JP5221035B2 - Fuel oils and lubricants using layered bed catalysts in hydroprocessing of waxy feedstocks including Fischer-Tropsch wax, and further solvent dewaxing - Google Patents

Description

  The present invention relates to a process for converting a waxy hydrocarbon feedstock into a product suitable for sale. More particularly, the present invention relates to a process for converting Fischer-Tropsch derived waxy feedstock into middle distillate fuel oil and lube base oil.

Fischer-Tropsch synthesis is used to convert gases consisting primarily of CO and H ₂ (commonly called synthesis gas) into a wide variety of gaseous, liquid and solid hydrocarbon-based products under catalytic conditions. it can. Many of these liquid and solid products contain waxy materials consisting of high molecular weight paraffins. These paraffinic waxes can crystallize upon cooling, and products containing these paraffinic waxes can have unacceptably high pour and cloud points. The pour point is the temperature at which the sample begins to flow under carefully controlled conditions and can be measured according to ASTM D5950-96. The cloud point is the temperature at which the sample begins to develop haze under controlled conditions and can be measured according to ASTM D 5773-95.

  It is known to catalytically convert waxy paraffins in hydrocarbon feedstocks to lower boiling hydrocarbons within the middle distillate product. This conversion can be achieved by hydroprocessing techniques such as hydrocracking and hydroisomerization. Hydrocracking converts larger molecules into smaller molecules and also introduces some branching into the cracked product. Hydroisomerization first introduces branching into paraffinic molecules to improve properties such as pour point and cloud point. Unreacted components of the hydrocarbon feedstock that have not been hydrocracked and / or not hydroisomerized are recycled for further processing to provide additional products whose boiling range is desired. Is possible.

  EP 0 544 766 B1 teaches that a paraffinic hydrocarbon feedstock is treated with a combination of hydrocracking and hydroisomerization to produce middle distillate hydrocarbons. EP 0 544 766 B1 is a low pour point middle distillate by contacting a hydrocarbon feedstock with a hydrocracking catalyst having a large pore and a catalyst comprising a silicoaluminophosphate molecular sieve of medium pore size and a hydrogenation component. A method for preparing hydrocarbons is taught.

  US Pat. No. 5,935,414 reduces the wax content of wax-containing hydrocarbon feedstocks and contains low freezing point jet fuel and / or low pour point and low cloud point diesel fuel and heating oil The present invention relates to a method for producing middle distillate products. In this process, feedstock is passed through a hydrocracking zone in the presence of hydrogen at high temperature and pressure at a high temperature and pressure in a carrier, at least one hydrogenated metal component of Group VIB and Group VIII metals, and pores such as Y-type zeolite. Contact with hydrocracking catalyst containing large zeolite. In the hydrocracking zone, the whole effluent from the hydrocracking zone is selected from metal silicates and silicoaluminophosphates in the presence of hydrogen at high temperature and pressure and a crystalline molecular sieve with a medium pore size. Contact with the dewaxing catalyst contained.

  US Pat. No. 5,139,647 relates to a process for producing middle distillates from hydrocarbon feedstocks by hydrocracking and isomerization. In the present process, the feedstock is contacted with a silicoaluminophosphate molecular sieve having a medium pore size and a catalyst containing a hydrogenation component.

  U.S. Pat. No. 4,859,312 relates to a process for making middle distillates. This method uses silicoaluminophosphate molecular sieves such as SAPO-11 and SAPO-41 and a catalyst containing platinum or palladium as a hydrogenation component, and simultaneously hydrocrackes and isomerizes heavy oil. This method selectively produces middle distillates with good cryogenic fluid properties, particularly with reduced pour point and viscosity, in high yield.

  European Patent No. 0323092A2 and US Pat. No. 4,943,672 relate to a process for converting Fischer-Tropsch wax to a lubricating oil having a high viscosity index and a low pour point. In the disclosed method, the wax is first hydrotreated under relatively severe conditions, after which the hydrotreated wax is hydrogenated with a specific type of fluorinated Group VIII metal catalyst on alumina in the presence of hydrogen. Is isomerized. The hydrogenated isomer is then dewaxed to yield a high grade lubricant base stock.

  US Pat. No. 4,080,397 discloses a method for enhancing the quality of the Fischer-Tropsch synthesis 350 ° F. + output. In the disclosed method, the Fischer-Tropsch synthesis product is hydrotreated and the hydrotreated material having a boiling point greater than about 600 ° F. is selectively decomposed.

  European Patent 0583836 Al discloses a process for preparing a hydrocarbon fuel. In the disclosed method, a substantially paraffinic hydrocarbon product is prepared and the hydrocarbon product is substantially subjected to isomerization or hydrocracking of the hydrocarbon product in the presence of a hydroconversion catalyst. Contact with hydrogen under conditions that do not occur. At least a portion of the hydrocarbon product derived from this process is contacted with hydrogen in the presence of a hydroconversion catalyst and under conditions such that hydrocracking and isomerization of the hydrocarbon feedstock occurs, and substantially paraffins are obtained. A hydrocarbon fuel of the type is obtained.

  European Patent 0147873 Al discloses a process for the preparation of middle distillates. The middle distillate is prepared from synthesis gas by a two-stage serial flow method. This process involves a Fischer-Tropsch synthesis with a specific Zr, Ti, or Cr activated Co-catalyst followed by a hydroconversion of the total synthesis product of a Fischer-Tropsch synthesis with a supported noble metal catalyst.

  Efficient and economical to convert waxy paraffinic feedstocks into high yield, both middle distillate fuel oils and lube base oils without compromising the desirable properties of paraffins in the original feedstock There is still a need for new methods. The main output of the process is desirably a lubricating base oil having good low temperature properties (ie, cloud point, pour point, clogging point, etc., and high viscosity).

  The present invention relates to a method for treating a wax-containing hydrocarbon feedstock. The method involves contacting feedstock with a hydrocracking catalyst in a hydrocracking zone, producing a hydrocracking effluent, and hydrotreating the hydrocracked effluent in a hydroisomerization zone. Contacting a isomerization catalyst to produce a hydroisomerization effluent. The hydroisomerization effluent is fractionated to provide a heavy fraction and middle distillate fuel oil, and at least a portion of the heavy fraction is dewaxed to provide a lubricant base oil. Lubricating base oils derived from this process have a viscosity index greater than 130, a pour point lower than −15 ° C., and a viscosity greater than 3 cSt at 100 ° C.

  The present invention further relates to a process for treating 650 ° F. + waxy hydrocarbon feedstock. The method involves contacting a feedstock with a hydrocracking catalyst in a hydrocracking zone, producing a hydrocracking effluent, and hydrotreating the hydrocracked effluent in a hydroisomerization zone. Contacting a hydroisomerization catalyst to produce a hydroisomerization effluent. The hydroisomerization effluent is fractionated to provide a heavy fraction and middle distillate fuel oil, and at least a portion of the heavy fraction is dewaxed to provide a lubricant base oil. This lubricating base oil has a viscosity index greater than 130, a pour point lower than −15 ° C., and a viscosity greater than 3 cSt at 100 ° C. Preferably, less than 60% by weight of the 650 ° F. + component in the feed is converted to 650 ° F.-product.

  In a further aspect, the present invention relates to a process for treating 650 ° F. + waxy hydrocarbon feedstock. In this process, feedstock is contacted with a hydrocracking catalyst in a hydrocracking zone to produce a hydrocracked effluent, and the hydrocracked effluent is passed through molecular sieve hydrogen in the hydroisomerization zone. In contact with a hydroisomerization catalyst to produce a hydroisomerization effluent. The hydroisomerization effluent is fractionated to provide a heavy fraction and middle distillate fuel oil, and at least a portion of the heavy fraction is dewaxed to provide a lubricating base oil. The lubricant base stock produced by this process has a viscosity index greater than 130, a pour point less than -15 ° C, and a viscosity greater than 3 cSt at 100 ° C, and 650 ° F + waxy hydrocarbon feedstock is 20 Contains more than 900% F + component by weight.

  The present invention relates to a method for producing a high-quality lubricating base oil from a wax-containing hydrocarbon feedstock in a high yield. A high-quality middle distillate fuel with a waxy hydrocarbon feedstock with a high initial boiling point and a high level of paraffinic waxes such as Fischer-Tropsch wax, with lube base oil as the main product. It has been discovered that it can be easily and economically converted to oils and high quality lubricating base oils. In the process of the present invention, these waxy hydrocarbon feeds are contacted with a hydrocracking catalyst followed by a hydroisomerization catalyst to separate the middle distillate product and the heavy fraction. The heavy fraction is dewaxed to provide a lubricating base oil. This method involves the conversion of a high boiling waxy hydrocarbon feedstock into a high quality middle distillate fuel oil having a low pour point and cloud point, and a high quality lubricating oil having a high viscosity index and a low pour point and cloud point. Convert to base oil. The process of the present invention results in less decomposition of the high boiling target of the high boiling waxy feed (ie, less conversion of the high boiling target of the feed to a lighter product). Thus, a high quality lubricant base oil with a high viscosity index and a low pour point and cloud point is produced.

(Definition)
The following terms are used throughout this specification and have the following meanings unless otherwise indicated.

  A “heavy fraction” is a heavier fraction that is separated after hydrocracking and hydroisomerization of a waxy hydrocarbon feedstock. The heavy fraction has an initial boiling point in the range of 600 to 750 ° F. and an end boiling point in the range of 950 to 1200 ° F. and higher. The heavy fraction includes a lubricating base oil and wax. The heavy fraction may have a wax content between 0.1 and 5% by weight. The heavy fraction may be fractionated so that a bottom fraction is obtained.

  A “bottom fraction” is a non-vaporized (ie, residual) fraction that is contained as part of a heavy fraction.

  “Derived from Fischer-Tropsch synthesis” means that the fuel or product of origin is from the Fischer-Tropsch process or is produced at any stage by the Fischer-Tropsch process.

  A “waxed hydrocarbon feedstock” useful in the process disclosed herein may be a synthetic waxy feedstock such as Fischer-Tropsch waxed hydrocarbon or derived from natural resources such as petroleum wax. It ’s good. The waxy hydrocarbon feedstock contains more than 50% wax, more preferably more than about 80% wax, most preferably more than about 90% wax. As used herein, the wax content is determined by a solvent dewaxing method. Solvent dewaxing is a standard method and is well known in the art. In this process, 300 grams of waxy product is diluted 50/50 by volume with a 4: 1 mixture of methyl ethyl ketone and toluene cooled to -20 ° C. The mixture is cooled to -15 ° C at a constant slow rate (ranging from about 0.5 ° to 4.5 ° C / min) and then filtered through a Coors funnel at -15 ° C using Whatman No. 3 filter paper. . Remove wax from filter paper and place in tarred 2 liter flask. Solvent remaining in the wax is removed with a hot plate and the wax is weighed.

  “650 ° F. + waxy hydrocarbon feedstock” has an initial boiling point of 650 ° F., where the boiling point of the feedstock is at least 70% by weight, preferably at least 85% by weight, exceeding 650 ° F.

  A “middle distillate fuel oil” or “middle distillate fuel oil fraction” is a lighter fraction that is separated after hydrocracking and hydroisomerization of a waxy hydrocarbon feedstock. It is a substance containing hydrocarbons with boiling points between approximately 300 ° F and 650 ° F. The term “distillation” means that this type of conventional fuel could be produced from a steam overhead stream derived from crude oil distillation. Within the broad category of distillate fuel oils are specific fuels including naphtha, jet fuel, diesel fuel, kerosene, aviation gasoline, fuel oil, and blends thereof.

  “Lubricant base oil” means a fraction that meets the specifications of the lubricant base oil. The lubricating base oil fraction is provided according to the method of the present invention by dewaxing the heavy fraction. The properties of the lubricating base oil provided in accordance with the present invention include initial boiling points in the range of 600 to 750 ° F., final boiling points in the range of 900 to 1200 ° F., viscosities in the range of 3 to 15 cSt at 100 ° C., from 115 A viscosity index in the range of 180, preferably in the range of 130 to 180, and more preferably in the range of 140 to 180, a pour point lower than -9 ° C, preferably in the range of -10 to -24 ° C, and from 0 to Includes cloud point in the range of -20 ° C.

  “Hydrocarbon or hydrocarbon-based” means a compound or substance containing hydrogen and carbon atoms, which may also contain heteroatoms such as oxygen, sulfur or nitrogen.

  In the method according to the present invention, the wax-containing hydrocarbon feedstock is obtained by bringing the feedstock into contact with a hydrocracking catalyst, and then with a hydroisomerization catalyst, to produce a middle distillate fuel oil product and a lubricant base. Convert to oil production. The process according to the present invention provides a lubricating base oil product having a high viscosity index and a low pour point and cloud point. The process of the present invention results in less decomposition of the high boiling target of the high boiling waxy feed (ie, less conversion of the high boiling target of the feed to a lighter product). Thus, a high quality lubricant base oil with a high viscosity index and a low pour point and cloud point is produced.

  The process described herein can convert a heavy waxy feedstock to a high quality middle distillate product and a high quality lube base oil product. The waxy hydrocarbon feedstock has an initial boiling point of less than 700 ° F. The waxy hydrocarbon feedstock has a terminal boiling point in the range of 1000 to higher than 1200 ° F. Preferably, the waxy hydrocarbon feedstock for the process described herein comprises greater than 70% by weight 650 ° F + material, and more preferably greater than 85% by weight 650 ° F + material. The feed preferably contains more than 20% by weight of 900 ° F. + material.

  The waxy feed for the process described herein consists of greater than 80% by weight wax, preferably greater than 95% by weight. As used herein, the wax content is determined by a solvent dewaxing method. Solvent dewaxing is a standard method and is well known in the art. In this process, 300 grams of waxy product is diluted 50/50 by volume with a 4: 1 mixture of methyl ethyl ketone and toluene cooled to -20 ° C. The mixture is cooled to −15 ° C. at a constant slow rate in the range of about 0.5 ° to 4.5 ° C./min and then filtered through a Coors funnel with Whatman No. 3 filter paper at −15 ° C. Remove wax from filter paper and place in tarred 2 liter flask. Solvent remaining in the wax is removed with a hot plate and the wax is weighed.

  The waxy hydrocarbon feedstock useful in the process disclosed herein may be a synthetic waxy feedstock such as Fischer-Tropsch waxy hydrocarbon or derived from natural resources such as petroleum wax. good. Thus, the waxy feedstock for this process is a waxy feedstock of Fischer-Tropsch origin, a waxy distillate feedstock such as petroleum wax, gas oil, a lubricant feedstock, a high pour point poly alpha-olefin, a foots. ) Oils, normal α-olefin waxes, crude waxes, deoiled waxes, and microcrystalline waxes, and mixtures thereof. Preferably, the waxy feedstock is derived from a Fischer-Tropsch waxy feed.

  The waxy hydrocarbon feedstock may be hydrotreated, if necessary, prior to the methods described herein. However, hydroprocessing is generally unnecessary for Fischer-Tropsch derived waxy feeds.

  Preferred waxy feeds of the present invention are Fischer-Tropsch derived waxy feeds. In a Fischer-Tropsch chemical reaction, synthesis gas is converted to a liquid hydrocarbon by contacting it with a Fischer-Tropsch catalyst under the reaction conditions. In general, methane, and optionally heavier hydrocarbons (ethane and heavier) can be sent through a conventional syngas generator to provide syngas. Generally, the synthesis gas contains hydrogen and carbon monoxide and may contain smaller amounts of carbon dioxide and / or water. The presence of sulfur, nitrogen, halogen, selenium, phosphorus and arsenic contaminants in the synthesis gas is undesirable. For this reason, and depending on the quality of the synthesis gas, it is preferable to remove sulfur and other contaminants from the feed before performing the Fischer-Tropsch chemistry. Means for removing these contaminants are well known to those skilled in the art. For example, a ZnO protective bed is preferable for removing sulfur impurities. Means for removing other contaminants are well known to those skilled in the art. It may also be desirable to purify the synthesis gas prior to the Fischer-Tropsch reactor to remove the carbon dioxide produced during the synthesis gas reaction and any additional sulfur compounds that have not yet been removed. This can be accomplished, for example, by contacting the synthesis gas with a mild alkaline solution (eg, aqueous potassium carbonate) in a packed column.

In the Fischer-Tropsch process, a synthesis gas containing a mixture of H ₂ and CO is contacted with a Fischer-Tropsch catalyst under appropriate temperature and pressure reaction conditions to form liquid and gaseous hydrocarbons. The Fischer-Tropsch reaction is generally performed at a temperature of about 300-700 ° F. (149-371 ° C.), preferably about 400-550 ° F. (204-228 ° C.), about 10-600 psia (0.7-41 bar), It is preferably carried out at a pressure of about 30-300 psia (2-21 bars) and a catalyst space velocity of about 100-10,000 cc / g / hr, preferably about 300-3,000 cc / g / hr. Examples of conditions for performing a Fischer-Tropsch type reaction are well known to those skilled in the art.

The output of the Fischer-Tropsch synthesis process can range from C ₁ to C ₂₀₀₊ , mostly in the C ₅ to C ₁₀₀₊ range. This reaction can be carried out in a variety of reactor types, such as a fixed bed reactor containing one or more catalyst beds, a slurry reactor, a fluidized bed reactor, or a combination of reactors of different types. Such reaction methods and reactors are well known and reported in the literature.

Generally, Fischer-Tropsch catalysts contain a Group VIII transition metal on a metal oxide support. The catalyst may also contain a noble metal activator (one or more) and / or a crystalline molecular sieve. Certain catalysts are known to provide the potential for relatively low to moderate chain growth, with reaction products having a relatively high proportion of low molecular weight (C _2-8 ) olefins and relatively low. _{Contains a} proportion of high molecular weight (C ₃₀₊ ) wax. Another class of catalysts is known to provide the potential for relatively high chain growth, with the reaction product having a relatively low proportion of low molecular weight (C _2-8 ) olefins and relatively high proportions _Contains high molecular weight (C ₃₀₊ ) wax. Such catalysts are well known to those skilled in the art and are readily available and / or ready.

Fischer-Tropsch derived products contain mostly paraffin, but may also contain C2 ₊ olefins, oxide deposits, and heteroatom impurities. The most abundant oxide deposits in Fischer-Tropsch products are alcohols, almost primary linear alcohols. A slightly lesser class of oxidized deposits in Fischer-Tropsch products include other types of alcohols such as secondary alcohols, acids, esters, aldehydes, and ketones. The output from the Fischer-Tropsch reaction generally contains a light reaction product and a waxy reaction product. Light reaction products (eg, condensate fractions) are mostly hydrocarbons with boiling points less than about 700 ° F. (eg, tail gas) in the C ₅ -C ₂₀ range, with decreasing amounts up to about C _30. To middle distillate fuel oil). The waxy reaction product (ie, the wax fraction) is mostly in the C ₂₀₊ range with decreasing amounts of hydrocarbons up to C ₁₀ with boiling points above about 600 ° F. (eg from heavy gas oil to heavy High quality paraffin).

  Both the light reaction product and the waxy product are substantially paraffinic. Waxed products generally contain more than 70% by weight normal paraffins and often more than 80% by weight normal paraffins. Light reaction products include paraffinic products where the ratio of alcohol to olefin is significant. Light reaction products may contain up to 50% by weight and even more of alcohol and olefins. Usable as feedstocks for the process of the present invention are waxy reaction products (eg, wax fraction).

  In accordance with the present invention, a waxy hydrocarbon feedstock is contacted with a hydrocracking catalyst in a hydrocracking zone to produce a hydrocracked effluent, and the hydrocracked effluent is hydroisomerized. Contact with a molecular sieve hydroisomerization catalyst in the zone to produce a hydroisomerization effluent. The hydrocracking catalyst and hydroisomerization catalyst may be arranged in various design options as long as the entire effluent from the hydrocracking zone passes to the hydroisomerization zone. Thus, the hydrocracking catalyst and hydroisomerization catalyst may be layered in a single reaction zone of a single reactor, or the hydrocracking catalyst and hydroisomerization catalyst may be reactors. It may be layered in a single reaction zone of a series of closely coupled reactors with no product withdrawal or feed injection between them. A preferred catalyst system is a layered catalyst system in which the hydrocracking catalyst is layered on top of the hydroisomerization catalyst, preferably in a ratio of about 1: 1 to 15: 1.

  The hydrocracking zone of the process contains a hydrocracking catalyst. During hydrocracking, the high molecular weight wax molecules are cracked to the desired boiling range. During degradation, at least some of the degraded molecules can also be isomerized. The resulting cracked product mainly comprises a mixture of paraffin and isoparaffin that is in the range boiling point of the desired fuel or lubricating oil product. In accordance with the present invention, it is desirable to minimize the decomposition of the feedstock so that a smaller amount of light product is produced.

  Hydrocracking catalysts are well known to those skilled in the art. Conventional hydrocracking catalysts generally include a cracking component, a hydrogenating component, and a binder or matrix. Such catalysts are well known in the art.

  The matrix component can be of many types, including some with acidic catalysis. Those having an acidic action include amorphous silica-alumina. The catalyst may also contain large pore zeolitic or non-zeolitic crystalline molecular sieves, where large pores are defined as having a pore diameter greater than 7.1 mm. Examples of suitable molecular sieves are zeolite Y, zeolite X, and so-called ultrastable zeolite Y, and those described in US Pat. Nos. 4,401,556, 4,820,402 and 5,059,567. Includes high structure silica: alumina ratio zeolite. Zeolite Y having a small crystal size as described in US Pat. No. 5,073,530 can also be used. Non-zeolitic molecular sieves that can be used include, for example, silicoaluminophosphate (SAPO), ferroaluminophosphate, titanium aluminophosphate, and various types described in US Pat. No. 4,913,799 and references cited therein. Includes ELAPO molecular sieve. Details regarding the preparation of various non-zeolite molecular sieves can be found in various references in US Pat. Nos. 5,114,563 (SAPO), 4,913,799 and 4,913,799. Mesoporous molecular sieves can also be used, such as the M41S material family (J. Am. Chem. Soc., 114: 10834-10843 (1992)), MCM-41 (US Patent). 5,246,689, 5,198,203, 5,334,368), and MCM-48 (Kresge et al., Nature 359: 710 (1992)). The contents of each patent and publication cited above are incorporated herein by reference in their entirety. Preferably, the molecular sieve component of the hydrocracking catalyst is less than 2% by weight.

  Suitable matrix materials are not only synthetic or natural materials, but also clays, inorganic substances such as silica and / or silica-alumina, silica-magnesia, silica-zirconia, silica-tria, silica-beryllia, silica-titania. Further, ternary metal oxides such as silica-alumina-tria, silica-alumina-zirconia, silica-alumina-magnesia, and silica-magnesia-zirconia may also be included. The latter can be either naturally occurring or a gel-like precipitate or gel containing a mixture of silica and metal oxide. Naturally occurring clays that can be incorporated into the catalyst include montmorillonite and kaolin family clays. These clays can be used in the raw state as mined or can be first subjected to calcination, acid treatment, or chemical modification.

  The hydrogenation component is a Group VI, Group VII or Group VIII metal, or an oxide or sulfide thereof, preferably one or more of molybdenum, tungsten, cobalt, or nickel, or a sulfide or oxide thereof. Let's go. If present in the catalyst, these hydrogenation components generally comprise from about 5% to about 40% by weight of the catalyst. Alternatively, platinum group metals, particularly platinum and / or palladium, may be present as a hydrogenation component, alone or in combination with a base metal such as molybdenum, tungsten, cobalt, or nickel. If present, the platinum group metal will generally comprise from about 0.1% to about 2% by weight of the catalyst. The hydrogenation component can be added to the catalyst by methods such as kneading, injection or ion exchange.

Typical hydrocracking conditions include: the reaction temperature is about 400 to 950 ° F. (204 to 510 ° C.), preferably 600 to 750 ° F. (316 to 399 ° C.); the reaction pressure is about 300 To 5000 psig (2.1 to 34.5 MPa), preferably 500-2000 psig (5.2 to 13.8 MPa); the hourly space velocity (LHSV) of the liquid is about 0.1 to 15 hr ⁻¹ , preferably 0. 25 to 2.5 hr ⁻¹ ; and the hydrogen recycle rate is about 500 to 5000 standard cubic feet (SCF) per barrel of liquid hydrocarbon feedstock (89.1 to 890 m ³ H ₂ / m ³ feed).

  The effluent from the hydrocracking zone is then contacted with a molecular sieve hydroisomerization catalyst of medium pore size in the hydroisomerization zone.

  The phrase “medium pore size” as used herein refers to an effective pore opening in the range of about 4.0 to about 7.1 mm when the porous inorganic oxide is in a calcined form. means.

  Hydroisomerization dewaxing is intended to improve the low temperature flow characteristics of lubricating base oils by selectively adding branching in the molecular structure. Hydroisomerization dewaxing would ideally achieve a high level of conversion of the waxy feed to non-waxy isoparaffins while simultaneously minimizing conversion by cracking.

  The hydroisomerization dewaxing catalyst useful in the present invention comprises a molecular sieve with a medium shape selective pore size on a refractory oxide support and optionally a catalytically active metal hydrogenation component. Molecular sieves with a medium shape-selective pore size used in the practice of this invention are generally 1-D 10-, 11-, or 12-ring molecular sieves. Preferred molecular sieves in the present invention are 1-D 10-ring variants, wherein 10- (or 11- or 12-) ring molecular sieves are 10 (or 11 or 12) tetrahedral bonded by oxygen. It has a coordination atom (T-atom). In 1-D molecular sieves, the 10-ring (or larger) pores are parallel to each other and are not connected to each other. The classification of intra-zeolite channels such as 1-D, 2-D and 3-D is R. M. R. M. Barrer “Zeolites, Science and Technology” F.F. R. Rodriguez, L. Day. Rollman and Sea. It is described in Nakache (F. R. Rodrigues, L. D. Rollman and C. Naccache), NATO ASI series, 1984, which is incorporated by reference in its entirety (see especially page 75).

  Preferred shape selective and medium pore size molecular sieves used for hydroisomerization dewaxing are based on aluminum phosphate, such as SAPO-11, SAPO-31, and SAPO-41. SAPO-11 and SAPO-31 are more preferred, and SAPO-11 is most preferred. SM-3 is a particularly preferred SAPO that is shape selective and has a moderate pore size, which has a crystal structure that is included in the crystal structure of the SAPO-11 molecular sieve. The preparation of SM-3 and its unique features are described in US Pat. Nos. 4,943,424 and 5,158,665. Zeolite is also a preferred molecular sieve for hydroisomerization dewaxing with a shape selective and medium pore size such as ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32. There are offretite and ferrierite. SSZ-32 and ZSM-23 are more preferred.

  Particularly preferred molecular sieves with moderate pore sizes in the present invention are described, for example, in US Pat. Nos. 5,135,638 and 5,282,958, the entire contents of which are incorporated herein by reference. . In US Pat. No. 5,282,958, such a medium pore size molecular sieve has a crystallite size of about 0.5 μm or less and a minimum diameter of at least about 4.8 mm and a maximum diameter of about 7.1 mm. Has holes. The catalyst has sufficient acidity, and when 0.5 gram is placed in a tubular reactor, at least 50 of hexadecane at 370 ° C., pressure 1200 psig, hydrogen flow 160 ml / min, and feed rate 1 ml / hour. Convert%. This catalyst has an isomerization selectivity of 40 or more (isomerization selectivity is determined as follows) when 96% of normal-hexadecane (n-C16) is used under conditions that convert it to other species. Also shown is 100x (wt% of branched C16 in the product) / (wt% of branched C16 in the product + wt% of C13- in the product).

  Such particularly preferred molecular sieves are further characterized by pores or channels having a crystallographic free diameter in the range of about 4.0 to about 7.1 mm, preferably in the range of 4.0 to 6.5 mm. obtain. The crystallographic free diameter of the molecular sieve channel is the “Atlas of Zeolite Framework Types” revised 5th edition, 2001, Sea Etch. Barroscher, W. M. Meyer and Dee. Etch. Ol., Elsevier (Ch. Baerlocher, W. M. Meier, and D. H. Olson, Elsevier), published on pages 10-15, which is incorporated herein by reference.

  If the crystallographic free diameter of the molecular sieve channel is unknown, the effective pore size of the molecular sieve can be measured using standard adsorption techniques and hydrocarbon-based compounds with the smallest known dynamic diameter. Breck, Zeolite Molecular Sieves 1997 (especially Chapter 8); Anderson et al. Journal of Catalysis, 58, 114 (1979); and US Pat. No. 4,440,871. For reference, these relevant portions are incorporated herein by reference. Standard techniques are used in making adsorption measurements to determine pore size. If less than about 10 minutes does not reach at least 95% of the equilibrium adsorption value on the molecular sieve (p / po = 0.5; 25 ° C.), it is convenient to consider that the particular molecule has been eliminated. A molecular sieve with a medium pore size will generally accept molecules with a dynamic diameter of 5.3 to 6.5 mm with little interference.

  The hydroisomerization dewaxing catalyst useful in the present invention optionally comprises a catalytically active metal hydride. The presence of a catalytically active metal hydride results in improved product, particularly viscosity index (VI) and stability. Typical catalytically active hydrogenation metals include chromium, molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and palladium. Platinum and palladium metals are particularly preferred, with platinum being most particularly preferred. When platinum and / or palladium is used, the total amount of active metal hydride is generally in the range of 0.1 to 5% by weight of the total catalyst, usually 0.1 to 2% by weight, 10% % Does not exceed.

  The refractory oxide support may be selected from the oxide supports conventionally used in catalysts and includes silica, alumina, silica-alumina, magnesia, titania and combinations thereof.

  Molecular sieve hydroisomerization catalysts with intermediate pores are particularly suitable for hydroisomerizing normal paraffins to produce low cloud point, low pour point products. Thus, the cloud point of the distillate fuel oil fraction recovered from the hydroisomerization stage is lowered. Furthermore, the hydroisomerization stage reduces the pour point of the heavy fraction and allows at least a portion of the heavy fraction to be recovered for lubricating oil. Although some cracking conversion is expected to occur with hydroisomerization catalysts, the conditions of the hydroisomerization stage are maintained such that the hydroisomerization reaction dominates.

  For previous hydroisomerization processes, we have found that the cloud base of lubricating base oils can be high (above 0 ° C.). Additional isomerization can lower the cloud point, which results in base oil yield, viscosity index, and loss of viscosity due to cracking and excessive branching.

  This hydrocracking / hydroisomerization process minimizes cracking conversion and achieves low pour points for lube base oil and middle distillate fuel oil products. The process of the present invention results in less decomposition of the high boiling target of the high boiling waxy feed (ie, less conversion of the high boiling target of the feed to a lighter product). Thus, a high quality lube base oil with high viscosity index, low pour point and higher viscosity is produced. According to the process of the present invention, preferably less than 60% by weight of 650 ° F. + in the feed is converted to 650 ° F.-product. Therefore, the process minimizes cracking conversion while achieving a low pour point of the product. In addition, less degradation provides a high yield of high quality lube base oil output.

  The product of this hydrocracking / hydroisomerization process is fractionated by conventional methods to provide at least a middle distillate fuel oil fraction and a heavy fraction. Fractionation is accomplished by conventional distillation methods with appropriate cut points for isolating middle distillate fuel oil and heavy fractions.

  A portion of the heavy fraction may be recycled to the hydrocracking reaction zone for further reaction, or the heavy fraction may be further fractionated by conventional methods including vacuum distillation, Minute and bottom fractions may be provided. The bottom fraction may be recycled to the hydrocracking reaction zone.

  At least a portion of the heavy fraction is dewaxed to provide a lubricating base oil. In the present invention, a solvent dewaxing step can be used to remove residual traces of wax from at least a portion of the heavy fraction to provide a high quality lubricant base oil with low pour point and low cloud point. .

  In a hydrocracking process that does not involve a subsequent hydroisomerization step, heavy, unreacted molecules in the output must be recycled for additional cracking until the boiling range is that of the desired output. Don't be. In this type of process, the hydrocracking conversion required to achieve the desired fuel output target is very high, involves a relatively non-selective cracking of the fuel, and the formation of a large amount of gaseous product. Accompany. By adding the hydroisomerization catalyst according to the method of the present invention, the product molecules are not only decomposed but also isomerized. The isomerized product results in a lower pour point, allowing heavier molecules to be included in the diesel boiling range, resulting in an increase in diesel yield. In addition, isomerized molecules boiling in the lubricant range are recovered as high quality lubricants. However, if it is required to remove all trace wax or normal paraffin from the heavy fraction to provide an acceptable cloud point, very high conversions in the hydrocracking / hydroisomerization stage will continue to be sought. I will.

  Thus, the heavy fraction from the hydrocracking / hydroisomerization stage will remove traces of wax or normal remaining dewaxed to provide a lubricant base oil that meets pour and cloud point specifications. Remove paraffin. Dewaxing allows hydrocracking to be performed under milder conditions. This is because it is unnecessary to remove all traces of wax from the heavy fraction in hydrocracking / hydroisomerization. Therefore, dewaxing the heavy fraction increases the production of high quality, high viscosity index lubricants.

  The dewaxing technique can be selected based on the amount of residual wax to be removed from the heavy fraction. For example, if the amount of residual wax is sufficiently small, the dewaxing technique may be a relatively gentle method. If the amount of wax is slightly higher, conventional dewaxing techniques can be used. Solvent dewaxing can be carried out by conventional methods well known to those skilled in the art and can be used for dewaxing heavy fractions.

  Solvent dewaxing can be accomplished by cooling the oil-solvent mixture under controlled conditions to crystallize the paraffinic wax present in the mixture. In such a process, the fraction or mixture of fraction and dewaxing solvent is heated to a temperature at which the wax melts. The heated charge is then passed through a cooling zone where a substantial portion of the wax crystallizes at a constant slow rate in the range of about 0.5 ° to 4.5 ° C./min. And cool until the dewaxed oil product reaches a temperature having a selected pour point temperature (eg, -10 to -20 ° C). Once the desired dewaxing temperature is achieved, the wax crystals, oil and solvent mixture are solid-liquid separated for the recovery of wax-free oil-solvent solutions and solid waxes containing trace amounts of oil. Solid-liquid separation techniques that can be employed to separate wax crystals from oil-solvent solutions include known solid-liquid separation methods, such as gravity sedimentation, centrifugation and filtration. Industrial methods most commonly employ filtration with a rotary vacuum filter followed by solvent washing of the wax cake. The solid wax / oil solution obtained after separating the solid wax is known as the crude wax.

  The separated oil-solvent solution is distilled to recover the solvent fraction and the dewaxed oil product fraction. This method is described in US Pat. No. 5,413,695, which is incorporated by reference in its entirety.

  Solvents known to be useful as dewaxing solvents include ketones containing 3 to 6 carbon atoms, such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK), mixtures of ketones, and ketones with benzene and It is a mixture with aromatic hydrocarbons including toluene. Halogenated low molecular weight hydrocarbons, including dichloromethane and dichloroethane, and mixtures thereof are also known as dewaxing solvents. Solvent dilution of the waxy oil feed maintains the fluidity of the oil for ease of handling, for optimal wax-oil separation, and optimal dewaxed oil yield. The degree of solvent dilution depends on the particular oil feed and solvent used, the approach to the filtration temperature in the cooling zone, and the desired final ratio of solvent to oil in the separation zone.

  Additional methods available in the art that can meet the requirements of the dewaxing process of the present invention include adsorbent treatments such as clay treatment, extraction, and catalyst defoaming. A mild catalytic approach in which the catalyst selectively removes the last traces of wax with minimal residual oil degradation is taught, for example, in US Pat. No. 4,822,476, For that reason, the entire disclosure is incorporated herein by reference. Exemplary adsorbent treatment methods are taught in US Pat. Nos. 6,468,417 and 6,468,418, the entire disclosures of which are incorporated herein by reference for all purposes.

  All or part of the wax removed in the dewaxing stage is recovered for use in the process of the present invention and recycled to the hydrocracking stage, and / or for other uses (eg, for sale) For processing to wax or use as such). When all or part of the recovered wax is recycled, the wax may be subjected to the hydrocracking stage of the present invention alone or in combination with another paraffinic feedstock. Recycling all or part of the recovered wax increases the yield of the process.

  After solvent dewaxing, a lubricating base oil is provided. Due to less decomposition of the high-boiling target of the waxy feedstock, the process of the present invention provides a higher viscosity lubricating base oil. Preferably, less than 60% by weight of 650 ° F + in the feed is converted to 650 ° F-product. The lubricating base oil recovered by the process of the present invention has a viscosity index greater than 130, preferably greater than 140, more preferably greater than 150. The provided lubricating base oil also has a pour point below -15 ° C. The lubricating base oil has a viscosity greater than 3 cSt at 100 ° C., preferably greater than 4 cSt at 100 ° C., more preferably greater than 5 cSt at 100 ° C.

  The recovered lubricant can optionally be hydrofinished with a mild hydrogenation process to improve thermal and oxidation stability. Hydrofinishing can be performed conventionally, for example, in the presence of a metallic hydrogenation catalyst such as platinum on alumina. Hydrofinishing has a temperature of about 190 to about 340 ° C., a pressure of about 300 to about 3000 psig (2.76 to 20.7 Mpa), an LHSV of between about 0.1 and 20, and a hydrogen recirculation rate of about 400. To about 1500 SCF / bbl.

  The lubricant base oil recovered by the method of the present invention can be used as a lubricant or the like, or can be mixed with another refined lubricant raw material having different characteristics. Alternatively, the lubricating base oil can be admixed with one or more additives such as antioxidants, extreme pressure additives, viscosity index improvers, etc. prior to use as a lubricant.

(Exemplary embodiment)
The figure schematically illustrates one embodiment of the present invention. Referring to the figure, a waxy hydrocarbon feedstock (10), a hydrocracking catalyst in hydrocracking zone (110), and a hydroisomerizing catalyst in hydroisomerizing zone (120), Here, the hydrocracking zone (110) is fed into a single reactor (100) above the hydroisomerization zone (120). The waxy hydrocarbon feedstock (10) is first contacted with a hydrocracking catalyst in the hydrocracking zone (110) and the effluent from the hydrocracking zone (110) is passed through the hydroisomerization zone (120). Contact with a hydroisomerization catalyst. The effluent (20) from the hydroisomerization zone (120) is then fractionated with a fractionator (200) to provide a heavy fraction (30), which is subsequently solvated off. Contacting the dewaxing solvent in the wax unit (300) removes substantially any residual wax or haze precursor to yield a lubricating oil (40). This lubricating oil has a pour point below −15 ° C., a viscosity index greater than 130, and a viscosity greater than 3 cSt at 100 ° C. Optionally, a portion of the heavy fraction (30) from fractionator (200) may be recycled (50) to hydrocracking zone (110) in reactor (100). In addition to the heavy fraction (30), the fraction also yields middle distillate fuel oil (60) and lighter output (80). Finally, the lubricating oil (40) can optionally be hydrofinished with a hydrofinishing device (400) to provide a hydrofinished lubricating oil (70).

  The invention is illustrated by the following examples, which are merely illustrative and not intended to be limiting in any way.

(Comparative Example A)
Light Fischer-Tropsch wax (Table I) was converted to 3/1 (V / V) sulfided nickel-tungsten / silica-alumina catalyst, followed by Pt / containing 15% Al ₂ O ₃ as binder. Hydrocracking in a SAPO-11 catalyst dual reactor system. The operating conditions were: overall LHSV 1 hr ⁻¹ , 1000 psig, 680 ° F. on Ni—W / SiO ₂ —Al ₂ O ₃ catalyst and 700 ° F. on Pt / SAPO-11 catalyst, and once through H _2. Was 6300 standard cubic feet (SCF) / Bbl. Under these conditions, conversion below 650 ° F. was 67.5% by weight. The yield and properties of the 650 ° F + stripper bottom are shown in Table II.

Example 1
The feedstock of Table I was prepared on the catalyst system of Comparative Example A, with an overall LHSV of 1 hr ⁻¹ , 1000 psig, Ni—W / SiO ₂ —Al ₂ O ₃ catalyst on 668 ° F. and Pt / SAPO-11 catalyst. Processing at less severe conditions, 687 ° F. above and Once through H ₂ of 6.3 MSCF / Bbl, resulted in less cracking conversion at the stripper bottom and higher pour point. The stripper bottom was then dewaxed to the same pour point as Comparative Example A. Solvent dewaxing removes small amounts of wax remaining in the oil and significantly increases both the lubricant yield and the lubricant viscosity index (VI). The results are shown in Table III.

  Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. By reviewing the previous description, other objects and advantages will become apparent to those skilled in the art.

1 schematically illustrates one embodiment of the method of the present invention.

Claims (15)

a) Fischer-Tropsch derived feedstock at a temperature of 204 to 510 ° C. and a pressure of 2.1 to 34.5 MPa in a single reaction zone of a single reactor with hydrocracking catalyst and medium pore size molecular sieve Contacting with a layered catalyst system comprising a hydroisomerization catalyst to produce a hydroisomerization effluent;
b) fractionating the hydroisomerization effluent to supply a heavy fraction and middle distillate fuel oil; and c) dewaxing at least a portion of the heavy fraction, from 130 Supplying a lubricating base oil having a large viscosity index, a pour point of −14 ° C. or less, and a viscosity of greater than 3 cSt at 100 ° C .;
The containing, comprise more than 80 wt% wax, and 700 ° F (371 ° C.) of less than the initial boiling point and 1000F ° Fischer from (538 ° C.) with a high range end boiling point of above 1200 ° F (649 ℃) - Tropsch A method for treating a wax-containing hydrocarbon feedstock derived therefrom.   The process of claim 1 wherein the Fischer-Tropsch derived waxy hydrocarbon feedstock comprises a feed at 343 ° C +.   The process according to claim 1, wherein the Fischer-Tropsch derived waxy hydrocarbon feedstock comprises more than 20% by weight of 482 ° C + components.   The Fischer-Tropsch derived waxy hydrocarbon feedstock contains more than 85% by weight of 343 ° C + component, and the hydrocracking and hydroisomerization result in less than 343 ° C + component less than 60% by weight. The process according to claim 1, wherein the process is converted to ° C-product. a) Fischer-Tropsch derived 343 ° C. + wax-containing hydrocarbon feedstock with hydrocracking catalyst in a single reaction zone of a single reactor at a temperature of 204 to 510 ° C. and a pressure of 2.1 to 34.5 MPa. Contacting with a stratified catalyst system comprising a molecular sieve hydroisomerization catalyst of medium pore size to produce a hydroisomerization effluent;
b) fractionating the hydroisomerization effluent to supply a heavy fraction and middle distillate fuel oil; and c) dewaxing at least a portion of the heavy fraction, from 130 Supplying a lubricating base oil having a large viscosity index, a pour point of −14 ° C. or less, and a viscosity of greater than 3 cSt at 100 ° C .;
Including
And the hydrocracking and hydroisomerization convert 343 ° C. + less than 60% by weight of the components into 343 ° C.-product, including 343 ° C. + from Fischer-Tropsch containing more than 80% by weight of wax. A processing method for wax hydrocarbon feedstock.   6. The process of claim 5, wherein the Fischer-Tropsch derived 343 [deg.] C + waxy hydrocarbon feedstock is not hydrotreated prior to hydrocracking.   6. The process of claim 5, wherein the Fischer-Tropsch derived 343 [deg.] C + waxy hydrocarbon feedstock contains more than 20% by weight 482 [deg.] C + components.   6. The process of claim 5, wherein the Fischer-Tropsch derived 343 [deg.] C + waxy hydrocarbon feedstock contains more than 85 wt% 343 [deg.] C + components. a) Fischer-Tropsch derived 343 ° C. + wax-containing hydrocarbon feedstock with hydrocracking catalyst in a single reaction zone of a single reactor at a temperature of 204 to 510 ° C. and a pressure of 2.1 to 34.5 MPa. Contacting a layered catalyst system comprising a molecular sieve hydroisomerization catalyst of medium pore size to produce a hydroisomerization effluent;
b) fractionating the hydroisomerization effluent to supply a heavy fraction and middle distillate fuel oil; and c) dewaxing at least a portion of the heavy fraction, from 130 Supplying a lubricating base oil having a large viscosity index, a pour point of −14 ° C. or less, and a viscosity of greater than 4 cSt at 100 ° C .;
Including
And in that case, the 343 ° C. + wax-containing hydrocarbon feedstock contains more than 20% by weight of 482 ° C. + component, Fischer-Tropsch derived 343 ° C. + wax-containing hydrocarbon feed containing more than 80% by weight of wax. Oil processing method.   10. The process of claim 9, wherein the Fischer-Tropsch derived 343 [deg.] C + waxy hydrocarbon feedstock contains more than 40% by weight 482 [deg.] C + components.   The process according to claim 9, wherein the Fischer-Tropsch derived 343 ° C + waxy hydrocarbon feedstock contains more than 60% by weight 482 ° C + components.   The method of any one of claims 1, 5, 9, and 11 wherein the lubricating base oil has a viscosity index greater than 140, a pour point less than -15 ° C, and a viscosity greater than 4 cSt at 100 ° C.   The method of any one of claims 1, 5, 9, and 11 wherein the lubricating base oil has a viscosity index greater than 150, a pour point less than -15 ° C, and a viscosity greater than 5 cSt at 100 ° C.   10. A method according to any one of claims 1, 5, and 9, wherein a portion of the heavy fraction is recycled to the single reaction zone.   The process according to claim 9, wherein the Fischer-Tropsch derived 343 ° C + 343 ° C of the waxy hydrocarbon feed plus less than 60% by weight of the component is converted to 343 ° C-output.

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