Process for producing biomass-based diesel from feedstocks comprising olefin oligomers

Abstract

The present invention relates to biofuels and, more particularly, to biomass-based diesel from olefin oligomers. Diesel fuel having a cetane number of 49 or greater is prepared by blending hydrocarbons resulting from olefin oligomerization with renewable diesel, resulting in a blended fuel having a cloud point lower than the cloud point of the renewable diesel. Various aspects relate to an integrated process for lipid HDO and olefin oligomerization in which the propane byproduct of the lipid HDO is dehydrogenated to produce a vapor stream having propylene and hydrogen. The propylene is then oligomerized to an isoolefin, and the isoolefin is combined with the lipid feed for hydrogenation in the HDO reactor.

Description

Technical Field

[0001] The present invention relates to biofuels, and more particularly, to biomass based diesel. Background Art

[0002] This application claims priority to U.S. Provisional Application No. 63 / 378,193, filed on October 3, 2022, the entire contents of which are incorporated herein by reference.

[0003] Hydroprocessing of lipids for producing renewable diesel (RD) fuels has been described in the prior art, such as U.S. Pat. Nos. 8,026,401 and 7,968,757, which are incorporated herein by reference. As described in these and several other references, RD is typically produced in two conversion steps. In the first step, a hydrodeoxygenation (HDO) reaction converts lipid fatty acid / glyceride molecules into hydrocarbons containing normal paraffins and propane in the diesel boiling range. Water, CO and CO 2 It is the main by-product of HDO. In order to convert C16+ normal paraffin "wax" and improve cloud point and other low temperature flow properties, the straight chain normal paraffins in the HDO product are converted into mainly methyl branched paraffins in the second step. This second step is called "catalytic dewaxing" or "hydroisomerization" (HI).

[0004] The HDO reactor is usually operated under the condition of partial recycling of hydrocarbon products. The hydrocarbon recycle serves as a solvent for diluting the lipid feed. Dilution provides many benefits for HDO performance. These benefits include controlling the heat release associated with the exothermic reaction, improving hydrogen solubility and minimizing undesirable side reactions. Some prior art references teach the use of at least 5:1 hydrocarbon: lipid dilution ratios. High dilution and recirculation rates usually require the use of large reactors and recirculation pumps. This means that the required capital and operating costs for producing RD per unit volume are correspondingly higher.

[0005] RD is considered a premium diesel fuel due to the virtual absence of aromatics in its paraffinic composition. Depending on the lipid feedstock, RD typically has 30-40 g CO 2 Carbon intensity is measured as e / MJ. Carbon intensity is a measure of life cycle greenhouse gas (GHG) emissions expressed as CO2 per MJ of combustion energy provided by the fuel. 2 It is expressed in grams equivalent. The quoted carbon intensity values ​​for RD are 60-70% lower than those reported for petroleum-based diesel fuel. Thus, RD production has grown rapidly over the past decade in response to climate change. With further increases in production announced, the availability of lipid feedstock for RD production has become a potential long-term concern.

[0006] Sugars represent another class of biofuel feedstocks. They can be fermented into alcohols for direct use in gasoline engines. Ethanol and isobutanol are examples of such alcohols. Although corn and sugar cane are currently commonly used for bioalcohols, fermentable sugars can also be produced by hydrolyzing cellulose and hemicellulose derived from woody biomass. Therefore, sugars and starches represent a potentially abundant source of renewable biofuel feedstocks with low carbon intensity.

[0007] In order to utilize these raw materials to manufacture middle distillate fuels (i.e., kerosene and diesel), alcohol is first converted into olefins via catalytic dehydration. Subsequently, the olefins (e.g., ethylene and butene) are oligomerized to produce mainly branched olefin dimers, trimers, tetramers, pentamers, and depending on conditions, even larger molecules (called isoolefins) are produced. As with all polymerization reactions, oligomerization produces a hydrocarbon molecular weight range that conforms to Schulz-Flory distribution. In most cases, these isoolefins are highly branched, with almost no straight-chain hydrocarbons in the product composition. Isoolefins can be hydrogenated and fractionated to provide isoparaffin middle distillates. U.S. Patent 8,975,461 describes such a method. U.S. Patent Publication 2017 / 0260548 discloses the production of isobutene (not first producing alcohol) directly by fermentation.

[0008] Due to the highly branched nature of the oligomer molecules (including multiple tertiary and quaternary carbons in the hydrocarbon chain), the corresponding fuels generally have very low cetane numbers. For example, the aforementioned '461 patent shows that C12 and C16 hydrocarbons from oligomerization / hydrogenation of isobutylene include 2,2,4,6,6-pentamethylheptane (isododecane) and 2,2,4,4,6,8,8-heptamethylnonane (isohexadecane). These compounds are reported to have cetane numbers of 9 and 15, respectively, in the Compendium of Experimental Cetane Numbers (National Renewable Energy Laboratory; 2017). The minimum cetane numbers for diesel fuels specified by industry standards ASTM D975 and EN 590 are 40 and 49, respectively, indicating that olefin oligomerization is not a suitable method for manufacturing diesel fuel products.

[0009] When ethylene (from ethanol dehydration) is used to produce middle distillate fuels, the oligomerization reactor system is usually operated so that ethylene is first dimerized to butenes, and then butenes are oligomerized to higher boiling hydrocarbons. In this way, similar branched isoparaffins are produced. According to the examples in U.S. Patent Publication 2017 / 02188283, the linear hydrocarbon product from ethanol-based ethylene oligomerization is only 0.2-0.3%.

[0010] The present invention solves at least two of the above unmet needs. First, it provides a method for producing high cetane number, ready-to-use renewable hydrocarbon diesel from sugar-based feedstocks. Second, it provides a method for operating a renewable diesel reactor without hydrocarbon product recycle, thereby allowing for more efficient use of reactor assets. Summary of the invention

[0011] In one aspect of the invention, a diesel fuel having a cetane number of 49 or greater is prepared by blending hydrocarbons produced by olefin oligomerization with renewable diesel, resulting in a blended fuel with a cloud point lower than the cloud point of the renewable diesel.

[0012] In various aspects of the invention, olefin oligomers (isoolefins) are hydrogenated to isoparaffins in a lipid hydrodeoxygenation (HDO) reactor, and the volume ratio of isoolefins to lipid feedstock is about 1:5 to 5:1. In embodiments, the olefins are derived from ethanol and / or isobutanol. In other embodiments, the HDO reaction is carried out without solvent or product recycling. In other embodiments, the HDO product is used as a renewable diesel fuel without a subsequent isomerization step. In still another embodiment, the HDO product has a cloud point below 0°C and a cetane number of 49 or higher.

[0013] Different aspects of the invention relate to integrated methods for lipid HDO and olefin oligomerization. In some embodiments, the propane byproduct of lipid HDO is dehydrogenated to produce a vapor stream with propylene and hydrogen. Propylene is then oligomerized into isoolefins, and the isoolefins are combined with lipid feed to hydrogenate in the HDO reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a process flow diagram illustrating a method for producing renewable diesel according to an embodiment of the present invention;

[0015] Figure 1A is a process flow diagram showing an alternative embodiment of producing biomass-based diesel according to the present invention; and

[0016] Figure 2 is a process flow diagram illustrating an alternative embodiment of the present invention in which propane from lipid HDO is dehydrogenated to propylene for oligomerization. DETAILED DESCRIPTION

[0017] In the present invention, the term hydrodeoxygenation or HDO is used to describe a reaction in which deoxygenation of a feedstock (e.g., removal of oxygen heteroatoms from a feedstock such as fatty acid glycerides) is carried out in the presence of a catalyst under hydrogen pressure. Although HDO specifically refers to the removal of oxygen with hydrogen in the form of water, the reaction is often accompanied by decarboxylation (with CO 2The HDO product is a hydrocarbon rich in straight-chain paraffins (n-paraffins).

[0018] In this specification, the term hydroisomerization or HI is used to describe the partial conversion of the HDO product into a mixture of straight chain and methyl branched paraffins. In this specification, the term paraffins includes both normal paraffins and methyl branched paraffins produced by hydroisomerization.

[0019] In this specification, the term oligomeric isoolefin refers to a distribution of branched hydrocarbons produced by oligomerization of olefins such as propylene or butene. The term oligomeric isoparaffin refers to the saturated product corresponding to the isoolefin; that is, the product of hydrogenation of the isoolefin.

[0020] Conversion of alcohols to olefins: The conversion of alcohols to olefins is given by Equation 1, where n is a value of 2 or greater.

[0021] C n H (2n+1) OH→C n H 2n + H 2 O (1)

[0022] Common alcohols from fermentation include ethanol (C 2 H 5 -OH) and butanol (C 4 H 7 -OH), although biobased processes for propanol and pentanol (also known as amyl alcohols) have also been disclosed and are known to those skilled in the art (e.g., U.S. Patent Publication No. 2009 / 0014689).

[0023] Equation 1 is referred to as alcohol dehydration, and is carried out using both heterogeneous catalysts and homogeneous catalysts. Examples of heterogeneous catalysts include various acid-treated and untreated aluminum oxide and silica catalysts and clay. These include zeolite (e.g., ZSM-5), fluoride-treated clay catalysts and sulfonic acid resins. Since the dehydration reaction produces water as a by-product, the catalyst used for the reaction generally needs to be water-resistant. Homogeneous catalysts used for alcohol dehydration include phosphoric acid, sulfuric acid and Lewis acids such as aluminum chloride and boron trifluoride.

[0024] The alcohol dehydration reaction is typically conducted at a temperature of about 450 to about 650°F and a pressure of 0-100 psig. A typical commercial embodiment involves introducing the alcohol in the vapor phase into a fixed bed reactor containing a zeolite catalyst. A process for converting Fischer-Tropsch alcohols to olefins is described in U.S. Patent 6,939,999.

[0025] Throughout the present invention, publications, patents, and patent applications are mentioned. All references cited herein are hereby incorporated by reference.

[0026] Paraffin Dehydrogenation: Propane and n-butane / isobutane dehydrogenation are commercial processes with technology licensed by companies such as UOP (OLEFLEX), CB&I McDermott / Clariant (CATOFIN), and ThyssenKrupp Industrial Solutions / Uhde (STAR). Unlike thermal cracking (e.g., steam cracking) of LPG / naphtha, which produces a wide variety of olefins and diolefins, these selective catalytic reactions maintain the feed hydrocarbon structure during unsaturation, as shown in Equation 2.

[0027]

[0028] Paraffin dehydrogenation is an endothermic reaction that is favored at high temperatures and low pressures (driving the gas phase equilibrium reaction in Equation 2 to the right hand side of the equation). In order to achieve about 50-65% conversion per pass using this equilibrium limited reaction, commercial dehydrogenators operate at pressures in excess of 1000 to 1200°F and slight vacuum to 40 psig. Due to such high operating temperatures, the catalyst tends to deactivate due to coking. Therefore, commercial reactor systems include means to regenerate the catalyst by burning off the coke. In one reactor system, steam is introduced to reduce carbon formation.

[0029] Commercial dehydrogenation processes use two types of catalysts: (1) supported noble metals, primarily Pt-Sn on alumina or aluminates of Zn and Mg, with alkali metal oxide promoters; and (2) chromium oxides supported on alumina or zirconia, promoted with cesium, potassium, or rubidium.

[0030] Commercial dehydrogenator designs include adiabatic fixed bed reactors with reaction, purge and / or regeneration cycles, isothermal top-fired multi-tube reactors, moving bed reactors with interstage heaters, and fluidized bed reactors with circulation through the regenerator (thereby providing heat for the reaction).

[0031] Olefin oligomerization: For the exemplary case of propylene, the conversion of light olefins to higher boiling isoolefins is given by Equation 3. The value of n represents the number of repeating units in the oligomer, with 2 corresponding to dimers, 3 to trimers, 4 to tetramers, and so on.

[0032] n CH 2 =CH-CH 3 →CH 3 -[CH(CH 3 )-CH 2 ] n-1 -CH=CH 2 (3)

[0033] Olefin oligomerization is a petroleum refining process dating back to the 1930s. It has been used to produce so-called "polymer gasoline" (dimers / trimers of propylene and / or butene). The method has also been used to produce chemical intermediates nonene and dodecene and end products used as surfactants, plasticizers and lubricants. The reaction is traditionally carried out on a solid phosphoric acid (SPA) catalyst bed at 300 to 1100 ° F, at a pressure close to atmospheric pressure to 2000 psig. The average molecular weight (or average carbon number) of the product is inversely proportional to the temperature, and lower temperatures are conducive to the production of heavier hydrocarbons. In order to increase the yield of the diesel boiling range fraction, a portion of the gasoline range hydrocarbons (i.e., dimers of propylene and butene) are partially recycled to the reactor. This recycling is usually carried out in the form of liquid quenching between the catalyst beds to alleviate the temperature rise associated with the exothermic oligomerization reaction. Acidic zeolite catalysts have been used in more recent commercial processes. Other catalysts reported in recent scientific and patent literature include zirconium oxide, tungstate zirconium oxide, sulfated titania, and nickel-modified tungstate zirconium oxide, which are reported to be more active and more water tolerant than SPA catalysts.

[0034] Hydrogenation and hydrodeoxygenation: The isoolefins produced by oligomerization are hydrogenated to convert them into isoparaffinic kerosene. Hydrogenation is usually carried out at relatively high pressures (100 to 2000 psig) at temperatures of 250-500°F. Preferred catalysts include palladium on alumina, or reduced nickel on the same support, or a sponge metal catalyst (e.g., RANEY catalyst).

[0035] For lipid hydrodeoxygenation, sulfided molybdenum or tungsten catalysts with hydrogenolysis activity are preferred. Promoters for HDO catalysts include nickel and cobalt. In the present invention, reactor conditions are selected so that isoolefin hydrogenation and lipid HDO occur simultaneously, as shown in Equation 4 below. Equation 4 is obtained at about 500 to 2500 psi H 2 It occurs at temperatures between 500 and 700°F under partial pressure.

[0036]

[0037] Embodiment of the present invention:

[0038] refer to Figure 1 In the depicted process embodiment, lipid feed 101A, which includes naturally occurring fatty acids and fatty acid esters / glycerides, is combined with oligomer feed 101B in tank 10 to provide a combined feedstock 102 for transfer to the HDO reactor 20 .

[0039] The exemplary components of lipid feed 101A include but are not limited to animal fat, animal oil, microbial oil, vegetable fat, vegetable oil, vegetable fat, vegetable oil, grease or any two or more mixtures thereof (broadly referred to as FOG). For example, lipid feed 101A may include plant and / or vegetable oil and / or microbial oil. These include but are not limited to corn oil, distilled corn oil, inedible corn oil, babassu oil, Ethiopian mustard oil, soybean oil, canola oil, coconut oil, rapeseed oil, tall oil, tall oil fatty acid, palm oil, palm oil fatty acid distillate, palm mud oil, jatropha oil, palm kernel oil, penny cress oil (penny cress oil), sunflower oil, castor oil, camelina oil, archaeal oil, bacterial oil, fungal oil, protozoan oil, algae oil, algae oil, oil from halophilic bacteria, seed oil from field penny cress and other flowering plants and any two or more mixtures thereof or combination. These can be classified as rough, degummed and RBD (refining, bleaching and deodorizing) grade, and this depends on pretreatment level and residual phosphorus and metal content.But any of these grades can be used in the present invention.As above used animal fat and / or oil include but not limited to inedible tallow, edible tallow, industrial tallow, float tallow, can bleach fancy tallow, lard, industrial lard, selected white grease, poultry fat, poultry oil, fish fat, fish oil and any two or more mixture among them.Grease can include but not limited to yellow grease, brown grease, waste vegetable oil, restaurant grease, from municipal collection grease such as water treatment facility, from the used oil of industrial packaged food operation and any two or more mixture among them.

[0040] Lipid feed 101A may include up to 90% free fatty acids (FFA). Specifically, renewable feed 101 may include about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, about 25% by weight, about 30% by weight, about 35% by weight, about 40% by weight, about 45% by weight, about 50% by weight, about 55% by weight, about 60% by weight, about 65% by weight, about 70% by weight, about 75% by weight, about 80% by weight, about 85% by weight, about 90% by weight, or include and / or be in any scope between any two of these values.

[0041] The lipid feed 101A may optionally be pretreated to remove phosphorus and metal contaminants to less than 10 wppm total, as disclosed in the prior art (eg, US Pat. No. 9,404,064 to Guay).

[0042] Oligomer feed 101B is a hydrocarbon comprising isoolefins (branched hydrocarbon molecular structures having carbon-carbon double bonds) formed by oligomerization of ethylene, propylene and / or butene (including 1-butene, 2-butene and isobutylene). In an embodiment, the isoolefins are produced by oligomerization of isobutylene. In an embodiment, the isobutylene is the product of the dehydration reaction of isobutylene, wherein the isobutylene is bioisobutylene formed by sugar / starch fermentation.

[0043] The carbon number of oligomer feed 101B is in the range of C6-C30, preferably C6-C24. The ratio of oligomer feed 101B to lipid feed 101A can vary widely. In an embodiment, the ratio of oligomer feed 101B to lipid feed 101A can vary between about 5:1 to about 1:5, preferably between about 3:1 to about 1:3 ratio. In an embodiment, the ratio of oligomer to lipid is about 3:1 to about 5:1.

[0044] Feeds 101A and 101B are combined in buffer tank 10 to form combined feed 102. The combined feed 102 is transferred to HDO reactor 20 with high pressure pump 12 to form pressurized liquid feed 103. The pressurized liquid feed 103 is further combined with pressurized hydrogen 133 to form mixed phase feed 118. The mixed phase feed 118 is then heated by feed-effluent exchanger 30 to form partially heated feed 119. The partially heated feed 119 is further heated with reactor preheater 46 to provide reactor feed 107. The reactor feed 107 is maintained at a temperature of 420 to 680°F, preferably 450 to 650°F.

[0045] The HDO reactor 20 includes at least one sulfided catalyst bed and includes molybdenum or tungsten. Preferred catalysts include sulfided nickel-molybdenum (NiMo), nickel-tungsten (NiW) or cobalt-molybdenum (CoMo) on an alumina or silica-alumina support. It should be understood by those skilled in the art that any catalyst or combination of catalysts may be used in the present invention as long as the catalyst system has the functions described herein according to the present invention.

[0046] In order to keep the active metal sulfide function of catalyst, although there is no organic sulfur or the concentration of organic sulfur is very low (<40wppm) in most oligomers and lipid raw materials, combined feed 102 can be supplemented with sulfur compound, which decomposes into hydrogen sulfide when heated and / or contacted with catalyst. Two kinds of preferred sulfur compounds are dimethyl disulfide and carbon disulfide. Their preferred concentration in combined feed 102 is about 100 to about 2000ppm sulfur by weight. Alternatively, feed 102 may include petroleum fractions, wherein the petroleum fractions provide sulfur.

[0047] Each of the HDO reactor 20 catalyst beds may be operated at a temperature of about 450° F. (232° C.) to about 750° F. (399° C.) The weighted average bed temperature (WABT) is commonly used in fixed-bed, adiabatic reactors to represent the "average" temperature of the reactor, which accounts for the nonlinear temperature distribution between the inlet and outlet of the reactor, according to Equation 5.

[0048]

[0049] In Equation 5, T i in and T i out are the temperatures at the inlet and outlet of catalyst bed i, respectively. As shown, the WABT for a reactor system having N different catalyst beds can be calculated using the WABT for each bed (WABT i ) and the weight fraction of catalyst in each bed (W ci The WABT of the HDO reactor 20 is 540 to 680°F, preferably 580 to 650°F.

[0050] exist Figure 1 , a reactor with two beds is shown, having a top bed 22A and a bottom bed 22B. Each bed 22A, 22B accounts for about half of the total catalyst mass in the reactor. In this embodiment, the hydrogen quench gas 104 is introduced through a mixing box 23 between the two beds 22A, 22B.

[0051] In embodiments, the top bed 22A comprises an inert medium graded by size to distribute any picked-up solid particles and mitigate pressure drop buildup. In other embodiments, the bottom bed 22B comprises a catalyst having isomerization activity. Examples of such catalysts include those having an acid-functional support, such as NiW on silica-alumina. The support may be crystalline or amorphous, with the former containing zeolites.

[0052] The HDO reactor 20 is operated at a pressure of 500 to 3000 psig, preferably 1000 to 2000 psig. The liquid hourly space velocity through the HDO reactor 20 is about 0.2 to about 10 h -1 , preferably about 0.5 to about 5.0h -1 (Volume flow rate of combined feed 102 / hour / volume catalyst). The ratio of hydrogen-rich treat gas 132 to combined feed 102 is about 4000 to about 15000 SCF / bbl, preferably 5000 to 12000 SCF / bbl. Hydrogen-rich treat gas 132 may contain about 70 to about 100 mol% hydrogen.

[0053] The HDO reactor effluent 110 is partially cooled by the feed-effluent exchanger 30 to provide a partially cooled HDO reactor effluent 111, and then further cooled by the cooler 32 to provide a cooled HDO reactor effluent 112. The cooled reactor effluent 112 includes a liquid hydrocarbon fraction and a vapor fraction containing unreacted hydrogen. The liquid includes normal paraffins and isoparaffins mainly in the C6-C24 range, wherein up to 2% of the compounds are heavier than C24. The hydrogen-rich vapor includes, in addition to hydrogen, C1-C6 hydrocarbons, water, carbon oxides, ammonia and hydrogen sulfide. The liquid and vapor in the two-phase cooled reactor effluent 112 are separated in the hot separator 34.

[0054] Hot separator 34 operates at the HDO reactor discharge pressure (about 500 to about 2000 psig in the preferred embodiment) and at a temperature of 250 to 500°F.

[0055] A vapor stream 124 comprising C1-C6 hydrocarbons, unreacted hydrogen, water, carbon oxides, ammonia, and hydrogen sulfide is cooled by a cooler 40 to provide a cooler effluent 126 comprising condensed liquid. The cooler 40 is operated so that the temperature of the cooler effluent 126 is about 80° F. to 150° F. A water stream 125 is introduced to clean the cooler 140 and minimize the deposition of salts such as those comprising ammonium and sulfide ions.

[0056] Cooler effluent 126 includes "sour" water, condensed hydrocarbons, and hydrogen-rich gas. These components are separated in cold separator 42 to produce sour water 128, condensed hydrocarbon stream 128A, and hydrogen-rich gas 129. Condensed hydrocarbon stream 128A includes lighter fractions of HDO reactor hydrocarbons, primarily those in the C3-C18 range. In still other embodiments, gas absorption solvent 127 is introduced into cold separator 42 to facilitate removal of impurities such as CO from hydrogen-rich gas absorption solvent 127. 2 and H 2 S. The gas absorption solvent 127 can be any alkaline aqueous solution such as those including amines or sodium hydroxide.

[0057] In addition to hydrogen, hydrogen-rich gas 129 also contains propane and small amounts of other non-condensable hydrocarbons. The gas is mostly recycled to the HDO reactor as recycle hydrogen stream 130, while bleed gas 129A is removed from the HDO reactor system to ensure that non-reactive components do not accumulate in the recycle gas.

[0058] Recycle hydrogen gas stream 130 is combined with make-up hydrogen gas 131 to provide treat gas 131A for compression in compressor 44. Compressor 44 pressurizes the treat gas to reactor pressure (500-3000 psig, preferably 1000-2000 psig) to provide pressurized hydrogen-rich treat gas 132 for HDO reactor 20 as previously described in the description of this embodiment.

[0059] Returning to the hot separator 34, the hydrocarbon liquid 114 including those of C8-C24 hydrocarbons, wherein up to 3% of the hydrocarbons are heavier than C24, is processed by the stripping tower 50, wherein steam 121 provides the evaporation duty. Tower 50 may alternatively use a reboiler instead of steam to achieve the purpose of tower 50. Condensed hydrocarbon stream 128A is also fed to the stripping tower 50 to provide a stripped hydrocarbon product 122 and a stripping tower overhead vapor 123. The stripping tower 50 operates at a pressure less than that of the hot separator 34 and the cold separator 42. In an embodiment, the stripping tower 50 operates at a pressure of 50 psig to 500 psig, preferably 60 psig to 200 psig. The purpose of the stripping tower 50 is to remove water, hydrogen sulfide, and ammonia from the hydrocarbon product 122. Therefore, the hydrocarbon product 122 includes less than 100 wppm of water, less than 5 wppm of sulfur, and less than 5 wppm of nitrogen. In embodiments, stripper 50 is operated to remove light hydrocarbons such that hydrocarbon product 122 has a flash point of 38° C. or greater, preferably 52° C. or greater. In embodiments, overhead vapor 123 comprises C8 or lighter hydrocarbons, including C6 and C8 isoparaffins.

[0060] The ratio of isoparaffins to normal paraffins of the hydrocarbon product 122 is about 5:1 to 1:5, wherein the isoparaffins are multi-branched; in other words, the isoparaffins have two or more alkyl substituents. In an embodiment, the ratio of isoparaffins to normal paraffins is about 3:1 to 1:3. Depending on the oligomer feedstock and the lipid fatty acid distribution, the carbon number of the hydrocarbon product 122 is in the C6-C24 range, wherein about 2-3% of the hydrocarbons are heavier than C24. In an embodiment, the carbon number of the hydrocarbon product 122 is in the C8-C24 range. In an embodiment, the cetane number of the hydrocarbon product 122 is 49 and higher, the cloud point is 10°C or lower, and the flash point is 52°C or higher. In an embodiment, the hydrocarbon product 122 is directly used as a ready-to-use renewable diesel fuel that meets ASTM D975 or EN 590 standards.

[0061] In some embodiments, particularly when the ratio of iso-paraffins to normal paraffins is less than 2:1, the hydrocarbon product 122 is hydroisomerized according to methods described in the prior art (e.g., US 5,814,109) to further reduce the cloud point and other low temperature properties of the renewable diesel product.

[0062] In other embodiments, isoparaffinic kerosene (the primary C9-C15 fraction of the renewable diesel fuel described herein) is separated by distillation of the hydrocarbon product 122.

[0063] exist Figure 1A In the Figure 1 , to emphasize an alternative embodiment. In this embodiment, lipid feedstock 101A and oligomeric isoolefin 101B are not combined into a single reactor feed. Instead, oligomeric isoolefin 101B is fed to the top bed 22A of HDO reactor 20 while lipid feedstock is fed (via a high pressure pump not shown) to the bottom bed 22B. Figure 1A In an embodiment of the present invention, the top bed 22A comprises a non-sulfided hydrogenation catalyst (e.g., reduced nickel or palladium on an alumina support), while the bottom bed 22B comprises the catalyst previously prepared in Figure 1 The sulfided catalyst described in the description. Figure 1A In the embodiment of the present invention, the hydrogen gas stream 130 is substantially free of H 2 S or treated to convert H 2 S is reduced to a level that does not affect the performance of the non-sulfided catalyst in the top bed 22B. Figure 1 The sulfur compound specified in the description of is introduced only into the bottom bed 22B containing the sulfurized catalyst.

[0064] In yet another embodiment, the hydrodeoxygenated propane byproduct (corresponding to the glycerol component of the glycerides) of the hydrodeoxygenation of mono-, di-, and tri-glycerides is dehydrogenated. The propylene product of the dehydrogenation reaction is then oligomerized and the oligomer product is directed to the HDO reactor 20. This embodiment effectively converts biopropane to renewable diesel and kerosene (e.g., for use as jet fuel blending stocks) while achieving the benefits described herein, such as reducing the amount of hydrocarbon recycle for lipid dilution and providing HDO hydrocarbons containing multi-branched isoparaffins. This embodiment is achieved by combining Figure 2 discussion to explain.

[0065] refer to Figure 2 , previously referenced Figure 1 In the embodiment described above, the bleed gas 129A from the HDO cold separator gas is directed to the gas membrane 60 where the gas is separated into a permeate 202 and a retentate 204. Smaller gas molecules are selectively concentrated in the permeate, while larger gas molecules are concentrated in the retentate. In the embodiment, the hydrogen concentration of the bleed gas 129A is about 75 to 90 mol%. The permeate 202 is enriched to 92-96 mol% H 2 , and the propane content is 0.5 mol% or less. The retentate 204 is enriched to 30-50 mol% propane, and the hydrogen concentration is reduced to 40-60%.

[0066] The retentate 204 is directed to the dehydrogenation reactor system 70. There, it is converted to propylene at a conversion rate of 50% to 65% under the low pressure and high temperature conditions previously described herein (under the subsection on the dehydrogenation prior art). The dehydrogenator effluent 206 containing propylene, propane and hydrogen is cooled and compressed in a cooler / compression unit 80 to provide a gas stream compressed to a pressure in the range of 100 to about 1500 psig to provide a compressed propylene-containing stream 208. In a preferred embodiment, the cooler / compression unit 80 pressurizes the dehydrogenator effluent to a pressure similar to the pressure of the vent 129A. The compressed propylene-containing stream 208 is oligomerized in an oligomerization unit 90 operated under the conditions previously described herein (under the subsection on oligomerization).

[0067] The oligomerization reactor effluent 210 leaving the oligomerization unit 90 includes propylene oligomers, propane and hydrogen. The propylene oligomers include isoolefins in the C6-C24 range. The oligomerization reactor effluent 210 is separated into an overhead vapor stream 214 and a liquid stream 212 in a separator unit 95. The separator unit can be a flash tank or a tower, which is well known to those skilled in the art. In a preferred embodiment, the overhead vapor stream 214 is recycled to the gas membrane 60 to separate hydrogen and propane, the hydrogen is recycled to the HDO unit, and the propane is recycled to the propane dehydrogenation system 70.

[0068] Separator liquid stream 212 represents isoolefins combined with lipid feed for HDO. Thus, according to aspects of the present invention, propane derived from lipid hydrodeoxygenation is converted into isoparaffinic diesel fuel or kerosene. In embodiments, the diesel product ( Figure 1 Stream 122 in the flask is used to separate isoparaffinic kerosene (the major C9-C15 fraction of the diesel fuel described herein).

[0069] From the above description, it is apparent that the present invention is well adapted to achieve the objects of the present invention and to obtain the advantages mentioned herein as well as those inherent to the present invention. Although the present preferred embodiments of the present invention have been described for the purposes of the present invention, it will be appreciated that many changes may be made, which are themselves readily conceivable to those skilled in the art and which are accomplished within the spirit of the disclosed and claimed invention. Therefore, in general, the present invention is more readily understood by reference to the following examples, which are provided by way of illustration and are not intended to limit the present invention.

[0070] Example

[0071] Example 1. Preparation of an isoparaffin composition to simulate the product of isobutylene oligomerization

[0072] Isododecane and isohexadecane were obtained from a commercial supplier, Making Cosmetics. A blend of 85 wt% isododecane and 15 wt% isohexadecane was prepared to simulate the isobutylene oligomerization product distribution, as disclosed in the prior art; for example, U.S. Patent Publication 2020 / 0010767, which is incorporated herein by reference. This isoparaffin composition was labeled "oligomeric isoparaffin" for subsequent studies.

[0073] Example 2. Renewable diesel from lipids

[0074] The cloud point of the renewable diesel sample produced by lipid hydroprocessing (lipid hydrodeoxygenation to normal paraffins, then the normal paraffin hydroisomerization) and the concentration of corresponding unconverted n-octadecane (nC18) were analyzed. Cloud point automation instruments such as Koehler and PhaseTech and older but official methods described by ASTM D2500 were measured. nC18 content was measured using gas chromatography (ASTM D2887), and its value was reported as GC peak area percentage (%). Various lipid raw materials (such as used edible oils, tallow and distiller corn oil) were used to produce these samples.

[0075] Hydrodeoxygenation (HDO) of the feedstock is carried out over a catalyst system comprising NiMo, at a WABT of 600-660°F, at a pressure of 1700-1800 psig. The HDO reactor system is operated with liquid product recycle. The HDO product is stripped of dissolved gas phase byproducts (e.g., hydrogen sulfide and ammonia) and isomerized in a hydroisomerization (HI). The HI reactor comprises a bifunctional noble metal catalyst (having hydrogenation-dehydrogenation and acid functions). The HI reactor is maintained at a pressure of approximately 970 psig, and the temperature is varied between WABT of 600 to 635°F to produce a series of samples with different nC18 conversions and product cloud points.

[0076] The cloud points of the 27 samples were plotted against the nC18 content, ranging from -35°C for 1.8% nC18 to +12°C for 34% nC18. The results fall under a smooth curve given by Equation 6 (where R 2 The correlation coefficient is 0.994).

[0077] Cloud point (℃) = 15.5 ln (% nC18) -43.0 (6)

[0078] A renewable diesel sample produced according to the method of this example was selected for blending studies with the oligomeric isoparaffin composition of Example 1. The sample was found to have a cloud point of -10°C (measured using the D2500 test method). Therefore, the %nC18 estimated using Equation 6 was 8.4%.

[0079] Example 3. Blends of oligomeric isoparaffins and renewable diesel

[0080] The oligomeric isoparaffin composition of Example 1 was blended with the -10°C cloud point renewable diesel (RD) of Example 2 at three different ratios as shown in Table I. The samples were analyzed using a Phase Technologies dual cloud point and freeze point analyzer (model CPA-70Xi). The cloud point method is ASTM D5773.

[0081] Table I. Fuel Properties of Blends of Oligomeric Isoparaffins and Renewable Diesel

[0082]

[0083] Since oligomeric isoparaffins do not have nC18, they act as diluents for this wax paraffin. Therefore, the nC18 content of the RD blends diluted with 50% and 75% values ​​of oligomeric isoparaffins is expected to be 4.2% nC18 (= 0.5 x 8.4%) and 2.1% nC18 (= 0.25 x 8.4%). If the oligomeric isoparaffin blends behave like typical RDs at different degrees of isomerization, the blends would have cloud points of -20.7°C and -31.5°C, respectively, as predicted by Equation 6. However, these blends surprisingly show cloud points of -29°C and -37°C, or a decrease of about 6 to about 8°C.

[0084] The derived cetane numbers of Table I are well above the minimum specification limits of 40 (ASTM D975) and 49 (EN 975) for diesel fuel, although the cetane numbers of the highly branched isobutylene oligomerization products are very low.

[0085] Example 4. Blends of oligomeric isoparaffins and HDO paraffins

[0086] The cloud point of the stripped, unisomerized HDO product (produced according to the HDO conditions described in Example 1) was measured and found to be above >20° C. This HDO product was blended with the oligomeric isoparaffins of Example 2. Three blends were prepared at different ratios of oligomeric isoparaffins:HDO product. The cloud points of these three blends are presented in Table II.

[0087] Table II. Cloud Points of Blends of Oligomeric Isoparaffins and HDO Products

[0088]

[0089] The results indicate that bio-based hydrocarbons comprising HDO products and isoparaffin oligomers are suitable for use as diesel fuels for climates where the 10th percentile minimum temperature (as shown in Section X5 of ASTM D975) is above 10° C. (50 / 50 blend) or above 0° C. (75 / 25 blend). Such fuels can be produced by subjecting a feedstock comprising olefin oligomers to HDO, as described herein.

[0090] Therefore, the preferred embodiments of the present invention have been described in conjunction with them, and it will be apparent to those skilled in the art that various modifications may be made to the preferred embodiments described herein without departing from the spirit and scope of the present invention. However, it is intended that all such modifications and changes apparent to those skilled in the art will be included within the scope of the following claims.

Claims

1. A method for producing a biomass-based diesel fuel, wherein include: a. Production of paraffins by hydrodeoxygenation of lipid feedstocks; b. Producing isoparaffins from sugars by the following steps: i. fermenting the sugar into alcohol; ii. dehydrating the alcohol to an olefin; iii. oligomerizing the olefin into a certain distribution of isoolefins; and iv. hydrogenating the isoolefins to isoparaffins; and c. blending the paraffins and the isoparaffins to produce the biomass-based diesel fuel; d. wherein the isoparaffin has a derived cetane number (DCN) of less than 40; e. wherein the biomass based diesel fuel has a DCN of 49 or higher.

2. The method of claim 1, wherein the biomass-based diesel fuel has a DCN greater than 55.

3. The method of claim 1, wherein the biomass based diesel fuel has a cloud point below 0°C.

4. The method of claim 1, wherein the biomass based diesel fuel has a cloud point below -10°C. The method according to claim 1 , wherein the alcohol is ethanol or isobutanol. The method according to claim 1 , wherein the olefin is propylene or butene.

7. A biomass-based diesel fuel product produced by the method of claim 1.

8. A method for producing a renewable diesel fuel, wherein The following steps are involved: a. combining the lipid and the hydrocarbon liquid to provide a combined feed; b. hydrodeoxygenating and hydrogenating the combined feed in a hydrodeoxygenation reactor to provide a reactor effluent comprising C3-C24 hydrocarbons; and c. separating a C9-C24 hydrocarbon fraction from the reactor effluent; wherein the C9-C24 hydrocarbon fraction has a deduced cetane number of 49 or higher and a cloud point below 0°C; wherein the hydrocarbon liquid comprises isoolefins produced by olefin oligomerization.

9. The process of claim 8, further comprising producing the isoolefin by oligomerization of isobutylene.

10. The process according to claim 9, wherein the isobutylene is a product of dehydration of isobutyl alcohol.

11. The method of claim 10, further comprising producing the isobutanol by fermentation of sugars.

12. The method of claim 9, further comprising producing the isoolefin by oligomerization of propylene.

13. The process of claim 12, wherein the propylene is a product of propane dehydrogenation.

14. The process of claim 8 wherein the product from the hydrodeoxygenation reaction is not used as a diluent for the reactor feed.

15. A method for producing a renewable diesel fuel, wherein The following steps are involved: a. combining the lipids with the hydrocarbon liquid to provide a combined feed; b. hydrodeoxygenating and hydrogenating the combined feed in a hydrodeoxygenation reactor to provide a reactor effluent comprising hydrocarbons including propane byproduct; c. separating a C9-C24 hydrocarbon fraction from the reactor effluent; d. dehydrogenating the propane byproduct to produce a vapor stream having propylene and hydrogen; and e. oligomerizing the propylene to produce isoolefins; wherein the C9-C24 hydrocarbon fraction has a deduced cetane number of 49 or more, and the hydrocarbon liquid comprises the isoolefin.

16. The method of claim 15, further comprising producing the isoolefin by oligomerization of butene.

17. The process of claim 16, wherein the butene is derived from ethanol and / or isobutanol.

18. The method of claim 9, further comprising producing the isoolefin by oligomerization of propylene.

19. The process of claim 8 wherein the product from the hydrodeoxygenation reaction is not used as a diluent for the reactor feed.

20. The process of claim 15, wherein the C9-C24 hydrocarbon fraction is distilled to provide a C9-C15 fraction kerosene.

21. The method of claim 20, wherein the C9-C15 fraction kerosene is used as a jet fuel blending stock.

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