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
  • C10G45/64—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 containing crystalline alumino-silicates, e.g. molecular sieves

Definitions

• porous inorganic solids that were originally found useful for catalytic processes included certain clays, aluminas, silica-aluminas and other silicas coprecipitated with magnesia, for example, and such solids are still extensively used in the industry. In general, all of these solids had pores that were not of uniform size, and most of the pore volume was in pores having diameters larger than about 30 Angstroms, with some of the pores as large or larger than 100 Angstroms.
• Zeolite molecular sieves have been found to be highly effective as hydrocarbon conversion catalysts.
• the conversion of gas oil to gasoline and distillate by catalytic cracking, the alkylation of benzene to ethylbenzene, the isomerization of xylenes and the disproportionation of toluene all involve molecules which are smaller in critical diameter than 1,3,5-triethylbenzene, and such molecules are occluded and acted upon by zeolite molecular sieves having an effective pore diameter of about 10 Angstroms.
• a particularly interesting catalytic transformation which requires a molecular sieve catalyst is the reduction of the pour point of waxy distillates and residual hydrocarbon fractions.
• Effective pour point reduction depends on the selective conversion of normal, high melting point paraffin molecules that have an effective critical diameter of about 5 Angstroms to substances of lower molecular weight that are easily separated from the low-pour product.
• Effective catalytic dewaxing depends at least in part on the regularity of the pore size of the crystalline zeolites, which allows selective conversion of unwanted constituents.
• Crystalline zeolite ZSM-11 is disclosed in U.S. Patent 3,709,979.
• Example 9 of this patent taught fluid catalytic cracking at 875°F of a gas oil having a pour point of 100°F. High yields of olefins were obtained. The pour point of the product was reduced.
• U.S. 4,332,670 taught catalytic dewaxing of middle distillates to produce a low pour fuel oil by using an intermediate pore size zeolite. There are no examples showing use of ZSM-11.
• US ⁇ A ⁇ 4 428 819 addresses the problem of how to get rid of residual wax remaining in an already dewaxed product, and to this end adds to the dewaxing operation a further process stage comprising a hydroisomerisation over a zeolite catalyst. Cloud point is reduced during the hydroisomerisation, and the hydroisomerate is said to be 'more soluble' than its precursor (column 10 line 13; claim 1). ). According to the citation a loss of yield is incurred by the addition of the hydroisomerisation step (column 2 lines 36-38).
• Exemplified isomerisation catalysts include ZSM-5/Pd, zeolites Y and Beta, and alumina. ZSM-11 is not exemplified.
• FR-A-2 374 402 discloses a catalytic dewaxing process for gas-oil whereby the charge is contacted with a zeolite catalyst in the presence of water.
• ZSM-5 is the preferred zeolite.
• ZSM-11 is not exemplified.
• ZSM-11 which has been ignored experimentally by all prior workers in the lube oil and fuel oil area, is better for catalytic dewaxing than ZSM-5.
• the present invention provides a process for catalytically dewaxing a waxy hydrocarbon feedstock to produce a dewaxed product which contains at least 10 moles, per 100 moles of waxy components in the feedstock, of paraffins derived from said components by hydroisomerisation, said process comprising contacting the feedstock at a temperature of 230 to 400°C, a pressure of atmospheric to 14,000 kPa, a liquid hourly space velocity of 0.1 to 20 and a hydrogen-to-hydrocarbon ratio of 90 to 1000 by volume with a catalyst comprising a crystalline zeolite and a hydrogenation/dehydrogenation component, characterised in that the zeolite has the crystal structure of zeolite ZSM-11 and the hydrogenation/ dehydrogenation component comprises a platinum group metal.
• the present invention provides a process for producing lubricating oil base stock with high viscosity index comprising contacting a lubricating oil base feedstock containing waxy components with a dewaxing catalyst comprising ZSM-11 and a refractory inorganic binder, desirably wherein the weight ratio of catalyst:binder is from 10:90 to 95:5 and preferably wherein the binder comprises alumina, silica or silica alumina, especially wherein the weight ratio of ZSM-11 1:alumina is from 10:90 to 95:5 in a catalytic dewaxing zone operated at 230 to 400°C, a pressure of atmospheric to 14,000 kPa, liquid hourly space velocity of 0.1 to 20 and wherein hydrogen is present and the ratio of hydrogen to hydrocarbon is 50 to 1000 volumes of H 2 at standard conditions per volume of liquid oil at standard conditions to product a lubricating oil base stock with reduced wax content.
• a dewaxing catalyst comprising ZSM-11 and a refractory
• the present invention provides a process for catalytic dewaxing of a wax containing oil comprising contacting said oil in the presence of hydrogen at a temperature of 230 to 450°C, a hydrogen partial pressure of atmospheric to 14,000 kPa with a fixed bed of catalyst comprising ZSM-11 and a platinum group metal component to produce a catalytically dewaxed oil.
• the silica to alumina mole ratio of ZSM-11, and other zeolites may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the rigid.anionic framework of the zeolite crystal and to exclude aluminum in the binder or in cationic or other form within the channels. Although zeolites with silica to alumina mole ratios of at least 10 are useful, it is preferred to use zeolites having higher ratios than about 12, preferably about 15 to 200. In addition, zeolites as otherwise characterized herein but which are substantially free of aluminum, that is zeolites having silica to alumina mole ratios of up to infinity, are found to be useful and even preferable in some instances.
• Such "high silica” or “highly siliceous” zeolite tend to be hydrophobic and are intended to be included within this description. Also included within this definition are substnatially pure silica analogues of the useful zeolites described herein, that is to say those zeolites having no measurable amount of aluminum (silica to alumina mole ratio of infinity) but which otherwise embody the characteristics disclosed.
• the acid activity may be adjusted by crystallizing the ZSM-11 with only a little, or a lot, of aluminum, steaming the ZSM-11, acid extracting, or any other means conventionally used to adjust acid activity.
• One method of measuring acid activity is to measure the cracking activity of a catalyst to obtain an alpha value or alpha activity.
• a method of determining alpha activity is described in U.S. Patent 4,106,218.
• the alpha test is a good measure of cracking activity, but not a measure of hydroisomerization activity.
• the process according to the invention proceeds by both cracking and hydroisomerization, so alpha activity provides some information about only one of the several reactions believed to occur during dewaxing.
• An activated large pore zeolite, e.g., RENaX might have an alpha activity of over 10,000 and be a good FCC catalyst but do little or no dewaxing.
• a good dewaxing catalyst e.g., Ni-ZSM-5, partially deactivated by coking, might have a low alpha activity and still do a good dewaxing job, so long as reactor temperatures were raised somewhat to adjust for the low alpha activity.
• the "Constraint Index” may be determined by passing continuously a mixture of an equal weight of normal hexane and 3-methylpentane over a sample of zeolite at atmospheric pressure according to the following procedure.
• a sample of the zeolite, in the form of pellets or extrudate, is crushed to a particle size about that of coarse sand and mounted in a glass tube.
• the zeolite Prior to testing, the zeolite is treated with a stream of air at 538°C for at least 15 minutes. The zeolite is then flushed with helium and the temperature is adjusted between 275 and 510°C to give an overall conversion of between 10% and 60%.
• the mixture of hydrocarbons is passed at 1 liquid hourly space velocity (i.e., 1 volume of liquid hydrocarbon per volume of zeolite per hour) over the zeolite with a helium dilution to give a helium to (total) hydrocarbon mole ratio of 4:1.
• a sample of the effluent is taken and analyzed, most conveniently by gas chromatography, to determine the fraction remaining unchanged for each of the two hydrocarbons.
• Constraint Index approximates the ratio of the cracking rate constants for the two hydrocarbons. Constraint Index (CI) values for ZSM-5 is about 8.3, while for ZSM-11 it is 8.7. Both values can vary, depending on test conditions.
• a crude oil that contains a suitable fraction of lubricant stock is selected for processing.
• the process of refining to isolate that lubricant stock consists of a set of subtractive unit operations which removes the unwanted components.
• the most important of these unit operations include distillation, solvent refining, and dewaxing, which basically are physical separation processes in the sense that if all the separated fractions were recombined one would reconstitute the crude oil.
• a refined lubricant stock may be used as such as a lubricant, or it may be blended with another refined lubricant stock having somewhat different properties. Or, the refined lubricant stock, prior to use as a lubricant, may be compounded with one or more additives which function, for example, as antioxidants, extreme pressure additives, and V.I. improvers.
• the term "stock”, regardless whether or not the term is further qualified, will refer only to a hydrocarbon oil without additives.
• raw stock will be used herein to refer to a viscous distillate fraction of crude petroleum oil isolated by vacuum distillation of a reduced crude from atmospheric distillation, and before further processing, or its equivalent.
• raffinate will refer to an oil that has been solvent refined, for example with furfural.
• dewaxed stock or “dewaxed raffinate” will refer to an oil which has been treated by any method to remove or otherwise convert the wax contained therein and thereby reduce its pour point.
• waxy as used herein will refer to an oil of sufficient wax content to result in a pour point greater than 0°C.
• stock when unqualified, will be used herein generically to refer to the viscous fraction in any stage of refining, but in all cases free of additives.
• the current practice is to vacuum distill an atmospheric tower residuum from an appropriate crude oil as the first step.
• This provides one or more raw stocks within the boiling range of 230-565°C.
• Raw stock is then extracted with a solvent, e.g., furfural, phenol, or chlorex, selective for aromatic hydrocarbons, and which removes undesirable components.
• the raffinate from solvent refining is then dewaxed, for example, by admixing with a solvent such as a blend of methyl ethyl ketone and toluene.
• the mixture is chilled to induce crystallization of the paraffin waxes which are then separated from the dewaxed dissolved raffinate in quantity sufficient to provide the desired pour point for the subsequently recovered raffinate.
• catalytic dewaxing process of the present invention is used instead of solvent dewaxing.
• Hydrotreating or hydrofinishing may be used in conjunction with catalytic dewaxing.
• Hydrofinishing or clay percolation may be used if needed to reduce the nitrogen and sulfur content or improve the color of the lubricating oil stock, and to improve oxidation resistance.
• Hydrotreating may be used instead of, or in conjunction with, solvent refining to prepare the feedstock for the present invention.
• a catalyst containing a hydrogenation component on a support preferably a non-acidic support, e.g., Co-Mo or Ni-Mo on alumina.
• the hydrotreater usually operates at relatively low temperatures, typically 200-450°C,. preferably at 300-425°C.
• the hydrotreating catalyst may be disposed as a fixed, fluidized, or moving bed of catalyst, though down flow, fixed bed operation is preferred because of its simplicity.
• the liquid hourly space velocity, or volume per hour of liquid feed measured at standard conditions volume of catalyst will usually be 0.1 to 10, preferably about 1 to 5.
• Typical hydrogen partial pressures are 1 to 100 atmospheres, absolute. Hydrogen can be added to the feed on a once through basis, or recycled by conventional means.
• Suitable hydrotreating/hydrogenation components include one or more of the metals, or compounds thereof, selected from Groups II, III, IV, V, VIB, VIIB, VIII and mixtures thereof of the Periodic Table of the Elements.
• Preferred metals include molybdenum, tungsten, vanadium, chromium, cobalt, titanium, iron, nickel and mixtures thereof.
• hydrotreating metal component will be present in an amount equal to 0.1 to 20 wt% of the support, with operation with 0.1 to 10 wt% hydrogenation metal, on an elemental basis, giving good results.
• the hydrogenation components are usually disposed on a support, preferably an amorphous support such as silica, alumina, silica-alumina, etc. Any other conventional support material may also be used. It is also possible to include on the support an acid acting component, such as an acid exchanged clay or a zeolite.
• the support does not have much acidity, it is the intent of the present invention to primarily conduct hydrotreating in the hydrotreating zone and minimize cracking or other reactions therein.
• the support has a low enough acid acting activity that the pour point of the lube oil stock passing through the hydrotreating zone is not changed at all, or is changed less than 5-6°C by hydrotreating.
• Viscosity index is a quality parameter of considerable importance for distillate lubricating oils to be used in automotive engines and aircraft engines. This Index is a series of numbers ranging from 0 to 100 or higher which indicate the rate of change of viscosity with temperature. A viscosity index of 100 indicates an oil that does not tend to become viscous at low temperature or become thin at high temperatures. Measurement of the Saybolt Universal Viscosity of an oil at 38 and 99°C (100 and 210°F) and referral to correlations, provides a measure of the V.I. of the oil. V.I. is defined in the Viscosity Index tabulation of the ASTM (D567), published by ASTM, 1916 Race Street, Philadelphia, Pa.
• Raw distillate lubricating oil stocks usually do not have a particularly high V.I.
• solvent- refining as with furfural for example, in addition to removing unstable and sludge-forming components from the crude distillate, also removes components which adversely affect the V.I.
• a solvent refined stock prior to dewaxing usually has a V.I. in excess of specifications.
• the catalyst hydrodewaxing process of the present invention operates at about 230 to 400°C, pressures of atmospheric to 14,000 kPa, liquid hourly space velocities of 0.1 to 20, preferably 0.5 to 4, and hydrogen to hydrocarbon ratios of 90 to 1,000 volumes of hydrogen at standard conditions per volume of liquid oil at standard conditions. Any conventional catalytic dewaxing conditions may be used.
• Catalytic dewaxing may be conducted by passing the feed over a fixed, fluidized or moving bed of catalyst comprising ZSM-11.
• the ZSM-11 catalyst may be used neat, although it is preferably incorporated in a binder such as alumina, or silica/alumina.
• the platinum group metal hydrogenation/dehydrogenation component is believed to promote hydroisomerization activity in addition to the shape selective cracking that occurs with ZSM-11. This combination of activities gives higher activity, better selectivity and lower pour point product than can be achieved with ZSM-5 catalysts. It may be added by ion exchange or impregnation, or any other method known to the art of incorporating hydrogenation/dehydrogenation components in a support, the support in this instance being either ZSM-11 alone or in admixture with a refractory inorganic oxide binder.
• Preferred platinum group metals are platinum, irridium and palladium, with platinum giving especially good results.
• the platinum group component will usually be added as a soluble, decomposable compound of the platinum group metal. After incorporation of this metal onto the ZSM-11 catalyst or binder or both, the resulting composite will usually be clacined to fix the metal components firmly to the catalyst.
• the metal component may be incorporated into the catalyst by impregnation, by ion exchange or by other means by contacting either the catalyst or a component thereof with a solution of a compound of the metal in an appropriate amount necessary to provide the desired concentration within the scope of the invention.
• the metal component may be incorporated either in any step during preparation of the catalyst or after the finished catalyst has been prepared.
• a preferred manner of incorporation is to ion-exchange a crystalline aluminosilicate and then compositing the ion-exchanged product with a porous matrix. Also useful is the ion-exchanging or impregnation of siliceous solids or clays.
• Suitable metal compounds include the metal halides, preferably chlorides, nitrates, amine halides, oxides, sulfates, phosphates and other water-soluble inorganic salts; and also the metal carboxylates of from 1 to 5 carbon atoms, alcoholates.
• Specific examples include palladium chloride, chloroplatinic acid, ruthenium penta-amine chloride, osmium chloride, rhodium chloride and the like.
• an oil-soluble or oil-dispersable compound of the metal may be added in stock, for incorporation in the catalyst as the charge is cracked.
• Such compounds include metal diketonates, carbonyls, metallocenes, olefin complexes of 2 to 20 carbons, acetylene complexes, alkyl or aryl phophine complexes and carboxylates of 1 to 20 carbons.
• platinum acetylacetonate tris (acetylacetonato) rhodium (III), triiodoiridium (III) tricarbonyl, ruthenocene, -cyclopentadienylosmium (I) dicarbonyl dimer, dichloro (ethylene) palladium (II) dimer (-cyclopentadienyl) (ethylene) rhodium (I), diphenylacetylenebis (triphenylphosphino) platinum (0), bromomethylbis (triethylphosphino) palladium (II), tetrakis (triphenylphosphino) palladium (0), chlorocarbonylbis(triphenylphosphino) iridium (I), palladium acetate, and palladium naphthenate.
• platinum acetylacetonate tris (acetylacetonato) rhodium (III), triiodoiridium (
• the hydrogenation/dehydrogenation component will also, to a certain extent, serve as a hydrogenation/dehydrogenation promoter but that is not the primary purpose of adding this component.
• the platinum group component is believed to promote hydroisomerization of long chain normal or slightly branched paraffins to more highly branched paraffins. This hydroisomerization converts the waxy long chain paraffins into materials which are compatible with the fuel oil product, permitting increased yields of fuel oil when using the process of the present invention. It is much more beneficial, from a liquid yield standpoint, to hydroisomerize long chain paraffins to other liquid products than it is to simply hydrocrack these materials.
• the amount of the hydrogenation/dehydrogenation component added to the catalytic dewaxing catalyst is not narrowly critical and may range from about 0.01 to 30 wt %, calculated as the elemental metal based upon the weight of the entire catalyst.
• Catalytic dewaxing of oils to reduce pour point is another application of catalytic dewaxing.
• the feed will usually not be given the solvent refining given lube oil stocks.
• catalytic dewaxing conditions used for pour point reduction of fuel oils are usually somewhat more severe than conditions used for lube oil dewaxing, usually 260 to 430°C, and a LHSV of 0.1 to 10.
• Catalytic dewaxing of fuels may be conducted using the same equipment used for dewaxing lube oils, e.g., passing the feed over a fixed, fluidized or moving bed of catalyst comprising ZSM-11, which may be used neat, although it is preferably incorporated in a binder such as alumina, or silica/alumina.
• a binder such as alumina, or silica/alumina.
• Suitable fuels or distillates include waxy hydrocarbon oils boiling within the range of 175 to 550°C. Gas oils, kerosenes, vacuum gas oils, whole crudes and oils derived from tar sands, shale and coal are contemplated for use herein.
• Catalysts containing ZSM-5 and ZSM-11 were each prepared by co-extrusion of a 65/35 weight ratio mixture of the zeolite with alumina, followed by calcination of the extrudate at 538°C and exchange with ammonium nitrate to remove sodium.
• the resulting material was then contacted with aqueous chloroplatinic acid solution in a rotary impregnator.
• CO 2 was added to the rotary impregnator, then the vessel was evacuated, the vacuum broken by further CO 2 addition and this cycle repeated several times to ensure a C0 2 atmosphere.
• Rotary impregnation continued for 60 minutes, after which the catalyst was dried at 121°C and calcined in air flow for 3 hours at 482°C.
• the finished catalysts each contained 0.5% wt Pt.
• Example 1 The catalysts prepared in Example 1 were each loaded into a fixed-bed unit, reduced with hydrogen at 2900 kPa (400 psig), 482°C (900°F) for one hour and tested with light neutral stock at the following conditions:
• Example 1 The catalysts prepared in Example 1 were also tested in the fixed bed unit with bright stock at the following conditions:
• the catalyst was disposed as a fixed bed of catalyst in a reactor.
• Example 5 Fuel oil dewaxing-ZSM-11
• the catalyst used in this study was prepared by flushing unsteamed HZSM-11, 65 wt % ZSM-11 (with a silica to alumina ratio, on a molar basis, of about 70) and 35 wt % alumina in particular size of approximately 0.60 to 1.2 mm (14-25 mesh), with CO 2 for a few minutes, followed by chloroplatinic acid- impregnation to 0.5% platinum by weight.
• the platinum ZSM-11 catalyst was loaded into the same fixed bed reactor used in Ex. 4 and reduced in situ at 2,900 kPa (400 psig) of hydrogen and 482°C (900°F) for one hour. Light neutral stock was then pumped into the reactor along with hydrogen after the reactor temperature was lowered to the desired setting.
• test conditions and properties of dewaxed distillate products processed with the Pt/ZSM-11 catalyst are compared to Ni-ZSM-5 (prior art), in Table 4.
• the product from ZSM-11 has a pour point lower than -54°C (-65°F) while that from Ni-ZSM-5 has a -7°C (20°F) pour, indicating that Pt-ZSM-11 is more active than Ni-ZSM-5 for distillate dewaxing.
• Example 6 Fuel oil dewaxing-ZSM-11
• Example 5 The catalyst of Example 5 was used for dewaxing Gas oil B. Results are reported in Table 5. The reactor pressure, LHSV and hydrogen circulation were identical to those reported in Table 4.
• the Pt/ZSM-11 catalyst is 42°C (75°F) more active than steamed Ni-ZSM-5 while the selectivities are comparable.
• Example 7 Fuel oil dewaxing-ZSM-11
• Example 5 The catalyst of Example 5 was used for dewaxing Gas oil C. Reactor pressure, LHSV, H 2 circulation remained the same as in Table 4. The results are shown in Table 6:
• the Pt/ZSM-11 catalyst offers a catalyst activity advantage of 31°C (55°F) over steamed Ni-ZSM-5.
• Pt/ZSM-1 improves the 166°C + (330°F + ) selectivity by 2.5%.
• ZSM-11 zeolite as a dewaxing catalyst will result in at least twice as much hydroisomerization of waxy components as can be achieved using conventional shape selective zeolites. It is possible to achieve five to ten times as much hydroisomerization with ZSM-11 as compared to, e.g., dewaxing with ZSM-5.
• waxy components such as the normal and singly branched paraffins are converted to less waxy components.

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