US 3124436 A
Description (OCR text may contain errors)
March 10, 1964 F, J. DENT ETAL GASIFICATION 0F HYDROCARBON-CONTAINING OILS Filed July 20, 1959 IN YEN TOR FREDERICK JAMES DENT LIONEL ARTHUR MO/GNARD M 9 ATTORNEYS United States Patent 3,124,436 GASIFICATION F HYDROCARBON- CGNTAHNING UHLS Frederick James Dent, Solihull, and Lionel Arthur Moignard, Olton, Solihull, England, assignors to The Gas Council, London, England Filed July 20, 1959, Ser. No. 828,297 Claims priority, application Great Britain July 21, 1958 Claims. (Cl. 48213) In copending application Serial No. 842,251, filed September 25, 1959, which is a continuation-in-part of now abandoned Serial No. 551,144, filed December 5, 1955, is described a process for gasifying hydrocarbon-containing oils by a hydrogenation treatment, which involves the splitting and hydrogenation of hydrocarbons, to produce gases which contain gaseous hydrocarbons consisting of methane with or without other gaseous hydrocarbons, such as ethane. In that process the oil and hydrogen or a gas containing hydrogen are passed under a pressure of at least 3 atmospheres, and advantageously 20 to 50 atmospheres, through a bed of a particulate solid material maintained in the fluidised state by the gas and having a temperature of at least 500 C. The process is advantageously carried out with the use of carbon, for example, in the form of coke, as the particulate solid material, and at a temperature within the range of 600 C. to 900 C. under a pressure of 20 to 50 atmospheres.
The hydrocarbon oil used may contain both aliphatic and aromatic hydrocarbons. In this case the aliphatic hydrocarbons react With hydrogen more readily, so that, if desired, only the aliphatic hydrocarbons need be reacted, and the aromatic hydrocarbons are recovered as valuable by-products. Alternatively, the reaction conditions may be so chosen that the aliphatic hydrocarbons are converted into gaseous hydrocarbons, and the aromatic hydrocarbons undergo reaction only to such an extent as to remove their aliphatic side chains and so yield simple aromatic hydrocarbons, such as benzene and naphthalene.
The present invention is based on the observation that in the hydrogenation of oils consisting of petroleum hydrocarbons having an average of 4 to carbon atoms, and of which at least 70 percent consist of aliphatic hydrocarbons, a yield of aromatic hydrocarbons, which is substantially greater than that obtainable only from the aromatic constituents of the oil, if present, can be obtained by increasing the proportion of oil used relatively to hydrogen above that required to convert the aliphatic hydrocarbons into gaseous hydrocarbons. In fact substantial yields of aromatic hydrocarbons can be obtained from hydrocarbon oils containing negligible quantities of aromatic constituents. It appears that aromatic hydrocarbons are formed by the condensation of a part of the unsaturated aliphatic hydrocarbon molecules or radicals formed during thermal decomposition of the oil, while a sufiicient further quantity of unsaturated molecules or radicals undergoes the exothermic hydrogenation to gaseous hydrocarbons to liberate the heat required to maintain the temperature for both reactions.
Accordingly, the present invention provides a process for the gasification of oils consisting of petroleum hydrocarbons (as defined above) to produce gases containing gaseous hydrocarbons and aromatic hydrocarbons, wherein the oil and hydrogen or a gas consisting mainly of hydrogen are passed at the rate of at least 10, and advantageously 10 to 40, gallons of oil per 1000 cubic feet of hydrogen (measured at 60 F. and 30 inches of mercury pressure, saturated) under a pressure of at least 10 atmospheres through a bed of a particulate solid material maintained in the fluidised state by the gas and having a temperature within the range of 700 C. to 800 C.
The pressure is preferably within the range of 10 to 50 atmospheres, and advantageously 10 to 25 atmospheres.
The bed of particulate solid material may be composed, for example, of a siliceous material or of carbon, for example, a carbonised material, such as coke.
As the hydrogenating gas there may be used substantially pure hydrogen or a gas consisting mainly of hydrogen, such as water gas.
With the high ratio of oil to hydrogen used in the process of this invention the aromatic hydrocarbons obtained do not consist principally of simple aromatic hydrocarbons devoid of side chains, such as benzene, naphthalene and small amounts of higher polynuclear aromatic hydrocarbons, but contain, in addition to such hydrocarbons, homologues thereof, for example, toluene and xylene, and the gaseous hydrocarbons include a considerable proportion of unsaturated gaseous hydrocarbons.
If desired, the benzene homologues may be converted into benezene by a subsequent hydrogenation with the use of a further proportion of hydrogen as such, or in the form of a gas consisting mainly of hydrogen, suificient to remove the side chains (dealkylation) and, if desired, to hydrogenate the unsaturated gaseous hydrocarbons. For this purpose, the gaseous mixture from the first hydrogenation treatment is passed in admixture with the necessary further proportion of hydrogen through a fluidised bed of solid particulate material at a temperature within the range of 700 C. to 850 C., and advantageously 750 C. to 850 C., for example, about 800 C., under a pressure such as is suitable for the first treatment. The further proportion of hydrogen supplied to the second stage plus the quantity of hydrogen supplied to the first stage (i.e. including the hydrogen consumed in the first stage) is generally 1000 cubic feet for every 5 to 10 gallons of oil used to produce the gaseous mixture in the first stage. The second stage may be carried out in a separate vessel or in another part of the vessel in which the first stage is carried out.
In the second stage of this process of the aromatic hydrocarbons containing side chains, principally homologues of benzene and naphthalene, can be converted substantially completely into the corresponding parent hydrocarbons free from side chains, and some polynuclear aromatic hydrocarbons higher than naphthalene are broken down to form naphthalene.
It is sometimes desirable that the oil consisting of petroleum hydrocarbons used should be free from sulphur compounds, for example, in order that the gas and aromatic hydrocarbons obtained shall be free from sulphur compounds. For this purpose, the oil is advantageously purified, before use, in the manner described in Research Communication GC41 of The Gas Council, at pages 32-36, by passing the oil in the form of vapour in admixture with a small proportion of hydrogen over molybdenum sulphide at a temperature within the range of 250 C. to 450 C., and preferably 300 to 400 C., whereby the sulphur compounds are converted into hydrogen sulphide, and removing the hydrogen sulphide by absorption with alkaline iron oxide at a temperature within the range of 250 C. to 400 C., and preferably 300 C. to 350 C.
The process of the invention is illustrated by way of example with reference to the accompanying drawing:
A suitable light distillate is supplied through a pipe 1 by means of a pump 2 to a coil 3 which is immersed in heated oil within a vessel 4, so that the light distillate is vaporised in the coil 3. Hydrogen or a gas containing hydrogen is supplied through a pipe 5 and is preheated in a coil 6, which is also heated by the hot oil in the vessel 4. The oil vapour passes from the coil 3 through a coil 7, which is located within the upper part of a fluidised bed Within a hydrogenation vessel indicated generally as 3 8, and in which the oil vapour is further heated. Similarly the gas leaving the coil 6 is further heated in a coil 9 located in the upper part of the said fluidised bed.
The preheated oil vapour flows along a pipe 10, in which it is mixed with a small proportion of hydrogen or hydrogen-containing gas from a branch pipe 11. The mixture then passes into a vessel 12 containing a molybdenum sulphide catalyst and from the vessel 12 into a vessel 13 containing an alkaline iron oxide preparation. In this manner sulphur compounds present in the oil vapour are converted into hydrogen sulphide followed by removal of the hydrogen sulphide, as described in Research Communication GC41 of The Gas Council, at pages 32-36. Fresh alkaline iron oxide preparation is periodically supplied to the vessel 13 from a hopper 14 through a lock hopper 15, and the spent material is discharged through a lock hopper 16.
The oil vapour freed from sulphur then flows together with unconsumed hydrogen through a pipe 17 into the base of the hydrogenation vessel 8. This vessel has a lower section 8a, in which the first hydrogenation stage is carried out, and which communicates with an upper section 812 of larger diameter than the lower section and in which the dealkylation of benzene homologues is carried out. Before entering the lower section 8a the oil vapour is mixed with the necessary proportion of hydrogen or hydrogen-containing gas from a pipe 18 that communicates with the outlet end of the pro-heating coil 9. The gaseous mixture flows upwardly through the fluidised bed in section 8a in which the hydrogenation takes place, and at the junction between sections 8a and 8b the further quantity of hydrogen or hydrogen-containing gas required for the dealkylation is introduced through inlets 19 that communicate through an annular conduit 20 with a pipe 21 communicating with the pipe 18.
The gaseous reaction mixture leaves the hydrogenation vessel 8 through a cyclone separator 22, by means of which entrained solids are returned through a pipe 23. The gaseous mixture then flows out through a pipe 24 into a scrubber 25, in which the heavier and less volatile products are condensed and collected as the hot oil for preheating in the vessel 4. The condensation of the volatile products and the collection of the condensate are assisted by recycling the hot condensate to the top of the scrubber 25 by means of a pump 26.
The gases and lighter vapours leave the scrubber 25 through a pipe 27 and enter a water-cooled condenser 28 in which benzene is condensed and flows into a receiver 29. The removal of the last traces of benzene from the gas leaving the condenser 28 through a pipe 30 can be carried out in known manner, for example, by scrubbing with gas oil or by absorption with active carbon, before the pressure of the gas is reduced to atmospheric pressure.
Any carbon that may be deposited in the fluidised bed by hydrocarbon cracking increases the volume of the bed, which can be kept constant by periodically withdrawing excess material through a pipe 31 and lock hopper 32.
When it is not desired to make sulphur-free gas and benzene, for example, if the available hydrogenating gas contains sulphur that cannot conveniently be removed, the pipe can be arranged so as to pass the oil vapour directly from the preheating coil 7 into the base of the reaction vessel 3, after the oil vapour has been mixed with hydrogen or hydrogen-containing gas from the pipe 18. Accordingly, the pipe 11, the portion of the pipe 10 leading to the vessel 12, the pipe 17 and vessels 12, 13, and 16 would be eliminated.
The following examples illustrate the invention:
Example 1 The oil used was a light petroleum distillate having a density of 0.649 (at C.), a boiling range of 37-72 C. and a content of aromatics of 1.2 percent, and of which the average molecule contained 5.9 carbon atoms. This oil was vaporised, and the vapour was mixed with hydrogen of 99.5 percent purity in the ratios given below in gallons of oil per 1000 cubic feet of hydrogen (measured at 15 C. and 760 mm. pressure). The mixture of oil vapour and hydrogen was passed at a temperature of 400-500 C. under a pressure of 10 atmospheres into a vessel containing coke having a particle size of 72 to +200 mesh B.S.S., the coke particles being maintained in the form of a fluidised bed by the gaseous mixture. The hydrogenating gas was supplied at a rate such that, under the conditions of temperature and pressure used, it would, if unmixed with oil vapour, traverse the space occupied by the fluidised bed in 10 seconds, so that the actual contact time of the gaseous mixture can be calculated for the given proportion of oil to hydrogen. In several experiments the vessel was heated in an electric furnace sufficient to maintain the fluidised bed at the temperatures given below. The composition of the products obtained are given in the following table:
Temperature Gallons of oil per 1000 cubic feet of hydrogen 28. 1 25. 6 27. 8 Products obtained (calculated as a percentage of the carbon content of the oil supplied):
Gas 79. 6 81. 8 78. 7 Benzene-.. 5. 5 6. 9 10. 1 Toluene. 2.6 3. 1 3. 1 Xylenes 0. 7 0. 8 1. 2 Naphthalen l. 3
6.8 4. 7 Higher ar0matics 4. 5 Deposited carbon 0. 0 O. 0 0. 0 Calorific value of gas in B. Th. U. per
cubic foot 1, 305 1, 295 1, 165 Composition of gas, percent by volume.
Unsaturated hydrocarbons CxHy. 20. 3 19. 4 16. 6 Hydrogen 22.8 19. 7 16. 9 56.0 60.4 65. 7 0. 9 0.5 0.8 2. 83 2.85 2. 48 77. in C I'Im 1. 56 1. 46 1. 29
In an experiment using a ratio of 11.6 gallons of oil per 1000 cubic feet of hydrogen and at a temperature of 700 C., the other conditions being the same, the following results were obtained.
Gas 92.5 Benzene 3.7 Toluene 1.2 Xylenes 0.4 Higher aromatics and naphthalene 0.9 Deposited carbon 0.0 Gas composition:
C H 12.6 Hydrogen 36.8 CNH2N+2 Nitrogen 0.7 x in C H 3.00 n in CNH2N+2 Example 2 The oil used was a petroleum distillate having a density of 0.764 (at 20 C.), a boiling range of 185 C. and a content of aromatics of 19.1 percent, and of which the average molecule contained 9.2 carbon atoms. In separate experiments the vapour of this oil was mixed with hydrogen of 99.5 percent purity and with a gas obtained by the Lurgi process having approximately the following percentage composition by volume: H =65, CO=20 and CH =15 (hereinafter referred to as Lurgi gas). The temperatures, pressures and ratios of oil to hydrogenating gas are given below, the other conditions The following results Temperature, C 725 720 725 755 755 Pressure in atmospheres (hydrogen)..- 10 10 10 25 Pressure in atmospheres (Lurgi gas)... 20
Gallons of oil per 1000 per cu. ft. of Hz: 26. 8 12. 1 11. 7 13. 7 12. 5
Gas 57. 64.0 63. 9 62. 7 63. 10. 8 12.2 10.6 11.8 12.8 10. 2 11. 4 11.0 9. 2 10. 3 6. 7 6. 2 5. 2 3. 7 3. 7 2. 1 1. 8 2. 2 0.0 0.0 2.2 1.6 -2.2 0.8 5.0 9. 9 3. 4 2. 3 9. 8 4. 0 1. 4 0.0 0. 7 1.0 1. 6 1, 150 1, 045 930 1, 040 1, 080
0.0 0.0 0.7 0.0 0. O 11.6 7. 7 3.5 5. 9 3. 3 15. 6 30. 1 19. 9 22. 2 16. 8 0.0 0.0 13.9 0.0 0. 0 72. 4 61. 5 61. 7 71. 5 79. 4 0. 4 0.7 0.3 0.4 0.5 2. 61 2. 73 2. 83 2. 50 3. 17 n in C HZN 1. 27 1. 37 1.30 1. 27 1. 29
Example 3 This example illustrates the two-stage process, in which the products from the first stage are further hydrogenated in a second stage. The oil was the same as that having a content of aromatics of 19.1 percent used in Example 2. In the first stage the oil vapour and hydrogen (99.5% purity) were passed through a fluidised bed in the manner described in Example 1 under the conditions given below. In the second stage the whole of the products from the first stage were passed together with additional hydrogen through a second fluidised bed similar to the first bed. The additional proportion of hydrogen supplied to the second stage plus the quantity of hydrogen supplied to the first stage (i.e. including the hydrogen consumed in the first stage) is related to the quantity of oil supplied to the first stage. The conditions used and results obtained were as follows:
First Second stage stage Temperature, C 725 745 800 Pressure in atmospheres 25 25 25 Gallons of oil per 1000 cu. ft. of H2 13 6. 3 6. 3
Residence time, secs 10 23 24 Products obtained:
Gas 57. 3 67. 1 59.6 Benzene-. 8.4 17. 9 19.4 Toluene. 8. 9 2. 2 1. 7 Xylenes 4. 7 0. 0 0. 0 Other monocyclics.- 3. 2 0. 0 0. 0 Naphthalene 2. 2 2. 0 6. 4 Higher aromatics. 12. 8 7. 2 4. 6 Deposited carbon- 2. 1 1. 1 4. 9 Calorific value of gas 1, 105 800 790 Composition of gas:
5. 6 0.6 0.4 16. 5 44. 8 37. 2 77. 3 54. 4 61. 4 0.6 0. 2 1.0 2. 36 3. 84 2.0 n in CNHmH 1.32 1. 24 1. 11
Examples 4 and 5 In these examples there was used a reaction vessel of the kind shown in the accompanying drawing, of which the overall length was 14 feet. The lower section had a length of 6 feet and an internal diameter of 3 inches, and the upper section had a length of 8 feet and an internal diameter of 5 inches. The oil vapour mixed with hydrogen was introduced directly into the lower section, in which the synthesis of aromatics occurred, and additional hydrogen was supplied at the base of the upper section, in which the dealkylation of aromatic hydrocarbons flowing upwards from the lower section took plate. The fluidised bed in both sections consisted of coke having a particle size of -72 to +200 mesh B.S.S. The characteristics of the hydrocarbon oil used, the operating conditions, and the results are given below.
Example Example 4 5 I. Characteristics of Hydrocarbon Oil:
Initial boiling point, 46C.- 4e 36 Final boiling point, "C 168 161 Aromatic hydrocarbon content, percent by volume 4. O 2. 5 Number of carbon atoms in the average molecule 6. 5 6. 0 II. Operating s:
Temperature in the synthesis section, C...-. 700 780 Temperature in the dealkylation section, C. 750 790 Oil supply to synthesis stage in gallons per hour 2. 47 4. 34 Hydrogen supply to synthesis section in cubic feet per hour hour (at 60 F. and 30 in. Hg saturated) 310 Hydrogen supply to dealkylation stage in cubic feet per hour (at 60 F. and 30 in. Hg saturated) 163 134 Oil in gallons per 1000 cubic feet of hydrogen supplied to synthesis section 13 14 Oil in gallons per 1000 cubic feet of the total hydrogen supplied to both sections 7 9. 8 Pressure, atm 25 25 Height in feet of fluidised bed in synthesis section 3 4 Height in feet of fluidised bed in dealkylation qrmtirm 5 6 Actual time of contact, synthesis stage, sccs 14 10 Actual time of contact, dealkylation stage,
see 34 32 III. Results:
Products obtained (calculated as a percentage of the carbon content of the oil supplied):
Gas 77.6 75. 5 Benzene 13. 8 12. 1 Toluene 0. 3 1. 3 Naphthalene and Higher Aromatics. 4 3 7. 4 Deposited Carbon 3. 6 3.2 Unaccounted 0. 4 0. 5 Composition of gas, percent by volume.
Unsaturated Hydrocarbons 0. 4 1. 15 Hydrogen 31. 35 21. 8 Pa s CNH2N+2 67. 05 76. 6 Nitrogen 1. 2 0.45 '/L in CNH2N+2--- 1, l9 1. 12 Calorific Value of Gas (calculated) in B.Th.U.
per cubic foot 865 925 We claim:
1. A process for the gasification of oil consisting of petroleum hydrocarbons having an average of 4 to 10 carbon atoms and of which at least 70 percent consist of aliphatic hydrocarbons to produce non-alkylated aromatic hydrocarbons and gaseous saturated hydrocarbons, said process comprising the steps of first passing said oil and a gas comprising mainly hydrogen at the rate of at least 10 gallons of oil per 1000 cubic feet of hydrogen, when measured at 60 F. and 30 inches of mercury pressure saturated, and under a pressure of at least 10 atmospheres through a first bed of particulate solid material maintained in the fluidized stage by the gas and having a temperature within the range of 700 C. to 800 C. for heating said oil and said gas to produce a gaseous mixture comprising alkylated and non-alkylated aromatic hydrocarbons and saturated and unsaturated gaseous hydrocarbons, and thereafter passing said gaseous mixture in admixture with a further proportion of said gas through. a second fluidized bed of solid particulate material having a temperature within the range of 700 C. to 850 C. and under a pressure of at least 10 atmospheres, the said further proportion of said gas containing a quantity of hydrogen such that the sum of the quantities of said hydrogen and of the hydrogen supplied to the first fluidized bed amounts to 1000 cubic feet for every 5 to 10 gallons of oil supplied to the first fluidized bed and such that the alkylated aromatic hydrocarbons are dealkylated and the unsaturated gaseous hydrocarbons are converted into saturated gaseous hydrocarbons.
2. The process defined in claim 1, wherein the pressure in the said first and second beds of particulate solid materials is within the range of 10 to 50 atmospheres.
3. The process as defined in claim 1 wherein the particulate solid material of said first and second beds is selected from the group consisting of carbon and coke.
4. The process as defined in claim 1 wherein said second bed has a temperature within the range of 750 C. to 850 C.
8 2,349,045 Layng etal May 16, 1944 2,512,570 Sartor June 20, 1950 2,573,906 Hufr" Nov. 6, 1951 2,639,982 Kalbach May 26, 1953 2,759,806 Pettyjohn Aug. 21, 1956 2,894,897 Post July 14, 1959 OTHER REFERENCES Kalichevsky and Kobe: Petroleum Refining With 5. The process as claimed in claim 1, wherein the oil 1 Chemicals, P Elsevief Publand gas comprising hydrogen are supplied to the first fluidized bed at the rate of 10 to 40 gallons of oil per 1000 cubic feet of hydrogen.
References Cited in the file of this patent UNITED STATES PATENTS 1,995,604 Davis Mar. 26, 1935 (Copy in Div. 31, US. Pat. Off.) Refers to following articles; C. D. Gard, California Oil World 41, pp. 3, 5, 7, 9, 11, 15 (December 1948). (Copy in US. P.O., Photostat Div.)
Sperr: Gas Age Record, 58, pp. 73-6, 80 (1926). Sachanen: Conversion of Petroleum, pp. 206, 210, 216, Reinhold Publ. Corp., NY. (1940).