Classifications

• • 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
  • C10G69/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process
  • C10G69/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only
  • C10G69/06—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only including at least one step of thermal cracking in the absence of hydrogen
• • 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
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/20—C2-C4 olefins

Definitions

• the present invention relates to a process for the production of gaseous olefins from petroleum distillate feedstocks.
• Ethylene, propylene and butadiene which are basic intermediates for a large proportion of the petrochemical industry are obtained in the main by thermal cracking of petroleum gases and distillates such as naphtha and gas oil.
• thermal cracking of petroleum gases and distillates such as naphtha and gas oil.
• lighter components of petroleum There is a world wide increase in demand on the use of these lighter components of petroleum and it is desirable that heavier feedstocks be utilised for olefin production.
• a number of problems arose in the cracking of heavier feedstocks which have so far prevented their use in the economic production of light olefins.
• the principle problems were:
• Feedstocks from many sources contain high levels of sulphur; this is not necessarily detrimental to the operation of the cracking process but may increase the cost of plant construction. Further the bulk of the sulphur is concentrated in the liquid products boiling above 200C which are therefore less valuable as fuel oil.
• a process for the production of olefins which process comprises hydrogenating a petroleum distillate feedstock in the presence of a hydrogenation catalyst and hydrogen and thermally cracking the resulting hydrogenated product in the presence of steam.
• Thermal cracking within the context of this application is intended to include steam cracking but not catalytic cracking.
• the preferred petroleum distillate feedstock is a vacuum distillate boiling within the range (at atmospheric pressure) 300 to 650C, though lighter distillate feedstocks such as gas oil boiling within the range 200 350C may be used.
• Hydrogenation catalysts embodying these requisites include for example nickel/molybdenum/alumina, cobalt/tungsten/alumina, nickel/tungsten/alumina, cobalt/molybdenum/alumina, nickel/cobalt/molybdenumlalumina, cobalt/mo]ybdenum/silica/alumina, nickel/molybdenum/silica/alumina, cobalt/tungsten/silica/alumina.
• a particularly active hydrogenation catalyst is nickel/- tungsten/silica/alumina.
• the catalyst may also be used in the sulfided form.
• the catalysts may conveniently be prepared by impregnating the support with an aqueous solution of a salt of each of the metals, either consecutively or simultaneously.
• nickel may be added in the form of nickel nitrate, tungsten as ammonium metatungstate, cobalt as cobalt nitrate, acetate, etc. and molybdenum as ammonium molybdate. It will usually be found convenient to impregnate the support first with the salt of the metal which is to be present in the highest concentration in the finished catalyst, though this is not essential.
• Other methods of preparing the catalyst include precipitating the metals on the support from a solution of their salts and coprecipitation of the metals with the hydrated support material.
• the catalysts be activated before use in the reaction by contact with a stream of hydrogen at a temperature in the range to 800C, preferably 300 to 600C, for a period of 1 minute to 24 hours.
• the sulfided form of the catalyst may conveniently be prepared by passing hydrogen through liquid tetrahydrothiophene and then over the catalyst maintained at a temperature in the range 100C to 800C, preferably 300C to 600C, for a period of 1 minute to 24 hours.
• the catalyst contains, in addition to the support, elemental metal, metal oxides, metal sulfides and complex aluminium or silicon/metal compounds.
• the hydrogenation temperature may be in the range 50 to 500C, preferably 300 to 400C, and the pressure may be in the range 50 to 5000 p.s.i.g., preferably 200 to 3000 p.s.i.g.
• the hydrocarbon Liquid Hourly Space Velocity may be in the range of 0.1 to 5.0, preferably 0.25 to 2.0.
• Hydrogen is preferably used on-a recycle basis, preferably at about 5 to 10 times the molar rate of the hydrocarbon feedstock, and may be passed through scrubbers to remove hydrogen sulfide and ammonia before recycle. However other methods of operation may also be used such as batch operation in an autoclave.
• reaction conditions may be different.
• Hydrogenation may be carried out in a single stage or in a series of two or more operations using the same or different catalysts.
• the feedstock from the hydrogenation reaction is vaporised in the presence of steam at a steam to hydrocarbon weight ratio of about 0.521 to 20:1 and passed through a heated zone, preferably a tube, at a maximum temperature in the range 700 to 1,000C with a residence time in this temperature range between 0.01 and 5 seconds, preferably 0.1 to 2 seconds.
• the products are rapidly cooled in a heat exchange system and separated and purified by conventional means.
• COMPARISON TEST 1 A full range Agha Jari vacuum distillate with a hydrogen to carbon atomic ratio of 1.73 and a sulfur content of 1.72 per cent weight was steam cracked in a 26 ml quartz reactor at a maximum temperature of 830C. Analysis by physical separation and spectroscopic methods (including U.V. Absorbance) indicated that the aromatic compound content was 49% weight.
• the steam to hydrocarbon feed weight ratio was 1 to 1 with an average total molar flow of 3.3 moles per hour.
• the ethylene and propylene yields were 23 and per cent weight respectively with a total conversion to cracked gas of 53 per cent weight on feed.
• Coke deposited in the cracking zone corresponded to 1,200 ppm of the hydrocarbon feed.
• EXAMPLE 1 The catalyst was prepared by calcining alumina at a temperature of 550C. The calcined alumina was then impregnated with an aqueous solution of ammonium molybdate, evaporated to dryness and further calcined at 550C. This procedure was then repeated using an aqueous solution of cobalt nitrate. The catalyst was then activated in a stream of hydrogen at 400C for 16 hours.
• a 250g sample of the Agha Jari vacuum distillate used in Comparison Test 1 was hydrogenated in a 1 litre rocking autoclave at 350C under 1,500 p.s.i.g. of hydrogen during 8 h using 100g of the cobalt/molybdenum/alumina catalyst prepared as above.
• the recovered hydrogenated vacuum distillate, sample A had a hydrogen to carbon atomic ratio of 1.84 and a sulfur content of less than 0.05 per cent weight.
• Analysis by physical separation and spectroscopic methods indicated that the aromatic compound content was 19% weight.
• This material was steam cracked under the same conditions as were used in Comparison Test 1.
• the ethylene and propylene yields were 26 and 10 per cent weight on feed respectively with a total conversion to cracked gas of 58 per cent.
• EXAMPLE 2 A g sample of the hydrogenated vacuum distillate sample A, was further hydrogenated in a rocking autoclave at 350C and 1,500 psig of hydrogen during 18 hours using 40 g of a 5 per cent nickel on silica catalyst prepared by impregnation as in Example 1.
• This further hydrogenated vacuum distillate has a hydrogen to carbon atomic ratio of 1.91 and a sulphur content of less than 0.02 per cent weight.
• Analysis by physical separation and spectroscopic methods indicated that the aromatic compound content was less than 2 per cent weight.
• the ethylene and propylene yields were found to be 29 and 1 1 per cent weight respectively, and the total cracked gas yield has increased to 64 per cent.
• the yields of fuel oil and tarry material were reduced to a quarter of the values obtained from the untreated vacuum distillate while the amount of coke deposited in the reactor was only 100 ppm on feed.
• COMPARISON TEST 2 A full range Kuwait vacuum distillate with a hydrogen to carbon atomic ratio of 1.74 and a sulfur content of 2.78 per cent weight was steam cracked in a 20 ml quartz reactor at a temperature of 830C. Analysis by physical separation and spectroscopic methods (including UV absorbance) indicated that the aromatic compound content was 52 per cent weight.
• the steam to hydrocarbon feed weight ratio was 1 to 1 with an average hydrocarbon feed rate of 62 g per hour.
• the ethylene and propylene yields were 23 and 10 per cent weight respectively with 52 per cent weight of the feed converted to cracked gas.
• Coke deposited in the cracking zone corresponded to 1,050 ppm weight of the hydrocarbon feed.
• the sulfur content of the fuel oil was 6.8 per cent weight.
• This Example is provided for purposes of comparison and is not an example according to the invention.
• EXAMPLE 3 A 200 g sample of Kuwait vacuum distillate used in Comparison Test 2 was hydrogenated in a 1 litre rocking autoclave at 350C under 2,200 psig of hydrogen during 8 hours using 50 g of cobalt/molybdenumlalumina catalyst prepared by impregnation as in Example 1.
• the recovered hydrogenated vacuum distillate has a hydrogen to carbon atomic ratio of 1.87 and a sulfur content of less than 400 ppm weight. Analysis by physical separation and spectroscopic methods (including UV absorbance) indicated that the aromatic compound content was 16 per cent weight.
• This material was steam cracked under the same conditions as Comparison Test 2.
• the ethylene and propylene yields were 27 and 12 per cent weight on feed respectively with 62 per cent weight of the feed converted to cracked gas.
• the yields of fuel oil and tarry material were reduced to one third of the values obtained from the untreated vacuum distillate. Coke deposited in the cracking zone corresponded to ppm weight of the hydrocarbon feed.
• EXAMPLE 4 A 200 g sample of Kuwait vacuum distillate used in Comparison Test 2 was hydrogenated in a 1 litre rocking autoclave at 350C under 2200 psig of hydrogen during 8 hours using 50 g of nickel/tungsten/- silica/alumina catalyst prepared by impregnation as in Example 1.
• the recovered hydrogenated vacuum distillate had a hydrogen to carbon atomic ratio of 1.95 and a sulfur content of 100 ppm weight.
• Analysis by physical separation and spectroscopic methods indicated that the aromatic compound content was less than 2 per cent weight.
• This material was steam cracked under the same conditions as Comparison Test 2.
• the ethylene and propylene yields were 28 and 14 per cent weight on feed respectively with 68 per cent of the feed converted to cracked gas.
• the yields of fuel oil and tarry material were reduced to one quarter of the values obtained from the untreated vacuum distillate while the amount of coke deposited in the reactor was only 100 ppm.
• the sulfur content of the fuel oil was only 300 ppm.
• EXAMPLE 5 A 200 g sample of the Kuwait vacuum distillate used in Comparison Test 2 was hydrogenated in a 3 litre rocking autoclave at 350C under 2200 psig of hydrogen during 75 hours using 60.0 g of a cobalt/molybdenum/alumina catalyst prepared by impregnation as in Example 1.
• the recovered hydrogenated vacuum distillate had a hydrogen to carbon atomic ratio of 1.95 and a sulphur content of 125 ppm weight.
• Analysis by physical separation and spectroscopic methods indicated that the aromatic compound content was less than 2 per cent weight.
• This material was steam cracked under the same conditions as Comparison Test 2.
• the ethylene and propylene yields were 28 and 14 per cent weight on feed respectively, with 67 per cent weight of the feed converted to cracked gas.
• the yields of fuel oil and tarry material were reduced to a quarter of the values obtained from the untreated vacuum distillate while the amount of coke deposited in the reactor was only 100 ppm.
• the fuel oil product had a much lower viscosity and a reduced tendency for emulsific'ation with water after condensation of the product and diluent steam by comparison with the fuel oil produced in the Comparison Tests, thus facilitating both pumping and handling at lower temperatures and separation and fractionation of the liquid products respectively.
• a process for the production of olefins which process comprises hydrogenating a petroleum vacuum distillate feedstock boiling in the range of 300 to 650C. in the presence of a nickel/tungsten/silica/alumina hydrogenation catalyst and hydrogen at a temperature in the range 50 to 500C and a pressure in the range 50 to 5,000 psig and thermally cracking the resulting hydrogenated product in the presence of steam.
• a process according to claim 1 wherein the feedstock from the hydrogenation reaction is varpourised in the presence of steam, at a steam to hydrocarbon weight ratio of 0.5:1 to 20:1 and is passed through a heated zone at a maximum temperature in the range 700 to l,000 with a residence time in this temperature range between 0.01 and 5 seconds.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 1971
  • 1971-01-06 GB GB60571*[A patent/GB1361671A/en not_active Expired
  • 1971-12-23 CA CA130,970A patent/CA948220A/en not_active Expired
  • 1971-12-28 DE DE2164951A patent/DE2164951B2/de not_active Ceased
  • 1971-12-30 US US00214468A patent/US3781195A/en not_active Expired - Lifetime
  • 1971-12-30 AU AU37458/71A patent/AU454473B2/en not_active Expired
• 1972
  • 1972-01-05 NL NL7200099.A patent/NL164319B/xx not_active Application Discontinuation
  • 1972-01-05 IT IT19092/72A patent/IT946344B/it active
  • 1972-01-05 BE BE777739A patent/BE777739A/xx not_active IP Right Cessation
  • 1972-01-05 FR FR7200177A patent/FR2121579B1/fr not_active Expired
  • 1972-01-06 JP JP443572A patent/JPS5530038B1/ja active Pending

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