Method of producing hydrocarbon fuels and low BOD water byproduct during hydroprocessing lipid feedstock containing refractory nitrogen

Abstract

Methods for converting renewable feedstock containing refractory nitrogen to hydrocarbon fuels such as renewable diesel and jet fuel. The method may include pretreating a lipid feedstock with refractory and non-refractory nitrogen compounds to produce a pretreated lipid. The pretreated lipid is processed through a hydroprocessing reactor system comprising hydrodeoxygenation and a hydropolishing catalyst beds. Effluent from the hydroprocessing reactor system comprises a paraffinic hydrocarbon and water vapor. The water vapor and the paraffinic hydrocarbon are separated to provide a paraffinic hydrocarbon with residual refractory nitrogen and liquid water with low turbidity and a low Biological Oxygen Demand (BOD) value. The paraffinic hydrocarbon is subsequently subjected to hydroisomerization to produce an isoparaffinic hydrocarbon effluent for fractionation into a naphtha fraction and a renewable diesel fraction and / or a jet fuel fraction.

Description

[0001] Atty. Docket No. T-12564-P1-WO01

[0002] PATENT APPLICATION

[0003] Method of Producing Hydrocarbon Fuels and Low BOD Water Byproduct During Hydroprocessing Lipid Feedstock Containing Refractory Nitrogen

[0004] FIELD

[0005] The present technology relates generally to hydrocarbon fuels comprising renewable content. More particularly, the technology relates to a method of producing renewable diesel and jet fuel from a feedstock containing refractory nitrogen compounds.

[0006] BACKGROUND

[0007] Methods of producing hydrocarbon fuels, such as renewable diesel and jet fuel, by hydrodeoxygenation (HDO) of lipids to n-paraffins followed by hydroisomerization (HI) of the n-paraffins to isoparaffins are known in the art. Lipids are mainly composed of fatty acids and fatty acid glycerides / esters. The HDO reaction removes the oxygen atom of the fatty acid / ester molecules as water, carbon dioxide, and carbon monoxide, while saturating the carbon-carbon double bonds of the fatty acid chains. The prior art also describes methods to pretreat lipid feedstock for the removal of contaminants such as phosphorus and metals before subjecting the lipids to HDO.

[0008] A class of lipid feedstock of interest for production of biofuels includes low-value animal fats, crude degummed vegetable oils, algal oils, and greases. These feeds are characterized by high levels of nitrogen, typically between 100 and 10,000 wppm.

[0009] Nitrogen compounds can be a problem for HI catalysts. HI reactor systems typically utilize bi-functional catalysts with hydrogenation-dehydrogenation metal active sites and acid active sites. The latter can be impacted by nitrogen. For example, the nitrogen compounds may inhibit the HI catalyst acidity needed for the conversion of n-paraffins to isoparaffins. Atty. Docket No. T-12564-P1-WO01

[0010] Some vegetable oil refining literature describes production of refined, bleached, and deodorized (RBD) oils for human consumption. Refining involves removal of phosphatides (a class of phosphorus containing lipid molecules) in a process step referred to as degumming. In the subsequent bleaching operation, color bodies are removed by contacting the degummed oil with an adsorbent clay (also referred to as bleaching earth). The color bodies may include chlorophyll, a nitrogen compound resembling porphyrin.

[0011] Low-value lipid feedstocks differ from crude vegetable oils in terms of contaminant profile and their high free fatty acid (FFA) content. Whereas crude vegetable oils have less than 1 wt % FFA, the low-value / waste lipid feedstock such as used cooking oils, distillers corn oil, palm oil mill effluent, and rendered animal fats have typical FFA values above 5 wt %.

[0012] Furthermore, in addition to the naturally occurring phosphorus, nitrogen, and metal species, these low-value / waste feedstock also contain contaminants introduced in the feedstock during prior use and handling (e.g. anti-foams, disinfectants, dissolved polyethylene from plastic films, and other adulterants). US Patent Nos. 11,118,133 (Slade et al.) and 11,459,523 (Abhari et al.) relate to methods for pretreatment of low-value and waste feedstocks for biofuel production. These two patents as well as the other patents and publications referenced herein are incorporated by this reference in their entirety.

[0013] US Patent Publication 2016 / 0289136 (Ellig et al.) suggests that under typical HDO conditions, a feedstock with 60 ppm or higher nitrogen is converted to a hydrocarbon product with less than 1 ppm nitrogen. No information about the type of nitrogen species is provided.

[0014] US Patent Publication 2020 / 0392426 (Pasanen et al.) describes a process for converting high nitrogen lipids derived from algae into lower nitrogen oils. The pretreatment process involves first hydrolyzing the algal oil feedstock to yield an oil and an aqueous phase. In an Atty. Docket No. T-12564-P1-WO01

[0015] example, the hydrolyzer feed has 25,633 ppm chlorophyll (6,100 ppm nitrogen). After hydrolysis, the chlorophyll content is reduced to 414 pm (4,000 ppm nitrogen). Distillation of the FFA-rich hydrolysis product is performed in a short path distillation unit to provide an overhead fraction with less than 10 ppm chlorophyll (630 ppm nitrogen).

[0016] Existing literature and methods provide no guidance on nitrogen types present in feedstocks for HDO, nor on how this information may be used to select feedstock blends and operating conditions for HDO such that the HDO product is suitable for hydroisomerization, and byproduct water will meet discharge quality standards.

[0017] The water byproduct of HDO represents around 10% of the mass of the total feedstock processed. Depending on quality, the HDO water may require treatment. As such, its disposal could represent a significant cost for the renewable fuels plant. One key water quality attribute is Biochemical Oxygen Demand (BOD). Water with high BOD results in increased consumption of the dissolved oxygen in the water. Since aquatic life depends on dissolved oxygen, discharge of high BOD water puts aquatic life at risk. The prior art is silent about HDO water quality in general, and process conditions that influence HDO water quality and BOD in particular.

[0018] There is therefore a need for an improved method for producing hydrocarbon fuels from a lipid feedstock containing refractory nitrogen compounds wherein the HDO reaction has a low BOD water byproduct.

[0019] SUMMARY

[0020] One aspect of the present disclosure relates to a method for converting renewable feedstock containing refractory nitrogen to premium hydrocarbon fuels, such as renewable diesel and jet fuel, having less than 2 wppm total nitrogen. In one embodiment the method comprises Atty. Docket No. T-12564-P1-WO01

[0021] pretreating a lipid feedstock with refractory and non-refractory nitrogen compounds to produce a pretreated lipid, wherein the concentration of the refractory nitrogen compounds is in the range of about 1 to 30 wppm, and between10 to 30 wppm in some embodiments. The pretreated lipid is processed through a hydroprocessing reactor system comprising hydrodeoxygenation and a hydropolishing catalyst beds. Effluent from the hydroprocessing reactor system comprises a paraffinic hydrocarbon and water vapor. The water and the paraffinic hydrocarbon are separated in at least two separation stages to provide a paraffinic hydrocarbon with residual refractory nitrogen and liquid water with low turbidity and a low Biological Oxygen Demand (BOD) value. The paraffinic hydrocarbon is subsequently subjected to hydroisomerization to produce an isoparaffmic hydrocarbon effluent for fractionation into a naphtha fraction and a renewable diesel fraction and / or a jet fuel fraction, wherein the renewable diesel / jet fuel has a total nitrogen content less than 2 wppm.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These, as well as other objects and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, of which:

[0024] FIG. 1 is a three-window distribution of organic nitrogen compounds in a straight-run vacuum gas oil (VGO) for sample ABQ1214 using the HPLC-MS method wherein each window shows the DBE vs. Carbon Number Spectra of a Straight-Run VGO ABQ1214. Window ABQ1214 N1W1 represents a group of nitrogen compounds containing one N atom in window 1. Atty. Docket No. T-12564-P1-WO01

[0025] FIG. 2 shows multiple plots of the DBE vs. Carbon Number Spectrum of sample DGQ0668.

[0026] FIG. 3 shows multiple plots of the DBE vs. Carbon Number Spectrum of sample DGQ0671. No nitrogen signal was detected in both N1W1 and N1W3.

[0027] FIG. 4 is a graph showing the temperature profiles for two conditions, expressed as % of total exothermic reaction conversion as a function of % of reactor catalyst volume.

[0028] FIG. 5 is a schematic for processing a lipid feedstock comprising a refractory nitrogen compound.

[0029] FIG. 6 is a schematic showing an alternative embodiment having multiple catalyst beds within a single reactor.

[0030] DETAILED DESCRIPTION

[0031] The present invention generally relates to methods for converting renewable feedstock containing refractory nitrogen to premium hydrocarbon fuels such as renewable diesel and jet fuel. A class of nitrogen compounds in lipid feedstock, referred to here as refractory nitrogen compounds, are generally not removed during feedstock pretreatment processes and remain in the HDO product at concentrations high enough to potentially negatively impact the HI step in the renewable diesel / jet fuel production process. This is in contrast with most of the nitrogen species in the lipid (the non-refractory nitrogen) that are partially removed during pretreatment and completely removed during HDO. It has also been observed that in the presence of refractory nitrogen compounds, the quality of the HDO water byproduct is impacted by the hydroprocessing reactor conditions and catalyst beds therein. As explained in more detail below, embodiments of the invention relate to providing a lipid feed to a hydroprocessing reactor system Atty. Docket No. T-12564-P1-WO01

[0032] having a hydropolishing catalyst bed, and operating the hydroprocessing reactor system to provide a HDO water byproduct having a BOD value less than 30 mg / L (as measured according to National Environmental Methods Index Standard Method 5210B; 5-Day BOD Test), wherein the lipid feed has a maximum of 30 wppm refractory nitrogen.

[0033] Various embodiments of the invention are described hereinafter. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment(s).

[0034] As used herein, “about” will mean up to plus or minus 10% of the particular term. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g, “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any nonclaimed element as essential. Atty. Docket No. T-12564-P1-WO01

[0035] Definitions

[0036] As used herein, “alkyl” groups include straight chain and branched alkyl groups.

[0037] Examples of straight chain alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, sec-butyl, t-butyl, neopentyl, and isopentyl groups. It will be understood that the phrase “C- alkyl,” such as C1-C4 alkyl, means an alkyl group with a carbon number falling in the range from / to j.

[0038] The term “aromatics” as used herein is synonymous with "aromates" and means both cyclic aromatic hydrocarbons that do not contain heteroatoms as well as heterocyclic aromatic compounds. The term includes monocyclic, bicyclic and polycyclic ring systems. The term also includes aromatic species with alkyl groups and cycloalkyl groups. Thus, aromatics include, but are not limited to, benzene, azulene, heptalene, phenylbenzene, indacene, fluorene, phenanthrene, triphenylene, pyrene, naphthacene, chrysene, anthracene, indene, indane, pentalene, and naphthalene, as well as alkyl and cycloalkyl substituted variants of these compounds. In some embodiments, aromatic species contains 6-14 carbons, and in others from 6 to 12 or even 6-10 carbon atoms in the ring portions of the groups. The phrase includes groups containing fused rings, such as fused aromatic-aliphatic ring systems (e.., indane, tetrahydronaphthene, and the like).

[0039] “Oxygenates” or an “oxygenated hydrocarbon” as used herein means carbon-containing compounds containing at least one covalent bond to oxygen. Examples of functional groups encompassed by the term include, but are not limited to, carboxylic acids / esters, carboxylates, acid anhydrides, aldehydes, esters, ethers, ketones, and alcohols. Oxygenates may also be Atty. Docket No. T-12564-P1-WO01

[0040] oxygen containing variants of aromatics, cycloparaffins, and paraffins as described herein. Fatty acids / glycerides are naturally occurring carboxylic acids / esters that define lipids.

[0041] The term “paraffins” as used herein means non-cyclic, branched or unbranched alkanes. An unbranched paraffin is an n-paraffin; a branched paraffin is an iso-paraffin. “Cycloparaffms” are cyclic, branched or unbranched alkanes.

[0042] The term “paraffinic” as used herein means both paraffins and cycloparaffms as defined above as well as predominantly hydrocarbon chains possessing regions that are alkane, either branched or unbranched.

[0043] The term “olefin” as used herein means non-cyclic, branched or unbranched alkenes. The term “olefinic” as used herein means both mono- or di-unsated (i.e., one or two double bonds) hydrocarbons, either cyclic, branched or unbranched.

[0044] Hydroprocessing as used herein describes the various types of catalytic reactions that occur in the presence of hydrogen without limitation. Examples of the most common hydroprocessing reactions include, but are not limited to, hydrogenation, hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrotreating (HT), hydrocracking (HC), aromatic saturation or hydrodearomatization (HD A), hydrodeoxygenation (HDO), decarboxylation (DCO), hydroisomerization (HI), hydrodewaxing (HDW), hydrodemetallization (HDM), decarbonylation, methanation, and reforming. Depending upon the type of catalyst, reactor configuration, reactor conditions, and feedstock composition, multiple reactions can take place that range from purely thermal i.e., do not require catalyst) to catalytic. In the case of describing the main function of a particular hydroprocessing unit, for example an HDO reaction system, it is understood that the HDO reaction is merely one of the predominant reactions that are taking place and that other reactions may also take place. Atty. Docket No. T-12564-P1-WO01

[0045] Decarboxylation (DCO) is understood to mean hydroprocessing of an organic molecule such that a carboxyl group is removed from the organic molecule to produce CO2, as well as decarbonylation which results in the formation of CO.

[0046] Hydrotreating (HT) involves the removal of elements from groups Illa, Va, Via, and / or Vila of the Periodic Table from organic compounds. Hydrotreating may also include hydrodemetallization (HDM) reactions. Hydrotreating thus involves removal of heteroatoms such as oxygen, nitrogen, sulfur, and combinations of any two more thereof through hydroprocessing. For example, hydrodeoxygenation (HDO) is understood to mean removal of oxygen by a catalytic hydroprocessing reaction to produce water as a by-product; similarly, hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) describe the respective removal of the indicated elements through hydroprocessing.

[0047] Hydropolishing as used herein refers to removal of trace species that can act as surfactants for oil droplets in water. Hydropolishing may be performed in HT reactor after substantiation HDO has been achieved and may include HDN.

[0048] Hydrogenation involves the addition of hydrogen to an organic molecule without breaking the molecule into subunits. Addition of hydrogen to a carbon-carbon or carbon-oxygen double bond to produce single bonds are two nonlimiting examples of hydrogenation. Partial hydrogenation and selective hydrogenation are terms used to refer to hydrogenation reactions that result in partial saturation of an unsaturated feedstock. For example, vegetable oils with a high percentage of polyunsaturated fatty acids (e.g., linoleic acid) may undergo partial hydrogenation to provide a hydroprocessed product wherein the polyunsaturated fatty acids are converted to mono-unsaturated fatty acids (e.g., oleic acid) without increasing the percentage of undesired saturated fatty acids (e.g., stearic acid). While hydrogenation is distinct from Atty. Docket No. T-12564-P1-WO01

[0049] hydrotreatment, hydroisomerization, and hydrocracking, hydrogenation may occur amidst these other reactions.

[0050] Hydrocracking (HC) is understood to mean the breaking of a molecule’s carbon-carbon bond to form at least two molecules in the presence of hydrogen. Such reactions typically undergo subsequent hydrogenation of the resulting double bond.

[0051] Hydroisomerization (HI) is defined as the skeletal rearrangement of carbon-carbon bonds in the presence of hydrogen to form an isomer. Hydrocracking is a competing reaction for most HI catalytic reactions, and it is understood that the HC reaction pathway, as a minor reaction, is included in the use of the term HI. Hydrodewaxing (HDW) is a specific form of hydrocracking and hydroisomerization designed to improve the low temperature characteristics of a hydrocarbon fluid.

[0052] It will be understood that if a composition is stated to include “C / - hydrocarbons,” such as C7-C12 n-paraffins, this means the composition includes one or more paraffins with a carbon number falling in the range from z to / '.

[0053] A “middle distillate” in general refers to a petroleum fraction in the range of about 200 °F (93 °C) to about 800 °F (427 °C). This includes kerosene (about 200-520 °F), diesel and light gasoil (about 400 to 650 °F), and heavy gasoil (about 610-800 °F).

[0054] A “catalyst bed” is a layer of a catalyst inside a fixed-bed reactor. A plurality of catalyst beds may be loaded as different catalyst layers in the same reactor vessel, on top of different bed supports configured one above the other within the same reactor vessel, or loaded in different reactor vessels in series. For example, a bed of a Cobalt / Molybdenum (CoMo) catalyst may be loaded directly on top of a bed of a Nickel / Molybdenum (NiMo) catalyst in the same reactor Atty. Docket No. T-12564-P1-WO01

[0055] vessel, loaded on different bed supports configured one above the other within the same reactor vessel, or loaded in two different reactor vessels in series.

[0056] A “lipid” as used herein refers to fats, oils, and greases. Lipids comprise of saturated and unsaturated fatty acids in the C8-C24 range, wherein the fatty acids can be in the form of esters of glycerin (i.e. as mono-, di-, and triglycerides), fatty acid alkyl esters, or as free fatty acids (FFA).

[0057] It is to be understood that a “volume percent” or “vol.%” of a component in a composition or a volume ratio of different components in a composition is determined at room temperature (about 23 °C) based on the initial volume of each individual component, not the final volume of combined components.

[0058] The term “refractory nitrogen” and “refractory nitrogen compounds” as used herein refers to organic nitrogen species that are not removed from lipid feedstock during conventional pretreatment steps such as degumming. An analytical method for quantifying refractory nitrogen content of lipid feedstock follows. Accordingly, organic molecules with one nitrogen atom (Nl) having carbon numbers in the 30 to 60 range are considered to be refractory nitrogen compounds (including dialkyl secondary amines or trialkyl tertiary amines where the alkyl groups is in the C15-C18 range). Other refractor nitrogen compounds include those with a nitrogen and at least one oxygen atom. These include fatty amides (N1O1), and nitrated fatty acids (N1O4). In general, the nitrogen in all N1O1, N1O2, N1O3, and N 104 molecules may be regarded as refractory nitrogen. In embodiments, the N1O1, N1O2, N1O3, and N 104 species have a carbon number in the 5 to 60 range. The refractory nitrogen compounds Nl, N1O1, N1O2, N1O3, and N1O4 have a DBE between 0 and 10.

[0059] An HPLC-MS method was developed and used to separate and identify refractory nitrogen compounds in the hydrocarbons. For HPLC, the mobile phase is dichloromethane Atty. Docket No. T-12564-P1-WO01

[0060] spiked with 0.05 vol.% trifluoroacetic acid. A C8 column was used as the stationary phase. High-Resolution Mass Spectrometry (HRMS) was used to analyze N compounds in the HPLC effluent through Electrospray Ionization (ESI) positive ion mode to focus on polar species. Mass spectra are processed with PetroOrg to assign elemental compositions and generate a 2D “DBE vs. carbon number” spectrum. Nitrogen compounds are grouped into three categories / windows according to the HPLC retention time (r.t.) of 2 to 3 min, 3 to 5 min, and 5 to 8 min, respectively. It is worth pointing out that the MS signal in each window is normalized to show the relative abundance of nitrogen species. The relative intensity of MS signals in different windows is not relevant and cannot be compared quantitatively. The technique was first described in US Patent Publication 2019 / 0128845 (Parulkar et al.).

[0061] FIG. 1 shows a three-window distribution of organic nitrogen compounds in a straight-run vacuum gas oil (VGO) for sample ABQ1214 using the HPLC-MS method. The DBE vs. Carbon Number Spectra of a Straight-Run VGO ABQ1214 is shown in each graph. ABQ1214 N1W1 represents a group of nitrogen compounds containing one N atom in window 1. These nitrogen compounds have an HPLC retention time of 2~3 min. The nitrogen compounds in N1W1 are polar nitrogen. Basic nitrogen compounds containing one N atom are separated in N1W3 with an HPLC retention time of 5~8 min. N1W2 lumps non-basic, less polar nitrogen compounds that contain one N atom. The HPLC retention time for N1W2 is 3~5 min.

[0062] The nitrogen compounds in VGO are refractory nitrogen with aromatic ring structures having a 6+ double bond equivalent (DBE). DBE is calculated using the formula below. C, H, and N are the number of carbon, hydrogen, and nitrogen atoms in the molecule.

[0063] DBE = (2C−H+N+2) / 2 Atty. Docket No. T-12564-P1-WO01

[0064] Biochemical Oxygen Demand (BOD) is a standard water quality test used to quantify organic pollution in water. As they decompose, the organic pollutants consume the dissolved oxygen in streams or lakes (which is typically in the range of 10-25 mg O2 / L water) thus depriving the aquatic life therein of oxygen. BOD is measured according to the National Environmental Methods Index Standard Method 5210B; 5-Day BOD Test.

[0065] FIG. 5 shows a schematic of an embodiment of the method wherein a lipid feedstock 101 comprising a total nitrogen value of at least 100 wppm and a refractory nitrogen compound concentration of at least 1 wppm is directed to a surge drum 10 for hydroprocessing. The lipid feedstock 101 may have a refractory nitrogen concentration between 1 and 10 wppm, between 1 and 30 wppm, or between 10 and 30 wppm. Exemplary lipid feedstocks include, but are not limited to, animal fat, animal oil, microbial oil, plant fat, plant oil, vegetable fat, vegetable oil, grease, or a mixture of any two or more thereof. Plant and / or vegetable oils and / or microbial oils include, but are not limited to, corn oil, inedible com oil, babassu oil, carinata oil, soybean oil, canola oil, coconut oil, rapeseed oil, tall oil, tall oil fatty acid, palm oil, palm oil fatty acid distillate, jatropha oil, palm kernel oil, sunflower oil, castor oil, camelina oil, archaeal oil, bacterial oil, fungal oil, protozoal oil, algal oil, seaweed oil, oils from halophiles, and mixtures of any two or more thereof. These may be classified as crude, degummed, and RBD (refined, bleached, and deodorized) grade, depending on level of pretreatment and residual phosphorus and metals content. However, any of these grades may be used in the present technology.

[0066] Animal fats and / or oils as used above includes, but is not limited to, inedible tallow, edible tallow, technical tallow, floatation tallow, lard, poultry fat, poultry oils, fish fat, fish oils, and mixtures of any two or more thereof. Greases may include, but are not limited to, yellow grease, brown grease, waste vegetable oils, restaurant greases, trap grease from municipalities such as Atty. Docket No. T-12564-P1-WO01

[0067] water treatment facilities, and spent oils from industrial packaged food operations, and mixtures of any two or more thereof. Depending on level of pretreatment, such biorenewable lipid feedstock may contain between about 1 wppm and about 800 wppm phosphorus, and between about 1 wppm and about 400 wppm total metals (mainly sodium, potassium, magnesium, calcium, iron, and copper). The lipid may also contain up to 20 wt % free fatty acid (calculated from Total Acid Number or TAN according to various standard test methods such as AOCS Ca 5a-40). The lipid may include about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, about 10 wt%, about 11 wt%, about 12 wt%, about 30 wt%, about 32 wt%, about 34 wt%, about 36 wt%, about 38 wt%, about 40 wt%, about 13 wt%, about 14 wt%, about 15 wt%, about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt%, or any range including and / or in between any two of these values.

[0068] Thus, the lipid feedstock of any embodiment herein may include corn oil, inedible corn oil, babassu oil, carinata oil, soybean oil, canola oil, coconut oil, rapeseed oil, tall oil, tall oil fatty acid, palm oil, palm oil fatty acid distillate, jatropha oil, palm kernel oil, sunflower oil, castor oil, camelina oil, archaeal oil, bacterial oil, fungal oil, protozoal oil, algal oil, seaweed oil, oils from halophiles, rendered fats, inedible tallow, edible tallow, technical tallow, floatation tallow, lard, poultry fat, poultry oils, fish fat, fish oils, frying oils, yellow grease, brown grease, waste vegetable oils, restaurant greases, trap grease from municipalities such as water treatment facilities, and spent oils from industrial packaged food operations, or a mixture of any two or more thereof.

[0069] The surge drum 10 provides a pump suction liquid 102 passed through pump 12 for pressurization and transfer as a pressurized feedstock 103. The pressurized feedstock 103 is combined with a hydrocarbon diluent, such as a hydrocarbon product recycle stream 104 shown Atty. Docket No. T-12564-P1-WO01

[0070] in FIG. 5. A hydrocarbon diluted feedstock 105 is combined with a pressurized hydrogen 133 to provide a heat exchanger feedstock inlet 106. The heat exchanger feedstock inlet 106 is heated through a feed-effluent exchanger 30 to provide a heat exchanger feedstock outlet 107. The heat exchanger feedstock outlet 107 is further heated in heater 36 to provide a heated reactor feed 108.

[0071] The heater 36 is preferably a shell and tube exchanger with the reactor feed flowing through the tubes with a heat transfer fluid flowing through the shell side. The heated reactor feed 108 has a temperature between about 500 °F and 700 °F. In embodiments, the heated reactor feed has a temperature of 520 °F, 540 °F, 560 °F, 580 °F, 600 °F, 620 °F, 640 °F, 660 °F, 680 °F, or a value between any two of these temperatures. For example, in one embodiment, the heated reactor feed is between 540 °F and 660 °F. Although a shell and tube heat exchanger is described for heat exchanger 30 and heater 36 in this embodiment of the method, those skilled in the art recognize that other types of heat exchanger or heating methods may be employed to meet the desired heated reactor feed temperatures. For example, in one embodiment the hydrocarbon product recycle stream 104 may be heated in a fired heater (not shown) to a temperature that when combined with pressurized feedstock 103 achieves the heated reactor feed temperatures described herein, thus avoiding heating of the lipid feedstock in a heat exchanger.

[0072] Returning to FIG. 5, the heated reactor feed 108 enters a hydroprocessing reactor system comprising HDO reactor 20 and hydropolishing reactor 21. Both reactors 20, 21 are loaded with fixed-bed hydrotreating (HT) catalysts. The hydroprocessing reactors 20, 21 are maintained at a pressure between 500 psig and 2,700 psig. In embodiments, the reactor system is maintained at 600 psig, 800 psig, 1,000 psig, 1,200 psig, 1,400 psig, 1,600 psig, 1,800 psig, 2,000 psig, 2,200 Atty. Docket No. T-12564-P1-WO01

[0073] psig, 2,400 psig, 2,600 psig, or a value between any two of these pressures. In one embodiment, the HDO reactor 20 is maintained between 1,200 and 2,200 psig.

[0074] The pressurized feedstock 103 is introduced to the reactor system at a liquid hourly space velocity (LHSV) between 0.3 and 6.0 h-1(vol / h of feedstock 103 per vol of total catalyst). The pressurized hydrogen gas 133 is at a ratio relative to the lipid feedstock 103 that is between 2,000 SCF / Bbl and 12,000 SCF / Bbl. In one embodiment, the reactor operates at LHSV values between 0.5 and 5.0 h-1and gas-to-oil ratios between 4,000 and 10,000 SCF / Bbl.

[0075] The HDO reactor 20 includes at least one bed of a sulfided HT catalyst comprising molybdenum or tungsten for HDO. Preferred catalysts also include nickel and / or cobalt promoters. Such catalysts include sulfided forms of nickel-molybdenum (NiMo), nickeltungsten (NiW), and cobalt-molybdenum (CoMo) on alumina or silica-alumina supports. It should be understood by one of ordinary skill in the art that any catalyst or combination of catalysts may be used in the present invention so long as the catalyst system functions in accordance with the present invention as described herein.

[0076] To maintain the active metal sulfide functionality of the catalyst despite the relatively low (<50 wppm) concentration of organic sulfur in most lipid feedstocks, the lipid feedstock 101 or diluted feedstock 105 may be supplemented with a sulfur compound that decomposes into hydrogen sulfide when heated and / or contacted with the catalyst. Two preferred sulfur compounds are dimethyl disulfide and carbon disulfide. On a lipid feed basis, the preferred concentration of the sulfur compound is between about 100 to about 2,000 ppm by weight sulfur.

[0077] In FIG. 5, the HDO reactor 20 includes catalyst beds 22A and 22B, and hydropolishing reactor 21 includes a bed 22C. The HDO reactor 20 is characterized by an adiabatic temperature rise across the beds 22A, 22B that corresponds to the heat released from the exothermic HDO Atty. Docket No. T-12564-P1-WO01

[0078] and hydrogenation reactions therein. Depending on the type of lipid (i.e. degree of fatty acid unsaturation) and its concentration in the diluted feed 105, the temperature rise across the HDO beds 22A and 22B (i.e. difference between the top / inlet bed and bottom / outlet bed temperatures) may be between 20 °F and 200 °F. For a lipid concentration range of 20-30 wt %, achieved during a preferred operating ratio of hydrocarbon product recycle 104 to lipid feedstock 103, the temperature rise across beds 22A and 22B is between 40 °F and 120 °F. Some of the heat of the reaction may be absorbed by use of a hydrogen quench 119 introduced between HDO beds 22A and 22B via mixing assembly 23 where the quench gas and hot reactor fluid come into contact.

[0079] The HDO effluent 109 includes the mostly hydrogenated and deoxygenated lipid wherein the heavies (above diesel boiling range or with a carbon number of 24 or greater) has been reduced to less than 2% and the acid number decreased to less than 1 mg KOH / g. The HDO effluent 109 enters the hydropolishing reactor 21 where it is contacted with a HT catalyst bed 22C. Unlike the HDO beds that are characterized by relatively high temperature rise values in the 40-120 °F range, the temperature rise across the hydropolishing reactor catalyst bed 22C is at a relatively low value below 12 °F. The temperature rise across bed 22C may be less than 10 °F, less than 8 °F, less than 6 °F, less than 4 °F, or less than 2 °F, or within a range between any two of these values. For example, the temperature rise across hydropolishing bed 22C is between 2 °F and 10 °F.

[0080] The low temperature rise across the hydropolishing bed 22C is an indication that the exothermic HDO and hydrogenation reactions are essentially complete in beds 22A and 22B. Nevertheless, to achieve the desired nitrogen content in the hydrocarbon product and quality of water byproduct, a hydropolishing reactor catalyst bed is needed. Atty. Docket No. T-12564-P1-WO01

[0081] The HT catalyst used in HDO beds 22A, 22B, and hydropolishing bed 22C are preferably of different properties and activities. In one embodiment, HDO bed 22A has a low activity catalyst with no metal promoter; the HDO bed 22B has an intermediate activity catalyst with 2% or less Ni promoter; and the hydropolishing bed 22C has a high activity catalyst with more than 3% Ni promoter.

[0082] In terms of relative catalyst volumes, each bed holds about 20-50% of total catalyst volume. For example, bed 22A is 30%, bed 22B is 40% and bed 22C is 30% of the total volume. The relative volume of each catalyst bed depends on the metals / phosphorus contaminants and refractory nitrogen in the feed. In general, the higher the metal / phosphorus content, a larger volume of bed 22A is needed. Similarly, the higher the refractory nitrogen content of the feed, the larger volume of bed 22C is required.

[0083] The catalyst average temperature (average of inlet and outlet temperatures) for bed 22C is between 620 °F and 740 °F, with preferred catalyst average temperatures between 640 and 700 °F, most preferably in the 650-680 °F range.

[0084] Although two reactor vessels are shown for the hydroprocessing reactor, catalyst beds 22A, 22B, and 22C may be included in a single reactor 24 as shown in FIG. 6, with all other reference numbers corresponding to the FIG. 5 embodiment.

[0085] Returning to FIG. 5, the reactor effluent 110 is cooled through the feed-effluent exchanger 30 to provide a partially cooled reactor effluent 111 that is further cooled in the reactor effluent cooler 32. The cooled reactor effluent 112 is at temperature of about 250 °F to about 400 °F and comprises liquid and vapor / gas phase (by)products in addition to unconverted hydrogen gas. A gas / vapor phase 124 is separated from a liquid hydrocarbon phase 114 in a high-pressure hot separator 34. The high-pressure hot separator 34 operates at the Atty. Docket No. T-12564-P1-WO01

[0086] hydroprocessing reactor system exit pressure (minus pressure drop across the pipe runs and exchangers). The gas / vapor phase 124 comprises hydrogen and the water vapor byproduct of the HDO reaction. This is cooled in a condenser 40 to provide a three-phase fluid 126 that is separated in cold separator drum 42, where it is separated into HDO water 128, a hydrocarbon fraction 127, and a gas phase 129 comprising mainly of hydrogen. In embodiments, a wash water 125 is introduced upstream of the condenser 40 to wash any solid deposits that may form on the condensing surface. Stream 125A is a combined stream comprising the wash water 125 and gas / vapor phase 124.

[0087] The gas phase 129 is split into a bleed stream 129A and a recycle stream 130. The purpose of the bleed is to mitigate buildup of propane, CO, and other non-condensed gas phase byproducts from building up in the hydrogen recycle. The recycle stream 130 is directed to hydrogen compressor 44 where it is combined with a makeup hydrogen 131, to provide a hydrogen compressor discharge gas stream 132. The ratio of bleed stream 129A to recycle stream 130 depends in part on the DCO side reactions and target hydrogen content for the hydroprocessing reactor system, typically between 80 and 95 mol%.

[0088] Returning to high-pressure hot separator 34, the liquid hydrocarbon phase 114 is split between a recycle stream 114A and a product steam 114B. The recycle stream 114A is transferred via pump 14 for diluting the lipid feed 103 as described previously herein. The product stream 114B is combined with hydrocarbon fraction 127 as combined stream 115 to be subjected to gas stripping in stripper column 50. The stripper column 50 removes the dissolved gas phase hydroprocessing byproducts 123 such as ammonia, hydrogen sulfide, and water via counter-current contact with a stripping gas 121. The stripping gas 121 may be nitrogen, steam, hydrogen, or natural gas. The stripper column 50 operates at conditions of temperature and Atty. Docket No. T-12564-P1-WO01

[0089] pressure to promote removal of the dissolved gas phase hydroprocessing byproducts 123 such that a stripped hydrocarbon product 122 has a total nitrogen content of 2 wppm or less, of which less than 1 wppm is in the form of refractory nitrogen. In embodiments, the stripper column operates at a temperature range between 240 and 400 °F under a pressure between 50 and 1000 psig. In embodiments, the stripped hydrocarbon composition is in the C11-C24 range with at least 90 wt% n-paraffins, an acid number of 0.02 or less, a water content of 100 wppm or less, and a sulfur content of 2 wppm or less.

[0090] In embodiments, the stripped hydrocarbon 122 is subsequently hydroisomerized in a hydroisomerization (HI) reactor system (not shown) whereby the n-paraffins are mostly converted to iso-paraffins. In embodiments, the HI reaction is performed under a hydrogen partial pressure between 500 and 1,000 psia at temperatures in the 580-680° °F range over a bifunctional catalyst providing both hydrogenation-dehydrogenation and acid functionalities. In embodiments, the hydrogenation-dehydrogenation functionality is provided by noble metals such as platinum (or platinum with palladium) or base metals such as tungsten (or tungsten with nickel). In embodiments, the acid functionality is from silica-alumina and silica-alumina- phosphate supports including zeolites. Due to hydrocracking side reactions, the HI reactor effluent includes hydrocarbons with a lower average carbon number than the stripped hydrocarbon product 122 The HI reactor effluent mainly composed of isoparaffins and n- paraffins in the C3-C18 range is separated via distillation into naphtha, jet fuel and / or diesel fuel tractions, each fuel with a total nitrogen content less than 2 ppm.

[0091] Returning to FIG.5, the HDO water 128 is directed to a sour water stripper 60 where it is contacted with steam 140 to remove the dissolved hydrogen sulfide, ammonia, and other gas phase byproducts 144 that may be dissolved in the HDO water 128. A stripped water 142 is thus Atty. Docket No. T-12564-P1-WO01

[0092] generated with a pH in the neutral range (6-7) and BOD less than 30 mg / L. In embodiments, the BOD of the HDO water is less than 28 mg / L, less than 26 mg / L, less than 24 mg / L, less than 22 mg / L, less than 20 mg / L, less than 18 mg / L, less than 16 mg / L, less than 14 mg / L, less than 12 mg / L, less than 10 mg / L, less than 8 mg / L, less than 6 mg / L, or less than 4 mg / L, less than 2 mg / L, or is in a range between any two of these values. For example, the stripped HDO water 128 may have a BOD value between 2 mg / L and 28 mg / L.

[0093] Typically, when processing lipids with refractory nitrogen, the HDO water separated from hydrocarbon product has a relatively high BOD value. For example, during separation of the hydrocarbon fraction 127 from the HDO water 128 in the cold separator drum 42, the HDO water 128 is characterized by a relatively high BOD value even after steam stripping (typically above 40 mg / L).

[0094] Without wishing to be bound to theory, it is believed that hydropolishing bed 22C achieves conversion of trace surfactant species that result from HDO conversion of lipid feeds with refractory nitrogen. These surfactant species can retain trace amounts of the hydrocarbon product phase as fine droplets in the water byproduct. Even when the HDO reaction is complete, as indicated by reaction exotherm, the surfactant species may remain. The hydropolishing bed 22C allows for conversion of these trace surfactants species such that the water byproduct is recovered without emulsified hydrocarbon droplets therein.

[0095] The present technology, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present technology. Atty. Docket No. T-12564-P1-WO01

[0096] Example 1. Analyzing a lipid feedstock for refractory nitrogen

[0097] A blend of low-value fats, oils, and greases (FOG) was processed through a pretreatment unit comprising of citric-acid treatment and centrifugation, followed by adsorption by amorphous silica and filtration as generally described in US Patents 11,118,133 (Slade et al.) and 11,459,523 (Abhari et al.). The pretreated FOG was subsequently subjected to hydroprocessing in a reactor with two HDO beds and one hydropolishing bed as described here. The FOG sample was labeled DGQ0668, the sample was centrifuged, treated by adsorbent, filtered, and then hydroprocessed to produce DGQ0671.

[0098] The lipid sample DGQ0668 was analyzed by the HPLC-MS method to investigate its nitrogen species. Its 2D DBE vs. Carbon Number spectrum is shown in FIG. 2. The nitrogen species in the lipid feedstock is very different from the petroleum-based VGO ABQ1214 shown in FIG. 1. DGQ0668 did not give any nitrogen MS signal in N1W3. In N1W1, only three types of nitrogen compounds were detected with carbon numbers 18, 20, and 22. All these nitrogen compounds have zero DBE, meaning paraffinic nature. It matches well with the lipid characteristic feedstock. Paraffinic nitrogen species with carbon number of 20 or less are easy nitrogen, which can be hydro-denitrogenated to convert to ammonium in the HDO process.

[0099] However, nitrogen compounds containing one nitrogen atom were detected in the second window, e.g. N1W2. Some of these nitrogen compounds contain 1 to 4 oxygen atoms. Thus, nitrogen signals in N1W2 are further differentiated and grouped into five sub-windows, e.g., N1W2, N101W2, N1O2W2, N1O3W2, and N1O4W2 as shown in FIG. 2. The numbers after N and O are nitrogen and oxygen atoms in one molecule. These nitrogen compounds are refractory nitrogen having a DBE greater than 1 or a naphthenic ring structure. The DBE vs. Carbon Atty. Docket No. T-12564-P1-WO01

[0100] Number spectrum of DGQ0668 sample is shown in Figure 2. wherein the N1 W3 window is not provided as no nitrogen signal was detected in window 3, or r.t. = 5~8 min.

[0101] The HDO sample DGQ0671 was analyzed by the HPLC-MS method to investigate nitrogen conversion in the HDO process. The DBE vs. Carbon Number spectrum is shown in Figure FIG. 3. Same as DGQ0668, the DGQ0671 sample did not give any nitrogen MS signal in window 3, e.g. N1W3. Furthermore, DGQ0671 did not have any nitrogen signal in window 1, indicating the full conversion of Cl 8, C20, and C22 paraffinic nitrogen compounds by the HDO process. This confirms that paraffinic nitrogen compounds are easy nitrogen as expected.

[0102] However, most of the nitrogen compounds in N1W2 observed in DGQ0668 remained in DGQ0671 as shown in Figure FIG. 3, which shows the DBE vs. Carbon Number Spectrum of DGQ0671 sample. With respect to DGQ0671, no nitrogen signal was detected in both N1W1 and N1W3. All five types of nitrogen species of N1W2, N101W2, N1O2W2, N1O3W2, and N1O4W2 were able to survive in the HDO process. This indicates the refractory features of these nitrogen compounds in the FOG feedstock. These nitrogen compounds are difficult to convert during the HDO process.

[0103] The MS signal and quantitative calculation of nitrogen compounds in DGQ0668 and DGQ0671 are summarized in Table 1. The presence of MS signal of Nl, N1O1, N1O2, N1O3, and N 104 suggests that the refractory nitrogen compounds in DGQ0668 are difficult to convert though the shift to less oxygen content was observed. The reduction of refractory nitrogen concentration is about 30% from 1.0 wppm to 0.66 wppm after the HDO process. Table 1 also indicates that the majority of nitrogen compounds in DQG0668 are paraffinic, 109 out of 110 wppm by the XRF method. Atty. Docket No. T-12564-P1-WO01

[0104] Table 1.

[0105] DGQ0668 DGQ0671 N1 MS signal 0.3 0.6 N1O1 MS signal 7.2 5.4 N1O2 MS signal 2.0 1.2

[0106] N1O3 MS signal 2.2 0.8

[0107] N1O4 MS signal 0.4 <0.1

[0108] Sum of MS signals 12.1 8.0 Refractory N by HPLC-MS, wppm 1.0* 0.66 Paraffinic nitrogen by calculation, wppm 109 0

[0109] Total N by XRF, wppm 110 0.66

[0110]

[0111] The value is calculated based on the sum of MS signals measured on DGQ0668 and DGQ0671, and the N concentration of DGQ0671 measured by the XRF method assuming N1, N1O1, N1O2, N1O3, and N1O4 have comparable MS coefficient because of their structure similarity.

[0112] Example 2, Hydroprocessing of FOG with and without hydropolishing

[0113] A blend of low-value fats, oils, and greases (FOG) with refractory nitrogen was processed through a pretreatment unit comprising of citric-acid treatment and centrifugation, followed by adsorption by amorphous silica and fdtration as generally described in US Patents 11,118,133 (Slade et al.) and 11,459,523 (Abhari et al.). The pretreated FOG was subsequently subjected to hydroprocessing in three reactors, the first reactor had one HDO bed and the second and third reactors had one HDO and one hydropolishing bed as described here in. The reactors Atty. Docket No. T-12564-P1-WO01

[0114] were run under varying conditions of temperature and space velocity to monitor catalyst performance. The products from these reactors were analyzed for Total Acid Number, C24+, and Nitrogen. The results are summarized in Table 2 below:

[0115] Table 2.

[0116] Reactor 1 (HDO Catalyst Reactor 2 (HDO + Reactor 3 (HDO +

[0117] only) Hydropolishing Catalyst) Hydropolishing Catalyst) C24+Conv, TAN, N, C24+Conv, TAN, mg N, C24+Conv, TAN, mg N, % mg PPm % KOH / g PPm % KOH / g PPm KOH / g

[0118] 89.16 0.892 26.68 91.64 0.041 13.39 92.16 0.016 3.99 86.08 0.954 46.47 90.72 0.024 2.36 94.72 0.023 0 81.24 1.204 40.27 91.2 0.02 1.01 92.16 0.018 0 80.6 0.908 41.66 90.6 0.029 7.7 92.48 0.013 1.15 84.88 0.977 37.5 91.48 0.033 0 93.96 0.0435 0 89.16 1.062 37.84

[0119]

[0120] As demonstrated by the data in the Table 2, a hydropolishing catalyst is required to decrease the nitrogen in the product to very low values. Atty. Docket No. T-12564-P1-WO01

[0121] Example 3, Effect of hydropolishing on BOD of water byproduct

[0122] A commercial hydroprocessing reactor was loaded with mainly three types of Mo hydrotreating catalyst for HDO, and a NiMo catalyst for hydropolishing. The hydropolishing catalyst made up about 30% of total hydroprocessing reactor catalyst volume. A pretreated lipid feedstock comprising bleachable fancy tallow, used cooking oil, and refractory nitrogen was combined with a hydrocarbon diluent and processed through the hydroprocessing reactor. The reactor operated with a total hydrogen to lipid ratio of about 10,000 SCF / Bbl, a hydrocarbon-to-lipid dilution ratio of between 3-to-l and 3.5-to-l (vol / vol), a liquid hourly space velocity of between 0.5 / h and 0.8 / h (vol / h lipid feed per vol of total catalyst), and a reactor pressure of around 1800 psig. The inlet temperature was varied between 550 °F and 620 °F. Since the hydroprocessing reactions are exothermic, a temperature rise of about 100 °F to 120 °F was observed across the reaction. Depending on inlet temperature and amount of quench hydrogen (introduced via a quench ring between two of the HDO catalyst beds), a different reactor temperature profile was observed. The temperature profiles for two conditions, expressed as % of total exothermic reaction conversion as a function of % of reactor catalyst volume are presented in FIG. 4.

[0123] Full conversion of lipid to paraffinic hydrocarbons was observed at both conditions, with GC confirmation of a paraffinic product with no residual oxygenates. Total acid number was below detection limit in both cases and total nitrogen below 1 wppm. However, the water byproduct corresponding to Condition 1 had a BOD value of 94 mg / L (BOD was measured after stripping of the water byproduct to remove dissolved H2S and ammonia). When hydroprocessing conditions were modified to produce the reactor temperature / conversion profile of Condition 2 (mainly by raising reactor inlet temperature and reducing hydrogen quench and overall LHSV within the ranges described in this example), the water byproduct BOD decreased Atty. Docket No. T-12564-P1-WO01

[0124] to 9 mg / L and remained below 30. Comparing the Condition 1 and Condition 2 reactor conversion profiles, we observe that the HDO beds need to achieve 90% of the conversion (as measured by temperature rise across the reactor). For a 100-110 °F temperature rise, this implies that the hydropolishing catalyst bed needs to operate at no more than a 10-11 °F temperature rise to ensure byproduct water BOD is maintained below 30 mg / L.

[0125] Example 4, Effect of pressure on nitrogen removal

[0126] A small fixed-bed hydroprocessing reactor was packed with a NiMo catalyst and sulfided for HDO. Lipid feedstock was diluted with SOLTROL-220 (a synthetic isoparaffmic solvent produced by CPChem) at a 3:1 solvent-to-lipid dilution ratio. The LHSV on a lipid basis was 0.9. Operating at hydrogen pressure of 1680 psi, near complete deoxygenation was confirmed at 540 °F (about 99% oxygen removal as estimated by density) with canola oil as the lipid feed. The lipid feed was then changed to FOG comprising bleachable fancy tallow, used cooking oil, and refractory nitrogen. Nitrogen removal was tested at the same temperature of 540 °F under two different hydrogen pressure conditions: 1680 and 1000 psi. The nitrogen removal was found to decrease from 77% at 1680 psi to 48% at 1000 psi. This experiment confirms that with feedstocks comprising refractory nitrogen, higher hydroprocessing pressures, such as in the 1200 to 2200 psig range, are required.

[0127] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it will be apparent to those of ordinary skill in the art that the invention is not to be limited to the disclosed embodiment, and that many modifications and equivalent arrangements may be made thereof within the scope of the Atty. Docket No. T-12564-P1-WO01

[0128] invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and products.

Claims

Atty. Docket No. T-12564-P1-WO01CLAIMS WHAT IS CLAIMED IS:

1. A method for producing hydrocarbon fuel comprising the steps of:(a) providing a hydroprocessing reactor configured to receive a hydroprocessing reactor feed at a temperature of about 500°F to 700°F, wherein the hydroprocessing reactor feed comprises a lipid feedstock with a refractory nitrogen compound concentration of about 1-30 wppm;(b) removing an effluent from the hydroprocessing reactor and separating the effluent into a liquid hydrocarbon product, a hydrodeoxygenation (HDO) water, and a gas phase;(c) stripping the HDO water to produce a stripped HDO water; and(d) stripping the hydrocarbon product to produce a stripped hydrocarbon product;wherein the stripped HDO water has a BOD content below 30 mg / L, and the stripped hydrocarbon product has a total nitrogen content less than 2 wppm.

2. The method of claim 1 wherein the hydroprocessing reactor comprises a first catalyst bed, a second catalyst bed, and a third catalyst bed.

3. The method of claim 2 wherein the first catalyst bed has a low activity, the second catalyst bed has an intermediate activity, and the third catalyst bed has a high activity.

4. The method of claim 3 wherein the first catalyst bed has no metal promoter, the second catalyst bed has 2% or less Ni promoter, and the third catalyst bed has more than 3% Ni promoter.

5. The method of claim 2 wherein the hydroprocessing reactor comprises a HDO reactor and a hydropolishing reactor.Atty. Docket No. T-12564-P1-WO016. The method of claim 5 wherein the first catalyst bed and the second catalyst bed are within the HDO reactor and the third catalyst bed is within the hydropolishing reactor.

7. The method of claim 2 wherein there is a first temperature rise across the first catalyst bed and the second catalyst bed of more than 40°F, and there is a second temperature rise across the third catalyst bed of no more than 10°F.

8. The method of claim 2 wherein the first catalyst bed, the second catalyst bed, and the third catalyst bed have a total catalyst volume, and the third catalyst bed contains between 20% and 50% of the total catalyst volume.

9. The method of claim 1 further comprising hydroisomerizing the stripped hydrocarbon product to produce a hydroisomerization effluent.

10. The method of claim 9 further comprising distilling the hydroisomerization effluent to produce a naphtha and one or both of a renewable diesel fraction and a jet fraction.

11. The method of claim 10 wherein one or both of the renewable diesel and the jet fuel fractions have less than 2 ppm total nitrogen.

12. The method of claim 1 wherein the concentration of the refractory nitrogen compound in the hydroprocessing reactor feed is about 2-10 wppm.

13. The method of claim 1 wherein the hydroprocessing reactor is operated at about 1200 to 2200 psig.

14. A method for producing hydrocarbon fuel comprising the steps of:(a) pretreating a lipid feedstock with refractory and non-refractory nitrogen compounds to produce a hydroprocessing reactor feed;Atty. Docket No. T-12564-P1-WO01(b) providing a hydroprocessing reactor having a first catalyst bed, a second catalyst bed, and a third catalyst bed, the hydroprocessing reactor configured to receive the hydroprocessing reactor feed;(c) removing an effluent from the hydroprocessing reactor and separating the effluent into a liquid hydrocarbon product, a hydrodeoxygenation (HDO) water, and a gas phase;(d) stripping the HDO water to produce a stripped HDO water; and(e) stripping the hydrocarbon product to produce a stripped hydrocarbon product.

15. The method of claim 14 wherein the hydroprocessing reactor comprises a HDO reactor and a hydropolishing reactor.

16. The method of claim 15 wherein the first catalyst bed and the second catalyst bed are within the HDO reactor and the third catalyst bed is within the hydropolishing reactor.

17. The method of claim 15 wherein the stripped HDO water has a BOD content below 30 mg / L, and the stripped hydrocarbon product has a total nitrogen content less than 2 wppm.

18. A method for producing hydrocarbon fuel comprising the steps of:(a) pretreating a lipid feedstock with refractory and non-refractory nitrogen compounds to produce a hydroprocessing reactor feed, wherein the hydroprocessing reactor feed comprises a lipid feedstock with a refractory nitrogen compound concentration of about 1-30 wppm;(b) providing a hydroprocessing reactor having a first catalyst bed having a low activity, a second catalyst bed having an intermediate activity, and a third catalyst bed having a high activity, the hydroprocessing reactor configured to receive the hydroprocessing reactor feed at a temperature of about 500°F to 700°F;Atty. Docket No. T-12564-P1-WO01(c) removing an effluent from the hydroprocessing reactor and separating the effluent into a liquid hydrocarbon product, a hydrodeoxygenation (HDO) water, and a gas phase;(d) stripping the HDO water to produce a stripped HDO water; and(e) stripping the hydrocarbon product to produce a stripped hydrocarbon productwherein the stripped HDO water has a BOD content below 30 mg / L, and the stripped hydrocarbon product has a total nitrogen content less than 2 wppm.

19. The method of claim 18 wherein the hydroprocessing reactor comprises a HDO reactor and a hydropolishing reactor.

20. The method of claim 19 wherein the first catalyst bed and the second catalyst bed are within the HDO reactor and the third catalyst bed is within the hydropolishing reactor.

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