Method for removing chlorine from fat, oil and grease

Abstract

An improved process for removing contaminants from low value waste fats and oils for the purpose of hydrodeoxygenation to diesel boiling range hydrocarbons. The method includes removing organically bound contaminants from fat, oil and grease (FOG) by adding water to the contaminated FOG stream, heating the mixture, and mixing to promote the reaction between the water and the FOG. The reacted FOG is then separated from the contaminants. The FOG of the reaction will result in reduced organically bound chlorine contaminants.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 350,751, filed on June 9, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present technology relates to biofuels, and more particularly to biomass based diesel fuels. Specifically, the present invention relates to an improved process for removing contaminants from low value waste fats and oils for the purpose of hydrodeoxygenation to diesel boiling range hydrocarbons. Background Art

[0004] Renewable hydrocarbons, as a way to reduce the carbon concentration of hydrocarbon products (such as fuels), have increasing importance in the global economy. The most common renewable hydrocarbon product used today is renewable diesel. However, other renewable hydrocarbons, such as renewable naphtha, sustainable aviation fuel, renewable propane and other, are also crucial. The hydrodeoxygenation (HDO) of lipids is a key step in the production of renewable hydrocarbons. Commercially valuable lipid raw materials include by-products of ethanol production, animal fat refining and food processing industries, such as distiller corn oil, inedible animal fat and used cooking oil, respectively. These raw materials are characterized by high free fatty acid (FFA) content, usually higher than 5% by weight, and relatively high levels of metals and phosphorus (usually totaling higher than 20wppm), and higher than 200mg / kg basicity values. Some lipid raw materials also contain elevated levels of chlorine, usually higher than 5wppm.

[0005] Chlorine can exist in lipids in water-soluble (WS) and water-insoluble (WIS) forms. WS chlorine generally exists in the form of chlorinated glycerol (i.e., monochloropropylene glycol), chloride salts (e.g., sodium chloride, potassium chloride), sodium hypochlorite (i.e., bleach), hydrochloric acid, and other chlorinated polar molecules. These impurities can be easily removed from lipid raw materials using conventional lipid pretreatment steps (e.g., water washing), and therefore they do not pose significant material problems for the production of renewable fuels. On the other hand, WIS chlorine is not easily removed from lipid raw materials using conventional pretreatment steps. WIS chlorine mainly exists in lipids in the form of fatty acid esters of monochloropropylene glycol (MCPD) isomers 2-MCPD and 3-MCPD or chlorinated fatty acids (CFAs). The molecular structures of typical 2-MCPD and CFA compounds are shown below, respectively. Figure 1 and Figure 2As shown. MCPD can exist in the form of chlorinated monoglycerides or chlorinated diglycerides, and it has been reported as the most common form of occurrence of chlorinated vegetable oils. CFA can exist in the form of free fatty acids, monoglycerides, diglycerides, triglycerides or fatty acid alkyl esters. Chlorinated wax esters and sphingolipids are also reported in the literature, although they are less common. Due to the introduction of chlorinated hydrocarbons used as detergents, hot fluids or other industrial additives, WIS chlorine may also be present in lipids. Analysis of brown grease from commercial sources shows the presence of ppm levels of ethyl chloride, chloroform, methyl chloride, 1,2-dichloroethylene, tetrachloroethylene and trichloroethylene (Ward, PML Journal of Food Protection, 2012, 75 (4); 731-737).

[0006] Current methods for lipid pretreatment include degumming / acid treatment, physical and chemical refining (including improved caustic refining, in which the oil is treated with a silica adsorbent as described in U.S. Pat. Nos. 5,231,201 and 5,298,639), and bleaching (as described in U.S. Pat. Nos. 7,179,491 and 8,394,975). Reduction of the 3-MCPD content of lipids is cited in U.S. Patent Publication 2020 / 0056116; however, the method includes refining and bleaching, followed by deodorization, thereby reducing the yield of the treated oil by stripping of FFA and lighter oil fractions. In general, the pretreatment methods of the prior art do not achieve chlorine reduction levels for optimal HDO reactor performance. In addition, existing methods for lipid pretreatment have little effect on WIS chlorine and can only moderately reduce WS chlorine species. Chlorine imposes unique challenges on the production of renewable hydrocarbons because the HDO process converts WIS chlorine into hydrochloric acid, which is a prominent corrosion concern for common building materials. In particular, austenitic stainless steels (e.g., 300 series 304 and 316) are highly susceptible to chloride stress corrosion cracking due to exposure to chlorides, which results in cracking in localized areas of high stress in the metal and is a significant mechanical integrity concern for high pressure components. Therefore, technologies that can reduce chloride and WS chloride concentrations are highly desirable, particularly for the production of renewable hydrocarbons by hydroprocessing lipids.

[0007] There are existing methods for removing common impurities such as phosphorus, iron, sodium, potassium, calcium and magnesium. Typically, these and other common impurities are removed by a combination of processes such as water washing, acidification, adsorbent filtration, absorbent filtration, degumming or any combination of two or more of these steps.

[0008] Existing methods also teach hydrolysis as an effective means to increase FFA content in lipid raw materials. This process, commonly referred to as fat cracking, is traditionally used for the purpose of producing purified fatty acids and / or purified glycerol feed streams. Exemplary methods for hydrolyzing lipid raw materials include enzymatic hydrolysis, catalytic hydrolysis using a catalyst (e.g., zinc oxide), Twitchell process, and Colgate-Emery process. The Colgate-Emery process uses a countercurrent liquid-liquid contactor to react clean lipids with water at approximately 490 ° F to achieve a hydrolysis greater than 90% of the raw material. It is the most widely used commercial hydrolysis method. Although it is a relatively well-understood method, the prior art does not mention the use and application of hydrolysis to remove chlorine and other impurities from waste lipid raw materials to produce renewable hydrocarbons.

[0009] In U.S. Pat. No. 10,071,322B2, Coppola et al. describe a "hydrothermal purification" or "HCU" process for rapidly and completely hydrolyzing lipid raw materials at temperatures higher than those used in the Colgate-Emery process (e.g., 300-500° C. versus 250-260° C., respectively). Coppola et al. teach that complete hydrolysis of the lipid raw material produces a clean oil with low inorganic impurities (e.g., phosphorus, potassium, sodium, silicon, iron, magnesium, barium, calcium, copper, magnesium, and zinc). Similar to other prior art techniques, the HCU process promotes complete hydrolysis, which is described as being close to the theoretical maximum, or converting about 100% of the combined fatty acids into free fatty acids. In addition, although the HCU process is described as being able to remove inorganic impurities, Coppola et al. do not mention the effect of the HCU process on removing chlorine from chlorine-contaminated lipid raw materials.

[0010] The prior art cited by Coppola et al. teaches that removal of pollutants is achieved with near-complete hydrolysis. However, complete hydrolysis of fatty acid glycerides is generally disadvantageous for the production of renewable fuels via HDO. Removal of bound glycerol from fatty acid glycerides translates into loss of propane byproduct. In addition, some unique corrosion concerns arise in the processing of very high FFA feedstocks.

[0011] Therefore, there is still an unmet need for lipid feedstock pretreatment methods that can remove chlorine from lipid feedstocks for the production of renewable hydrocarbons. In addition, there is a need for hydrolysis-based pretreatment methods for HDO reactors that achieve high contaminant removal without significant loss of bound glycerol from fatty acid glycerides. Summary of the invention

[0012] One aspect of the present invention relates to a method for removing organically bound contaminants from fats, oils and greases (FOG). The method comprises the steps of adding water to a contaminated FOG stream, and heating and mixing the mixture to promote a reaction between the water and the FOG, and then separating the reacted FOG from the removed contaminants. Thus, the reacted FOG will result in reduced organically bound chlorine contaminants. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] These and other objects and advantages of the present invention will be more fully understood and appreciated by reference to the following more detailed description of preferred exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0014] Figure 1 This is the structural diagram of monochloropropylene glycol stearate.

[0015] Figure 2 It is a structural diagram of fatty acid glyceride with chlorinated stearic acid.

[0016] Figure 3 is a block flow diagram showing an embodiment of the method of the present invention.

[0017] Figure 4A .1 and B.1 show the reaction schemes for the hydrolysis of water-insoluble monochloropropanediol (MCPD) fatty acid esters to produce water-soluble hydrochloric acid and glycerol fatty acid esters.

[0018] Figures 5C.1 and 5C.2 show reaction schemes for the stepwise reaction for the hydrolysis of water-insoluble monochloropropanediol (MCPD) fatty acid esters to produce free fatty acids (FFA) and water-soluble MCPD.

[0019] Figures 6D.1, D.2 and D.3 show reaction schemes for the reaction network for the hydrolysis of fatty acid glycerides to produce free fatty acids (FFA) and glycerol.

[0020] Figure 7 is a graph showing experimental results comparing the concentration of chlorine and bound glycerol throughout the hydrolysis reaction. The solid line represents the linear proportional change of chlorine and bound glycerol, while the circle and arc dashed line represent the experimental data generated in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0022] Various embodiments are described below. It should be noted that the specific embodiments are not intended to be exhaustive descriptions or as limitations on the broader aspects discussed herein. An aspect described in conjunction with a specific embodiment is not necessarily limited to that embodiment, but can be practiced with any other embodiment.

[0023] As used herein, "about" will refer to at most positive or negative 10% of a particular term. Unless otherwise specified herein or obviously contradictory to the context, in the context of describing an element (especially in the context of the following claims), the term "one" and "an" and "the" and similar pronouns used should be interpreted as covering both the singular and the plural. Unless otherwise specified herein, it is only intended that the recording of the numerical range herein be used as a shorthand expression method for quoting each individual numerical value falling within the range, and each individual numerical value is incorporated into the specification, as if it is recorded separately in this article. Unless otherwise specified herein or obviously contradictory to the context, all methods described herein can be performed in any suitable order. Unless otherwise specified, any and all examples provided herein, or the use of exemplary language (such as "for example") are only intended to better illustrate the embodiment, rather than to impose restrictions on the scope of the claim. The language in the specification should not be interpreted as specifying any unclaimed element as necessary.

[0024] As used herein, hydroprocessing describes various types of catalytic reactions that occur in the presence of hydrogen, but is not limited thereto. 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 (HDA), hydrodeoxygenation (HDO), decarboxylation (DCO), hydroisomerization (HI), hydrodewaxing (HDW), hydrodemetallization (HDM), decarbonylation, methanation, and reforming. Depending on the catalyst type, reactor configuration, reactor conditions, and feedstock composition, a variety of reactions ranging from purely thermal (i.e., no catalyst is required) to catalytic can occur. When describing the primary function of a particular hydroprocessing unit (e.g., an HDO reaction system), it should be understood that the HDO reaction is only one of the primary reactions occurring and that other reactions may also occur.

[0025] Hydrotreating (HT) includes removing elements of Groups IIIa, Va, VIa and / or VIIa of the Periodic Table from organic compounds. Hydrotreating may also include hydrodemetallization (HDM) reactions. Thus, hydrotreating includes the removal of heteroatoms such as oxygen, nitrogen, sulfur and combinations of any two or more thereof by hydrotreating. For example, hydrodeoxygenation (HDO) should be understood to refer to the removal of oxygen by a catalytic hydrotreating reaction to produce water as a by-product; similarly, hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) describe the removal of specified elements, respectively, by hydrotreating. Hydrotreating is also understood to include the removal of covalently bound chlorine to produce hydrochloric acid as a by-product.

[0026] Water-insoluble (WIS) chlorine is defined as chlorine that is present in the lipid material and does not wash out when in contact with water at ambient conditions (i.e., room temperature). Without being bound by any particular theory, it is hypothesized that WIS chlorine is a chlorine moiety covalently bound to a lipid or hydrocarbon and is most prevalent as one of a chlorinated fatty acid or chlorinated glyceride.

[0027] Water-soluble (WS) chlorine is defined as chlorine that is present in the lipid raw material and that is easily washed out when in contact with water at ambient conditions (i.e., room temperature). It is assumed that the WS chlorine is primarily one of chlorinated glycerol (i.e., monochloropropylene glycol), chloride salts (e.g., sodium chloride, potassium chloride), sodium hypochlorite (i.e., bleach), hydrochloric acid, or other chlorinated polar molecules. It should be understood that if a composition is stated as comprising "C i -C j Hydrocarbons", such as C7-C 12 n-paraffin, then it means that the composition comprises one or more paraffins having a carbon number in the range i to j.

[0028] "Middle distillates" generally refers to the fraction of petroleum 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 gas oil (about 400-650°F) and heavy gas oil (about 610-800°F).

[0029] As used herein, "lipid" refers to fats, oils and greases. 24 The fatty acids may be in the form of glycerides (ie, as mono-, di- and tri-glycerides) or as free fatty acids (FFA).

[0030] The term "monochloropropanediol" or "MCPD" is defined as a chlorinated glycerol molecule in which one of the oxygen moieties has been replaced by a chlorine moiety. The chlorine moiety may be present in position 1, 2 or 3. As used herein, the term monochloropropanediol or MCPD may also be understood to refer to both a chlorinated glycerol moiety bound to a fatty acid via an ester bond or a chlorinated glycerol present as a free alcohol.

[0031] The term "bound glycerol" is defined as glycerol bound to fatty acids via ester bonds, such as found in mono-, di- and tri-glycerides. As used herein, the term bound glycerol may also be understood to include monochloropropanediol bound to fatty acids.

[0032] The term "free glycerol" is defined as glycerol that exists as a free alcohol and is not bound to any fatty acid by an ester bond. As used herein, the term bound glycerol may also be understood to include MCPD. Glycerides or total glycerides are the sum of monoglycerides, diglycerides, and triglycerides. Total glyceride content is a measure of bound glycerol in lipids, and glyceride conversion is a measure of glycerol released by converting glycerides into FFAs via hydrolysis.

[0033] It should be understood that the "volume percent" or "volume %" of a component in a composition or the volume ratio of different components in a composition is measured at room temperature (about 23°C) based on the initial volume of each individual component, not the final volume of the combined components.

[0034] One aspect of the invention relates to a method of producing a pretreated lipid feedstock having a total chlorine and WIS chlorine concentration that is lower than the starting or unconditioned total chlorine and WIS chlorine concentration. Table 1 provides typical total chlorine and WIS chlorine contents for various unconditioned spent lipid feedstocks.

[0035] In one aspect, a method of producing a preconditioned lipid feedstock having WIS chlorine and phosphorus concentrations that are lower than the starting or unconditioned WS chlorine and phosphorus concentrations is provided. Table 1 provides typical WIS chlorine and phosphorus contents for various unconditioned waste lipid feedstocks.

[0036] Table 1. Representative total chlorine, water soluble (WIS) chlorine, and phosphorus values ​​for crude waste lipid feedstock*

[0037] Lipid feed type Total chlorine (wppm) WIS Chlorine Phosphorus (wppm) UCO#1 21 14 12 UCO#2 49 24 5 UCO#3 350 95 22 BFT 6 3 59 CWG 8 4 133 DCO 4 3 6 YG 9 7 59

[0038] *Used cooking oil (UCO), Fancy Tallow (BFT), Selected White Grease (CWG), Distillers Corn Oil (DCO) and Yellow Grease (YG)

[0039] The method comprises the following steps: initially, the waste lipid feed stream is contacted with an aqueous stream, then the combined stream is subjected to enough temperatures and mixed to produce a lipid feed stream that reduces chlorine and a heavy phase that is enriched in chlorine. In some embodiments, an acid catalyst is added to the mixture to promote the conversion of WIS chlorine to WS chlorine. In some embodiments, the pretreated lipid feed is a FFA concentration greater than that of unpretreated lipid feed.

[0040] Exemplary lipid raw materials 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.Plant and / or vegetable oil and / or microbial oil include but are not limited to, corn oil, inedible corn oil, babassu oil, carinata oil, soybean oil, rapeseed (canola) oil, coconut oil, rapeseed oil, tall oil, tall oil fatty acid, palm oil, palm oil fatty acid distillate, jatropha oil (jatropha), palm kernel oil, sunflower oil, castor oil, camelina (camelina) oil, archaeal (archaeal) oil, bacterial oil, fungal oil, protozoan (protozoal) oil, algae oil, algae oil, from the oil of halophiles (halophiles) and any two or more mixtures thereof.According to the level of pretreatment and the content of residual phosphorus and metal, these can be divided into roughing grade, degumming grade and RBD (refining, bleaching and deodorizing) level. However, any of these grades can be used in the present technology. Animal fats and / or oils used as above include, but are not limited to, inedible tallow, edible tallow, industrial tallow, flotation tallow, lard, poultry fat, poultry oil, fish fat, fish oil, and mixtures of any two or more thereof. Greases may include, but are not limited to, yellow grease, brown grease, waste vegetable oil, restaurant grease, oil trap grease from municipalities (e.g., water treatment facilities), and waste oil from industrial packaged food operations, and mixtures of any two or more thereof.

[0041] The lipid raw material of biorenewable can contain the phosphorus of about 1wppm to about 800wppm, and the total metal (mainly sodium, potassium, magnesium, calcium, iron and copper) of about 1wppm to about 400wppm.Lipid also can contain the free fatty acid of about 40 weight % at the most.The FFA content of lipid can be about 1 weight %, about 2 weight %, about 3 weight %, about 4 weight %, about 5 weight %, about 6 weight %, about 7 weight %, about 8 weight %, about 9 weight %, about 10 weight %, about 11 weight %, about 12 weight %, about 13 weight %, about 14 weight %, about 15 weight %, about 16 weight %, about 17 weight %, about 18 weight %, about 19 weight %, about 20 weight %, about 30 weight %, about 32 weight %, about 34 weight %, about 36 weight %, about 38 weight %, about 40 weight %, or comprise and / or in any scope between any two of these numerical values.

[0042] The lipid raw material contains fatty acids in the form of glycerides (the sum of monoglycerides, diglycerides, and triglycerides) bound to glycerol (or simply bound glycerol). The lipid raw material may contain up to 90% by weight of glycerides. The glyceride content of the lipid raw material may be about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, or about 90% by weight, or between any two values ​​within this range. For example, the lipid raw material may contain a glyceride content in the range of 20% to 90% by weight or in the range of 30% to 80% by weight.

[0043] The lipid raw material can contain up to about 1000wppm of total chlorine. The total chlorine content of lipid can be about 1wppm, 2wppm, 3wppm, 4wppm, 5wppm, 6wppm, 7wppm, 8wppm, 9wppm, 10wppm, 20wppm, 30wppm, 40wppm, 50wppm, 60wppm, 70wppm, 80wppm, 90wppm, 100wppm, 110wppm, 120wppm, 130wppm, 140wppm, 150wppm, 160wppm, 170wppm, 180wppm, 190wppm, 200wppm, 300wppm, 400wppm, 500wppm, 600wppm, 700wppm, 800wppm, 900wppm, 1000wppm, or include and / or in any scope between any two of these numerical values. The lipid feedstock may also contain up to about 200 wppm WIS chlorine. The WIS chlorine content of the lipid may be about 1 wppm, 2 wppm, 3 wppm, 4 wppm, 6 wppm, 7 wppm, 8 wppm, 9 wppm, 10 wppm, 20 wppm, 30 wppm, 40 wppm, 50 wppm, 60 wppm, 70 wppm, 80 wppm, 90 wppm, 100 wppm, 110 wppm, 120 wppm, 130 wppm, 140 wppm, 150 wppm, 160 wppm, 170 wppm, 180 wppm, 190 wppm, 200 wppm, or any range including and / or between any two of these numerical values.

[0044] Thus, the lipid feedstock of any embodiment herein may include corn oil, distiller's corn oil, non-edible corn oil, babassu oil, carinata oil, soybean oil, canola oil, coconut oil, rapeseed oil, tall oil, tall oil fatty acids, palm oil, palm oil fatty acid distillate, jatropha oil, palm kernel oil, sunflower oil, castor oil, camelina oil, archaeal oil, bacterial oil, fungal oil, crude oil, Protozoal oils, algae oils, algal oils, oils from halophiles, rendered fats, inedible tallow, edible tallow, industrial tallow, flotation tallow, lard, poultry fat, poultry oil, fish fat, fish oil, frying oil, yellow grease, brown grease, waste vegetable oils, restaurant grease, oil trap grease from municipalities (e.g., water treatment facilities), and waste oils from industrial packaged food operations, or mixtures or combinations of any two or more thereof.

[0045] It has been surprisingly observed that the reaction of a chlorine-containing lipid feedstock with water at a temperature of about 500°F for 15 to 360 minutes results in a reduction of up to 99% in the chlorine content of the lipid feedstock. In addition, it has been surprisingly observed that the reaction conditions can be controlled so that the reaction of the chlorine-containing lipid feedstock with water produces a greater degree of chlorine removal than the degree of removal of bound glycerol. In terms of glyceride conversion, the rate at which WIS chlorine is removed from the lipids exceeds the rate at which glycerides are converted, thereby allowing the reaction to be optimized to achieve a desired balance of WIS chlorine removal and bound glycerol content in the product.

[0046] The conversion rate of glycerides (the sum of monoglycerides, diglycerides and triglycerides, representing the bound glycerol compounds in the lipids) is less than 90%. In embodiments, the glyceride conversion rate is less than 85%. In embodiments, the glyceride conversion rate is less than 80%. For example, the glyceride conversion rate can be about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 45% or about 40%, or between any two of these numerical values. For example, the glyceride conversion rate is between 40% and 90%, or between 45% and 85%. The chlorine-reduced product according to the present technology contains a glyceride content of at least about 8% by weight (the sum of monoglycerides, diglycerides and triglycerides, representing the bound glycerol compounds in the lipids). In an embodiment, the product comprises about 10 wt %, about 12 wt %, about 14 wt %, about 16 wt %, about 18 wt %, about 20 wt %, about 22 wt %, about 24 wt %, about 26 wt %, about 28 wt %, about 30 wt %, about 32 wt %, about 34 wt %, about 36 wt %, about 38 wt %, about 40 wt %, about 42 wt %, about 44 wt %, about 46 wt %, about 48 wt % or about 50 wt % glyceride. In the product, it contains a glyceride content between any two numerical values ​​within the scope. Therefore, the product reduced by chlorine can contain glyceride between about 10 wt % and 50 wt % or glyceride between 20 wt % and 40 wt %.

[0047] Reference Figure 3 , more generally describing other aspects of the method, Figure 3 1 is a schematic diagram of an embodiment of the present invention, wherein a lipid feedstock stream 101 contacts a water stream 102 and reacts in a reactor system 100. In some embodiments, the water stream 102 may be liquid water, steam, or any combination thereof. In some embodiments, the lipid feedstock stream 101 may undergo a pretreatment step before entering the reactor 100. The pretreatment step may include water washing, acidification (e.g., phosphoric acid, citric acid, etc.), caustic neutralization (e.g., sodium hydroxide, potassium hydroxide, etc.), adsorbent filtration (e.g., silica hydrogel, bleaching clay, ion exchange resin, etc.), absorbent filtration (e.g., diatomaceous earth, cellulose, etc.), FFA stripping, degumming (e.g., water degumming, acid degumming, etc.), or any combination of two or more of these steps.

[0048] Regardless of the pretreatment method, feedstock 101 has a WIS chlorine content between 5 wppm and 200 wppm. In some embodiments, feedstock 101 has a WIS chlorine content between 10 wppm and 100 wppm.

[0049] Reactor 100 operates at a temperature between 450 and 500 ° F for 15-360 minutes. The reactor system 100 can be operated in an intermittent or continuous mode. In some embodiments, reactor 100 can be a continuous stirred tank reactor (CSTR), a stirred batch reactor, a co-current liquid-liquid contactor, a countercurrent liquid-liquid contactor, a static mixer, a high shear online mixer or other liquid reactors known to those skilled in the art. Intermittent reactor embodiments include equipment for heating and stirring. Heating can be provided by steam or heat transfer fluid (hot oil) circulation through a reactor jacket or heating coil, and stirring is provided by mechanical agitators, steam injection and / or pumps around the circulation. Continuous reactors include a single CSTR or multiple CSTRs in series, so that the volume of the kettle provides a residence time of 15-360 minutes required for conversion. Other continuous reactor embodiments include countercurrent water contact columns (with equipment for steam injection) or tubular reactors with steam jacketed pipe networks, in which the turbulence of lipid / water is maintained for at least 15 minutes under the desired temperature range. In an embodiment, the reactor system includes one or more of these reactors. Regardless of the type of reactor, the system is maintained at a sufficiently high pressure to ensure that the water remains in the liquid phase. Typical pressures for reactor system 100 are in the range of 500-1200 psig.

[0050] Under these conditions, 40-90% of the glycerides in the feedstock 101 are converted. After the reactor 100, the mixed effluent 105 is directed to a separator 110 to separate a phase having a density less than that of water (i.e., a light phase) 111, and a phase having a density greater than or equal to that of water (i.e., a heavy phase) 112. In an embodiment, the light phase 111 is a lipid stream comprising mainly glycerides and fatty acids, while the heavy phase 112 is an aqueous stream having mainly water, glycerol, metal ions, and salts. In an embodiment, the light phase 111 has a chlorine content that is lower than the starting chlorine content of the feed stream 101, which is 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt%, or any range including and / or between any two of these values. In some embodiments, light phase 111 has a WIS chlorine content that is lower than the starting WS chlorine content of stream 101 by 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt%, or any range inclusive and / or between any two of these values.

[0051] Light phase 111 has a WIS chlorine content between 0.2 and 10 wppm, depending on the WIS chlorine content of feedstock 101. In a preferred embodiment, the WIS chlorine content is less than 5 wppm.

[0052] Without being bound by theory, the reduction of WIS chlorine content of lipids can be achieved by two main approaches. The first is to hydrolyze the chlorine structure part directly from the glycerol backbone of the fatty acid ester of MCPD to produce WS hydrochloric acid and fatty acid glyceride, as shown in Figure 4. Figure 4 shows that the hydrolysis of water-insoluble monochloropropanediol (MCPD) fatty acid ester produces water-soluble hydrochloric acid and glycerol fatty acid ester. Any one of reaction A.1 or reaction B.1 can occur. The position of the chlorine structure part can be changed so that the chlorine can also be located on the terminal carbon instead of the internal carbon, as shown. The second is to hydrolyze the WIS fatty acid structure part of the fatty acid monoester and diester of MCPD to produce free fatty acids (FFA) and MCPD, as shown in Figure 5. Figure 5 shows a stepwise reaction, which is used for the hydrolysis of water-insoluble monochloropropanediol (MCPD) fatty acid ester to produce free fatty acids (FFA) and water-soluble MCPD. The reaction can also be carried out in different orders, so that fatty acid R2 is removed in step C.1 and fatty acid R3 is removed in step C.2. The position of the chlorine moiety can be varied so that the chlorine can also be located on an internal carbon instead of an external carbon, as shown. Following the reaction scheme shown in Figure 6, the hydrolysis of fatty acid glycerides to produce FFA and glycerol is a competitive series of reactions that can occur simultaneously with the reaction schemes shown in Figures 4 and 5. As shown in Figure 4, reactions A.1 and B.1 are preferred pathways for reducing the WIS chloride content of lipids because these reactions produce neither FFA, free glycerol, nor MCPD. The reactions shown in Figure 6 can be performed in different orders so that the fatty acids (Rx) can be removed in any order in steps D.1-D.3.

[0053] FFA is not desirable as a feedstock for the production of renewable hydrocarbons for a variety of reasons, including metallurgical effects, catalyst attrition, and reduced yields of renewable propane obtained from hydroprocessing glycerol. Similarly, free glycerol and MCPD have poor solubility in hydrocarbons and are therefore not desirable as feedstocks for HDO reactors, which generally rely on hydrocarbon dilution for efficient operation. Given these limitations, efficient conversion of glycerol to propane in a renewable hydrocarbon conversion unit reactor requires that the glycerol remain bound to the fatty acids as glycerides.

[0054] It has surprisingly been observed that the reaction in reactor 100 can be controlled to favor the dechlorination reaction so that the reduction in the total number of moles of bound glycerol (in the form of mono-, di-, and triglycerides) is less than the reduction in the total number of moles of chlorine in light phase 111.

[0055] In embodiments, an acid or acidic solution is metered into reactor 100 to reduce the pH of the contents of reactor 100 to less than 6, less than 5, less than 4, less than 3, less than 2, less than 1, or any range including and / or between any two of these values.

[0056] In an embodiment, separator 110 can be a decanter, a stacked disc centrifuge, a horizontal centrifuge, a settling tank, a 3-phase separator, or other liquid-liquid separation device known to those skilled in the art. In an embodiment, reactor 100 and separator 110 can be the same process unit.

[0057] In embodiments, a heat exchanger or other temperature reduction device known to those skilled in the art is placed between reactor 100 and separator 110 to reduce the temperature of stream 105 to facilitate separation of streams 111 and 112 .

[0058] In some embodiments, increasing the residence time in reactor 100 can be used to control the extent of chlorine removal. This can be accomplished by controlling the level in a CSTR, the cycle time in a batch reactor, or the flow rate through a liquid-liquid contactor reactor.

[0059] In some embodiments, light phase 111 has monoglycerides, diglycerides, triglycerides, and free fatty acids. In some embodiments, light phase 111 has a glyceride content greater than 20 wt% and a WIS chlorine content less than 5 wppm.

[0060]

[0066] The present technology thus generally described will be more readily understood by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present technology. Example

[0061] Example 1. Reduction of WIS chlorine, impurities in used cooking oil using a non-catalytic hydrolysis reaction

[0062] The used cooking oil samples obtained from each commercial restaurant in the United States were merged and pre-treatment process was performed before the hydrolysis reaction. The UCO pre-treatment process consists of the following steps: acidification, shear mixing, neutralization, centrifugation, filtration and drying. UCO was placed in a beaker and stirred on a hot plate maintained at 80°C, and a gear pump (Cole-Parmer 75211-10 Micropump) was used to continuously meter it out from the beaker at 44mL / min. Then, this oil was merged with a citric acid aqueous solution (9.89 weight %, in deionized water) metered at 1.38mL / min using a piston pump (Eldex Optos 2HM). UCO and citric acid aqueous solution were mixed in a beaker placed on a hot plate to maintain a liquid temperature of 60°C. Mixing was provided by a high shear mixer (Silverson L5M-A) operated at 1800RPM. The liquid level in the beaker was set to achieve an average residence time of about 22 minutes. A second gear pump was used to meter the flow rate out of the beaker to maintain a constant liquid level. The UCO citric acid aqueous solution mixture was contacted with an aqueous sodium hydroxide solution (0.98% by weight in deionized water) metered at 1.24 mL / min using a peristaltic pump (Ismatec 78017-07) to generate a neutralized composition. The neutralized UCO was pumped into a continuous centrifugal separator (CINC V-02) maintained at 60°C and operated at 5700 RPM. The heavy phase overflow weir was adjusted to minimize water in the light phase. The light phase obtained by centrifugation was then filtered in batches in a pressurized 1 L filter assembly (Millipore YT30142 HW) at a flow rate of 50 mL / min using a syringe pump (Teledyne 260D). The filter feed oil was pumped from the flask onto a stirring hot plate, maintaining the liquid temperature at 60°C. The filter contains the following layers from the bottom: mesh support and metal mesh, filter paper (Whatman cellulose grade 5), diatomaceous earth and silica hydrogel (WR Grace Trisyl 300). When the pressure difference reaches 80 PSI, the pump is stopped and the filtered oil is purged with nitrogen. As a final processing step, the filtered oil is dried on a stirred hot plate using a vacuum bottle, the liquid is maintained at about 95° C., and a vacuum pump is used to maintain a pressure of about 25 inches of mercury. The removed moisture is collected in a cold trap. The UCO properties after pretreatment are shown in Table 2.

[0063] Then in a 1L 316 stainless steel stirred reactor (Autoclave Engineers EZE-Seal reactor system), a batch hydrolysis reaction was carried out using 405.36g of deionized water and 376.84g of treated used cooking oil. First, the water was placed in the reactor, which was then sealed and pressurized to about 800PSIG with nitrogen. This pressure was selected so that it was sufficiently above the minimum pressure required to keep the water as a liquid at a reaction temperature of 260°C. The magnetic drive mixer was set to about 1300RPM, and a 1200W electric heater was set to maintain the internal liquid temperature at 260°C. Once the water was heated to the desired reaction temperature (260°C), the pressure accumulated due to the heating was vented to return the reactor internal pressure to about 800PSIG. The pretreated UCO was poured into a separate, isolated 316 stainless steel feed barrel (500mL), which was maintained at about 60°C by means of an electric heating belt. The feed cylinder was pressurized with nitrogen to a pressure above that of the 1 L reactor (approximately 1000 PSIG) and then loaded into the reactor by opening a valve connected to a dip tube terminating inside the reactor directed to a mixer element. After the feed was added to the reactor, the reactor pressure was approximately 1000 PSIG and a timer was started to indicate the start of the reaction. The reaction temperature dropped momentarily to approximately 248°C (indicating successful addition of the feed to the reactor) but was quickly heated back to the set point temperature. Liquid samples were periodically removed from the reactor by opening a needle valve connected to a dip tube extending into the reactor (which initiated outflow from the reactor due to the pressure differential from the reactor conditions to atmospheric pressure). The sample tube flowed through the inner tube of a tube-in-tube heat exchanger with a larger diameter outer tube having domestic water flowing countercurrently therethrough. As the sampling procedure reduced the internal pressure in the reactor, the nitrogen supply valve was periodically opened to allow flow into the reactor to maintain approximately 1000 PSIG.

[0064] After pretreated UCO was loaded into the reactor, reactor samples were collected at 3, 7, 11, 16, 30, 45, 360 minutes. Subsequently, all samples pushed out of the reactor were washed with deionized water (about 5 mL of deionized water was added to the 20 mL sample) and separated in a laboratory centrifuge (Ample Scientific, Champion F-33D) operated at 2800 RPM for 3 minutes. The centrifugal light phase was removed by pipette and considered to be a water-insoluble (WIS) reaction product. According to the method shown in Table 3, additional analysis of the product was performed at the following sampling times (in minutes): 3, 7, 11, 16, 30, 45 and 360. The sample at 360 minutes represented the final reaction product after completing the experiment.

[0065] Table 2. Pretreated used cooking oil properties

[0066]

[0067]

[0068] Table 3. Properties of hydrolyzed used cooking oil as a function of reaction time

[0069]

[0070]

[0071] As shown in Table 3, the reduction in WIS chlorine relative to the pretreated UCO (Table 2) was a 46% reduction (12.27 PPM) within 7 minutes and a 98.9% reduction by the end of the reaction.

[0072] Upon further analysis of the data presented in Table 3, it was surprisingly observed that the reduction in bound glycerol occurred at a much slower rate than the reduction in WIS chlorine. From the concentration data shown in Table 3, the moles of chlorine were calculated by multiplying the concentration by the total mass of the sample and then dividing by the molar mass of chlorine (35.45 g / mol). Similarly, the moles of bound glycerol were calculated by multiplying each concentration of monoglycerides, diglycerides, and triglycerides shown in Table 3 by the sample mass and then dividing by the molar mass of monoolein (356.54 g / mol), diolein (620.99 g / mol), and triolein (885.43 g / mol), respectively. Each mole of monoglycerides, diglycerides, and triglycerides represents one mole of bound glycerol.

[0073] Figure 7 Describes the total number of moles of chlorine (y-axis) versus the total number of moles of bound glycerol (x-axis) as the reaction proceeds. The solid straight line represents the hypothetical change in WIS chlorine (if it is hydrolyzed in proportion) relative to bound glycerol, while the arc-dashed line represents the actual change in chlorine measured by the experiment relative to bound glycerol. Without being bound by theory, if the reduction of chlorine follows the reaction network shown in Figure 5, the actual results should fall on or above the solid line, indicating that WIS chlorine is removed as MCPD together with free glycerol through complete hydrolysis of glycerides. However, because the arc-dashed line, representing the actual experimental results, is below the theoretical solid line, the data surprisingly show that, as shown in Figure 4, direct hydrolysis of chlorine by MCPD is the main reaction. Therefore, complete (i.e., near-theoretical) hydrolysis is not required to achieve meaningful dechlorination of lipids. For example, an 88% reduction in the number of moles of WIS chlorine was achieved, while only 33% of the bound glycerol was removed.

[0074] Another measure of the relative selectivity of chlorine removal versus glycerol release is the conversion of total glycerides. Starting with a total glyceride content of 70% (the sum of monoglycerides, diglycerides, and triglycerides in Table 2), the results for this example summarized in Table 3 show that a WIS chlorine level of 2.71 ppm (an 88% reduction in WIS chlorine) was achieved, but with only 56% glyceride conversion (see results for 30 minutes reaction time in Table 3).

[0075] Example 2. Reduction of WIS Chlorine in Used Cooking Oil Using a Non-Catalytic Hydrolysis Reaction

[0076] In this example, the same pre-processed UCO as in Example 1 was subjected to the same conditions as Example 1, but with a changed sampling frequency, to produce the results shown in Table 4.

[0077] Table 4. Properties of hydrolyzed used cooking oil as a function of reaction time

[0078]

[0079] As shown in Table 4, the results are similar to those shown in Table 3 of Example 1. In this example, after 15 minutes, the WIS chlorine was reduced by 39.4% (13.66 PPM), and after 300 minutes, the chlorine was reduced by 98.6% (0.33 PPM).

[0080] Example 3. Reduction of WIS Chlorine in Used Cooking Oil Using Acid-Catalyzed Hydrolysis

[0081] In a 1L 316 stainless steel stirred reactor (Parr Instrument Company, 4525 benchtop reactor system), a batch hydrolysis reaction was carried out using 316.75 g of deionized water, 268.6 g of the pretreated UCO described in Example 1 and Table 1, and 10.93 g of sulfuric acid (95 wt % in water). The water, pretreated UCO, and sulfuric acid were added to the reactor, which was then sealed. The 1 / 8 hp magnetic drive mixer was turned on to approximately 25%, and a 1000 W electric heater (which is part of the Parr 4525 reactor system) was set to maintain an internal temperature of 204° C. The internal temperature was maintained at a set point of 204° C. by an external temperature control unit (Parr Instrument Company, 4848 reactor controller). No cooling water was used for temperature control. The reaction pressure was the equilibrium pressure of the reactor contents at 204° C., which was expected to be approximately 230-235 PSIG. The reaction mixture took about 1 hour to reach the desired reaction temperature of 204° C., at which point the first sample could be obtained. A 1 / 2" OD sample tube (316 stainless steel) with a volume of approximately 20 mL was assembled with needle valves on both ends. The bottom needle valve was opened to the atmosphere, and the top needle valve was connected to a dip tube on the reactor using 1 / 4" tubing; the dip tube terminated near the bottom of the reactor. The sample tube was placed in an isolated open top container with domestic water to cool the sample before processing. When the top needle valve was open, the pressure differential between the reactor and the sample tube (at atmospheric pressure) would cause the reactor material to flow into the sample tube. After a period of allowing cooling, the sample tube was removed from the water bath, and the bottom needle valve was slowly opened to depressurize the sample tube and collect the sample. The collected sample was then washed with deionized water (approximately 5 mL of deionized water was added to the 20 mL sample) and separated in a laboratory centrifuge (Ample Scientific, Champion F-33D) operated at 2800 RPM for 3 minutes. After this centrifugation step, the light phase oil was removed by pipette and was considered to be the water-insoluble (WIS) reaction product. The product was subjected to additional analysis according to the method shown in Table 5 for the following sampling times (in hours): 1. 2, 3, 4, 5, 6. The 6 hour sample represented the end of the reaction.

[0082] Table 5. Properties of acid hydrolyzed used cooking oil as a function of reaction time

[0083]

[0084] As shown in Table 5, the final WIS chlorine value was 3.76 PPM, which was reduced by 83.5% from the initial value (22.85 PPM as shown in Table 2).

[0085] Example 4. Reduction of WIS Chlorine in Used Cooking Oil Using a Non-Catalytic Hydrolysis Reaction

[0086] In the 1L 316 stainless steel stirred reactor described in Example 3, an intermittent hydrolysis reaction was carried out using 330.55g of deionized water and 278.43g of the pretreated UCO described in Example 1. The water and pretreated UCO were added to the reactor and then sealed. The 1 / 8hp magnetic drive mixer was turned on to about 25%, and the 1000W electric heater (which is part of the Parr 4525 reactor system) was set to 260°C (based on internal temperature measurement). The internal temperature was maintained at a set point of 260°C by an external temperature control unit (Parr Instrument Company, 4848 Reactor Controller). No cooling water was used for temperature control. The reaction pressure was the equilibrium pressure of the reactor contents at 260°C, which was expected to be about 650PSIG. Compared with Example 3, the reaction mixture took a little longer to reach the set point, but after 1 hour of reaction, the first sample was still obtained, at which time the temperature was about 235°C. In this example, the sampling and water washing procedures for the samples were the same as those described in Example 3. According to the method shown in Table 6, additional analyses were performed on the product for the following sampling times (in hours): 1.2, 3, 6 and 7.

[0087] Table 6. Properties of hydrolyzed used cooking oil as a function of reaction time

[0088]

[0089]

[0090] Compared to Table 5 of Example 3, where the hydrolysis reaction was catalyzed with sulfuric acid and conducted at a lower temperature of 204° C., Table 6 demonstrates improved WIS chlorine reduction. After 1 hour, WIS chlorine was reduced by 57.9% (9.63 PPM), and after 3 hours, WIS chlorine was reduced by 99.6% (0.10 PPM).

[0091] Thus, it can be seen that according to the present invention, a highly advantageous method for removing contaminants from fats, oils and greases is provided. While the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it will be apparent to those skilled in the art that the invention is not limited to the disclosed embodiments and that numerous modifications and equivalent arrangements are possible within the scope of the invention, the scope of the invention being consistent with the broadest interpretation of the appended claims so as to encompass all equivalent structures and products.

Claims

1. A method for reducing the chloride content of a lipid raw material, comprising the steps of: Feeding a lipid raw material having a chloride content greater than 5 ppm into a reactor; contacting the lipid material with an aqueous stream; combining the lipid feedstock and the aqueous stream to produce a mixed effluent; as well as The mixed effluent is separated into a chlorine-reduced light phase and a chlorine-enriched heavy phase.

2. The method of claim 1, wherein the lipid feedstock and the water stream are mixed at a temperature between about 450-550°F.

3. The method of claim 1, wherein the chloride content of the lipid raw material is greater than 10 ppm.

4. The method of claim 1, wherein the chloride content of the lipid raw material is greater than 15 ppm.

5. The method of claim 1, wherein the chloride content of the lipid raw material is greater than 20 ppm.

6. The method of claim 1, wherein the chloride-reduced light phase has a chloride content that is less than 60% of the chloride content of the lipid raw material.

7. The method of claim 1, wherein the chloride-reduced light phase has a chloride content that is less than 50% of the chloride content of the lipid raw material.

8. The method of claim 1, wherein the chloride-reduced light phase has a chloride content that is less than 20% of the chloride content of the lipid raw material.

9. The method of claim 1, wherein the chlorine content is water-insoluble chlorine.

10. The process of claim 1 wherein the chlorine reduced light phase has a reduction in moles of bound glycerol that is less than 50% of the reduction in moles of chlorine.

11. The method of claim 1 further comprising subjecting the chlorine-reduced light phase to a hydrotreating process to produce renewable hydrocarbons.

12. The method of claim 1, wherein the total glycerides (sum of mono-, di- and tri-glycerides) is at least 18 wt%.

13. A method for removing water-insoluble (WIS) chlorine from a lipid material, comprising the steps of: feeding the lipid raw material into a reactor; contacting the lipid feedstock with an aqueous stream at a temperature between 450°F and 550°F to produce a mixed effluent; as well as separating the mixed effluent into a chlorine-reduced light phase and a chlorine-enriched heavy phase; wherein the lipid feedstock has a total glyceride content of less than 90 wt. % and a WIS chlorine content of greater than 10 wppm, the reactor is operated to convert less than 70% of the glycerides, and the chlorine-reduced light phase has a WIS chlorine content of less than 5 wppm.

14. The process of claim 13, wherein the chlorine-reduced light phase has a glyceride content greater than 18% by weight.

15. A method for reducing the chloride content of a lipid raw material, comprising the steps of: Feeding a lipid raw material having a chloride content greater than 5 ppm into a reactor; contacting the lipid material with an aqueous stream; combining the lipid feedstock and the aqueous stream to produce a mixed effluent; separating the mixed effluent into a chlorine-reduced light phase and a chlorine-enriched heavy phase; as well as The chlorine-reduced light phase is subjected to a hydroprocessing process to produce renewable hydrocarbons.

16. The method of claim 15, wherein the lipid feedstock has a total glyceride content of less than 90 wt.% and a WIS chlorine content of greater than 10 wppm, the reactor is operated to convert less than 70% of the glycerides, and the chlorine-reduced light phase has a WIS chlorine content of less than 5 wppm.

17. The method of claim 15, wherein the chloride content of the lipid material is greater than 10 ppm.

18. The method of claim 15, wherein the chloride content of the lipid material is greater than 15 ppm.

19. The method of claim 15, wherein the chloride-reduced light phase has a chloride content that is less than 60% of the chloride content of the lipid raw material.

20. The method of claim 15, wherein the chloride-reduced light phase has a chloride content that is less than 50% of the chloride content of the lipid raw material.

Images