WO1985000164A1

WO1985000164A1 - High temperature production of benzene from natural gas

Info

Publication number: WO1985000164A1
Application number: PCT/US1984/000949
Authority: WO
Inventors: William Bartok; Yih H. Song
Original assignee: Exxon Research And Engineering Company
Priority date: 1983-06-20
Filing date: 1984-06-20
Publication date: 1985-01-17
Also published as: AU3105384A; NO850636L; IT8421493A0; EP0145784A1; IT1174210B

Abstract

Benzene is produced from methane containing gases such as natural gas by heating the gas to a temperature of from about 1300 K to 1800 K and then contacting the hot gas with from about 0.7 to 10 volume percent oxygen in a reaction zone for a time sufficient to form a benzene containing product and then quenching the mixture of product and unreacted gas. The oxygen and methane are separatly introduced into the reaction zone.

Description

HIGH TEMPERATURE PRODUCTION OF BENZENE FROM NATURAL GAS

FIELD OF THE INVENTION

This invention relates to producing higher hydrocarbons from methane. More particularly, this invention relates to the high temperature conversion of methane and methane containing gases to C₂ and higher hydrocarbons, including benzene, in the presence of minor amounts of oxygen separately added to the reaction zone as a free radical initiator.

BACKGROUND OF THE DISCLOSURE

For over fifty years scientists have been attempting to find efficient processes for producing useful liquid hydrocarbon products from natural gas. In October of 1931, the United States Bureau of Mines published a report by Smith et al. titled "The Production of Motor Fuels From Natural Gas" Report No. R.I. 3143. In this report. Smith and coworkers summarized the results of extensive investigations directed toward optimizing the production of benzene and C₂ unsaturates from methane by the high temperature pyrolysis of natural gas. Their process employed furnace temperatures ranging from about 1150 to 1240 °C and, under their optimum conditions, they obtained a feed conversion of 29% with a selectivity towards benzene production of 18.5 wt.% of the feed converted. Other products produced by the Smith et al process were ethylene, acetylne, hydrogen and tar and carbonaceous solids. The selectivity of feed converted to tar was 21 wt.%. Selectiv.ity means the amount of product produced from the converted feed. Thus for every pound of methane that was converted to higher hydrocarbons, 21 wt.% of the product was tar and 18.5 wt.% was benzene. During their experiments. Smith and coworkers first purged the reactor of air using a stream of nitrogen to insure the absence of oxygen in the reaction zone, after which a methane or methane containing natural gas was introduced directly into the reactor. Shortly thereafter, Smith and coworkers were granted U.S. Patent 2,061,597 directed to optimization of the reaction time for maximiz- ing benzene production over the cracking range of 1000-1200°C. At the optimum conversion temperature of 1150°C, the reaction time was determined to be 42 milliseconds. It should be noted that Smith employed relatively short reaction times in order to avoid the formation of tar and carbonaceous materials. In his article. Smith disclosed that at a furnace temperature of 1200°C a benzene to tar yield ratio of about 1.6 was obtained (tar does not include solid, carbonaceous materials). One can calculate that the reaction time at 1200°C was about 270 milliseconds.

in U.S. 2,063,133, Hans Tropsch disclosed that liquid products could be obtained from paraffinic and olefinic hydrocarbon gases at relatively low temperature conditions of 500-1000°C. The pyrolysis occurred in the presence of from about 0.1 to 1.0% of chlorine or chlorine-containing compounds, with 1.0% being regarded as the upper limit. Unfortunately, details of the Tropsch process are not disclosed. That is, Tropsch did not discuss the amount of tar and carbon that was generated using his process. Another attempt to produce benzene from methane or low molecular weight hydrocarbons is disclosed in U.S. 2,875,-l413 which used two-stage catalytic process to form liquid products such as benzene. Much of the art relating to the pyrolysis of low molecular weight hydrocarbon gases such as methane, ethane, etc. relates to the production of acetylene therefrom as is disclosed in U.S. 2,721,227 and 2,912,475. It should be noted that U.S. Patent 2,875,148 and 2,912,475 both teach processes which specifically exclude the presence of oxygen in the reaction zone. Thus, the reactions disclosed in these patents relate strictly to thermal pyrolysis in the absence of materials added to the reaction zone which could initiate or promote free radical reactions. Also, they do not disclose the formation of benzene and the hydrocarbon feed must contain at least two carbon atoms in the molecule. Suitable feeds disclosed include ethylene, benzene and a naphtha stream.

U.S. Patent 2,608,594 to Robinson discloses a two-stage methane cracking process for producing benzene. In this process, the methane feed is heated to about 1367 K and then mixed with an oxygen-free, hot combustion gas containing free hydrogen to produce a mixture of feed and hydrogen rich gas at a temperature of about 1900 K. This hot mixture is held at 1900 K for about 0.01 seconds which produces an acetylene containing gas rich in hydrogen. The acetylene containing gas is then quenched with additional, cooler hydrogen rich gas to a temperature of about 1422 K and held at this temperature for about 0.8 seconds to produce a product rich in benzene. It should be noted that this process also produces substantial quantities of tar and solid carbonaceous products.

Despite more than fifty years of activity directed towards trying to pyrolyze low molecular weight gases to liquid hydrocarbons such as benzene, there is still a need for a process that will accomplish this with negligible or relatively low carbon and tar formation and with relatively high selectivity of the feed converted to liquid hydrocarbons rich in benzene.

SUMMARY OF THE INVENTION

A process has now been discovered for producing useful higher hydrocarbon products, including liquids rich in benzene, by a free radical initiated, thermal conversion of methane or methane containing gas feeds, with a relatively high selectivity of feed conversion to benzene and negligible production of tar and solid carbonaceous materials. In this process the methane containing gas feed contacts oxygen, in a reaction zone, wherein the oxygen acts as the free radical initiator. An important part of this process is that the oxygen and gas feed should not be premixed, but should be separately introduced into the reaction zone.

Thus, the present invention relates to producing C₂ and higher gaseous hydrocarbons and hydrocarbon liquids rich in benzene from methane containing gas feeds by a process which comprises contacting said feed with oxygen at a temperature of at least about 1300 K for a time sufficient to convert at least a portion of said feed to benzene, wherein the oxygen is separately introduced into the reaction zone and is present in the reaction zone in an amount greater than 0.5 volume % of the methane. Liquid hydrocarbon means of course, hydrocarbons that are liquid at 25°C and one atmosphere pressure. By methane containing gas feed is meant natural gas, methane containing synthesis gas produced by the partial combustion of coal, coke or other, carbonaceous material, and the like. By negligible tar and solid carbonaceous materials is meant less than about 2 wt.% of the total product. It has also been found and forms a part of this disclosure that the methane can be heated to relatively high temperatures of 1300 K or more in the presence of alumina without the formation of carbon on the alumina surface. This is surprising in view of the fact that those skilled in the art know that methane starts to decompose and cause fouling of surfaces at temperatures as low as about 923 K. Thus, it has also been found that alumina may be used as a heat exchange medium for preheating methane without incurring decomposition of the methane into carbonaceous materials.

DETAILED DESCRIPTION OF THE INVENTION

The reaction time, temperature and the amount of oxygen required in the process of this invention are interrelated. Higher reaction temperatures require less reaction time and smaller amounts of oxygen and vice-versa. In general, the reaction temperature will range from about 1300 to 1800 K. Preferred and optimum reaction temperatures will depend on the reaction pressure. At atmospheric pressure the reaction temperature will preferably range between about 1400 to 1700 K, and more preferably from about 1400 to 1600 K. Under these conditions the reaction time will broadly range from about 0.1 to 1 seconds, preferably 0.2 to 0.5 seconds, and still more preferably from about 0.2 to 0.3 seconds. If the reaction is allowed to continue for too long a time, the selectivity for benzene production will decrease, and significant amounts of undesirable tarry and carbonaceous materials will be formed.

It is important to the process of this invention for the oxygen and methane not to be mixed until the methane has reached the reaction temperature and then to mix them at the reaction temperature as rapidly as possible in order to achieve a free radical reaction initiated by the oxygen and thereby minimize undesirable reactions and concomitant formation of undesirable compounds. As a practical matter this is easily achieved by separately introducing the oxygen and methane containing gas feed into the reaction zone. Similarly, the methane should be heated to the reaction temperature as rapidly as possible to avoid degradative pyrolysis of the methane. The methane can, if desired, be preheated to a temperature as high as about 975 to 1075 K in the absence of oxygen for relatively short periods of time without cracking or polymerizing to carbonaceous materials or precursors thereof. Thus, it may be advantageous to preheat the methane by any convenient means to such temperature in order to minimize the heat duty of the reactor or reactor feed heater. In the Examples, infra, methane was heated in one step from room temperature to the reaction temperature at a rate, of from about 10⁴ to 10⁵ K/sec. If desired, the methane or methane-containing gas feed may be at least partially heated by burning some of the feed, mixing unburned feed with the combustion products and introducing the mixture into the reaction zone wherein it contacts the oxygen or oxygen precursor.

it is also important to rapidly cool or quench the reaction products formed by the process of this invention down to temperature levels sufficiently low to stop further reaction and concomitant loss of desired products to tar and carbonaceous materials. Suitable low temperatures will broadly range from about 500 to 1,000 K depending on (a) the products desired (i.e., C₂ and higher saturated or unsaturated hydrocarbon gases, or liquids such as benzene and toluene) , (b) the time that the products are held at such temperature, and (c) the secondary cooling rate from such temperature to temperature where no degradation occurs such as ambient temperatures. It is understood of course that degradation of benzene and other reaction products (especially unsaturates such as acetylene, ethylene and other olefins) may occur even at temperatures as low as 500 K, the extent of such degradation being a function of time and temperature. The quench rate employed will depend on the reaction products desired. Thus, it will be appreciated that a faster quench rate will be needed if acetylene is a desired product than if the desired product is benzene and acetylene is not desired. As an illustrative, but nonlimiting example, quench rates ranging between 10⁴ K/sec and 10⁶ K/sec have been successfully employed in the process of this invention when quenching methane reaction products from a reaction temperature of about 1500 K down. to about 500 K. A quench rate of 10⁴ K/sec and 10⁶ K/sec, respectively, will cool from 1500 K down to 500 K in 100 milliseconds and 1 milliseconds, respectively.

As previously stated, more than 0.5 volume percent of oxygen based on the methane content of the feed gas is required for the process of this invention. Preferably, at least 0.7 volume percent and more preferably at least about 1.0 volume % of oxygen will be used. This oxygen content is based on molecular oxygen. However, the oxygen may be present as either molecular oxygen or compounds which on heating yield oxygen containing free radicals wherein one or more unpaired electrons are on the oxygen atom, such as ROO. peroxy compounds, RO- ,. etc. While not wishing to be held to any particular theory, it is believed that the process of this invention is initiated by free radicals such as 0-, Q.H , and hydrocarbon free radicals formed by the reaction of oxygen with methane. The maximum amount of oxygen employed as a free radical initiator will depend on considerations of yield and product selectivity, but in general it is preferred not to exceed about 10 volume % and more preferably 5 volume % oxygen based on the methane content of the feed. Thus, those skilled in the art will appreciate that the process of this invention is not a conventional combustion process or partial oxidation process.

Although benzene is a particularly desirable product of the process of this invention, other useful C₂ and higher gaseous and liquid hydrocarbon products are also formed. The following table, obtained using the procedure in Example 2, below, gives a breakdown of a typical product slate from a methane feed contacted with 2.0 volume percent oxygen for 250 milliseconds at a reaction temperature of 1425 K. The extent of methane conversion was about 25 wt.%. Negligible amounts of solid carbonaceous materials or tarry materials were detected.

As previously stated, negligible means less than about 2 wt.% based on the total product. In general it has been found that from about 0.4 to 2 wt.% of tarry and solid carbonaceous materials, based on total product (or 0.1 to 0.5 wt.% based on methane feed) will be produced by the process of this invention. Another way of expressing this is the ratio of tar and solid carbonaceous materials produced to the amount of benzene produced which is 1.1 to 5.7 wt.%. This is in marked contrast to prior art processes such as those of Smith et al. which produced 21 wt.% tar and 18.5 wt.% benzene based on the methane converted which can be expressed as a tar/benzene ratio of 113.5 wt.%. Hydrocarbon Product Selectivity, PRODUCT Wt. % of Total Product

C₂'s 48 acetylene (75% of total C2's) ethylene ethane

C₃'s 6 propylene methyl acetylene

C₄'s 4 butadiene vinyl acetylene

C₆ 35 benzene

C₇ 6 toluene

Tar and solid carbonaceous products 1

Total 100.0

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic drawing of the apparatus used in the Examples. Figure 2 is a graph illustrating percent methane converted to higher hydrocarbon products as a function of oxygen content at a reaction temperature of 1425 K and a reaction time of 250 milliseconds.

Figure 3 is a plot of hydrocarbon product distribution as a function of reaction temperature at a reaction time of 250 milliseconds with 2% oxygen.

Figure 4 is a plot of hydrocarbon product distribution as a function of reaction time with 2% oxygen at a reaction temperature of 1425 K.

The invention will be more readily understood by the reference to the following examples.

EXAMPLES

Experimental Procedure

The experimental reactor apparatus used is schematically shown in Figure 1. It comprised alumina tube 10 which was 61.0 centimeters long and had an I.D. of 7.0 centimeters surrounded by graphite heating element 12. Graphite heating element 12 was fitted over the alumina tube such that a space, 11, of roughly about 0.3 centimeters existed between it and the exterior wall of the alumina tube. Thus, the graphite heating element did not touch the alumina tube. The space, 11, in between element 12 and tube 10 was continuously purged with an inert gas such as helium or argon. About 6.4 centimeters of graphite felt insulation 13 were then placed over heating element 12. A water-cooled, aluminum jacket, 15, was placed over graphite insulation 13. Tube 10 was fitted with an alumina honeycomb 14 and capped at one end by aluminum end plate 16. The other end of tube 10 was fitted with a warm-water cooled assembly 34 and capped with aluminum end plate 18. During operation, the methane containing feed gas entered the reaction chamber via inlet ports 20 and 22 and from there passed through honeycomb 14 which served, to both straighten out the gas flow and heat same to the reaction temperature. After passing through honeycomb 14 the feed gas then entered reaction zone 24. Oxygen was admitted into reaction zone 24 via line 26 and injector head 28. The oxygen and hydrocarbon feed streams were separately introduced into reaction zone 24 in order to insure that the oxygen initiated a free radical reaction of the methane at the desired temperature and not before. Reaction zone 24 was defined by the distance between honeycomb heater 14 and the tip of moveable sample probe 30.

Reaction products were quenched and removed at various axial distances from honeycomb 14 using a hot water cooled sample probe, 30, which comprised three concentric stainless steel tubes. In sampling the gas products, probe 30 was inserted into reaction zone 24 from the bottom of the furnace to a predetermined axial position. A sampling pump (not shown) connected to the probe was then turned on and regulated so that isokenetic gas samples were extracted through the probe from the tip thereof. The quenched sample was then passed into a gas chromatograph (not shown) equipped with flame ionization and thermal conductivity detectors for analysis. The reaction time for a particular run was determined by the distance between the tip of probe 30 and honeycomb 14 and could be varied by adjusting the axial position of probe 30 in order to decrease or lengthen the distance between it and honeycomb 14. Cooling water used for probe 30 was preheated to about 75°C in order to avoid both external and internal condensation of product thereon. It should be noted that hot wa-her and not steam was discharged from probe 30. The quenching rate of the reaction products provided by this probe ranged from about 10⁴ K/sec to 10⁶ K/sec. A Teflon line (not shown) connected probe 30 to the gas chromatograph and was heated to 110°C to prevent adsorption and condensation of product in the line. During operation, gaseous product that was not removed by sample probe 30 passed down through tube 10 and cooling assembly 34 and was withdrawn via vent line 32.

The temperature of the reactor was controlled and monitored by a boron-graphite/graphite thermocouple inserted through insulation 13 and located next to heating element 12. The exterior wall temperature of alumina tube 10 was checked using an optical pyrometer aimed through sight windows in the wall of cooling jacket 15 and graphite insulation 13. The temperature in reaction zone 24 was determined using a zirconium oxide-coated platinum/platinum-13% rhodium thermocouple inserted into the reaction zone through the bottom of the furnace.

Ceramic honeycomb 14 was 2.54 cm thick, perforated with a number of straight, axially aligned and radially spaced holes having a nominal pore diameter of 0.318 cm and was cut into a cylindrical shape to just fit the inside diameter of alumina tube 10 in order to maximize the heat transfer between it and the reactor wall. The honeycomb served to both heat and straighten out the feed gas flow. Under the experimental conditions employed, heat transfer calculations showed that the honeycomb provided a heating rate to the gas feed of from about 10⁴ to 10⁵ K/sec. These calculations indicated that the gas temperature approached that of the temperature of the honeycomb itself upon exiting therefrom. These. calculations were confirmed by measuring the temperature of the reaction zone with the zirconium oxide-coated, platinum/plat inum-13% rhodium thermocouple. Under typical run conditions at a wall temperature of 1500 K for tube 10, the reaction tiirieaveraged temperature of the gases in reaction zone 24 was about 1425 K. It should be added that in all the experiments there was no sign of carbon deposition on or in alumina honeycomb 14, there was no fouling of the honeycomb or pressure drop through same after many hours of use.

The oxygen injector assembly was made of a feeder tube, 26, attached to a cylindrical head, 28. Head 28 contained six radially-drilled holes 0.022 cm in diameter which were evenly distributed near its closed end. The injector assembly was inserted through a central passage of honeycomb 14 and was positioned in a manner such that the holes in head 28 were just beneath the bottom surface of honeycomb 14. During the runs, oxygen was injected through the holes as radial jets outward from the center of the reaction zone. Cross flow jet mixing calculations revealed that, under the conditions used in the experiments, the time required for complete jet mixing of the oxygen with the hydrocarbon feed gas stream was negligible compared to the reaction time in the reaction chamber.

The surface to volume ratio of reaction zone 24 was about 0.57 cm^-1 which was relatively small in order to insure that wall effects would be insignificant. Experiments were run in order to verify this. To determine this, a gas flow restrictor was placed on top of honeycomb 14. This restrictor was a toroidal shaped alumina plate which just fit inside alumina tube 10 and had a hole therein 2.77 cm in diameter. The methane gas flow was thus restricted to the central portion of reaction zone 24, which amounted to about 15% of the entire cross sectional area of the reaction chamber, before it expanded again downstream of reaction zone 24. Comparing the product species distributions at the same reaction times revealed little difference between the products from the reactor both with and without the gas flow restrictor. This thus substantiated that there was no wall effect under the experimental conditions employed.

EXAMPLE 1

This experiment determined the effect of oxygen concentration on the extent of conversion of methane to higher hydrocarbons and was conducted using the apparatus and procedure set forth under Experimental Procedures. The temperature of the reaction zone was 1425 K and the reaction time was 250 milliseconds. Ten liters per minute of methane were mixed with one liter per minute of argon and the mixture fed into the reactor shown in Figure 1 through honeycomb 14 which heated the methane to the reaction temperature. The argon was used as a tracer for carbon balance determinations which, on average, gave carbon balances ranging between 98 and 100%. This range was within experimental error since there was evidence of only negligible (i.e., 1 wt. % of the product) formation of solid carbonaceous materials having been formed in the reaction zone. At the same time 0.2 liters per minute of a mixture of oxygen and helium were separately fed into the reactor through inlet 26 and head 28. The oxygenhelium stream was introduced in such a manner that its momentum was always kept constant to ensure the same mixing pattern with the methane-argon stream. To this end, the amount of He was varied so that the total flow rate of the oxygen-helium mixture was maintained constant at 0.2.1/min at different oxygen concentrations. After about 1-2 minutes the reaction reached steady state conditions. During the reaction, product was continuously removed from reaction zone 24 via sample probe 30 and fed to the gas chromatograph. The volume percent of oxygen present based on the methane content of the feed gas was varied from 0-2%.

Figure 2 is a plot of the results of this experiment which clearly demonstrate the unexpected and unanticipated effect of a minimum amount of at least about 0.5 volume percent of oxygen required in the reaction zone. in order to achieve free radical initiated methane conversion. In all cases the selectivity to benzene formation from methane was about 35 wt.% and about 75% of the C₂'s were acetylene. It should be noted that at the end of each experiment significant amounts of carbonaceous products were found to have accumulated at the bottom of the reaction chamber. This was due to the fact that most of the reaction products were not removed from the reaction chamber by the sample probe but continued to pass down to vent 32. As they continued to proceed down the- hot reaction chamber they continued to react and polymerize, ultimately forming tar and carbonaceous products.

However, it should be emphasized that, in this and in the examples below, the amount of solid carbonaceous and tarry materials formed in the reaction zone, in the sample probe or in the products removed from the reaction zone by the sample probe was negligable. EXAMPLE 2

This experiment was similar to that of Example 1 except that the oxygen concentration was maintained at 2 volume percent of the methane and the reaction time was maintained at 250 milliseconds. In this experiment, a series of runs were made varying the temperature in order to determine its effect on the methane conversion and the product distribution of the converted methane. The results of this experiment are shown in Figure 3 and illustrate an increasing amount of C₂ hydrocarbon (75% acetylene) formation as well as increasing benzene production with increasing temperature.

EXAMPLE 3

This experiment was similar to Example 1 except that the reaction zone temperature was maintained at 1425 K and the oxygen at 2 vol. % of the methane feed. In this experiment the reaction time was varied in order to determine its effect on the extent of methane conversion and the product distribution of the converted methane. The results are shown in Figure 4 and show gradually increasing C₂ and benzene production as the reaction time increased (again, about 75% of the C₂'s were acetylene).

EXAMPLE -4

This experiment demonstrates that premixing the methane and oxygen before the methane has reached the reaction temperature does not result in the process of this invention. In this experiment, two separate reactors were used. Reactor A was used to demonstrate the separate addition case and reactor B was used to demonstrate the premixed case. Both reactors comprised a 1.4 cm I.D. quartz tube axially fitted through a cyclindical electrically heated muffle furnace. The reaction products were analyzed by gas chromatography and the reaction temperature was 1373 K.

In reactor A, a 0.6 to 1 volume ratio of oxygen to argon was preheated and fed into the reaction zone via a quartz tube having an I.D. of 7 mm and an I.D. of 9 mm axially located inside the reactor tube. The preheat zone was 12.5 cm long and the reaction zone was 94 cm long. Methane was separately added into the reaction zone through the annular space between the inside of the reactor tube and the outside of the oxygen/argon injection tube. The preheat zone for the methane was also 12.5 cm long. The overall volume ratio of CH₄:O₂:Ar fed into the reaction zone was 1:0.06:0.1.

In reactor B, a 1:0.06:0.1 volume ratio of CH₄:O₂:Ar was premixed and fed into the reaction zone via a quartz preheating tube having a 3 mm I.D. The preheating zone or length of the 3 mm tube inside the furnace was 28 cm. The reaction zone was 79 cm long.

in both cases reactions were conducted at reaction times of about 250, 380 and 500 msec. It was found that the presence of the oxygen increased the methane conversion and the benzene yield only for the separate addition case, reactor A and not for the premixed case, reactor B. In the premixed case no enhancement was observed with the oxygen. That is, in the premixed case essentially the same results were obtained without oxygen. The results obtained for the separate injection case showed essentially the same level of improvement in methane conversion as in the apparatus used for obtaining the data in Examples 1, 2 and 3 , but at the lower temperature of 1373 K.

Claims

CLAIMS :

1. A process for producing liquid hydrocarbons and gaseous hydrocarbons having two or more carbon atoms in the molecule from a methane-containing gas feed characterized by contacting said feed with oxygen in a reaction zone at a temperature of at least about 1300 K for a time sufficient for said methane to react in the presence of said oxygen to form said gaseous and liquid hydrocarbon products, wherein said oxygen is present in said reaction zone in an amount greater than 0.5 volume percent of the methane content of said feed and wherein said oxygen and feed are separtely introduced into the reaction zone.

2. A process according to claim 1 further characterized in that said oxygen and said feed are not pre-mixed prior to their introduction into the reaction zone.

3. The process of claim 1 or claim 2 further characterized in that the said hydrocarbon products are quenched from said reaction temperature down to a lower temperature to prevent decomposition and degradation of said products.

4. The process of any one of claims 1-3 further characterized in that the said reaction time ranges from about 0.1 to 1 seconds.

5. The process of any one of claims 1-4 further characterized in that the said reaction temperature ranges from about 1300 to 1800 K.

6. The process of any one of claims 3-5 further characterized in that the said quench temperature is no higher than about 1000 K.

7. The process of any one of claims 3-6 further characterized in that the said quench rate is at least about 10⁴ K/sec.

8. The process of any one of claims 3-7 further characterized in that the said so-formed reaction products are quenched from said reaction temperature to a temperature ranging between about 500 K and 1000 K to prevent decomposition and degradation of said products.

9 . The process of any one of claims 1-8 further characterized in that the sa id oxygen is present in sa id reacti on in an amount no greater than about 10 volume percent of the methane content of said feed.

10. The process of any one of claims 1-9 further characterized in that the said oxygen is present in said reaction zone in an amount of at least about 0.7 volume percent of the methane content of said feed.

11. The process of any one of claims 1-10 further characterized in that the said C₂ gaseous hydrocarbons formed by said process comprise acetylene.

12. The process of any one of claims 1-11 further characterized in that the said liquid hydrocarbon products comprise benzene.

13. The process of any one of claims 1-12 further characterized in that negligible amounts of tarry or carbonaceous products are produced.

14. A process for producing gaseous and liquid hydrocarbons from a methane-containing gas feed substantially as hereinbefore described with particular reference to the Examples.