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
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
  • C10G45/60—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used

Definitions

• the distillate is contacted in the presence of hydrogen with a catalyst having dehydrogenating and/ or cracking activity and comprising a silica-alumina base, at a temperature of at least 400 C. but below the temperature at which substantial cracking occurs, a pressure of at least 100 p.s.i.g., and a space velocity of the liquid feedstock not exceeding 30 v./v./hr., the temperature and space velocity being correlated so that the pour point of the stabilized distillate is at least 5 C. lower than the pour point of the feedstock.
• a catalyst having dehydrogenating and/ or cracking activity comprising a silica-alumina base
• substantial cracking is understood to occur when more than 20% wt. of the feedstock is converted to material boiling below 150 C. Preferably not more than 15% wt. of the feedstock is converted to material boiling below 150 C.
• the temperature employed will not usually exceed 480 C. and in general the lower the temperature, the lower the space velocity.
• the pressure employed will normally be between 100 and 1500 p.s.i.g. and the hydrogen to hydrocarbon mole ratio will normally be from 5 to 1 to 20 to 1.
• a further advantage of operating with an overall consumption of hydrogen is that a reduction of the diesel index is minimized or avoided.
• Hydrogen may be added on a once-through basis, or it may be recycled.
• the distillate fraction used as feedstock may have a low initial sulfur content, for example 0.1% wt. sulfur or less.
• Such low sulfur feedstocks may be straight-run materials or the products of previous refining treatments, for example, products of a hydrocatalytic desulfurization process.
• the process according to the invention may result in aconsiderable reduction in the sulfur content.
• the process may be accompanied by an increase in specific gravity.
• Some lower boiling material will be produced by, for example, dehydrogenation, desulfurization and/ or a small amount of cracking, and this is separated from the product, preferably by fractionation, to stabilize it and give a material of the required boiling range and flash point.
• a convenient cut point is in the region of 170 C.
• catalysts for the purposes of the present invention consist of molybdenum trioxide, M00 supported on a silica/alumina base, and a mixture of molybdenum trioxide, M00 and cobalt oxide, CoO, supported on a silica/alumina base.
• a particularly effective catalyst may have the following composition by wt.
• the catalyst may have the following composition by weight:
• the ratio of cobalt to molybdenum necessary to produce the desired reduction in the sulfur content is considerably less than in the case of conventional cobalt molybdate catalysts used for desulfurization. This may be due to the fact that more severe process conditions, i.e. higher temperature and pressure and lower space velocity, are required to produce the desired reduction in the pour point.
• the catalyst may be employed as a fixed bed, a moving bed, or in the fluidized state.
• the degree of reduction in pour point is a function of the catalyst activity and in the case of a fixed bed process, in which the catalyst is not continuously regenerated, the greatest reduction in pour point is obtained during the early stages of a processing period. In such circumstances, the operating temperature may be gradually increased to compensate for loss of activity. Alternatively, continuous catalyst regeneration may be employed, using either a moving or fluidized catalyst bed process.
• a part only of a particular distillate may be treated by the process according to the invention and the resulting product blended with the untreated portion of the distillate to give a final product of reduced pour point.
• the optimum values for the hydrogen partial pressure and the hydrogen to hydrocarbon ratio depend upon the nature of the feedstock. For example, these conditions are compared in the following table, No. 2, for a light gas oil having an I.B.P. of 220 C., an F.B.P. of 400 C. and a pour point of 1 C. and a heavy gas oil having an I.B.P. of 290 C., an F.B.P. of 390 C., and a pour point of +17 C.
• Satisfactory treatment of a heavy gas oil at constant pressure may be achieved by adding between 20 and by volume of a lower boiling distillate such as kerosine to the heavy gas oil.
• a lower boiling distillate such as kerosine
• a silica-alumina base suitable for preparing a catalyst for use in accordance with the present invention may be made in a variety of ways.
• the silica gel is precipitated in situ in the pores of the alumina by hydrolyzing a silicon compound with which the alumina is impregnated.
• the silicon compound may be organic or inorganic and suitable compounds include ethyl silicate, trichlorosilane and tetrasilane. It is advantageous to add to the ethyl silicate, for example, a sufficient quantity of alcohol to saturate the alumina almost completely to ensure homogeneous distribution of the silicate in the alumina. Ethyl, methyl and other alcohols may be used for this purpose.
• the silicate is hydrolyzed by means of acidified water and the formation of the gel assisted by the addition of ammoniacal water.
• the silica-alumina composite is then dried and calcined. The following is a specific example of preparing a silica-alumina base by this method:
• Hydrogen/Hydrocarbon Ratio 10l1 moles/mole Temperatures, C 430 440 456 Pressure, kgjcm. 73 73 73 74 74 76 77. 5 77.5 80 82 82 HOS 32 56 80 104 123 152 176 206 224 243 272 296 Feedstock Heavy Gas Oil Density at 15 0 881 342 342 343 844 346 349 846 347 347 347 343 Pour Point, 0--..
• L.68 A37 4.4% SiOz, 10.64% M003, 0.55% C00, 84.41% A1203.
• L68 A38 8.9% S102, 10.64% M00 0.55% 000, 79.91% A1203.
• Table 9 [Catalyst 14.43 (see Table 3)] Temperature, C 415 390 390 390 360 415 390 Pressure, kg/cm. 35 70 55 40 70 H l./h 100 100 60 100 100 120 80 160 Space Velocity, v.lv./l1r 5 5 7 3 5 5 8 6 4 8 Feedstock Density at 15 C 1. 869 851 854 854 851 858 852 856 Pour Point, O +11 +11 +11 +11 +11 +11 +11 +11 Cloud Point, 0- +13 +12 +12 +12 +12 +12 +12 +12 Sulphur, Percent W 1. 6 0.36 0. 57 0. 74 0.30 O. 9" 0. 40 0.76 Distillations ASTM,
• a process for the treatment of distillate petroleum fractions boiling within the range 150-450 C. to lower the pour point at least C. without material reduction in the specific gravity and diesel index of said distillate fractions comprising contacting the distillate fraction as feedstock in a treating zone and in the presence of hydrogen with a dehydrogenation catalyst on a silica-alumina base whose silica content is in the range 5 to 14% by Weight of total catalyst, the hydrogen to hydrocarbon mole ratio being from 5 to 1 to 20 to 1; maintaining a selected temperature and a selected space velocity in said zone, said selected temperature in said zone being maintained at least about 400 C. but not higher than about 480 C. and being a temperature at which, at said selected space velocity, not more than 20% wt.
• the selected space velocity being at least equal to the space velocity at which at said selected temperature not more than 20% wt. of the feedstock is converted to material boiling below 150 C. but not exceeding 3.0 v./v./hr.; maintaining a selected pressure in said zone in the range 100-1500 p.s.i. ga., said selected temperature and said selected space velocity being correlated to reduce the pour point of the feedstock such that the pour point of the material of the treated distillate fraction boiling above 150 C. is at least 5 lower than the pour point of the feedstock, and recovering the treated distillate fraction.
• feedstock consists of a heavy gas oil in admixture with to 100% by volume of a lower boiling distillate such as kerosine.
• silicaalumina base of the catalyst consists of a mixture of preformed alumina and silica.
• a process for the treatment of distillate petroleum fractions boiling within the range ISO-450 C. to lower the pour point at least 5 C. without material reduction in the specific gravity and diesel index of said distillate fractions comprising contacting the distillate fraction as feedstock in a treating zone in the presence of hydrogen with a catalyst consisting essentially of 5-15 by weight of molybdenum trioxide supported on a silica-alumina base, the silica content being in the range 5-14% by weight of total catalyst, the hydrogen to hydrocarbon mole ratio being from 5 to 1 to 20 to 1; maintaining a selected temperature and a selected space velocity in said zone, said selected temperature in said zone being maintained at least about 400 C. but not higher than about 480 C.
• catalyst further includes cobalt oxide in an amount of .2-1% by weight with the molybdenum trioxide being present in an amount of 5 to 15%.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Crystallography & Structural Chemistry (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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