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
  • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
  • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
  • C10G65/12—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including cracking steps and other hydrotreatment steps
• • 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
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/107—Atmospheric residues having a boiling point of at least about 538 °C

Definitions

• the hydrodesulfurization of hydrocarbon liquids is well known and has been practiced for several years in the refining of petroleum.
• the catalytic hydrodesulfurization processes of the prior art comprise contacting the sulfur-containing charge stock with a catalyst in the presence of hydrogen at elevated temperatures and pressures to convert the sulfur present in the charge stock to hydrogen sulfide.
• the hydrogen-rich effluent gas is subjected to a hydrogen sulfide removal treatment and recycled to the reaction zone.
• Typical catalysts comprise cobalt and molybdenum or nickel and molybdenum or nickel and tungsten on a support such as alumina.
• sulfur is present in petroleum fractions in the form of mercaptans, sulfides, disulfides and in complex ring compounds containing ring structures such as thiophenes.
• lighter fractions such as gasoline, naphtha and kerosine
• the sulfur is present to a large extent in the form of easily removable mercaptans which require less severe reac tion conditions and thus long catalyst life is obtained.
• residual fractions not only is the sulfur present in more difficulty removable form, but the fraction contains materials such as tar and metals which severely affect the activity of conventional catalysts.
• reaction conditions are selected to yield a product having the desired sulfur content as for example 0.3 wt. percent sulfur or L wt. percent sulfur as the case may be.
• the desulfurization activity of the catalyst declines so that in order to obtain a product meeting the desired specifications it becomes necessary to increase the temperature of the reaction zone or catalyst bed.
• the rate of temperature increase necessary to maintain the desired sulfur content of the product is termed deactivation rate and is expressed in terms of F. per unit of time.
• an objct'of'thk invention to provide a process for reducing the sulfur content of heavy petroleum hydrocarbon oils. Another object is to provide a desulfurization process in which the catalyst does not require frequent regeneration or replacement. Still another object is to provide a process in which the catalyst deactivation rate is low.
• a process for the production of petroleum hydrocarbon fractions of reduced sulfur content which comprises contacting a residue-containing petroleum fraction in the presence of hydrogen with a supported catalyst comprising a member selected from the group consisting of Group V] metals, Group VIII metals, their compounds and mixtures thereof under hydrocracking conditions comprising a temperature between about 750 and 950 F., a pressure between about 500 and 5,000 psig, a space velocity of 0.1 l0 and a hydrogen rate between about 1,000 and 30,000 SCFB, cooling the effluent and passing same into contact with a supported catalyst comprising a member selected from the group consisting of Group Vl metals, Group VIII metals, their compounds, and mixtures thereof under desulfurization conditions comprising a temperature between about 600 and 850 F., a pressure between about 500 and 5,000 psig, a space velocity of between about 0.1 and 10 and a hydrogen rate between about 1,000 and 30,000 SCFB and recovering from the effluent a fraction of reduced sulfur content.
• a supported catalyst comprising a member selected
• the charges used as feed to the process are those heavy petroleum fractions containing asphalt and residue which are traditionally extremely difficult to desulfurize.
• Such materials include whole crudes such as San Ardo crude, shale oil, tar sand oil, vacuum residua and mixtures thereof. Typically they contain at least 1 percent Conradson carbon residue and generally at least about 50 percent of the charge boils above 1,000F.
• the charge is introduced with hydrogen into the first or hydrocracking zone.
• the hydrogen used in the process of this invention need not be pure, hydrogen having a purity of at least 50 percent and preferably about -90 vol. percent being satisfactory.
• the hydrogen may be obtained from any suitable source hydrogen such as that obtained by partial oxidation of petroleum hydrocarbons followed by shift conversion and carbon dioxide removal, electrolytic hydrogen or catalytic reforming by-product hydrogen, are satisfactory.
• the charge in admixture with hydrogen is introduced into contact with a hydrocracking catalyst.
• the catalyst preferably is in particulate form and may be used as a fixed bed, a moving bed or a fluidized bed.
• the reactant flow may be either upward or downward or the hydrogen flow may be countercurrent to the downward flow of the charge.
• the mixture of hydrogen and charge is introduced into the upper end of a reactor containing a fixed bed of pelletized catalyst and is passed downwardly through the bed.
• hydrogen may be introduced at various points in the bed to control the reactant temperature.
• the catalyst used in the hydrocracking zone comprises a Group V] metal, a Group VIII metal, mixtures thereof and compounds thereof on an amorphous inorganic oxide support.
• Suitable metals include iron, cobalt, nickel, chromium, vanadium, tungsten and molybdenum.
• Preferred catalysts contain from about 28 percent of a Group VIII metal and 5-30 percent of a Group VI metal. Preferred combinations are cobalt and molybdenum, nickel and molybdenum and nickel and tungsten.
• the metals are present in the forrifof the oxide when prepared but may be converted'to the sulfide prior to activating the onstream period. The sulfiding may take place either prior to the introduction of the catalyst in the reactor vessel or may be carried out in situ after the catalyst has been loaded to the reactor.
• the hydrocracking catalyst also comprises an amorphous support such as alumina advantageously having acidic properties produced by the addition of activated silica or boron oxide or by treatment of the alumina with a halogen acid such as hydrofluoric acid.
• the support should have a surface area of at least 250 m /g preferably 275 to 350 m /g and should have a pore volume of at least 0.6 cc/g preferably between 0.7 and 1.0 cc/g.
• the support should also have an average pore diameter of less than 100 preferably 75l00 Angstrom units.
• the average pore diameter is represented by the formula 4V/A where V is the pore volume and A is the surface area.
• the pore volume is ordinarily expressed as cc/g and the surface area as m lg.
• the reaction conditions of the first or hydrocracking zone include a temperature between about 750 and 950F., a pressure between about 500 and 5,000 psig, a space velocity between about 0.1 and volumes of liquid charge per volume of catalyst per hour with a hydrogen rate of between about 1000 and 30,000 SCFB per barrel of charge.
• Preferred conditions are a temperature of 750900F., a pressure between I500 and 3,000 psig, a space velocity between 0.25 and 1.5 and a hydrogen rate between 3,000 and 10,000 SCFB.
• the effluent from the hydrocracking zone is then cooled to a suitable temperature prior to introduction into the second or desulfurization zone.
• the cooling may be effected by direct or indirect heat exchange, the former being preferred. Since some light hydrocarbons are formed in the hydrocracking step, there may be a tendency when certain charge stocks are used for asphalt to precipitate as a result of the temperature reduction and the presence of these lighter hydrocarbons. To avoid such precipitation and the concomitant plugging of the apparatus, advantageously the cooling is accomplished by the addition of an aromatic-rich fraction which is introduced at a temperature sufficient to effect the desired reduction in the temperature of the first stage effluent.
• aromatic-rich fraction is meant a fraction having at least 50 vol. percent aromatics.
• a particularly suitable coolant in this respect is a heavy cycle gas oil withdrawn from a fluid catalytic cracking unit.
• the hydrocracking effluent may be separated into hydrogen and various fractions and the hydrogen purifkd if desired and recycled to the first zone with only a fraction or portion of the effluent being introduced into the desulfurization zone.
• the entire effluent from the first or hydrocracking zone is introduced into the second or desulfurization zone.
• the catalyst used in the desulfurization zone is to a large extent similar to the catalyst used in the first zone in that it comprises a Group VI metal, a Group VIII metal, compounds or mixtures thereof.
• the Group VI metal may be present in an amount between about 5 and 30 weight percent preferably 8-25 percent and the group VIII metal in an amount between about 2 and 10 weight percent, preferably 28 percent.
• the metals are generally in the form of the oxide or sulfide.
• the desulfurization catalyst also comprises an amorphous inorganic oxidesupport which need not necessarily have cracking activity such as alumina, zirconia, silica and magnesia. However, it is possible to use a catalyst having the same composition and characteristics as the hydrocracking catalyst in the desulfurization zone.
• the hydrocracking unit should be operated to obtain 25 percent conversion of the l000F+ portion of the charge to materials boiling below 1,000F. If the conversion is less than 25 percent, the charge to the desulfurization zone behave more like vacuum residuum such that low desulfurization levels and high deactivation rates are experienced in the second zone. If the conversion of the 1,000F.+ fraction is greater than 70 percent the quality of the unconverted 1,000F.+ residuum becomes worse than the charge stock.
• the charge is an Arabianvacuum residuum having the following characteristics:
• composition and properties of the catalyst are as follows:
• the reaction zone is maintained at the following conditions:
• an average catalyst bed temperature of 745F. is required to provide a liquid product having a sulfur content of 1.0 wt. percent.
• the average catalyst bed temperature is 800F. showing a catalyst deactivation rate of l.2F./day.
• EXAMPLE ll This example is similar to Example I, the difference being that a product containing 0.5 wt. sulfur is produced. After the initial edge has been removed the average catalyst bed temperature required to produce the desired product is 780F. After 48 days of operation, the temperature is 825F. but due to the conversion of more than 70 percent of the 1,000F+ material in the charge and the resulting asphaltene precipitation in the reactor outlet line, the run is terminated. The ],000F+ portion of the product is found to corfiaina higher Conradson Carbon Residue than the charge stock. The catalyst deactivation rate is 0.94F./day.
• EXAMPLE III This example represents the process of our invention.
• the same catalyst used in Example I is loaded into two reactors.
• the reaction conditions in the first hydrocracking reactor A and the second desulfurization reactor B are tabulated below:
• the average desulfurization catalyst bed temperature is 775F.
• These results represent catalyst deactivation rates of 0. 1 06F day for the hydrocracking and 0.23F./ day for the desulfurization with an average deactivation rateof 0. l7F./day.
• the product from the first reactor increased in sulfur content from 0.9 to 2.2 wt. percent, indicating that the deactivation rate of the catalyst for desulfurization was much higher than its deactivation rate for hydrocracking.
• the aromatic-rich fraction mixed with the effluent from the hydrocracking zone need not be low in sulfur and actually may have a high sulfur content so that in its passage through the desulfurization zone, its sulfur content is reduced.
• a process for the production of petroleum hydrocarbon fractions of reduced sulfur content which comprises contacting a residue-containing petroleum fraction of which at least about 50 percent boils above l,00OF. with hydrogen and with a supported catalyst comprising a member selected from the group consisting of Group VI metals, Group VIII metals, their compounds and mixtures thereof under hydrocracking conditions comprising a temperature between about 750 and 950F., a pressure between about 500 and 5,000 psig, a space velocity of 0.1 l0 and a hydrogen rate between about 1,000 and 30,000 SCFB to obtain a 25 volume percent conversion of material boiling above 1,000F.
• a supported catalyst comprising a member selected from the group consisting of Group Vl metals, Group VIII metals, their compounds, and mixtures thereof under desulfurization conditions comprising a temperature between about 600 and 850F.
• a pressure between about 500 and 5,000 psig, a space velocity of between about 0.1 and 10 and a hydrogen rate between about l,000 and 30,000 SCFB and recovering from the hydrodesulfurized effluent a product fraction of reduced sulfur content and gradually increasing the temperature of the desulfurization zone to maintain the sulfur content of said product fraction substantially constant.
• the process of claim 1 in which the conversion is catalyst comprises cobalt and molybdenum. within the range of 40 to 70 volume percent.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (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)
• Catalysts (AREA)

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Citations (8)

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• 1970
  • 1970-12-28 US US00102251A patent/US3716476A/en not_active Expired - Lifetime
• 1971
  • 1971-12-20 GB GB5916571A patent/GB1324580A/en not_active Expired
  • 1971-12-24 CA CA131,166A patent/CA968291A/en not_active Expired
  • 1971-12-24 DE DE2164449A patent/DE2164449B2/de not_active Ceased
  • 1971-12-27 IT IT32977/71A patent/IT951966B/it active
  • 1971-12-27 FR FR7146721A patent/FR2120022B1/fr not_active Expired
  • 1971-12-27 NL NL7117858A patent/NL7117858A/xx unknown
  • 1971-12-28 BE BE777428A patent/BE777428A/xx unknown
  • 1971-12-28 JP JP47003733A patent/JPS5129164B1/ja active Pending
  • 1971-12-28 ES ES398415A patent/ES398415A1/es not_active Expired
  • 1971-12-30 AU AU37495/71A patent/AU452024B2/en not_active Expired

Patent Citations (8)

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