US3691248A - Selective hydrogenation of acetylenes - Google Patents
Selective hydrogenation of acetylenes Download PDFInfo
- Publication number
- US3691248A US3691248A US109037A US3691248DA US3691248A US 3691248 A US3691248 A US 3691248A US 109037 A US109037 A US 109037A US 3691248D A US3691248D A US 3691248DA US 3691248 A US3691248 A US 3691248A
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- catalyst
- hydrogenation
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- nickel
- acetylenes
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G70/00—Working-up undefined normally gaseous mixtures obtained by processes covered by groups C10G9/00, C10G11/00, C10G15/00, C10G47/00, C10G51/00
- C10G70/02—Working-up undefined normally gaseous mixtures obtained by processes covered by groups C10G9/00, C10G11/00, C10G15/00, C10G47/00, C10G51/00 by hydrogenation
Definitions
- the selective hydrogenation occurs by the addition of liquid carbon disulfide into the gas stream in an amount to provide between 5 and 20 parts per million of sulfur in the hydrogenation zone.
- a catalyst comprising nickel, for example, a nickel-cobalt-chromium sulfide supported catalyst, is employed and the acetylene content of the product is reduced to a level of about 30 to 200 ppm.
- An ethylene stream can be separated and the acetylene content further reduced in a secondary hydrogenation zone using any suitable hydrogenation catalyst.
- This invention relates to a process for treating an impure gas stream obtained by the pyrolysis of hydrocarbons such as ethane and propane and comprising ethylene, butadiene and acetylenes.
- this invention relates to the addition of liquid carbon disulfide to a hydrogenation zone containing a catalyst comprising nickel sulfide to improve the selectivity of the catalyst for the selective hydrogenation of acetylenes in said gas mixture.
- Ethylene is one of the largest volume products produced in commercial quantities. Ethylene is normally produced by the pyrolysis of petroleum hydrocarbons such as ethane and propane. When ethylene is produced via this pyrolysis route the entire gas stream from the pyrolysis furnace contains certain impurities which must be removed before the ethylene can be considered to be of acceptable commercial purity. The most objectionable impurity in the pyrolysis stream is the acetylenic materials, such as acetylene itself and methylacetylenes. Other unsaturated hydrocarbons, and in particular butadiene, are also present in the pyrolysis gas stream and must also be removed from the ethylene.
- the butadiene content of the pyrolysis gas stream is of considerable value as a commercial product itself and thus it is desirable to recover it for sale if possible.
- the entire pyrolysis gas stream is cooled to condense out a liquid highly unsaturated product termed an aromatic distillate which boils primarily in the naphtha range.
- the remaining gases require further purification.
- prior art processes namely U.S. Pat. No.
- impure pyrolysis gas from the cracking of ethane and propane usually contains from 1.0 to 2.5 mole percent C, monoolefins and thus it would be expected from the teachings of Fleming et al. that the hydrogenation of the acetylenes in the impure gas stream would have to be limited to between 85 and 92 percent in order to prevent the simultaneous hydrogenation of the butadiene content.
- the product from the partial hydrogenation can then be treated to separate.
- the impure gas stream which is treated by the .process of this invention is obtained by the pyrolysis of light hydrocarbons, such as ethane and propane, which are substantially free of sulfur containing compounds.
- substantially free is meant that the cracked gas products have less than 5, usually 3 to 4, ppm of sulfur.
- Table I A typical analysis of a cracked gas stream suitable for treatment in accordance with this invention is shown in Table I below.
- hydrogen is charged downflow to a hydrogenation reactor containing a bed of a catalyst comprising nickel at a space velocity of from 1,000 to 3,5000 volumes of gas per volume of reactor space per hour (preferably a space velocity of 2,500 to 3,500 v/v/hr); a temperature from about 225 to 500 F. (preferably 375 to 450 F.); and an operating pressure of from 50 to 600 psig (preferably 200 to 300 psig).
- the partial pressure of hydrogen is usually from 30 to 50 psig.
- an amount of liquid carbon disulfide is injected into the gas stream so that the total parts per million of sulfur in the gas stream entering the hydrogenation zone is from 5 to 20 ppm, preferably from 6 to 12 ppm.
- Liquid carbon disulfide has the advantage of being easily metered and pumped into the entering gas stream.
- the carbon disulfide does not tend to plug valves as gaseous sulfur compounds might and is conveniently employed in smaller chemical plants in lieu of gaseous sulfur compounds.
- the temperature increase through the first hydrogenation zone was from 80 to 120 F. and sometimes higher.
- the hydrogenation catalyst which is employed in the first hydrogenation zone comprises a supported nickel containing catalyst.
- the nickel catalyst can be promoted with one or more of the metals from Groups Vlb and VIII of the Periodic Table.
- the metals can be present on the support in the form of the metals per se, the oxides, sulfides or mixtures of these forms.
- the metals from Groups Vlb and VIII include chromium, molybdenum, tungsten, iron, cobalt, palladium, platinum, ruthenium, rhodium, osmium and iridium.
- the preferred metals for promoting the nickel catalyst are chromium, cobalt, palladium, molybdenum and mixtures thereof.
- the amount of nickel calculated as the metal can suitably be from 0.5 to 20 percent, preferably 1 to 10 percent, by weight of the catalyst.
- the weight ratio of nickel as the metal to the total amount of promoting metals from Groups V1 and VIII is suitably from 0.511 to 500:1 but is preferably from 2:1 to 200:1.
- the most preferred catalysts are the supported sulfur insensitive catalysts containing from 1 to 6 weight percent nickel; from 0.01 to 0.5 weight percent cobalt; from 0.01 to 0.2 weight percent chromium and from 0.01 to 0.1 weight percent palladium.
- the supported catalysts can be prepared in a variety of different ways, such as by impregnation of the various metals from a solution of their soluble salts onto the support.
- a cobalt and chromium promoted nickel catalyst can be prepared by immersing a suitable support material in an aqueous solution of nickel and cobalt nitrate containing some chromic acid anhydride.
- the catalyst if desired, can be sulfided by the addition of sulfuric acid to the impregnating solution or by treating the finished catalyst with a sulfiding agent such as hydrogen sulfide.
- the support material should be a rugged attrition resistant support since polymeric materials are produced in the reaction and the catalyst support must be able to withstand the repeated regenerations to which it is subjected.
- Suitable support materials include alumina, silica, silica-aluminas, magnesias or mixtures thereof which have the requisite ruggedness of structure.
- Silica-alumina supports which have been suitably treated as by steaming to reduce their cracking activity are preferred.
- the gas products issuing from the first hydrogenation zone contain on the order of 25 to 250, usually 25 to 95, ppm of acetylenes.
- the total gas product is then fractionated and an ethylene stream is recovered containing on the order of 30 to 200, usually 30 to 80, ppm of acetylene.
- the acetylene content of the ethylene stream is still too high for commercial pure acceptance.
- This ethylene stream containing from 30 to 200, usually 30 to 80, ppm of acetylene is normally. passed through a second hydrogenation zone containing a suitable hydrogenation catalyst to reduce the acetylene content to 10 ppm or less, which is an acceptable level for commercially pure ethylene.
- the conditions in the second hydrogenation zone include a temperature from to 350 F preferably from to 200 F.; a pressure from 100 to 450 psig, preferably from 370 to 390 psig; a space velocity from 1,000 to 6,000, preferably from 4,700 to 5300, volumes of gas per volume of reactor space per hour; and an amount of hydrogen which is in the range of two to six times the amount necessary to hydrogenate the acetylenes.
- the partial pressure of hydrogen is from 0.25 to 0.35 psig.
- Any suitable hydrogenation catalyst can be utilized in the second hydrogenation zone.
- Those catalysts which are elective for the hydrogenation of acetylene from monoolefins are, of course, preferred.
- a suitable group of catalysts which may be employed in the second hydrogenation zone are those which were employed above in the first hydrogenation zone.
- Other suitable catalysts include those consisting essentially of palladium or platinum on a suitable support such as alumina.
- the catalyst may or may not be sulfur sensitive since the charge to the second hydrogenation zone may be sulfur-free and no sulfur containing compounds are added.
- the metals in the catalyst for the second hydrogenation zone are therefore usually in the form of the metal or metal oxide.
- the metals can be any one or more metals from Groups VIb and VIII of the Periodic Table.
- the total metals content can be from 0.5 to 30 weight percent of the total catalyst and is preferably from 2 to 15 weight percent.
- the most preferred catalysts are the nickel-alumina supported catalysts containing from 4 to weight percent nickel promoted with minor amounts (0.01 to 0.1 weight percent) of other metals from Groups VI and VIII, especially chromium, cobalt and palladium.
- the catalysts for the second hydrogenation zone may be prepared by any suitable procedures as those defined above for the first hydrogenation zone.
- the supports may be the same as those for the first zone hydrogenation catalysts.
- a mixture of weight percent ethane and 85 weight percent propane and less than 5 ppm sulfur was pyrolyzed at a temperature from 1450 to 1550 F.
- the pyrolysis products were cooled to condense out an aromatic distillate fraction and the acid gases (40 ppm of CO and traces of H 5) were removed by scrubbing the total gas stream with dilute monoethanolamine, followed by dilute caustic treatment.
- the remaining gases had a typical composition as shown in TABLE 11 below.
- a gas mixture having the composition shown in TABLE 11 above was passed downflow through a reactor containing a bed of a supported nickel-cobaltchromium sulfide catalyst at a pressure maintained in the range of 225 to 275 psig, a temperature maintained in the range of from 380 to 500 F. and a space velocity of from 2,500 to 3,500 v/v/hr.
- the catalyst contained about two weight percent nickel, 0.3 weight percent cobalt 0.1 weight percent chromium calculated as the metals on a silica-alumina refractory support. The results of this run are shown in Table III below.
- Example 1 was repeated except from 5 to 9 ppm of sulfur asliquid carbon disulfide was metered into the gas stream entering the reactor.
- the temperature increase through the catalyst bed was from 402 to 454 F or only 52 F.
- the results of this run are shown in Table 111 above. Referring to Table III, the amount of ethylene hydrogenation was reduced (compare Examples l and 2) and the amount of butadiene hydrogenation was reduced from 37 to l2 percent.
- the concentration of butadiene in the butene fraction removed in subsequent fractionation was increased from 12 to 34 weight-percent, showing reduced butadiene hydrogenation.
- EXAMPLE 3 The product from Example 2 was fractionated at 380 psig and an ethane-ethylene stream containing 85 ppm acetylene was recovered. This stream was passed downflow through a bed of a supported nickel on alumina catalyst (about 6 weight percent nickel) containing minor amounts of chromium and palladium at F., 380 psig and a space velocity of 5,250 v/v/hr. The results of this run are summarized in Table III above and show the product to contain less than 1 ppm acetylene, which is an acceptable commercial level.
- a process according to claim 1 wherein the catalyst comprises from 0.5 to 20 weight percent nickel on a refractory support.
- a process for the production of improved yields of commercially pure ethylene and butadiene from the products of the pyrolysis of substantially sulfur-free light hydrocarbons which process comprises cooling said products of pyrolysis to produce a liquid aromatic distillate product and a first gaseous stream comprising ethylene, from 0.8 to 1.0 mole percent butadiene and from 0.10 to 0.25 mole percent acetylenes;
- a hydrogenation catalyst comprising nickel in a first hydrogenation zone in the presence of hydrogen under hydrogenation conditions including a temperature from 225 to 500 F.; a pressure from 50 to 600 psig; and a space velocity of from 1,000 to 3,500 v/v/hr.;
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- Oil, Petroleum & Natural Gas (AREA)
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
Claims (4)
- 2. A process according to claim 1 wherein the catalyst comprises from 0.5 to 20 weight percent nickel on a refractory support.
- 3. A process according to claim 2 wherein the catalyst contains a promoting amount of at least one other metal from Groups VI and VIII and wherein the weight ratio of nickel to the total amount of promoting metals is from 0.5:1 to 500:1.
- 4. A process for the production of improved yields of commercially pure ethylene and butadiene from the products of the pyrolysis of substantially sulfur-free light hydrocarbons, which process comprises cooling said products of pyrolysis to produce a liquid aromatic distillate product and a first gaseous stream comprising ethylene, from 0.8 to 1.0 mole percent butadiene and from 0.10 to 0.25 mole percent acetylenes; adding to said first gaseous stream an amount of liquid carbon disulfide to insure a sulfur level in said first gaseous stream of from 5 to 20 ppm; contacting said first gaseous stream with a hydrogenation catalyst comprising nickel in a first hydrogenation zone in the presence of hydrogen under hydrogenation conditions including a temperature from 225* to 500* F.; a pressure from 50 to 600 psig; and a space velocity of from 1,000 to 3,500 v/v/hr.; and recovering a second gas stream containing from 30 to 200 ppm of acetylEnes and without substantial reduction in the butadiene content; separating from said second gas stream an ethylene fraction containing from 30 to 200 ppm of acetylene; hydrogenating said ethylene fraction in a second hydrogenation zone with a hydrogenation catalyst under hydrogenation conditions including a temperature from 150* to 350* F.; a pressure from 100 to 450 psig; and a space velocity of from 1, 000 to 6,000 v/v/hr. to selectively hydrogenate the acetylene content to a concentration of less than 10 ppm of said ethylene fraction.
- 5. A process according to claim 4 wherein the catalyst in the first hydrogenation zone is a nickel-cobalt-chromium catalyst and the recovered second gas stream contains from 30 to 80 ppm of acetylenes.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10903771A | 1971-01-22 | 1971-01-22 |
Publications (1)
Publication Number | Publication Date |
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US3691248A true US3691248A (en) | 1972-09-12 |
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US109037A Expired - Lifetime US3691248A (en) | 1971-01-22 | 1971-01-22 | Selective hydrogenation of acetylenes |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030089465A1 (en) * | 2001-11-02 | 2003-05-15 | David Schaible | Process for producing microcrystalline cellulose |
US20050154241A1 (en) * | 2002-08-08 | 2005-07-14 | Catalytic Distillation Technologies | Selective hydrogenation of acetylenes |
-
1971
- 1971-01-22 US US109037A patent/US3691248A/en not_active Expired - Lifetime
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030089465A1 (en) * | 2001-11-02 | 2003-05-15 | David Schaible | Process for producing microcrystalline cellulose |
US20050154241A1 (en) * | 2002-08-08 | 2005-07-14 | Catalytic Distillation Technologies | Selective hydrogenation of acetylenes |
US7319176B2 (en) | 2002-08-08 | 2008-01-15 | Catalytic Distillation Technologies | Selective hydrogenation of acetylenes |
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AS | Assignment |
Owner name: CHEVRON RESEARCH COMPANY,CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CHEVRON U.S.A. INC.;REEL/FRAME:004688/0451 Effective date: 19860721 Owner name: CHEVRON RESEARCH COMPANY, SAN FRANCISCO, CA. A COR Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CHEVRON U.S.A. INC.;REEL/FRAME:004688/0451 Effective date: 19860721 |
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Owner name: CHEVRON U.S.A. INC. Free format text: MERGER;ASSIGNOR:GULF OIL CORPORATION;REEL/FRAME:004748/0945 Effective date: 19850701 |