Process for producing jet fuel from isomerizing bio-renewable feed - Patent Application 20070229633

Abstract

The new catalyst hydroisomerizes C18 paraffins from fatty acids to a high degree to produce a composition with an acceptable freezing point that retains 18 carbon atoms in the hydrocarbon molecules for jet fuel. The inventors have discovered a fuel composition that includes at least 14 wt.% of the hydrocarbon molecules with at least 18 carbon atoms and a freezing point of -40°C or less. The composition may also exhibit a final boiling point of 300°C or less. The hydroisomerization process may be once-through, or a portion of the product diesel stream may be selectively hydrocracked or recycled to hydroisomerization to obtain a fuel composition that meets jet fuel specifications.

Description

[Technical field]

[0001] (Statement of priority) This application claims priority to U.S. Provisional Application No. 63 / 292,992, filed December 22, 2021, which is incorporated herein in its entirety.

[0002] FIELD OF THEINVENTION This field produces hydrocarbons useful as aviation fuels from bio-renewable feedstocks such as triglycerides and free fatty acids found in materials such as plant and animal fats and oils. [Background technology]

[0003] As the demand for fuels increases worldwide, there is growing interest in producing fuels from sources other than crude oil and blending components. These sources, often referred to as bio-renewable sources, include, but are not limited to, vegetable oils such as corn, rapeseed, canola, soybean, microbial oils such as algal oil, animal fats such as non-edible tallow, fish oil, and various waste streams such as yellow and brown grease and sewage sludge. A common feature of these sources is that they are composed of glycerides and free fatty acids (FFAs). Both triglycerides and FFAs contain aliphatic carbon chains with 8 to 24 carbon atoms. The aliphatic carbon chains in triglycerides or FFAs can be fully saturated or mono-, di-, or polyunsaturated.

[0004] Hydroprocessing may include processes that convert hydrocarbons into more valuable products in the presence of hydroprocessing catalysts and hydrogen. Hydrotreating is the process of contacting hydrogen with hydrocarbons in the presence of hydrotreating catalysts that are primarily active for removing heteroatoms such as sulfur, nitrogen, oxygen, and metals from the hydrocarbon feedstock. In hydrotreating, hydrocarbons with double and triple bonds, such as olefins, may be saturated.

[0005] The production of diesel boiling range hydrocarbon products can be achieved by hydrotreating the biorenewable feedstock. The biorenewable feedstock can be hydroprocessed by hydrotreating to deoxygenate, decarbonate and / or decarbonylate the oxygenated hydrocarbons. Decarbonation and decarbonylation remove carbon from paraffin molecules, whereas deoxygenation does not. Hydroprocessing can be followed by hydroisomerization to improve the cold flow properties of the product diesel and jet fuels. Hydroisomerization or hydrodewaxing is a hydroprocessing process that increases the alkyl branching on the hydrocarbon backbone in the presence of hydrogen and a hydroisomerization catalyst to improve the cold flow properties of the hydrocarbons. Hydroisomerization, as used herein, includes hydrodewaxing.

[0006] Hydrocracking is a hydroprocessing process in which hydrocarbons are cracked into lower molecular weight hydrocarbons in the presence of hydrogen and a hydrocracking catalyst. Depending on the desired production output, a hydrocracking unit may contain one or more beds of the same or different catalysts.

[0007] When producing jet fuel from triglycerides (also called "fats"), some degree of hydrocracking and isomerization is required to meet the jet fuel specifications outlined in ASTM D7566 Annex 2 and ASTM D1655. These key specifications required for jet fuel in D7566 are a freezing point of -40°C or less (ASTM D5972, D7153, or D7154), a viscosity of 772 kg / m 3 The jet fuels have a density below 100° C. (ASTM D1298 or D4052), a T10 below 205° C. (ASTM D86), and a final boiling point (FBP) below 300° C. (ASTM D86). Larger molecules that do not meet these jet fuel specifications are primarily hydrocracked to meet these specifications, which inherently results in lower yields in the production process and undesirable low energy density fuels. Aviation fuels are valued for their high energy per volume.

[0008] It would be desirable to provide a renewable fuel from a process that meets these three major specifications of freezing point, final boiling point, and density, while having a higher yield from triglycerides and producing a higher energy density jet fuel. Furthermore, as specifications evolve, it is anticipated that even higher densities may be approved, as higher densities translate into more energy density in the fuel. Thus, a process that meets the other performance specifications of ASTM D7566 Annex 2, but does not meet the 772 kg / m 3 Fuels with higher densities would be highly beneficial in future scenarios. Summary of the Invention

[0009] By extensively hydroisomerizing C18 paraffins from fatty acids with a new hydroisomerization catalyst, the inventors have produced a composition that retains 18 carbon atoms in the hydrocarbon molecules for jet fuel and has an acceptable freezing point. The inventors have discovered a fuel composition that includes at least 14 wt.% of the hydrocarbon molecules with at least 18 carbon atoms and a freezing point of -40°C or less. The composition may also exhibit a final boiling point of 300°C or less. The hydroisomerization process may be once-through, or a portion of the product diesel stream may be selectively hydrocracked or recycled to hydroisomerization to obtain a fuel composition that meets jet fuel specifications. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic process flow diagram of the present disclosure. [Diagram 2] FIG. 2 is a schematic process flow diagram of an alternative embodiment of FIG. 1. [Diagram 3] FIG. 2 is a schematic process flow diagram of a further alternative embodiment of FIG. 1. [Figure 4] 1 is a plot of jet fuel freezing point vs. C18 paraffin concentration. [Diagram 5] 1 is a plot of jet fuel density versus C18 paraffin concentration. [Figure 6]1 is a plot of jet fuel FBP versus operating hours. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] definition The term "communication" means operatively permitting the flow of materials between the recited components.

[0012] The term "downstream communication" means that at least a portion of the material flowing to the object in the downstream communication can operatively flow from the object in communication.

[0013] The term "upstream communication" means that at least a portion of the material flowing from an object in the upstream communication can operatively flow to the communicating object.

[0014] The term "direct communication" means that a stream from an upstream component enters a downstream component without passing through a fractionation or conversion unit and undergoing a change in composition by physical fractionation or chemical conversion.

[0015] The term "indirect communication" means that a stream from an upstream component enters a downstream component after passing through a fractionation or conversion unit and undergoing a change in composition by physical fractionation or chemical conversion.

[0016] The term "bypass" means that an object is out of downstream communication with a bypass subject, at least to the extent that it bypasses.

[0017] The term "column" refers to a distillation column or columns for separating one or more components of different volatility. Unless otherwise indicated, each column includes a condenser at the top of the column to condense and reflux a portion of the overhead stream returning to the top of the column, and a reboiler at the bottom of the column to vaporize and return a portion of the bottom stream to the bottom of the column. The feed to the column may be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the column. The bottom temperature is the liquid bottom outlet temperature. The overhead and bottom lines refer to the net lines from column to column downstream of any reflux or reboil. A stripper column may omit the reboiler at the bottom of the column and instead provide the required heat and driving force for the separation from a fluidized inert medium such as steam. A stripping column typically feeds the feed to a top tray and removes the main product from the bottom.

[0018] As used herein, the term "component rich stream" means that the rich stream exiting a vessel has a higher concentration of a component than the feed to the vessel.

[0019] As used herein, the term "component lean stream" means that the lean stream exiting a vessel has a lower concentration of a component than the feed to the vessel.

[0020] As used herein, the term "boiling point temperature" means the atmospheric equivalent boiling point (AEBP) calculated from the observed boiling point and the distillation pressure calculated using the equation provided in ASTM D86 or ASTM D2887.

[0021] As used herein, the term "True Boiling Point" (TBP) refers to a test method for determining the boiling point of a substance which corresponds to ASTM D-2892 for producing liquefied gases, distillate fractions, and bottoms of standardized quality for which analytical data can be obtained, and for determining the yield of said fractions by both mass and volume, where a graph of temperature vs. mass % distilled is produced using 15 theoretical plates in a column having a reflux ratio of 5:1.

[0022] As used herein, the terms "T5" or "T95" refer to the temperature at which 5 percent or 95 percent, by weight, of a sample boils using ASTM D-86 or TBP, respectively, as the case may be.

[0023] As used herein, the term "initial boiling point" (IBP) means the temperature at which a sample begins to boil using ASTM D2887, ASTM D-86, or TBP, as the case may be.

[0024] As used herein, the term "final boiling point" (FBP) means the temperature at which a sample has completely evaporated using ASTM D2887, ASTM D-86, or TBP, as the case may be.

[0025] As used herein, the term "diesel boiling range" means that the hydrocarbons boil within the range of IBP between 125°C (257°F) and 175°C (347°F) or T5 between 150°C (302°F) and 200°C (392°F) and "diesel cut points" including T95 between 343°C (650°F) and 399°C (750°F) using the TBP distillation method.

[0026] As used herein, the term "diesel conversion" means the conversion of a feed boiling above the diesel cut point to a material boiling below the diesel cut point within the diesel boiling range.

[0027] As used herein, the term "separator" means a vessel having an inlet and at least an overhead vapor outlet and a bottom liquid outlet, and may also have an aqueous outlet from a boot. A flash drum is a type of separator that may be in downstream communication with a separator that may be operated at a higher pressure.

[0028] As used herein, the term "predominant" or "predominantly" means greater than 50%, suitably greater than 75%, and preferably greater than 90%.

[0029] As used herein, "C x " should be understood to refer to a molecule having the number of carbon atoms represented by the subscript "x." x The term "-" refers to a molecule containing less than or equal to x, preferably less than or equal to x, carbon atoms. x The term "+" refers to a molecule having more than or equal to x, preferably x and more, carbon atoms.

[0030] As used herein, the term "carbon number" refers to the number of carbon atoms per hydrocarbon molecule, typically a paraffin molecule.

[0031] Detailed Description In the production of jet fuel from triglycerides, the first step is to hydrodeoxygenate the bio-renewable feed. The hydroprocessed products are primarily normal C18 paraffins and normal C16 paraffins. Normal C18 paraffins do not meet the ASTM D7566 jet fuel specification. Normal C18 boils at 317°C, exceeding the FBP specification of 300°C and reaching 772 kg / m 3 Exceeds density standard of 777kg / m 3and a melting point of 29°C above the freezing point specification according to D7566 of -40°C. Furthermore, the remainder of the triglycerides is typically mostly linear C16 paraffins, boiling at 286°C, making even this lighter fraction too heavy to meet the ASTM D7566 requirement of a maximum T10 boiling temperature of 205°C. Traditionally, a hydrocracking step with a small degree of isomerization was required to move these linear C18 paraffins into a specific jet boiling point, freezing point, and density range. Unfortunately, hydrocracking typically results in the production of monomethyl C16-paraffins. With this process, the freezing point specification was met via isomerization and hydrocracking, the FBP specification by hydrocracking, the T10 specification by hydrocracking, and the density specification by hydrocracking. The yield of the resulting jet fuel product, as well as the energy density of the jet fuel product, was significantly reduced due to the extensive hydrocracking.

[0032] We propose to increase hydroisomerization and reduce hydrocracking of the hydroprocessed product to maintain the concentration of C18 paraffins in the product, which would reduce the concentration of linear C18 paraffins and convert them to iso-C18 paraffins while maintaining the energy density. The selectivity of the conversion process is changed from hydrocracking to hydroisomerization by using a hydroisomerization catalyst that may be based on SAPO-11, rather than a high acid cracking catalyst such as one containing amorphous silica-alumina. Fractionation may be performed to produce a jet fuel product stream that meets the ASTM D7566 jet fuel standard. The jet fuel yield may be greater than 70% by weight, preferably greater than 80% by weight, of the paraffinic feed to the hydroisomerization reactor.

[0033] In FIG. 1, a process 10 for processing biorenewable feedstock is shown according to one exemplary embodiment. A feed line 12 transports a feed stream of fresh biorenewable feedstock to a feed surge drum 14. The biorenewable feedstock may be blended with a mineral feed stream, but preferably the biorenewable feedstock predominates. The mineral feedstock is a conventional feed derived from crude oil extracted from the earth. The biorenewable feedstock may contain nitrogen concentrations of 50 wppm to 800 wppm. The biorenewable feedstock may contain high oxygen content, which may be up to 10 wppm or more. The biorenewable feedstock may also contain 1 to 500 wppm sulfur, typically 200 wppm or less.

[0034] A variety of different bio-renewable feedstocks may be suitable for process 10. The term "bio-renewable feedstock" is meant to include feedstocks other than those derived from crude oil. Bio-renewable feedstocks may include any of those feedstocks that contain glycerides and / or free fatty acids. Most of the glycerides will be triglycerides, but mono- and diglycerides exist and may be similarly processed. Free fatty acids may be derived from phospholipids, which may provide the phosphorus in the feedstock. Examples of these bio-renewable feedstocks include, but are not limited to, camelina oil, canola oil, corn oil, soy oil, rapeseed oil, soybean oil, rapeseed oil, tall oil, sunflower oil, hempseed oil, olive oil, linseed oil, coconut oil, babassu oil, castor oil, peanut oil, palm oil, mustard oil, tallow, yellow and brown grease, lard, whale oil, milk fat, fish oil, algae oil, sewage sludge, etc. Further examples of bio-renewable feedstocks include non-edible vegetable oils from the group including Jatropha curcas (ratanjo, wild castor, jangulierandi), Madhuca indica (mowa), Pongamia pinnata (karanji, hongji), calophyllum inophyllum, moringa oleifera, and Azadirachta indica (neem). Typical vegetable or animal fat triglycerides and FFAs contain aliphatic hydrocarbon chains having 8 to 30 carbon atoms in their structure. As will be appreciated, the biorenewable feedstock may include a mixture of one or more of the foregoing examples. The biorenewable feedstock may be pretreated to remove contaminants and filtered to remove solids.

[0035] The biorenewable feed stream in feed line 12 flows from a feed surge drum 14 via a charging pump and mixes with a hot recycle stream in recycle line 16 and a recycled hydroprocessed hydrogen stream in hydroprocessed hydrogen line 20 to provide a combined biorenewable feed stream. The recycle to feed ratio can be from 2:1 to 5:1. The combined biorenewable feed stream 12 can be heated in a combined feed exchanger 22 by heat exchange with a hydroprocessed stream in hydroprocessing line 42. The heated combined biorenewable feed stream in combined feed line 24 can then be charged to a hydroprocessing reactor section 25.

[0036] The hydrotreating reactor section 25 may include a guard bed reactor 26. The guard bed reaction temperature may range from 246° C. (475° F.) to 343° C. (650° F.), preferably from 288° C. (550° F.) to 304° C. (580° F.). The reaction temperature is operated low enough to prevent the olefins in the FFA from polymerizing, but high enough to encourage olefin saturation, hydrodemetallation, hydrodeoxygenation, hydrodesulfurization, and hydrodenitrification reactions to occur. The hydrodeoxygenation reaction preferably minimizes the hydrodecarbonylation and hydrodecarboxylation reactions to preserve the carbon atoms on the paraffin chains.

[0037] The guard bed may include a base metal on a support. Base metals that can be used in the process include non-precious metals, nickel, chromium, molybdenum, and tungsten. Other base metals that may be used include tin, indium, germanium, lead, cobalt, gallium, and zinc. The process may also use metal sulfides, where the metal in the metal sulfide is selected from one or more of the listed base metals. The biorenewable feedstock may be charged through the base metal catalyst at a pressure of 1379 kPa(abs) (200 psia) to 13790 kPa(abs) (2000 psia). In further embodiments, the guard bed catalyst may include a second metal, where the second metal includes one or more of the following metals: tin, indium, ruthenium, rhodium, rhenium, osmium, iridium, germanium, lead, cobalt, gallium, zinc, and thallium. An alumina supported nickel molybdenum catalyst may be a preferred catalyst in guard bed reactor 26. Multiple guard beds, such as two, three or more, may be contained in guard bed reactor 26, and hydrogen quench from hydrogen quench line 18 may be injected at interbed locations to control temperature exotherm.

[0038] The contacted biorenewable feed stream is discharged from guard bed reactor 26 into contacting feed line 32. Within guard bed reactor 26, the majority of hydrodemetallization and hydrodeoxygenation reactions will occur, with some hydrodenitrification and hydrodesulfurization occurring. Metals removed will include alkali and alkaline earth metals and phosphorus.

[0039] The contacted biorenewable feed stream may be heated in guard bed discharge heat exchanger 34 by heat exchange with the hydrotreating stream in hydrotreating line 42 to increase the temperature of the contacted biorenewable feed stream. Additionally, the contacted biorenewable feed stream may be further heated in charge heater 36, which may be a fired heater, to increase the temperature of the contacted biorenewable feed stream. Hydrotreating reactor section 25 may also include a hydrotreating reactor 44. The heated, contacted biorenewable feed stream is charged to hydrotreating reactor 44 of hydrotreating reactor section 25.

[0040] In the hydrotreating reactor 44, the heated and contacted biorenewable feed stream is contacted with a hydrotreating catalyst in the presence of hydrogen at hydrotreating conditions to saturate the olefinic or unsaturated portions of the n-paraffinic chains in the biorenewable feedstock. The hydrotreating catalyst also catalyzes hydrodeoxygenation reactions, including hydrodecarbonylation and hydrodecarbonylation reactions, to remove oxygenated functional groups from the hydrocarbon molecules in the biorenewable feedstock, and the biorenewable feedstock is converted to water and carbon oxides. The hydrotreating catalyst also catalyzes hydrodesulfurization of organic sulfur and hydrodenitrogenation of organic nitrogen in the biorenewable feedstock. In essence, the hydrotreating reactions remove heteroatoms from the hydrocarbons to saturate the olefins in the feed stream.

[0041] The hydrotreating catalyst may be provided in one, two or more beds with an interbed hydrogen quench stream from the hydrogen quench stream from hydrogen quench line 18. Two hydrotreating catalyst beds are shown in Figure 1, although one or more are contemplated.

[0042] Hydrotreating catalysts may include nickel, nickel / molybdenum, or cobalt / molybdenum dispersed on a high surface area support such as alumina. Other catalysts include one or more precious metals dispersed on a high surface area support. Non-limiting examples of precious metals include platinum and / or palladium dispersed on an alumina support such as gamma-alumina. Suitable hydrotreating catalysts include BDO 200 or BDO 300 or BDO 400 available from UOP LLC of Des Plaines, Illinois. Hydrotreating reaction temperatures may range from 271°C (520°F) to 427°C (800°F), preferably from 304°C (580°F) to 400°C (752°F). Typically, hydrotreating conditions include pressures of 700 kPa (100 psig) to 21 MPa (3000 psig).

[0043] The hydrotreated stream is produced in hydrotreating line 42 from hydrotreating reactor 44 of hydrotreating reactor section 25 and includes a hydrocarbon fraction having a significant n-paraffin concentration. The oxygenate concentration in the hydrocarbon fraction is essentially zero while the olefin concentration is substantially reduced relative to the contacted biorenewable feed stream. The organic sulfur concentration in the hydrocarbon fraction is less than or equal to 500 wppm and the organic nitrogen concentration in the hydrocarbon fraction is less than 10 wppm.

[0044] The hydrotreat stream in hydrotreating line 42 may first flow to combined isomerization feed exchanger 46 to heat the hydroisomerization feed stream in hydroisomerization feed line 90 and to cool the hydrotreat stream. As explained above, the cooled hydrotreat stream in hydrotreating line 42 may then exchange heat with the contacted biorenewable feed stream in guard bed discharge heat exchanger 34 to cool the hydrotreat stream in hydrotreating line 42 and to heat the contacted biorenewable feed stream in contacting line 32. The twice-cooled hydrotreated steam in hydrotreating line 42 may then be further cooled in combined feed exchanger 22 by heat exchange with the combined biorenewable feed stream in combined feed line 24 to heat the combined biorenewable feed stream and to cool the hydrotreat stream in hydrotreating line 42. The thrice cooled hydrotreated stream may be cooled still further, possibly after producing water vapor, and separated to provide a hydrotreated vapor stream and a hydrotreated liquid stream having a lower oxygen concentration than the bio-renewable feed stream.

[0045] The hydrotreating stream may be separated in a high temperature separator 48 to provide a high temperature hydrocarbonaceous vapor stream in a high temperature separator overhead line 50 and a high temperature hydrocarbonaceous liquid stream in a high temperature separator bottoms line 52. The high temperature separator 48 may be in downstream communication with the hydrotreating reactor 44. The high temperature separator 48 operates at between 177°C (350°F) and 371°C (700°F), and preferably between 232°C (450°F) and 315°C (600°F). The high temperature separator 48 may be operated at a slightly lower pressure than the hydrotreating reactor 44, taking into account pressure drops through intervening equipment. The high temperature separator 48 may be operated at a pressure between 3.4 MPa (gauge) (493 psig) and 20.4 MPa (gauge) (2959 psig). The high temperature vapor stream in the high temperature separator overhead line 50 may have a temperature of the operating temperature of the high temperature separator 48.

[0046] The hot liquid stream in hot separator bottoms line 52 may be separated into two streams: a hot process liquid stream in process line 54, which is taken from the hot liquid stream in hot separator bottoms line 52, and a hot recycle liquid stream in recycle line 16, which is also taken from the hot liquid stream in hot separator bottoms line 52. The hot recycle liquid stream in recycle line 16 may be combined with the bio-renewable feed stream in line 12, as described above.

[0047] A hot process liquid stream removed from the hot liquid stream in process line 54 may be further separated in hydrotreater separator 56, which may comprise an enhanced hot separator (EHS), with the aid of stripping gas removed from isomerization overhead line 58 and fed in stripping line 59. The hot process liquid stream is separated to provide a hydrotreated vapor stream in hydrotreater overhead line 60 and a hydrotreated liquid stream in hydrotreater bottoms line 62. Hydrotreater separator 56 may be a high pressure stripping column. In hydrotreater separator 56, the hot process liquid stream from process line 54 flows down through a column where it is partially stripped of potential isomerization catalyst poisons hydrogen, carbon dioxide, carbon monoxide, water vapor, propane, hydrogen sulfide, and phosphine by contact with stripping gas from stripping line 59. The stripping gas may include make-up hydrogen gas that has passed through isomerization reactor 74 and isomerization separator 80, as described below.

[0048] The stripping gas in stripping line 59 enters hydrotreater separator 56 below the inlet for the hot process liquid stream in process liquid line 54. Hydrotreater separator 56 may include internals, such as trays or packing, located between the inlet for the hot process liquid stream in process liquid line 54 and the inlet for the stripping gas in stripping line 59 to facilitate stripping of the hot process liquid stream in process line 54. The stripping gas with the stripped gas exits into a hydrotreater vapor stream in hydrotreater overhead line 60 extending from the top of hydrotreater separator 56 and mixes with the hot vapor stream in hot overhead line 50, an optional bypass stream in bypass line 83, an isomerized liquid stream in isomerization bottoms line 82, and optionally a cold aqueous stream in cold aqueous line 87 from the cold separator boot.

[0049] The hydrotreated liquid stream, which may have been stripped, collects at the bottom of hydrotreating separator 56 and flows in hydrotreating bottoms line 62 to the suction side of the bottoms pump. The hydrotreated liquid stream contains diesel range material with high paraffin concentrations due to the composition of the bio-renewable feedstock.

[0050] Because the high temperature liquid stream contains a higher concentration of normal paraffins, especially normal C18 paraffins, while a desired product such as transportation fuel may be provided to hydroprocessing bottoms line 62, the product will have poor cold flow properties and high FBP that would render it unsuitable to meet jet fuel specifications. Thus, to improve cold flow properties and reduce FBP, the hydroprocessed liquid stream may be contacted with a hydroisomerization catalyst under hydroisomerization conditions in hydroisomerization reactor 74 to hydroisomerize the normal paraffins to branched paraffins.

[0051] The hydrotreated liquid stream may be hydroisomerized over a hydroisomerization catalyst in the presence of a hydroisomerization hydrogen stream. Make-up hydrogen gas in make-up line 86 may be compressed in make-up gas compressor 88 and mixed with the hydrotreated liquid stream pumped from hydrotreating bottoms line 62 to provide a hydroisomerization feed stream in hydroisomerization feed line 90. The hydroisomerization feed stream in hydroisomerization feed line 90 may be heated in isomerization feed exchanger 46 by heat exchange with the hydrotreated stream in hydrotreating line 42. Prior to charging the hydroisomerization feed stream to hydroisomerization reactor 74, the hydroisomerization feed stream may be heated in hydroisomerization charge heater 72 to bring the hydroisomerization feed stream to a hydroisomerization temperature.

[0052] Hydroisomerization (including hydrodewaxing) of linear hydrocarbons in hydroisomerization reactor 74 may be accomplished over one or more beds of hydroisomerization catalyst, and hydroisomerization may be operated in a co-current mode of operation. Both fixed bed trickle bed downflow mode or fixed bed liquid charged upflow mode are suitable. A make-up hydrogen quench stream removed from make-up line 86 may be fed to hydroisomerization reactor 74 for interbed quenching.

[0053] As with most chemical reactions, multiple parallel reactions can occur. These parallel reactions can often be hydrocracking reactions that produce naphtha range products in the case of dewaxing via hydroisomerization, which represents a yield loss in the jet fuel and diesel pools and therefore an economic loss as well as a cost due to the cost of consuming hydrogen. The present inventors have discovered a hydroisomerization catalyst that is highly effective in isomerizing linear C18 paraffins to iso-C18 paraffins without hydrocracking some of the C18 molecules into smaller molecules.

[0054] The hydroisomerization catalyst comprises a dehydrogenation metal, a molecular sieve, and a metal oxide binder. The hydroisomerization catalyst may comprise a dehydrogenation metal comprising a Group VIII metal. The dehydrogenation metal may be selected from platinum, palladium, nickel, nickel molybdenum sulfide, or nickel tungsten sulfide. Preferably, the dehydrogenation metal is selected from platinum or nickel tungsten sulfide. The concentration of the dehydrogenation metal on the hydroisomerization catalyst may comprise 0.05 to 5% by weight based on the transition metal.

[0055] The dehydrogenation metals are distributed between the molecular sieve and the binder, with 40-65 wt. %, preferably 45-60 wt. %, of the metals being distributed on the molecular sieve and 40-65 wt. %, preferably 45-60 wt. %, of the metals being distributed on the binder. An associated advantage of the hydroisomerization catalyst is high activity and selectivity for hydroisomerization. In a further embodiment, the hydroisomerization catalyst further comprises less than 0.5 wt. % carbon, with the associated benefit of high activity and selectivity for hydroisomerization.

[0056] In one embodiment, the hydroisomerization catalyst comprises one or more molecular sieves having a topology selected from AEI, AEL, AFO, AFX, ATO, BEA, CHA, FAU, FER, MEL, MFI, MOR, MRE, MTT, MWW, or TON, such as EU-2, ZSM-11, ZSM-22, ZSM-23, ZSM-48, SAPO-5, SAPO-11, SAPO-31, SAPO-34, SAPO-41, SSZ-13, SSZ-16, SSZ-39, MCM-22, zeolite Y, ferrierite, mordenite, ZSM-5, or zeolite beta, with the associated benefit that the molecular sieve is active in the hydroisomerization of linear hydrocarbons. SAPO-11 has been found to be particularly useful.

[0057] The metal oxide binder may be taken from the group comprising alumina, silica, silica-alumina, and titania, or mixtures thereof. Preferably, the metal oxide binder is alumina, preferably gamma alumina.

[0058] The hydroisomerization catalyst may comprise a molecular sieve having an AEL topology, and more specifically may be SAPO-11. Most of the acid sites on SAPO-11 are weak to moderate acid sites. More specifically, at least 50% of the total acidity on SAPO-11 is weakly acidic, and at least 60-80% of the external acidity on SAPO-11 is weakly acidic.

[0059] Hydroisomerization catalysts typically comprise particles having diameters between 1 and 5 millimeters. Catalyst production typically involves the formation of a stable porous support followed by impregnation with the active metal. Stable porous supports typically include metal oxides as well as molecular sieves which may be zeolites. Stable supports are produced with high porosity to ensure maximum surface area, and it is typically desirable to distribute the active metal over the entire internal and external surface area of ​​the support.

[0060] DI-200, available from UOP LLC, Des Plaines, Illinois, may be a suitable hydroisomerization catalyst.

[0061] Hydroisomerization conditions generally include temperatures between 150° C. (302° F.) and 450° C. (842° F.), and pressures between 1724 kPa (abs) (250 psia) and 13.8 MPa (abs) (2000 psia). In another embodiment, hydroisomerization conditions include temperatures between 300° C. (572° F.) and 388° C. (730° F.), pressures between 3102 kPa (abs) (450 psia) and 13790 kPa (abs) (2000 psia), and pressures between 0.5 and 3 hr. -1 Includes LHSV of.

[0062] The hydroisomerized stream in hydroisomerization line 76 from isomerization reactor 74 is a branched paraffin rich stream. Preferably, the hydroisomerized stream is a predominantly branched paraffin stream. It is contemplated that the hydroisomerized effluent may contain 80, 90, or 95% by weight of the total paraffin content of branched paraffins. The hydroisomerization conditions in hydroisomerization reactor 74 are selected to avoid undesired cracking, and thus the predominant products in the hydroisomerized stream in hydroisomerization line 76 are branched paraffins. By avoiding undesired cracking, the hydroisomerized stream in hydroisomerization line 76 will have close to the same composition, in terms of carbon number, as the hydroisomerization feed stream in hydroisomerization feed line 90, with only slightly less. For example, the hydroisomerization feed stream may have 18% by weight paraffins with 18 carbon atoms, but the hydroisomerized stream will generally have close to 18% by weight paraffins with 18 carbon atoms, with perhaps slightly less paraffins as well. The hydroisomerization stream will have a greater proportion of paraffins that are iso-C18 than the hydroisomerization feed stream, and the hydroisomerization feed stream will have a greater proportion of paraffins that are normal C18 than the hydroisomerization stream. The optimum amount of residual normal paraffins in line 76 will depend on the selectivity of the hydroisomerization catalyst, but may typically be 1 to 7 wt.%.

[0063] The hydroisomerized stream in hydroisomerization line 76 from isomerization reactor 74 flows to isomerate exchanger 77 where it is cooled by heat exchange with a cold liquid stream in cold bottoms line 92 before entering hydroisomerization separator 80 where it is separated into a liquid hydroisomerized stream and a steam hydroisomerized stream. The steam hydroisomerized stream in hydroisomerization overhead line 58 extending from the top of hydroisomerization separator 80 may provide stripping gas in stripping line 59 of hydrotreater separator 56. A portion of the steam hydroisomerized stream may optionally bypass hydrotreater separator 56 in bypass line 83 and through a control valve into cold feed line 84.

[0064] The liquid hydroisomerized stream in hydroisomerization bottoms line 82 extending from the bottom of hydroisomerization separator 80 may be sent directly to distillation column 140 to produce a product stream without condensation and cooling. However, the liquid hydroisomerized stream from hydroisomerization separator 80 in hydroisomerization bottoms line 82 may be further separated in cold separator 94 along with a hot vapor stream in hot overhead line 50, a hydrotreating vapor stream in hydrotreating overhead line 60, a bypass stream in bypass line 83, and a cold aqueous stream in cold aqueous line 87 from the boot of cold separator 94, all of which are combined in a cold separator stream in cold separator feed line 84. The cold aqueous stream in cold aqueous line 87 supplemented with water from line 85 is added to cold separator feed line 84 to dissolve salts that may be present in the hydrocarbon phase. The cold separator stream in cold separator feed line 84 may be cooled and fed to cold separator 94.

[0065] In cold separator 94, the vapor components in the hydroisomerized liquid stream will separate and rise with the hydrotreated vapor stream from hydrotreating overhead line 60 and the hot vapor stream in hot overhead line 50 to provide a cold vapor stream in cold overhead line 96. The cold vapor stream in cold overhead line 96 may be passed to a tray or pack type recirculating scrubbing column 104 where it is scrubbed with a scrubbing liquid, such as an aqueous solution provided by scrubbing liquid line 102, to remove acid gases, including hydrogen sulfide and carbon dioxide, by extraction into the aqueous solution. Preferred scrubbing liquids include amines such as Selexol™ available from UOP LLC, Des Plaines, Illinois, and alkanolamines including diethanolamine (DEA), monoethanolamine (MEA), methyl diethanolamine (MDEA), diisopropanolamine (DIPA), and diglycolamine (DGA). Other scrubbing liquids can be used in place of or in addition to the preferred amines. The lean scrubbing liquid contacts the low temperature vapor stream to absorb acid gas pollutants such as hydrogen sulfide and carbon dioxide. The resulting "sweetened" cold vapor stream is removed from the top outlet of the recycle scrubber column 104 in a recycle scrubber overhead line 106, and acid gas rich scrubbing liquid is removed from the bottom at the bottom outlet of the recycle scrubber column 104 in a recycle scrubber bottoms line 108. Spent scrubbing liquid from the bottom can be regenerated and recycled back to the recycle scrubber column 104 in a scrubber liquid line 102.

[0066] The scrubbed hydrogen-rich stream exits the scrubber via recycle scrubber overhead line 106 and may be compressed in recycle compressor 110. The compressed hydrogen stream in scrubber overhead line 106 supplies hydrogen to the hydrotreating hydrogen stream in hydrotreating hydrogen line 20, the guard bed reactor 26, and the interbed quench stream through quench line 18 for hydrotreating reactor 44.

[0067] The recycle scrubbing column 104 may be operated at a gas inlet temperature between 38° C. (100° F.) and 66° C. (150° F.), and an overhead pressure between 3 MPa (gauge) (435 psig) and 20 MPa (gauge) (2900 psig). Suitably, the recycle scrubbing column 104 may be operated at a temperature between 40° C. (104° F.) and 125° C. (257° F.), and a pressure between 1200 and 1600 kPa. The temperature of the cold vapor stream 96 to the recycle scrubbing column 104 may be between 20° C. (68° F.) and 80° C. (176° F.), and the temperature of the scrubbing liquid stream in the scrubbing liquid line 102 may be between 20° C. (68° F.) and 70° C. (158° F.).

[0068] The isomerized liquid stream and liquid isomerized fuel components from the hot vapor stream will exit the cold separator in cold bottoms line 92. The cold liquid stream in cold bottoms line 92 contains hydrocarbons useful as fuels in the diesel and jet boiling ranges, as well as other hydrocarbons such as propane, naphtha, and jet fuel. Thus, they may be fractionated in distillation column 140. A cold aqueous stream may be collected from the boot of the cold separator in cold aqueous line 87.

[0069] In one embodiment, the cold liquid stream may first be stripped in stripping column 120 to remove hydrogen sulfide and other gases. The cold liquid stream in cold bottoms line 92 may be heated in isomerate exchanger 77 by heat exchange with the hydroisomerization stream in hydroisomerization line 76 to heat the cold liquid stream and fed into stripping column 120 from an inlet that may be in the lower half of the column. A stripping medium that is an inert gas such as steam from stripping medium line 122 may be used to strip the light gases from cold bottoms line 92. Stripping column 120 feeds an overhead stripping stream of naphtha, LPG, hydrogen, hydrogen sulfide, steam, and other gases to stripper overhead line 126 and a stripped liquid isomerization stream to stripped bottoms line 128. The overhead stripping stream may be condensed and separated in stripping receiver 130. A net stripper overhead line 132 from the receiver 130 may carry a net stripper gas stream to a sponge absorber 160 for LPG recovery. Unstabilized liquid naphtha from the bottom of the receiver 130 in a liquid overhead stream may be transported in stripper receiver bottoms line 134 to a debutanizer column 170 for naphtha and LPG recovery. A sour water stream may be collected from the boot of the overhead receiver 130.

[0070] Stripping column 120 may be operated at a bottom temperature between 149° C. (300° F.) and 288° C. (550° F.), preferably at or below 260° C. (500° F.), and an overhead pressure between 0.35 MPa (gauge) (50 psig), preferably at or above 0.70 MPa (gauge) (100 psig) and 2.0 MPa (gauge) (290 psig). The temperature in overhead receiver 130 ranges from 38° C. (100° F.) to 66° C. (150° F.), and the pressure is essentially the same as in the top of stripping column 120.

[0071] The stripped liquid hydroisomerization stream in stripper bottoms line 128 may be fed to distillation column 140. Distillation column 140 may be reboiled by heat exchange with a suitable hot stream or in a fired heater to provide the heat required for the distillation. Alternatively, a stripping medium that is an inert gas such as steam from stripping medium line 142 may be used to heat the column. Distillation column 140 provides an overhead gas stream of naphtha and steam in overhead line 146 and a distillation bottoms liquid stream in distillation bottoms line 148. The distillation overhead stream may be completely condensed and separated from water in distillation receiver 178. Unstabilized liquid naphtha from the bottom of receiver 178 in distillation overhead liquid line 154 may be combined with the naphtha stream in line 176. A sour water stream may be collected from the boot of distillation receiver 178.

[0072] A jet fuel stream may be removed from the side of the distillation column 140 in a side line 144. The jet fuel stream removed in the side line 144 typically has a viscosity of 768 kg / m 3 More than 770 kg / m 3 More than 772 kg / m 3 More than 774 kg / m 3 In one embodiment, the jet fuel stream may have a density of 772 kg / m or greater. 3The jet fuel stream withdrawn in the side line 144 may have a density of 0.1 to 1.0 MPa (0.2 to 1.5 MPa). The jet fuel stream withdrawn in the side line 144 may meet both the -40°C freezing point and preferably -47°C freezing point jet fuel specifications. The jet fuel stream withdrawn in the side line 144 may have an FBP of 300°C or less, preferably 290°C or less, according to ASTM D86. The C18 paraffins in the jet fuel stream are highly isomerized to significantly reduce the amount of nC18 paraffins in the jet fuel stream. The amount of C18 paraffins in the jet fuel stream may be greater than 14% by weight, suitably greater than 20% by weight, preferably greater than 30% by weight, more preferably greater than 40% by weight. The degree of isomerization may be characterized by the conversion of normal C18 paraffins having a pure boiling point of 317°C to iso-C18 paraffins boiling at 311°C. Iso-C18 paraffins boiling at 311° C. are well within the range that can be recovered to make a jet fuel product with an ASTM D86 FBP of less than 300° C. Iso-C18 paraffins with more polymethyl substitution result in jet fuel with enough components with an FBP of less than 300° C. and a freezing point of −40° C. or less to meet the D7566 specification for jet fuel. Polymethyl substitution means more than two methyl substitutions.

[0073] The presence of polymethyl C18 paraffins in the jet fuel allows for easier distillation of the C18 paraffins into jet fuel fractions due to their lower boiling point compared to other C18 paraffins. The jet fuel stream may have a T5 of 115°C (239°F) to 130°C (266°F) and a T90 of 240°C (464°F) to 270°C (518°F). The jet fuel stream may have a cloud point of -20°C or lower.

[0074] This jet fuel product stream has a viscosity of 8 mm at -20°C. 2 / s D1655 standard and 12mm at -40℃ 2The high C18 paraffin content jet fuel will likely have a viscosity in excess of the D7566 specification of 1000 s / s and may have to be blended to meet the specification. This mode of operation and production of high C18 paraffin content jet fuel is particularly attractive when co-producing diesel products to maximize overall distillate yields.

[0075] The C18 paraffin molecules are highly branched. We have found that 4-25 wt% of the C18 paraffin molecules in the jet fuel stream are monomethyl substituted, typically 15-20 wt% of the C18 paraffin molecules. We have found that 7-33 wt% of the C18 paraffin molecules in the jet fuel stream are dimethyl substituted, typically 20-30 wt% of the C18 paraffin molecules. We have found that 8-25 wt% of the C18 paraffin molecules in the jet fuel stream are polymethyl substituted, typically 15-23 wt% of the C18 paraffin molecules.

[0076] This process provides highly isomerized C18 paraffins, but no yield loss has been observed. We have recorded jet fuel yields of at least 70% and at least 80% based on the hydroisomerization feed rate.

[0077] Optionally, a light diesel stream may be taken in a second side line, not shown. The distillation bottoms liquid stream in distillation bottoms line 148 may be a diesel stream having a T5 of 230° C. (446° F.) to 296° C. (590° F.) and a T90 of 343° C. (650° F.) to 399° C. (750° F.). Both side streams may be stripped in a side stripper, not shown.

[0078] The normal C18 paraffins will be concentrated in the heavier hydrocarbon stream. Distilling the jet fuel in the first side stream in side line 144 and then the light diesel in the second side stream will significantly enrich the concentration of normal C18 paraffins in the heavy diesel stream in distillation bottoms line 148, allowing the jet fuel stream to meet jet fuel specifications. If necessary, the heavy diesel stream in distillation bottoms line 148 with an increased concentration of normal C18 paraffins can then be subjected to additional hydroisomerization or hydrocracking in a hydrocracking reactor by recycling to produce more jet fuel that meets specifications.

[0079] Distillation column 140 may be operated at a bottoms temperature of 149° C. (300° F.) to 288° C. (550° F.), preferably up to 260° C. (500° F.), and an overhead pressure of 0.35 MPa (gauge) (50 psig), preferably from 0.70 MPa (gauge) (100 psig) to 2.0 MPa (gauge) (290 psig). The temperature in overhead receiver 178 ranges from 38° C. (100° F.) to 66° C. (150° F.), and the pressure is essentially the same as in the top of distillation column 140. It is also envisioned that distillation column 140 may simply provide a net overhead stream comprising jet fuel in distillation overhead liquid line 154, with naphtha and lighter streams being taken in a receiver overhead line (not shown), and a diesel stream being taken in distillate bottoms line 148.

[0080] The sponge absorber column 160 may receive the net stripper gas stream in net stripper overhead line 132. A lean absorbent stream in lean absorbent line 162 may be fed to the sponge absorber column 160 through an absorbent inlet. The lean absorbent may include a naphtha stream in lean absorbent line 162 from a debutanizer bottoms stream, possibly in line 176. In the sponge absorber column 160, the lean absorbent stream and the net stripper gas stream are contacted in a countercurrent manner. The sponge absorbent absorbs LPG hydrocarbons from the net stripper gas stream into an absorbent rich stream.

[0081] The hydrocarbons absorbed by the sponge absorbent consist of some of the methane and ethane in the net stripper gas stream, as well as most of the LPG, C3 and C4 hydrocarbons, and any C5 and C6 hydrocarbons. 6+ and light naphtha hydrocarbons. The sponge absorber column 160 may be operated at a temperature of 34° C. (93° F.) to 60° C. (140° F.)° C. and at a pressure essentially the same as or lower than the stripping receiver 130 with little friction loss. A sponge absorbed off-gas stream depleted in LPG hydrocarbons is withdrawn from the top of the sponge absorber column 160 at an overhead outlet through sponge absorber overhead line 164. The sponge absorbed off-gas stream in sponge absorber overhead line 164 may be transported to a hydrogen recovery unit, not shown, for hydrogen recovery. A rich absorbent stream rich in LPG hydrocarbons is withdrawn from the bottom of the sponge absorber column 160 at a bottom outlet into rich absorber bottom line 166 and may be fed to debutanizer column 170 via the stripper liquid overhead stream in stripper receiver bottom line 134.

[0082] In one embodiment, the debutanizer column 170 converts the stripper liquid overhead stream and the rich absorbent stream in the stripper receiver bottoms line 134 into a stream of primarily C 5+ The debutanizer column 170 may be fractionated into a debutanizer bottoms stream comprising the hydrocarbons and a debutanizer overhead stream comprising the LPG hydrocarbons. The debutanizer overhead stream in debutanizer overhead line 172 may be completely condensed into a debutanizer overhead liquid stream in net receiver bottoms line 174, with reflux to the debutanizer column 170 and recovery of LPG. The debutanizer bottoms stream may be withdrawn from the bottom of the debutanizer column 170 in debutanizer bottoms line 176. A reboil stream removed from the bottom of the debutanizer column 170 or from the debutanizer bottoms stream in debutanizer bottoms line 176 may be boiled in the reboil line and sent back to the debutanizer column 170 to provide heat to the column. Alternatively, a hot inert medium stream, such as steam, may be fed to column 170 to provide heat.

[0083] The distillation bottoms stream in distillation bottoms line 148 may contain heavy diesel boiling range hydrocarbons. In the embodiment of FIG. 1, the jet fuel stream in side line 144 and the diesel stream in line 148 may be taken once through without recycle. The cut point in product fractionation column 120 between the diesel stream in bottoms line 148 and the jet fuel stream in side line 144 may be adjusted to ensure that the jet fuel stream, at least after blending, has the appropriate composition to meet jet fuel specifications, in particular jet fuel density specifications. However, normal C18 paraffins are concentrated in the diesel product stream and are therefore well suited for hydrocracking or further hydroisomerization.

[0084] If the density or other properties of the jet fuel stream are too high to meet ASTM 7566 standards, the refiner may want to convert a portion of the diesel stream into reduced density jet fuel to enable the jet fuel product stream to exhibit a density that meets the standards.

[0085] Figure 2 illustrates an alternative embodiment in which a hydrocracking reactor 150 is used to hydrocrack large linear hydrocarbons into the lower density jet fuel boiling range to reduce the overall density of the jet fuel product stream. Elements in Figure 2 that have the same configuration as Figure 1 have the same reference numbers as Figure 1. Elements in Figure 2 that have a different configuration than the corresponding elements in Figure 1 have the same reference numbers but are indicated with a prime symbol ('). The configuration and operation of the embodiment of Figure 2 is essentially the same as Figure 1, with the following exceptions.

[0086] The diesel stream in distillation bottoms line 148' may be split into a diesel product stream in line 149 and a recycle stream in line 151. The diesel product stream in line 149 may be removed to a diesel pool. The recycle stream in line 151 may be mixed with a hydrocracked hydrogen stream in line 152, removed from the compressed make-up hydrogen stream in line 86, heated in heater 155, and fed in line 156 to the hydrocracking reactor 150.

[0087] Hydrocracking reactor 150 may be a fixed bed reactor including one or more vessels, single or multiple catalyst beds in each vessel, and various combinations of hydrocracking catalysts in one or more vessels. Hydrocracking reactor 150 may be operated in a conventional continuous gas phase, moving bed, or fluidized bed hydroprocessing reactor. It is also envisioned that hydrocracking reactor 150 and hydroisomerization reactor 74 may share the same vessel.

[0088] The heavy diesel stream is hydroprocessed over a hydrocracking catalyst in a hydrocracking reactor in the presence of a hydrocracked hydrogen stream from hydrocracking hydrogen line 152 to provide a hydrocracked stream. A portion of the diesel stream in line 168 may be used as an interbed quench to cool the hydrocracked effluent between the catalyst beds. In an alternative embodiment, additional hydrogen may be added between the catalyst beds.

[0089] The hydrocracking reactor may provide an overall conversion of at least 20% by volume, typically greater than 60% by volume, of the heavy diesel stream in the distillation bottoms line 148 to products boiling below the heavy diesel range of 293° C. (560° F.) to 310° C. (590° F.). The hydrocracking reactor 150 may be operated at a partial conversion of greater than 30% by volume of the feed, or at least a full conversion of 90% by volume, based on the overall conversion. The hydrocracking reactor 40 may be operated at mild hydrocracking conditions that provide an overall conversion of 20-60% by volume, preferably 20-50% by volume, of the hydrocarbon feed stream to products boiling below the heavy diesel boiling range.

[0090] The hydrocracking catalyst may utilize an amorphous silica-alumina base or a zeolite base combined with one or more Group VIII or Group VIB metal hydrogenation components to selectively produce a balance of light diesel and jet fuel distillates. In another embodiment, catalysts comprising generally any crystalline zeolite cracking base on which a Group VIII metal hydrogenation component is deposited may be suitable. Additional hydrogenation components may be selected from Group VIB for incorporation into the zeolite base. Additionally, the hydroisomerization catalyst from hydroisomerization reactor 74 may be used as a hydrocracking catalyst in hydrocracking reactor 150, but may be operated at the upper end of the hydroisomerization temperature range.

[0091] Zeolite cracking bases, sometimes referred to in the art as molecular sieves, are usually composed of silica, alumina, and one or more exchangeable cations, such as sodium, magnesium, calcium, and rare earth metals. They are further characterized by relatively uniform crystal pore diameters of 4-14 angstroms. It is preferred to use zeolites having a relatively high silica / alumina molar ratio of 3-12. Suitable zeolites found in nature include, for example, mordenite, stilbite, heulandite, ferrierite, dachyardite, chabazite, erionite, and faujasite. Suitable synthetic zeolites include, for example, B, X, Y, and L crystal types, such as synthetic faujasite and mordenite. Preferred zeolites are those having crystal pore diameters of 8-12 angstroms and a silica / alumina molar ratio of 4-6. One example of a zeolite in the preferred group is the synthetic Y molecular sieve.

[0092] Naturally occurring zeolites are usually found in sodium, alkaline earth metal, or mixed forms. Synthetic zeolites are almost always prepared in the sodium form. In any case, for use as a cracking base, it is desirable to ion-exchange most or all of the original zeolite monovalent metal with a polyvalent metal and / or with an ammonium salt, followed by heating to decompose the ammonium ions associated with the zeolite, leaving hydrogen ions and / or exchange sites at those sites which are in effect decationized by further removal of water. This type of hydrogen or "decationized" Y zeolite is described in more detail in U.S. Pat. No. 3,100,006.

[0093] Mixed polyvalent metal-hydrogen zeolites can be prepared by ion-exchanging with ammonium salts, followed by partial back-exchanging with polyvalent metal salts, and then calcining. In some cases, as in the case of synthetic mordenite, the hydrogen form can be prepared by direct acid treatment of the alkali metal zeolite. In one aspect, the preferred cracking bases are those that are at least 10% by weight, and preferably at least 20% by weight, deficient in metal cations, based on the initial ion-exchange capacity. In another aspect, a desirable and stable class of zeolites are those in which at least 20% by weight of the ion-exchange capacity is filled by hydrogen ions.

[0094] The active metals used as hydrogenation components in the preferred hydrocracking catalysts of the present invention are those of Group VIII, i.e., iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. In addition to these metals, other promoters may be used therewith, including metals of Group VIB, such as molybdenum and tungsten. The amount of hydrogenation metal in the catalyst may vary within a wide range. In general, any amount between 0.05% and 30% by weight may be used. In the case of noble metals, it is usually preferred to use 0.05 to 2% by weight of noble metal. Noble metals may deactivate noble metal catalysts, but may be preferred as hydrogenation metals on hydrocracking catalysts to provide selectivity to jet fuel due to the absence of hydrogen sulfide and ammonia being removed upstream in the process.

[0095] The method for incorporating the hydrogenation metals is to contact the base material with an aqueous solution of a suitable compound of the desired metal, where the metal is present in cationic form. After addition of the selected hydrogenation metal or metals, the resulting catalyst powder is filtered, dried, pelletized with the addition of lubricants, binders, etc. as required, and calcined in air, for example at temperatures between 371°C (700°F) and 648°C (200°F), to activate the catalyst and decompose the ammonium ions. Alternatively, the base component can be pelletized, followed by addition of the hydrogenation component and activation by calcination.

[0096] The aforementioned catalysts may be used in undiluted form or the powder catalyst may be mixed and co-pelletized with other less active catalysts, diluents, or binders, such as alumina, silica gel, silica-alumina cogels, activated clays, etc., in proportions ranging from 5 to 90% by weight. These diluents may be used neat or may contain small amounts of added hydrogenation metals, such as Group VIB and / or Group VIII metals. Additional metal-promoted hydrocracking catalysts may also be utilized in the process of the present invention, including, for example, aluminophosphate molecular sieves, crystalline chromosilicates, and other crystalline silicates. Crystalline chromosilicates are more fully described in U.S. Pat. No. 4,363,178.

[0097] In one approach, hydrocracking conditions include a temperature of 290°C (550°F) to 468°C (875°F), preferably 300°C (572°F) to 445°C (833°F), a pressure of 2.7 MPa (gauge) (400 psig) to 20.7 MPa (gauge) (3000 psig), and a reaction time of 0.4 to 2.5 hours. 1 and a liquid hourly space velocity (LHSV) of less than 421 Nm 3 / m 3 Oil (2,500scf / bbl)~2,527Nm 3 / m 3 The hydrogen rate of the oil (15,000 scf / bbl) may be included.

[0098] The hydrocracked stream may exit the hydrocracking reactor 150 in a hydrocracking line 158. In one embodiment, the hydrocracked stream may be separated and returned to fractionation. The hydrocracked stream in hydrocracking line 158 may be transported to and separated by hydrocracking separator 180. The hydrocracked stream may be separated in hydrocracking separator 180 to provide a vapor hydrocracked stream in a hydrocracking separator overhead line 182 and a liquid hydrocracked stream in a hydrocracking separator bottoms line 184. The hydrocracking separator 180 may be in downstream communication with the hydrocracking reactor 150.

[0099] Hydrocracker separator 180 operates at between 177°C (350°F) and 371°C (700°F), and preferably between 232°C (450°F) and 315°C (600°F). Hydrocracker separator 180 may be operated at a slightly lower pressure than hydrocracker reactor 150 to account for pressure drops through intervening equipment. Hydrocracker separator 180 may be operated at a pressure between 3.4 MPa (gauge) (493 psig) and 20.4 MPa (gauge) (2959 psig). The steam hydrocracked stream in hydrocracker separator overhead line 182 may have a temperature at the operating temperature of hydrocracker separator 180. The steam hydrocracked stream in hydrocracker separator overhead line 182 may be combined with stripping gas in isomerization overhead line 58 for stripping the process stream in line 54 taken from the hot separator bottoms stream.

[0100] The hydrocracked liquid stream in hydrocracker separator bottoms line 184 may be treated with the cold separator feed stream in line 84 to be cooled and separated in cold separator 94 along with a hot vapor stream in hot overhead line 50, a hydrotreated vapor stream in hydrotreating overhead line 60, a bypass stream in bypass line 83, a liquid hydroisomerized stream in hydroisomerization bottoms line 82, and a cold aqueous stream in cold aqueous line 87.

[0101] The jet fuel and diesel components in the hydrocracked liquid stream in isomerization bottoms line 92 are then optionally stripped in stripping column 120 and distilled in distillation column 140 to produce a jet fuel stream in line 144 and a diesel stream in line 148. The jet fuel stream in side line 144 will easily meet jet fuel specifications, particularly with respect to density.

[0102] FIG. 3 is a further alternative embodiment of FIG. 1 in which the diesel stream is recycled to a hydroisomerization reactor 74 to further hydroisomerize diesel range hydrocarbons that do not exhibit properties that would meet jet fuel specifications. Elements in FIG. 3 that have the same configuration as FIG. 1 will have the same reference numbers as FIG. 1. Elements in FIG. 3 that have a different configuration than the corresponding elements in FIG. 1 will have the same reference numbers but will be designated with a double prime symbol ("). The configuration and operation of the embodiment of FIG. 3 is essentially the same as FIG. 1 with the following exceptions.

[0103] The diesel stream in distillation bottoms line 148" is split into a diesel product stream in line 149" and a recycle stream in recycle line 151". The hydroisomerization feed stream in hydroisomerization feed line 90" may be heated in isomerization feed exchanger 46 by heat exchange with a hydroprocessing stream in hydroprocessing line 42. The heated hydroisomerization feed stream may be mixed with the recycle stream in recycle line 151" to provide a combined hydroisomerization feed stream in combined hydroisomerization feed line 100. Prior to charging the combined hydroisomerization feed stream to hydroisomerization reactor 74, the combined hydroisomerization feed stream may be heated in hydroisomerization charge heater 72 to bring the combined hydroisomerization feed stream to the hydroisomerization temperature.

[0104] By recycling the recycle diesel stream to the hydroisomerization reactor, the recycle diesel stream is hydroisomerized to iso-C18 paraffins, which are more of the remaining normal C18 paraffins, bringing them within the jet fuel product specifications and are incorporated into the jet fuel stream 144. EXAMPLES

[0105] Example 1 Molecular sieve SAPO-11 was extruded with Versal-251 pseudoboehmite alumina peptized with 4 wt. % aqueous nitric acid. The extrudates were dried and then calcined with steam to convert the Versal-251 pseudoboehmite to gamma alumina. Typical conditions for calcination were 30-90 minutes residence time, 1000-1300°F, with and without steam. The resulting calcined support was impregnated with 0.25 wt. % platinum in tetraammineplatinum chloride solution and then oxidized in a furnace / oxidizer at 700-900°F for 30-90 minutes with or without steam. The catalyst was then reduced at 650-700°F at atmospheric pressure with flowing hydrogen for 4-6 hours. After the dehydrogenation metals are reduced, the catalyst is capable of processing up to 100% hydrodeoxygenated renewable feedstocks at the following process condition ranges: 500-1400 psig, 1500-10000 SCFB hydrogen per feed, 550-750°F, 0.25-2.5 LHSV.

[0106] Chemical mapping of samples of catalysts prepared as described showed that the platinum levels on the SAPO-11 and gamma alumina supports were essentially equivalent at 0.27 wt% ± 0.07 wt% Pt / SAPO-11 and 0.29 wt% ± 0.09 wt% Pt / alumina. Chemical mapping was performed by scanning transmission electron microscopy. Atom counting was achieved by collecting a series of images at atomic resolution (5.1 Mx magnification) over a sufficiently thin area of ​​the support. Intensity contributions from individual atoms were calculated at 265 nm for each of the three samples. 2 The counts were made over a scanned area of ​​1000 x 1000 nm. For simplicity, topography was ignored, and therefore the individual atom density per square area represented the number of individual atoms per area of ​​the image, as opposed to the surface area of ​​the support.

[0107] Further characterization of the material was performed by measuring the acidity of the molecular sieves. In the tests carried out, SAPO-11 was tested for external acidity by testing for the absorption of collidine and for total acidity by the absorption of pyridine. The samples were 10 mg each, ground into fine powder and pressed into self-supporting pellets of 13 mm diameter. Separate experiments were carried out for each sample of pyridine and collidine. The samples were pretreated in helium at 500°C for 2 hours, then adsorbed with pyridine or collidine at 150°C for 1 hour, then desorbed three separate times at 150°C, 300°C, and 450°C for 1 hour each. The Brønsted acid strength distribution for the total acidity showed mainly weak and moderate acidity. For the external sites, in the case of SAPO-11 powder, the acid strength distribution was mainly biased towards weak acidity, followed by moderate acidity with very little strong acidity. Tests with pyridine yielded weak 0.07, medium 0.06, and strong 0.0005 for a total of 0.14, all measurements in Brønsted peak area / mg. Similar results were found for the acidity of the external sites, with relative values ​​for the weak sites being 0.11, the medium sites 0.03, and the strong sites 0.01, for a total of 0.15 area / mg.

[0108] Example 2 Molecular sieve SAPO-11 with the same gamma alumina support as in Example 1 was impregnated with nickel and tungsten metals in a 3.5 / 18 weight percent ratio. The inventors carried out the disclosed process in a pilot plant where a hydrotreating stream went through isomerization. The isomerization conditions were an average bed temperature of 337°C (640°F) to 343°C (650°F), a 1.25 hr. -1 LHSV, 3624Nm 3 / m 3 (1550SCF / bbl)~3858Nm 3 / m 3 (1650 SCF / bbl), and a pressure of 5.6 MPa (815 psig). Normal C18 paraffins were isomerized and retained in high proportions in the jet fuel product stream.

[0109] Figure 4 is a plot of jet fuel freezing point versus C18 paraffin concentration. Some samples had freezing points below -40°C and some had freezing points below -47°C. At higher concentrations of C18, such as above 35 or 40 wt%, the freezing points were below -50°C or -60°C, respectively. The triangles indicate that a portion of the isomerized diesel stream was recycled to the selective hydrocracking, while the other data points indicate runs with only isomerization.

[0110] FIG. 5 is a plot of jet fuel density versus C18 paraffin concentration. Some samples have a density of 0.772 kg / m 3 Density is less than 0.770 kg / m 3 Most of the samples had a density of less than 0.774 kg / m 3 It was less than.

[0111] Figure 6 is a plot depicting the FBP of the jet fuel streams depicted in Figures 4 and 5 over time on-stream based on ASTM D86. All of the samples had an FBP below 300°C.

[0112] Example 3 The inventors analyzed the degree of branching of the C18 paraffin molecules produced in Example 2. The C18 paraffin molecules were highly branched. The inventors found that 4-25 wt% of the C18 paraffin molecules in the jet fuel stream were monomethyl substituted, with 15-20 wt% monomethyl C18 paraffin molecules being most prevalent in the jet fuel stream. The inventors found that 7-33 wt% of the C18 paraffin molecules in the jet fuel stream were dimethyl substituted, with 20-30 wt% dimethyl C18 paraffin molecules being most prevalent in the jet fuel stream. The inventors found that 8-25 wt% of the C18 paraffin molecules in the jet fuel stream were polymethyl substituted, with 15-23 wt% polymethyl C18 paraffin molecules being most prevalent in the jet fuel stream.

[0113] The disclosed process and catalyst can provide jet fuel that meets ASTM D7566 jet fuel specifications.

[0114] Specific embodiments While the following will be described in conjunction with specific embodiments, it will be understood that this description is illustrative, but not intended to limit the scope of the foregoing description and appended claims.

[0115] A first embodiment of the invention is a composition of fuel comprising at least 14% by weight of hydrocarbon molecules having at least 18 carbon atoms and a freezing point of -40°C or less. An embodiment of the invention is any one, any or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph further comprising a freezing point of -47°C or less. An embodiment of the invention is any one, any or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph further exhibiting a final boiling point of 300°C or less. An embodiment of the invention is any one, any or all of the preceding embodiments of this paragraph up to the first embodiment of this paragraph further exhibiting a final boiling point of 768 kg / m 3 Any one, any, or all of the preceding embodiments of this paragraph through the first embodiment of this paragraph, further comprising a density of at least 8 wt.% of the C18 paraffins are polymethyl substituted. An embodiment of the present invention is any one, any, or all of the preceding embodiments of this paragraph through the first embodiment of this paragraph, further comprising at least 8 wt.% of the C18 paraffins are polymethyl substituted. An embodiment of the present invention is any one, any, or all of the preceding embodiments of this paragraph through the first embodiment of this paragraph, further comprising at least 20 wt.% of the hydrocarbon molecules have at least 18 carbon atoms. An embodiment of the present invention is any one, any, or all of the preceding embodiments of this paragraph through the first embodiment of this paragraph, further comprising a cloud point of -20°C or less.

[0116] A second embodiment of the invention is a process for hydroprocessing a biorenewable feed stream comprising: hydrotreating the biorenewable feed stream in the presence of hydrogen over a hydrotreating catalyst to hydrodeoxygenate the biorenewable feed stream to provide a hydrotreating stream; hydroisomerizing a hydroisomerization feed stream removed from the hydrotreating stream in the presence of hydrogen over a hydroisomerization catalyst to provide a hydroisomerized stream, the hydroisomerization catalyst comprising a metal component, a molecular sieve, and a metal oxide binder, wherein 40-65 wt. % of the metal component is dispersed on the molecular sieve and 40-65 wt. % of the metal component is dispersed on the metal oxide binder; and distilling the hydroisomerized stream, optionally after separation and stripping, to produce a jet fuel stream and a diesel stream. An embodiment of the invention is any one, some, or all of the preceding embodiments of this paragraph up to the second embodiment of this paragraph, further comprising hydrocracking a hydrocracked stream removed from a diesel stream to provide a hydrocracked stream comprising a jet fuel. An embodiment of the invention is any one, some, or all of the preceding embodiments of this paragraph up to the second embodiment of this paragraph, further comprising distilling the hydrocracked stream with a hydroisomerization stream. An embodiment of the invention is any one, some, or all of the preceding embodiments of this paragraph up to the second embodiment of this paragraph, further comprising hydroisomerizing the hydrocracked stream. An embodiment of the invention is any one, some, or all of the preceding embodiments of this paragraph up to the second embodiment of this paragraph, further comprising hydroisomerizing the hydrocracked stream with a hydroisomerization feed stream. An embodiment of the invention is any one, some, or all of the preceding embodiments of this paragraph up to the second embodiment of this paragraph, further comprising hydroisomerizing a hydroisomerized recycle stream removed from a diesel stream. An embodiment of the present invention is one, some, or all of the preceding embodiments of this paragraph through the second embodiment of this paragraph, further comprising hydroisomerizing the hydroisomerization recycle stream with the hydroisomerization feed stream.

[0117] A third embodiment of the invention is a process for hydroprocessing a hydroisomerization feed stream comprising: hydroisomerizing the hydroisomerization feed stream in the presence of hydrogen over a hydroisomerization catalyst to provide a hydroisomerized stream, the hydroisomerization catalyst comprising a metal component, a molecular sieve, and a metal oxide binder, wherein 40-65 wt.% of the metal component is dispersed on the molecular sieve and 40-65 wt.% of the metal component is dispersed on the metal oxide binder; and separating the hydroisomerized stream into a liquid hydroisomerized stream, the liquid hydroisomerized stream comprising at least 14 wt.% hydrocarbon molecules having at least 18 carbon atoms and a freezing point of -40°C or less. An embodiment of the invention is any one, any, or all of the preceding embodiments of this paragraph through the third embodiment of this paragraph, wherein the final boiling point of the liquid hydroisomerized stream is 300°C or less. An embodiment of the invention is wherein the density of the hydroisomerized stream is 772 kg / m 3 One, some, or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, which are as follows: An embodiment of the present invention is one, some, or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, further comprising hydrotreating the biorenewable feed stream in the presence of hydrogen over a hydrotreating catalyst to hydrodeoxygenate the biorenewable feed stream to provide a hydrotreated stream, and removing a hydroisomerization feed stream from the hydrotreated stream. An embodiment of the present invention is one, some, or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, further comprising distilling the liquid hydroisomerization stream to provide a jet stream and a diesel stream. An embodiment of the present invention is one, some, or all of the preceding embodiments of this paragraph up to the third embodiment of this paragraph, further comprising removing a recycle stream from the diesel stream, and hydrocracking the recycle stream or hydroisomerizing the recycle stream.

[0118] Without further elaboration, it is believed that, using the preceding description, one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of the present invention without departing from the spirit and scope of the present invention, and can make various changes and modifications to the present invention to adapt it to various uses and conditions. Therefore, the preceding preferred specific embodiments are to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way, and are intended to cover various modifications and equivalent arrangements falling within the scope of the appended claims.

[0119] Above, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A fuel composition comprising at least 14% by weight of hydrocarbon molecules having at least 18 carbon atoms and exhibiting a freezing point of -40°C or less and a final boiling point of 300°C or less.

2. 1. A process for hydroprocessing a biorenewable feed stream, comprising: hydrotreating the biorenewable feed stream over a hydrotreating catalyst in the presence of hydrogen to hydrodeoxygenate the biorenewable feed stream to provide a hydrotreated stream; hydroisomerizing a hydroisomerization feed stream removed from the hydrotreated stream over a hydroisomerization catalyst in the presence of hydrogen to provide a hydroisomerized stream, the hydroisomerization catalyst comprising a metal component, a molecular sieve, and a metal oxide binder, wherein about 40 to about 60 weight percent of the metal component is dispersed on the molecular sieve and about 40 to about 60 weight percent of the metal component is dispersed on the metal oxide binder; separating the hydroisomerized stream into a liquid hydroisomerized stream, wherein the liquid hydroisomerized stream comprises at least 14 wt.% hydrocarbon molecules having at least 18 carbon atoms and exhibits a freezing point of −40° C. or less; and distilling the liquid hydroisomerization stream, optionally after stripping, to produce a jet fuel stream and a diesel stream; The process includes:

3. 1. A process for hydroprocessing a hydroisomerization feed stream comprising: hydroisomerizing the hydroisomerization feed stream in the presence of hydrogen over a hydroisomerization catalyst to provide a hydroisomerized stream, the hydroisomerization catalyst comprising a metal component, a molecular sieve, and a metal oxide binder, wherein about 40 to about 60 weight percent of the metal component is dispersed on the molecular sieve and about 40 to about 60 weight percent of the metal component is dispersed on the metal oxide binder; and separating the hydroisomerized stream into a liquid hydroisomerized stream, wherein the liquid hydroisomerized stream comprises at least 14 wt.% hydrocarbon molecules having at least 18 carbon atoms and exhibits a freezing point of −40° C. or less.

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