US1963092A - Treatment of hydrocarbons - Google Patents

Description

June 19, 1934. 1 LAWRENCE 1,963,092

TREATMENT OF HYDROCARBONS Fild May 25, 1955 Inventor FranlIinILLamm Patented June 19, 1934 UNITED STATES PATENT OFFICE TREATMENT OF HYDROCARBONS Franklin I. L. Lawrence, Philadelphia, Pa., as-

signor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvama Application May 25, 1933, Serial No. 672,821

17 Claims.

This invention relates to a process of cracking and polymerizing hydrocarbons, under suitable conditions of temperature and pressure, to convert the same into polymers, which include and products such as tar and fixed gases, e. g., methane mation of the least amount of tar and fixed gas,

and thereafter separating the aromatic products from the tar and unreacted low boiling hydrocarbons.

I have found that the operating conditions most 3: suitable for effecting eflicient cracking and polymerization vary with the particular hydrocarbons undergoing treatment, e. g., ethane, requires a much higher cracking temperature to form unsaturated compounds which will polymerize than 40 do the higher boiling hydrocarbons, as propane and butane. In general, the greater the number of carbon atoms in the compound, the less drastic is the treatment necessary to decompose it, particularly with the view of forming unsaturated hydrocarbons.

I separate the gaseous-hydrocarbons into fractions according to boiling point and subject the several fractions in a unitary system to those conditions most suitable for the maximum production of the desired polymers. In carrying on my process, a mixture of low boiling hydrocarbons, such as comprises refinery or pressure still gas, is subjected to compression in one or more stages, preferably with partial reboiling of the condensate and partial condensation of the vapors, and fractionation of the gas to cause a separation into fractions varying according to their respective boiling points.

It will be evident from Table I, that the different hydrocarbon groups may be separated substantially from each other, the variance in the boiling ranges of the C2, C3, and C4 hydrocarbons and the fixed gases making such fractionation feasible.

Table I Propane Assuming the charging gas to contain hydrogen, methane, ethane and ethylene, propane and propylene, and butanes and butylenes, the liquid formed in the first stage of a three stage compression system preferably will beprimarily hydrocarbons of the C4 type, i. e., butane and buty-,- lenes; in the second stage the Ca hydrocarbons, and in the third stage the C2 hydrocarbons. If only two stages are used the C: hydrocarbons may appear in either or both of the other fractions, depending uponthe operating conditions. Hydrogen, methane, and other fixed gases which remain unliquefied in the operation, will be conducted from the system as gas.

As hereinafter explained, one or more of the liquid fractions thus obtained are passed into their respective heating or cracking coils, the C: hydrocarbon fraction being heated to a sufficient temperature and for a suflicient time to secure the maximum conversion to olefines without excessive formation of secondary decomposition products, as fixed gas and tar. The heater for the C2 hydrocarbons is preferably operated at a temperature of from 1150 F. to 1400 F'., the heater for the C3 hydrocarbons from about 400 F. to 800 F., and for the C4 hydrocarbons a variable temperature up to but usually not exceeding 800 F. However, it is tobe understood that the temperatures maintained in the respective heat-' ers may be varied according to the type and amount of hydrocarbons introduced, the pressure under which the system may be operated, and the time of exposure of the gases to the operating temperature. The time'of exposure is generally less than one minute, although in the lower temperature ranges the time may be somewhat less than seconds. I prefer to operate the heating and polymerization systems at a pressure of 5 from 100 lbs. to 1000 lbs/sq. in., and more preferably at from 100 lbs. to 500 lbs/sq. in. However, my process may be operated at pressures up to 2000 lbs/Sq. in.

After the endothermic formation of the unsaturated hydrocarbons from the C2 fraction by the high temperature treatment, the gases are cooled by the addition of the C3 and/ or C4 hydrocarbon fraction, said C3 and/or C4 fraction being heated as above stated or to a lesser degree or being in an unheated condition, and are introduced into an unheated reaction chamber wherein simul- 1150 F. to 1200 F. most preferred. I preferably effect the cooling of the products of the heating step by adding condensate from'an earlier stage of compression, i. e., the C3 and/or the C4 hydro carbon fraction, this condensate added thus being raised to a suitable temperature for cracking and/or polymerization of the constituents thereof to form relatively low boiling aromatic or cyclic hydrocarbons. The liquids used for the cooling stepmay, if necessary, be preheated in their respective heaters in order to insure the proper temperature during the cracking and/or polymerization step.

The products withdrawn from the reaction chamber may be separated into low boiling aromatic compounds suitable as motor fuel, higher boiling reaction products such as tar, recycle gas, and vent gas, as hydrogen and methane. I may effect the separation by cooling the treated material withdrawn from the reaction chamber to a temperature which causes condensation of components of higher boiling range than the desired liquid polymers, removing such condensate from the system and fractionating under pressure the polymers from the unreacted hydrocarbons and fixed gas. I prefer to carry out this fractionation under such conditions that hydrogen, methane and other undesirable gases are withdrawn from the fractionating column as gas, while the unpolymerized hydrocarbons containing 2, 3, or 4 carbon atoms to the molecule may be removed as liquids and recycled for further cracking and polymerization. I contemplate the removal of one or more side-streams of liquefied gas, the said stream or streams thus removed preferably being added to the corresponding fractions from the initial compression operation. The liquefied gas streams withdrawn from the fractionating column may be subjected to a stripping or reboiling operation to effect a further separation of the constituents before the same are recycled.

When more than two liquids fractions are to be treated, it may be desirable to'preheat the higher boiling one and pass it through only a portion of the reaction chamber, introducing it at an intermediate point, thereby reducing the time of exposure to the elevated temperature.

My invention may be further understood by reference to the accompanying drawing which illustrates diagrammatically apparatus suitable for effecting my treatment.

Refinery or pressure still gas is introduced into the system thru pipe 1, partially liquefied by compressor 2, cooled in heat exchanger 3 and passed into the fractionating column 4, provided with heating coil 7 and cooling coil 8. 'Assuming the gas charged to be a mixture of hydrogen, methane and C2, C3 and C4 hydrocarbons, the hydrogen, methane and C2 compounds are withdrawn from .the top of the column 4 and passed thru pipes 20 and 22 into compressor 23, being compressed therein and passed thru pipe 24 and cooler 25, into fractionating column 26, provided with heating coil '7 and cooling coil 8. The fixed gases, hydrogen and methane are withdrawn from the top of column 26, thru pipe 27 and are removed from the system. The C2 hydrocarbons are drawn from the bottomof column 26 through pipe 38 and are forced by pump 39 thru valve 40 and pipe 41 into heatingcoil 42, under a pressure of 100- 1000 lbs./sq.in., wherein such hydrocarbons are heated to a temperature of from 1150 F. to 1400 F., to efiect cracking of the C2 hydrocarbons to form unsaturated compounds such as ethylene, together with some methane and hydrogen.

From the middle of column 4 there is withdrawn the C3 hydrocarbon fraction, which is passed thru pipe 1'7 into the reboiler 18 where any C2 or lighter hydrocarbons are stripped and returned thru pipe 19 to column 4. The fraction withdrawn from the bottom of column 18 is composed of substantially the C3 hydrocarbons. This material is passed through pipe 31, pump 32, valve 33, and pipe 34 into heating coil 35 under a pressure of from approximately 100 to 1000 lbs/sq. in., and therein is heated to a temperature of the order or from 400 F. to 800 F., with substantially no cracking taking place.

The fraction removed from the bottom of column 4, comprising substantially the C4 hydrocarbons, passes thru pipe 5, pump 6, valve 9, and pipe 10 into heating coil 11, and is raised to a temperature not exceeding 800 F., while under a pressure of the order or from about 100 to 1000 lbs./ sq. in., wherein preheating of the C4 hydrocarbons is accomplished without substantial decomposition. The products from the heating coil 11 are withdrawn thru pipe 12, and are then either passed by valve 14 into pipe 37 to be admixed with the products from coil 35, and then to the reaction chamber 16, or passed through valve 13 and pipe 15 into the unheated reaction chamber 16. The heated products from coil 35 are passed thru pipe 36, valve 44, pipe 37, and thence into the reaction chamber at the same point of introduction as the products from coil 42 passed thereinto through .pipe 43. The C4 hydrocarbons from the bottom of column 4 may be passed directly to the reaction chamber 16 through pipe 10 and valve controlled by-pass 9', said fraction being cracked and polymerized by the contained heat of the gases present in the reaction chamber 16. The C3 hydrocarbons from the bottom of tower 18 may. likewise be by-passed directly from pipe 34 through valve 33, pipe 36,

valve 44 and pipe 37 into pipe 43 and thence.

into the reaction chamber 16.

The reaction chamber 16, in which a major portion of the polymerization of unsaturates to aromatics occurs is maintained by the heated gases introduced thereinto, at a temperature of from about 1150" F. to 1200 F. and at substantially the same pressure as the heating coils, i. e., 100 to 1000 lbs/sq. in. The products from the three heating coils 11, 35, and 42, after polymerization in the reaction chamber 16 are withdrawn through. pipe 45, cooler 46, valve 4'7 and pipe 48, into a tar stripping column 49. The heavy polymers, in the form of tar are fractionated out and removed from the bottom of the column thru pipe 50 and valve 51. The desired low boiling aromatic polymers, together with any unreacted C2, C3 and C4 hydrocarbons as well as hydrogen and methane, are withdrawn as vapors from the top of column 49 and passed through pipe 52 into the fractionating column 53 intermediate its top and bottom. Therein a fractionation under. pressure is effected, the aromatic polymers being removed from the bottom of the column through pipe 54 and valve 55.

The heaviest side stream, comprising for the most part the C4 hydrocarbons, is withdrawn through pipe 56 and valve 57 into a reboiler column 58 wherein a further fractionation is accomplished, any C3 hydrocarbons or lighter being removed from the top of the column through pipe 59 and returned to column 53. The C4 compounds are drawn from the bottom of the reboiler 58 through pipe 60, and are forced by pump 61, through valve 62, pipe 63, valves 64 and 65, into pipe 10 for recycling to the heater 11.

Similarly, a second side stream is taken from column 53, through pipe 68 and valve 69 into reboiler 70. This stream comprises mainly the C3 hydrocarbons, but also contains some of the C2 and lighter compounds, the same being withdrawn from the top of reboiler '70 through pipe '72 and returned to column 53. The liquid drawn from the bottom of the reboiler 70, substantially the C3 hydrocarbons, passes through pipe 71, pump 73, valve '74, pipe '75, valves '76 and 77, into pipe 34 for recycling to heater 35.

The lightest side stream, other than the fixed gases, is withdrawn from column 53 through pipe '78 and valve '79 and passed into reboiler 80. This stream comprises substantially all of the C2 hydrocarbons, together with some gaseous methane and hydrogen. The fixed gases are removed from the top of reboiler through pipe 82 and are returned to column 53. The C2 hydrocarbons are drawn from the bottom of 80 through pipe 81, and are passed by means of pump 83, thru valve 84, pipe 85, valves 86 and 8'7, into pipe 41 for recycling to heater 42.

The remaining fixed gases, as hydrogen and methane are withdrawn from the top of column 53 through pipe 88 and may either be discharged from the system through valve 28 and pipe 2'7 or if they still have admixed therewith substantial amounts of materials having boiling points higher than methane, they may be recycled through the fractionating system. The recycling may be accomplished either by closing valve 28 and passing the gases thru valve 29, pipe 30 and valve-controlled by-pass 24a into cooler 25 and column 26, the valves 21 and 21a being closed, or the gases may be passed from pipe 88 thru valve 29, valve28 being closed, thence thru pipe 30 and valve controlled by-pass 21 into cooler 3 and column 4, the valves 24a and 21a being closed.

The side streams taken from column 53, may, by regulation of pumps 61, '73, and 83, and valves 66, 6'7, 86, '76, and 64, be diverted from their normal course of flow into any desired heater, or a mixture of two or more side streams may be recycled to any particular heater.

It may be desirable to operate my process so that the Ca and C4 hydrocarbons are segregated as a group and are preheated together in the same heater, the C2 hydrocarbons being separated and cracked according to the normal procedure described hereinbefore. In such case, the C3 and C4 fractions are removed from the bottom of column 4, the column 18 being cut out of the system by closing valves 17a' and 19a. The C3-C4 mixture withdrawn from column 4 through pipe 5 is passed by pump 6 through valve 9, and pipe 10 into heater 11 and thence by means of pipe 12, valve 14, pipe 3'7, and valve 44 into reaction chamber 16. The C2 hydrocarbon fraction, following its normal passage from the bottom of column 26, is passed through heater 42 and thence into reaction chamberv 16 wherein the cracking and/or polymerization of the gases occurs;

While the foregoing description of my processillustrates the treatment of only three hydrocarbon fractions, namely C2, C3 and C4 compounds, additional fractions may be obtained from each stage of compression by removing side streams of intermediate boiling range between the condensate removed from the bottom of the fractionating column 4 and the vapor leaving the top. It is preferable to subject such side streams to a stripping or reboiling operation to remove low boiling components present therein, and the revaporized portion may be returned to the fractionating tower or otherwise disposed of. Whn several fractions are thus obtained from a single stage of compression, they may each be subjected to the particular treatment-which will produce the maximum yield of desirable polymers.

Also, while the accompanying drawing illustrates the separation of the charging gas into fractions by means of fractionating columns oper ating under elevated pressures, I contemplate the use of any fractionating means, such as for example, asystem of absorption whereby the components of the charging gas are selectively absorbed in oil or other medium and the absorbed gas fractions either along with the absorbent or stripped from the absorbent are subjected to thermal treatment according to my process. Furthermore, the time of cracking and of polymerization, and the temperatures and pressures required may be varied considerably from those given by way of illustration, depending upon the character of the hydrocarbons undergoing treatment and the polymers desired.

In carrying out my process upon certain gaseous mixtures, it may be found advantageous or desirable from an economic or other standpoint, to obtain polymers, for example, from only the C3 and the higher fractions. In such cases the system would be operated so that the lower fractions, for instance, the C2 fraction would not be subjected to cracking and polymerization, but would, for example, be conducted from the system along with the fixed gases, whereupon at least two of the remaining fractions would each be subjected to that thermal treatment best suited for its cracking and/or polymerization. This and similar variations are within the scope of my invention.

In the appended claims, there are claims limited to a species of my invention, as well as broader claims'which in addition to covering such species, also cover another or other species. In my copending application, Serial No. 717,086, filed March 28, 1934, there are claims limited to another or other species or modifications therein disclosed and broader claims covering additional species.

Herein, and in the appended claims "C2, C3, and C4 hydrocarbons are to be understood to comprehend ethane and ethylene, propane and propylene, and butanes and butylenes, respectively. Likewise, the term aromatic hydrocarbons is to be understood to comprehend the hydro-aromatic or hydro-cyclic compounds such as cyclohexane and cyclo-hexene, as well as the true aromatic hydrocarbons such asbenzene, toluene, and similar homologues.

What I claim is:

The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydro-- carbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing at least two of the fractions under a pressure greater than atmospheric, separately heating one of said compressed fractions to a temperature at which said fraction will decompose to form substantial quantities of unsaturated hydrocarbons, introducing the heated fraction andanother of said compressed fractions into a reaction zone wherein formation of polymers occurs, and removing the products of reaction from the zone last mentioned.

2. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure greater than atmospheric, separately heating at least one of said compressed fractions to a temperture at which said fraction will decompose to form substantial quantities of unsaturated hydrocarbons, introducing a fraction so heated and at least one other of the said compressed fractions into a reaction zone wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

3. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure greater than atmospheric separately heating at least one of the compressed fractions to a temperature at which the fraction will decompose to form substantial quantities of unsaturated hydrocarbons, introducing the heated fraction and at least one other of the compressed fractions into a reaction zone wherein formation of polymers occurs, removing the prodnets of reaction from the zone last mentioned, fractionally separating the reaction products into a tar fraction, an aromatic polymer fraction, and unpolymerized hydrocarbon fractions of successively lower boiling range,'and recycling an unpclymerized hydrocarbon fraction for further heat treatment.

4. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a pluralityrof the-fractions to a pressure greaterthan atmospheric, separately heating each of the compressed fractions, introducing the heated gases into a reaction zone wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

5. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure greater than atmospheric, separately heating each of the compressed fractions, introducing the heated gases into a reaction zone wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, fractionally separating the said reaction products into a tar fraction, an aromatic polymer fraction, and unpolymerized hydrocarbon fractions of successively lower boiling ranges, and returning at least one of the said unpolymerized hydrocarbon fractions, under pressure, to its respective heating zone.

6. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure of the order of from about 100 lbs. to about 2000 lbs/sq. in., separately heating the lowest boiling compressed hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., whereby'decomposition is effected and substantial quantities of unsaturated hydrocarbons are formed, introducing the heated gaseous products and at least one other of the said compressed fractions into a reaction zone at a temperature of the order of from about 950 to about 1300 F., wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatlc polymers therefrom.

7. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure of the order of from about '100 lbs. to about 1000 lbs/sq. in., separately heating the lowest boiling compressed hydrocarbon fraction to a temperature of from about 1150 F. to about 1400 F., whereby decomposition is effected and substantial quantities of unsaturated hydrocarbons are formed, introducing the heated gaseous products and at least one of the other of the said compressed fractions into a reaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

8. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the lower molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure of the order of from about 100 to about 500 lbs/sq. in., separately heating the lowest boiling compressed hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., whereby decomposition is effected and substantial quantities of unsaturated hydrocarbons are formed, introducing the heated gaseous products and at least one of the compressed fractions into a reaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

9. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, compressing a plurality of the fractions to a pressure of the order of from about 100 to 2000 lbs/sq. in., separately heating the lowest boiling compressed hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., whereby decomposition is effected and substantial quantities of unsaturated hydrocarbons are formed, introducing the heated gaseous products and at least one of the compressed fractions into a reaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing the products 0' reaction from the zone last mentioned, fractionally separating the reaction products into a tar fraction, an aromatic polymer fraction, and unpolymerized hydrocarbon fractions of successively lower boiling ranges, and recycling at least one of the unpolymerized hydrocarbon fractions for further heat treatment.

10. The process for obtaining liquid aro-, matic polymers from low molecular weight gaseous mixtures containing C2, C3 and C4 hydrocarbons, methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially C2, C3 -and C4 hydrocarbons respectively, compressing a plurality of the fractions to a pressure greater than atmospheric, separately heating at least one of said compressed fractions .to a temperature at which said fraction will decompose to form substantial quantities of unsaturated hydrocarbons, introducing the heated fraction and at least one other of the said compressed fractions into a reaction zone wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

11. The process for obtaining liquid aromatic polymers from low molecular weight gaseous mixtures containing C2, C3, and C4 hydrocarbons, 4

methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially C2, C3, and C4 hydrocarbons respectively, compressing a plurality of the fractions to a pressure greater than atmospheric, separately heating at least one of the said compressed fractions to a temperature at which said fraction will decompose to form substantial quantities of unsaturated hydrocarbons, introducing the heated fraction and at least one other of the said compressed fractions into a reaction zone wherein the formation of polymers occurs, removing the products of the reaction from the zone last mentioned, fractionally separating the said reaction products into a tar fraction, an aromatic polymer fraction, and unpolymerized hydrocarbon fractions containing substantially C2, C3 and C4 hydrocarbons respectively, and recycling at least one of the said unpolymerized fractions for further heat treatment.

12. The process for obtaining liquid aromatic polymers from low molecular weight gaseous mixtures containing C2, C3, and C4 hydrocarbons, methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially Ca, Ca, and C4 hydrocarbons respectively, compressing each of the said fractions to a pressure of the order of from about 100 to about 2000 lbs/sq. in., separately heating the C2 hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., the C3 hydrocarbon fraction to .a temperature of the order of from about 400 F. to 800 F., and the C4 hydrocarbon fraction to a temperature not exceeding substantially 800 F., introducing the compressed heated gases into a reaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing the productsof reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

13. The process for obtaining liquid aromatic polymers from low molecular weight gaseous mixtures containing C2, C3, and C4 hydrocarbons, methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially the C2, C3, and C4 hydrocarbons respectively, compressing each of the said fractions to a pressure of the order of from about .100 to 1000 lbs./sq. in., separately heating the C:

hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., the Ca hydrocarbon fraction to a temperature of the order of from about 400 F. to about 800 F., and the C4 hydrocarbon fraction to a temperature not exceeding substantially 800 F., introducing the compressed heated gases into a reaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom.

14. The process for obtaining liquid aromatic polymers from low molecular weight gaseous mixture containing C2, C3, and C4 hydrocarbons, methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially the C2, C3, and C4 hydrocarbons respectively, compressing each of the said fractions to a pressure of the order of about 100 to 500.lbs. /sq. in., separately heating the C2 hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F.,

the C3 hydrocarbon fraction to a temperature of,

the order of from about 400 F. to about 800 F.,

and the C4 hydrocarbon fraction to a temperature not exceeding substantially 800 F., introducing the compressed heated gases into a reaction zone at a temperature of the order or from about- 950 F. to about 1300 F., wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, and separating the liquid aromatic polymers therefrom. v

15. The process for obtaining liquid aromatic polymers from low molecular weight gaseous mixtures containing Ca, Ca and C4 hydrocarbons, methane and fixed gases, which comprises separating the gaseous mixture into fractions containing substantially the C2, C3, and C4 hydrocarbons respectively, compressing each of the said fractions to a pressure of the order of from about 100 to 2000 lbs/sq. in., separately heating the C2 hydrocarbon fraction to a temperature of the order of from about 1150 F. to about 1400 F., the C3 hydrocarbon fraction to a temperature of the order of from about 400 F. to about 800 F., and the C4 hydrocarbon fraction to a temreaction zone at a temperature of the order of from about 950 F. to about 1300 F., wherein formation of polymers occurs, removing the products of reaction from the zone last mentioned, fractionally separating the said reaction products into a tar fraction, an aromatic polymer fraction, and unpolymerized C2, C3 and C4 hydrocarbon fractions, and returning at least one of the said unpolymerized hydrocarbon fractions, under pressure, toits respective heating zone.

. 16. The process for obtaining liquid aromatic hydrocarbons from low molecular weight hydrocarbons, which comprises separating the low molecular weight hydrocarbons into fractions of successively lower boiling ranges, heating at least one of the fractions so separated to a temperature at which said fraction will decompose to sub-v stantial extent to form unsaturated hydrocar bons, introducing the heated fraction and at least one other of the fractions into a reaction zone wherein formation of polymers occurs. removing the products of reaction from the zone last mentioned, separating polymers therefrom, and recycling at least a portion of the unpolymerized materials. I

17. The process for. converting low molecular weight hydrocarbons into polymers, which comprises first compressing the hydrocarbons, then separating them into fractions of successively lower boiling ranges, heating one or more of said fractions under superatmospheric pressure to a temperature at which portions thereof will decompose to form unsaturated hydrocarbons, bringing the heated fraction into contact with another compressed fraction to efiect formation of polymers, and thereafter effecting a separation of the polymers.

FRANKLIN r. L. LAWRENCE.

Images