly poorer whenever the reaction temperature is allowed to vary more than 200 to 300 F. from the desired maximum. In order to maintain substantially uniform desired temperature conditions in the reaction zone the apparatus illustrated includes means for introducing steam with the gas-air mixture entering the reaction chamber. The presence of this steam in the entering mixture gives rise to endothermic reactions resulting in the formation of water gas, and thus serves to keep down the temperature in the reaction zone. It has been found,

however, that when steam is used as a medium for controlling the temperatures in the reaction zone the yields of desired intermediate reaction products and particularly the yields of methanol.

are adversely affected. Cooling of the catalyst by indirect heat interchange may be employed, but the preferred method for controlling the temperatures to be maintained in the reaction zone in cases where the desired amount of intermediate oxidation products can only be obtained by the addition to the hydrocarbon gas of a greater volume of oxygen-bearing gas than can safely be used in one stage without exceeding the maximum desired reaction temperature limits at which the best yields are obtainable, is by the multiple stage oxidation treatment of the gasl already referred to and more fully hereinafter discussed.

According to this multiple step or stage oxidation method -of treatment the natural gas is passed successively through a number of reaction chambers I2 connected in series, with addition of a small enough proportion of the total air required to produce the desired types and amounts of intermediate oxidation products, to the gas entering the reaction chamber in each of the several stages so that the desired vor preferred reaction temperature is maintained in each stage without overheating and without permitting substantial amounts of free oxygen to be left in the reaction products from any stage. Thus in carrying out a three-stage oxidation treatment, for example, the gas after passing the compressor and meter shown in the accompanying -flgure may be withdrawn at 26 and passed in series through or around the heater 8, thence through the heat interchanger 30, thence in admixture with suflicient air to just maintain the desired reaction temperature, into the reaction chamber l2. The highly heated products of the oxidation treatment in this first stage are thence passed by line 32 back through the first heat interchanger 30 in heat transferring relationship'with fresh gas on its way to the reaction chamber, the gaseous products being thereby cooled and the condensable intermediate oxidation products formed separated therefrom in the condenser and absorber units. The gaseous -residue is now passed from the condenser in series through another heat interchanger 30 and is subjected to partial oxidation with another suitable proportion of air to maintain the desired reaction temperatures in the second reaction chamber |12, after which the products of reaction of this second stage of treatment are cooled by passing through the second interchanger, and condensable intermediate oxidation. Products formed in the second stage of the treatment are separated therefrom in the second condenser and absorber units. The

gaseous residue of the second stage passes in turn through an exactly similar cycle, traversing in turn another heat interchanger, another reaction chamber, back through the heat interchanger, and after passing another condenser and absorber and a separator wherein the last recoverable traces of the condensable intermediate oxidation products are separated therefrom, the final,

air and fresh untreated hydrocarbon gases. The number of stages necessary for suitably treating the gas is determined by the maximum temperature desired in each stage and by the total amount of air which it is ,necessary to add in order toeilect production of the desired amount of liquid intermediate oxidation products. As already indicated the hot gaseous products of each stage of the treatment are preferably cooled and the liquid condensate formed is preferably trapped off therefrom before admixing air with the residue for treatment in the next stage. The same catalyst may be used in all stages, or different types of catalyst may be used in any one or all of the stages, as desired. Likewise the conditions of operation in the several stages may be varied with the object of producing one type of hydrocarbon intermediate oxidation product, for example methanol or other alcohol, as the prinm cipal product in one stage, while later producing another entirely different type of principal product, such as formaldehyde, for example, in another stage. As shown in the drawing, the apparatus is preferably so arranged that the treatment can be completed in one stage if desired, 25

each unit apparatus assembly of heat interchanger, reaction-chamber and condenser being so arranged that it can be operated in parallel with the other unit assemblies in the treatment of separate portions of gas taken from the main 30 supply, with separate portions of air abstracted from the main air supply line leading from the compressor. This single stage method of treatment may be used in cases where the production of only a limited volume of liquid intermediate 35 oxidation products, together with a combustible gaseous residue having substantially no free oxygen content and a suitably controlled lower caloriilc value than the original gas, is desired.

It has been found that pressure plays an important part in determining the character of the liquid intermediate oxidation products formed during the partial oxidation reactions. Thus it has been found for example that pressures of at least lbs. gauge are necessary with a platinum catalyst and with other reaction conditions within the limits hereinafter referred to in order to obtain even small yields of alcohol and aldehyde oxidation products (with the exception of formaldehyde, which is obtainable at lower pressures with some types of catalysts). From a minimum pressure of about 100 lbs. per square inch the alcohol-aldehyde yield in general increases with an increase in pressure. Relatively large yields of methanol and aldehyde products have been obtained by the operation of the present process at pressures ranging from to 300 lbs. per square inch.

It has been found that a careful and accurate control o f reaction temperatures is an extremely important factor in the production of commercial yields of alcohol from natural gas. Moreover experiments have apparently shown that the manner in which this temperature control is effected also materially affects the character of the' liquid intermediate oxidation products obtained. Thus, while it would seem that if the optimum temperatures in the catalyst reaction chamber are maintained by any means the formation of a maximum yield of a desired alcohol product would result, apparently this is not true. It has been observed that the maximum yield of methanol, for example, is obtained when the gas is first preheated to within 100 to 200 F. of thedesired reaction temperature, as by interchange or other aotaisa.4

externally applied heat, and after thus having so that by the heat of the reaction set up in the reaction chamber the desired temperature for the best yields of alcohol is just reached. By comparison of a run in which an approximately maximum yield of methanol was obtained by control of the conditions of preheat and air addition for best results in the manner above described, with a similar run using a relatively larger percentage of air with the introduction of steam for the purpose of controlling the reaction temperature, it was observed that while the pyrometers indicated about the same reaction temperature in both cases, the yield of methanol in the second run was grealty reduced, and the aldehyde yield was also quite small, while greatly increased amounts of carbon monoxide and hydrogen appeared in the exit gases. This indicates that while in the rst run the mixture of air and gas is carried gently and uniformly to the desired reaction temperature without the occurrence of local overheating, in the second case the methanol and aldehyde 4intermediate oxidation products were probably largely decomposed by local overheating. Furthermore when a gas-air mixture under 300 pounds pressure contains just sufficient amounts of air to make the partial oxidation reaction self-sustaining, without preheat, as in the second run mentioned above, the reaction temperature set up is above 1000v F., and accordingly the percentage yield of alcohol and aldehyde products is greatly reduced. For the above reasons it has been found that the best yields of alcohol and aldehyde products are obtained by preheating the gas to within 50-100 F. of the desired reaction temperature, and then adding air in proportions less than 50% by volume,-and preferably from 4 to 20% by volume of the-gas, the amounts of air used within these limits being governed by the amount of preheat imparted to the gas and by the eflciency of heat interchange and of insulation ofthe -system. For this reason when the operation of the process is directed toward the production of alcohol and aldehyde oxidation products as the principal products, as distinguished from their production as by-products of a treatment directed primarily to the production of a fuel gas of uniform lower caloric value, the small amount of oxygen supplying material that can be'added to the gas at any one time suggests the use of a -multiple step or stage treatment of the gas by passing it through a number of catalyst chambers in series, the number to be controlled by economic considerations. 'I'he temperature control of the process of the present'invention is 'y therefore preferably effected by the use 'of a multiple step or stage oxidation treatment, with preheating of the gas for each stage, addition of regulated quantities of air and 'interchange cooling of the exit gases, with condensation, absorption, and collection of the condensate between stages.

The formation of the intermediate oxidation products by the'process ofthe present invention involves exothermic reactions and a decrease in volume of reaction products over the corresponding volume of constituents taking part in the reaction. Likewise decomposition of the reaction products formed involves an increase in volume of decomposition products. By maintaining uniform controlled superatmospheric pressure reaction, the reactions, the products of which have a lesser volume than the reacting constituents, are promoted and caused to take place under optimum pressure conditions giving the best yields of oxidation products, while at the same time the decomposition of such products into other compounds of greater volume is prevented or retarded. Similarly by controlling the temperature of the reaction and the character and degree of preheat imparted to the gases entering the reaction zone, as well as the degree of cooling of the products of the reaction-as by heat interchange between the products -of reaction, the catalyst bed, and the gas entering the reaction zone-it is possible to maintain suitable moderate .temperature gradients between the gases entering and leaving the point of optimum temperature of the catalyst bed to produce desired yields of oxidation products while at the same time protecting the reaction products from thermal decomposition.

It is extremely important that the presence of free oxygen in the gaseous products of the oxidation reaction be carefully avoided, not only because the presence of free oxygen in the exit gases indicates that the reaction is not properly completed and accordingly that the yields are lower than they should be, but also that the exit gas will have corrosive properties.

It will be evident that various types of apparatus of the character described may be used for carrying out the process of the invention and for effecting the necessary preheating, reaction contact, and cooling of the reacting gases, as well as -for initiating and maintaining the proper temperature for the catalytic reaction. It will be also evident that the various conditions of reaction may be varied in accordance with the character of intermediate oxidation products desired. Chief among these conditions are the temperature and pressure under which the reaction is. 4 carried out, relative proportions of the reaction constituents, the methods of temperature control employed, and the time of contact of the reaction mixture with the catalyst. The catalytic oxidation may be varied to produce products of variable character by varying the time of contact of the reacting gases with the catalyst. vIt has been observed that the yields and character of desired alcohol-aldehyde intermediate oxidation products of natural gas vary with variations in the time of contact of the reaction gases with the cataylst, other conditions remaining constant. Thus satisfactory yields of methanol and aldehydes have been obtained byoperating the present process in such a way that thek time of contact of the reaction mixture with the catalyst is less than A second. Likewise satisfactory yields have been obtained by operating so that the reaction mixture remains in contact with the catalyst for a period of several seconds. This contact time may be varied in the range 1A second to six seconds. 'I'hus it has been found thatby preheating a body-of natural gas under 300 lbs. per square inch pressure to a temperature of 750 F. and then admixing airtherewith to the extent of approximately 7.2% by volume of the gas and passing the mix- `ture in indirect heat interchange relationship `volume of the mixture is in contact with an equal volume of the catalyst for a period of 4.2 seconds, the-'liquidseparated from the gaseous product on cooling and condensation contains 45% by volume of methanol, 31% of a 40% solution of formaldehyde, and 4% of acetaldehyde, together with water and other products of the oxidation treatment. A volume of methanol equal to that obtained from the gaseous product by condensationvcan be recovered from the gas residue leaving the condenser by absorption with water. The gaseous residue of this treatment contains substantially no free oxygen. A long exposure of the reaction products to the catalyst at the higher reaction temperatures tends to decompose Valcohol-aldehyde intermediate oxidation products with consequent formation of carbon oxides and hydrogen. It is believed that the partial oxidation reactions resulting in the formation of these intermediate oxidation products approximate the of course, a paramount requirement in handling gas under high pressures. By using catalysts with the present process the iron and other materials employed in the construction of the apparatus are never heated to a temperature approaching that at which their physical strength or properties would be materially alfected. Another advantage of using catalysts with resultant lower reaction temperatures is that the reaction temperature may be maintained with the addition of a comparatively small portion of air to the gas under treatment, thus allowing successful operation of the process without addition of external heat, even when the character of the desired products of thereaction permit the use of only relatively small ,proportions of air.

The foregoing description of the process and of the conditions under which it is carried out has been limited more or less to the treatment of natural gas hydrocarbons. However, it is to be understood that the invention is not limited to the treatment of natural gas, but that on the contrary the principles thereof may be applied to the treatment of other hydrocarbons, such as those present in coal or in the gases derived therefrom, or in the gases and vapors formed by the thermal treatment of petroleum and oil shale. While the process of the present invention relates chiefly to the production of alcohols and aldehydes it will be understood that by suitably varying the time of contact of the reaction'mixture with the catalyst, the temperatures and pressures, the character of catalyst and the degrees of superheat and proportions of air or other oxygen supplying material in the reaction mixture, other valuable intermediate oxidation products may be obtained. For example, in the preferred method of operation above discussed, aldehydes, specifically acetaldehyde and formaldehyde, usually constitute more than 30% by weight of the total nonaqueous condensate recovered, of whichover 60% of the remainder is usually methanol. However, by varying some of the reaction conditions named the al- `dehyde yield can be considerably increased at'the expense of a decreasein the proportionate yields of alcohols. It has been observed that under the gaseous residue of the flrst stage of the oxidation treatment after separation of liquid condensatesy therefrom usually contains noticeable proportions of carbon monoxide, hydrogen and unsaturated hydrocarbons over and above the amounts of these 5 respective constituents present in the original natural gas under treatment. Likewise the pro-4 portion of unsaturated hydrocarbons in the gas residue from the treatment appears to bear a direct relation to the pressure under which the reaction is carried out.

It has been found that while the liquid condensate which is recovered from the treatment of natural gas in accordance with the process of the invention has a water content of substantially 40% by volume, it is neverthelesscombustiblewithout separation of this Water content, probably due to the high proportion of combustible alcohols in its non-aqueous component.

Pure oxygen, ozone, carbon oxides or other materials capable of supplying oxygen under the conditions of pressure, temperature and the like maintained within the reaction zone may be used in place of air as the oxidizing agent. Likewise materials other than the nitrogen of the air 25 may sometimes be used to advantage as inert diluents for the oxidizing agent or for the hydroc'arbons under treatment. Thus for example the hydrocarbons which it is desired to treat may be diluted with other more stable hydrocarbons 30 which will not respond to partial oxidation treatment under the conditions of temperature, pressure and the like maintained in the reaction zone of the treating equipment.

It may be found necessary to change many or 35 all of the factors controlling the reaction, iricluding the temperatures, pressure, time of contact o f reacting constituents with the catalyst, proportions of reacting constituents and the like, in response to changes in other factors, and par- 40 ticularly in response to changes in the pressures and catalysts employed.

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

1. In the manufacture of partial oxidation 45 products of hydrocarbons, the process which comprises heating an intimate mixture of a fluid aliphatic hydrocarbon and 0.8%-10% its volume of available oxygen to a temperature favoring partial oxidation of said hydrocarbon to intermediate oxidation products, carrying out the reaction under a pressure exceeding 100 lbs. per square inch, and separating the intermediate oxidation products formed from the unreacted residue.

2. A method of converting hydrocarbons into intermediate oxidation products, comprising treating ahydrocarbon body to partial oxidation reactions with an oxygen supplying material in the proportions of 0.8%10% its volume of free 60 oxygen equivalent at a temperature of 600 F.- 1000 F., and separating the intermediate oxi- Vdation productformed from the residue of the treatment.

3. In the manufacture of partial oxidation G5 products of hydrocarbons, the process which comprises placing an intimate mixture of a hydrocarbon and oxygen under a pressure in excess of 100 lbs. per square inch, and passing said mixture through a reaction zone heated to a temperature of 600 F.l000 F. at a rate such that the time of sojourn of the mixture in the reaction. zone is between 1)irish second and one second.

4. In the manufacture of partial oxidation products of hydrocarbons, the process which comprises passing an intimate mixture of a hydrocarbon and oxygen, under a.v pressure exceeding 150 lbs. per square inch, through a reaction zone maintained at a temperature of 600 F.-1000 F.,

and maintaining a temperature diierence of about 200 F. between the gas mixture entering the reaction zone and the point of maximum reaction temperature therein, while rapidly cooling the gas leaving the reaction zone.

5. In the manufacture of partial oxidation products of hydrocarbons, the process which comprises heating an intimate mixture of a fluid aliphatic hydrocarbon and oxygen to a temperature of 600 F.1000 F., While maintaining it under a pressure in excess of 150 lbs. per square inch, and separating the intermediate oxidation product formed from the residue of the treatment.

6. 'I'he process which comprises heating an intimate mixturev of a normally gaseous hydrocarbon and less than its volume of available oxygen to a temperature of 600 F.-1000 F., under a pressure in excess of 100 lbs. per square inch,

cooling the products of the reaction thus set up, Y

and separating condensable liquid products from the residue of the treatment. y

7. Theprocess'of converting a hydrocarbon into an intermediate oxidation product, comprising treating said hydrocarbon to partial oxidation reactions at a temperature of 600 F.1000 F. and under superatmospheric pressure above 150 lbs. per square inch, in the presence of a catalyst, with an oxygen supplying gas admixed with the hydrocarbon under treatment in the proportions of 0.8%-10% by volume of free oxygen equivalent for every volume of hydrocarbon.

8. The process comprising heating a mixture comprising an aliphatic hydrocarbon and less than 1/2 its volume of air to a temperature of 600 F.1000 F., while maintaining said mixture under a pressure in excess of 100 lbs. per square inch, cooling the products of the reaction thus set up, and separating the condensable liquid products from the residue of the treatment.

9. The process as described in claim 2 in which the reaction is carried out under a pressure aboveV 100 pounds per square inch.

10. A process of converting a hydrocarbon into an intermediate oxidation product, comprising subjecting said hydrocarbon and an oxygen supplying material to partial oxidation reactions at a temperature of 600 F.1000 F. and under a superatmospheric pressure above 100 lbs. per square inch, and maintaining the reacting constituents in the reaction zone for a period of between 1/ith second and six seconds.

11. The method of partially converting natural gas into intermediate oxidation products comprising admixing air with said gas in proportions of less than one-half volume of air to each volume of gas, passing the said mixture under a pressure exceeding 150 lbs. per square inch through a hot reaction zone, separating the intermediate oxidation products formed in the reaction from the gaseous residue, and maintaining a temperature diierence of less than 200 F. between the hydrocarbon entering the reaction zone and the point of maximum reaction temperature in said zone.

12. The process for producing aliphatic alcohols and other valuable liquid products from fluid aliphatic hydrocarbons, which comprises forming a mixture of` said hydrocarbon and air in such proportions that the mixture contains 0.8%- 10% lof uncombined oxygen and a high percentage of inert material consisting mainly of nitrogen, heating the'mixture to a. temperature in the range 600 F.-'1000 F. while under a pressure in excess of 100 pounds per square inch, maintaining the mixture at reaction temperature until combination of the free oxygen is substantially complete, cooling the product of the reaction and separating `condensable. liquids therefrom, and admixing unreacted hydrocarbon residue of the reaction with fresh quantities of air in preparation for further reaction.

13. The method of partially converting a hydrocarbon into `intermediate oxidation products, comprising treating said hydrocarbon to partial oxidation with 0.8%-10% its volume of oxygen at an elevated temperature in the range 600 F.- 1000 F., and maintaining a temperature difference of less than 200 F. between the hydrocarbon entering the reaction zone and the point of maximum reaction temperature in said zone. l

14. The method of converting a uid aliphatic hydrocarbon into a liquid hydrocarbon-oxygen compound comprising, treating said hydrocarbon to partial oxidation reaction with oxygen in proportions of 0.8%-10% by volume of oxygen per volume of reaction mixture, maintaining a substantially uniform pressure exceeding 100 pounds per square inch, on the reaction mixture entering, passing through and leaving the reaction zone, and maintaining a Itemperature difference not exceeding 200 F. between the material entering the reaction zone and the point of maximum reaction temperature therein while rapidly cooling the products leaving the reaction zone.

15. The method of converting natural gas into intermediate oxidation products, comprising placing a body of said gas under a pressure exceeding 150 lbs. per square inch, admixing air therewith in proportions of about one volume of gas to less than 1/2 volume of air, and contacting said gas-air mixture with a catalyst at a temperature of 600 F.-1000 F.

16. In the `manufacture of partial oxidation products of hydrocarbons, the process which comprises heating a mixture of a hydrocarbon which is gaseous at normal temperature and `pressure and less than its volume of air, in a suitable reaction chamber, to a temperature of 600,F.1000 F., while maintaining it under a pressure greater `than 150 lbs. per square inch,

andvrecovering methanol and formaldehyde from theresultant reaction gases.

17. The method of converting an aliphatic hydrocarboninto alcohols, aldehydes and other intermediate oxidation products comprising, reacting said hydrocarbon under a pressure above 150 lbs. per square inch, with an oxygen supplying gas admixed therewith in proportions of less than 116 volume of free oxygen equivalent perv volume of hydrocarbon, at a temperature `of 600 F.1000 F., cooling the products ofthe reaction thus set up by heat interchange with the hydrocarbons entering the reaction zone, and

separating the intermediate voxidation products formed from the residue ofthe treatment.

18. The method of converting a gaseous aliphatic hydrocarbon into, intermediate oxidation products comprising reacting a body of said hydrocarbon under a superatmospheric pressure above 150 lbs. per square inch, with air admixed therewith in proportions of less than one volume of air to each volume of hydrocarbon in the presence of a suitable catalyst at a temperature of 600 F.-1000 F., cooling the gaseous product of the reaction,.separating the intermediate oxidation products formed from the thus cooled gaseous product, and controlling the conditions under which the reaction is caused to take place to produce a gaseous residue of controlled caloriilc value containing substantially no free oxygen.

19. The process for producing liquid hydrocarbon-oxygen products including alcohols from aliphatic hydrocarbons, which comprises passing the hydrocarbon in admixture with between 0.8% and 10% of its volume of oxygen through a reaction zone while holding the mixture under a pressure in excess of 100 pounds per square inch, maintaining a rate of ow of the mixture through the reaction zonesuch that the mixture sojourns therein for a period of between Vgth second and 6 seconds, and cooling the products of the reaction.

20. The process for producing liquid hydrocarbon-oxygen products including alcohols from aliphatic hydrocarbons, which comprises passing a mixture of aliphatic hydrocarbon and oxygen through a reaction zone while maintaining said zone under a pressure above 100 pounds per square inch and at a temperature between 600 F. and 1000 F., maintaining'a rate of now of the mixture Athrough the reaction zone such that the mixture sojourns in the reaction zone for a period between 11th second and 6 seconds, and keeping the oxygen concentration in the reaction mixture below 10%.

21. The method of partially converting a hydrocarbon gas into intermediate oxidation products, comprising passing a mixture of said gas and oxygen through a catalytic reaction zone maintained at a temperature of 600 F.1000 F., and under a pressure above 150 lbs. per square inch, at a rate such that each unit volume of the reaction mixture is in the high temperature reaction zone for a period of between 541th second and one second, and separating intermediate oxidation products formed from the gaseous residue of the treatment.

22. The method of converting a hydrocarbon which is gaseous at normal temperature and pressure into an intermediate oxidation product, which comprises admixing air with said hydrocarbon in proportions of less than one half volume of air to each volume of hydrocarbon, passing the mixture under a pressure exceeding 150 lbs. per square inch through a heated re-` action zone, maintained at a temperature of 600 F.-1000 F., at a rate such that the hydrocarbon-air mixture remains in the reaction zone for a period of between 1/sth second and one second, separating the intermediate oxidation products formed from the gaseous residue' of the treatment, and maintaining a temperature dif- 4 ference of less than 200 F. between the mixof a second and 6 seconds, cooling the gaseous products of the reaction, and separating therefrom condensable hydrocarbon-oxygen compounds thereby formed.

24. In a process for manufacturing liquid hydrocarbon-oxygen compounds from fluid aliphatic hydrocarbons, the step of reacting the hydrocarbons in a vaporized form with uncombined oxygen under a superatmospheric pressure and at a temperature of 600 F.1000 F. while keeping the oxygen concentration in the reaction mixture between 0.8% and 10%.

25. A method of converting a hydrocarbon into intermediate oxidation products comprising heat- 5 ing the hydrocarbon admixed with 4%-50% of its volume of air to a temperature of 600 F.-

l000 F.and under a. pressure-in excess of 100 pounds per square inch.

26. In the manufacture of partial oxidation products, of hydrocarbons, the process which comprises passing an intimate mixture comprising a reactive aliphatic hydrocarbon and 0.8% to ten per cent by volume of oxygen rapidly through a vreaction zone heated to a temperature of 600 F. 15

chamber separate from the heating zone to produce liquid partial oxidation products in a single step directly from the original constituents.

28. An improved synthetic and addition process of partially oxygenating a normally gaseous hy- 30 drocarbon which comprises preheating the hydrocarbon gas and an oxidizing gas separately and subsequently reacting the two gases in a chamber separate from the heating zone, controlling the temperatures of the reacting gases 3'5 to prevent overheating, and controlling the time of the reaction to produce liquid partial oxidation products in a single step directly from the original constituents. y

29. A process of oxidizing natural gas which 40 comprises separately and independently heating4 and compressing the natural gasand an oxidizing gas, then combining the two gases in a closed chamber separate from and independent of the compression zone, regulating the temperature of the reaction, and then separating the liquid and vapor products of the reaction.

30. A process for producing normally liquid, partially oxidized hydrocarbons from normally gaseous hydrocarbons and an oxidizing gas in a single reaction step from the original constituents, which process comprises compressing and heating the gaseous hydrocarbon, and separately compressing and heating the oxidizing gas, then passing the two gases withoutvprior admixture and without reduction of pressure directly into and continuously through a. reaction zone separate from the zones of compression.

31. A processV for producing normally liquid, partially oxidized hydrocarbons from normally gaseous hydrocarbons and an oxidizing gas in a single reaction step from the original constituents, which process comprises compressing and heating the gaseous hydrocarbon, and separately compressing and heating the oxidizing gas, then 05 passing the two gases without prior admixture and.without reduction of pressure directly into and continuously through a reaction zone separate from the zones of compression, and controlling the temperature of. the reaction.

32. A process for producing normally liquid, partially oxidized hydrocarbons .from normally gaseous hydrocarbons and an oxidizing gas in a single reaction step from the original constituents, which process comprises compressing andheating 75 the gaseous hydrocarbon, and separately compressing and heating the oxidizing gas, then passing the two gases without prior admixture and without reduction of pressure directly into and continuously through a reaction zone separate from the zones of compression, the reaction being carried out in the presence of a 'platinum catalyst.

33. In a process as herein described, the improvement which comprises compressing and heating a normally gaseous hydrocarbon, `and separately compressing andheating an oxygencarrying gas, then passing the two gases without reduction oi pressure into and continuously through a reaction zone separate from the zones of compression without admixture of the gases prior to the reaction zone, and controlling the period and temperature of the reaction to produce a normally liquid, partially oxidized hydrocarbon mixture from the original constituents in a single step.

34. A process i'or producing normally liquid, partially oxidized hydrocarbons from normally gaseous hydrocarbons and an oxidizing gas in a single reaction step from the original constituents, which process comprises compressing and heating the gaseous hydrocarbon and separately compressing and heating the oxidizing gas, then 1o passing the two gases without prior admixture and without reduction of pressure directly into and continuously through a reaction zone separate from the zones of compression, the reaction being carried out in the presence oi a catalyst. l5

J OHN CHARLES WALKER.

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