Method for treating a lipid-matrix based feedstock from renewable sources

Abstract

The present invention relates to a method for treating a lipid matrix-based feedstock from renewable sources. The method comprises the steps of: i. providing the lipid matrix-based feedstock comprising contaminants; ii. providing a polyol into the feedstock by: a. adding the polyol to the feedstock, b. forming the polyol in the feedstock by chemical or enzymatic reaction, such as by enzymatic hydrolysis by adding water and an enzyme to the feedstock, or c. using both a) and b); and iii. polyol-conditioning the feedstock by reacting the provided polyol with the feedstock; and iv. purifying the polyol-conditioned feedstock from the step by iii) by using further refining techniques. By the method it is possible to remove contaminants, which are normally difficult to remove with conventional refining techniques. Thereby a lower level of contaminants can be obtained in the purified feedstock by the present method.

Description

[0001] Method for treating a lipid-matrix based feedstock from renewable sources

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method for treating a lipid-matrix based feedstock from renewable sources, such as, for example low-quality oils and fats or blends thereof that that are of difficult processability with the standard refining techniques, and generally unfit for use as feed or food. The method provides a purified feedstock suitable for further use as a source of biofuel or HVO production, and the scope is defined in the appended claims.

[0004] BACKGROUND

[0005] The population is getting larger around the globe, and the rapid increase of population elevates the complexity on keeping its existence in a harmonic and less harmful relationship with the rest of the planet. This synergy balance is the leading point for the constant search for renewable sources, including fuel. There is a need to replace the largely used petroleum-based fuels, which increase the harm related to greenhouse gas emission. Technologies available to materialize this solution, such as Hydrotreating Vegetable Oil (HVO) are getting more attention and expanding the alternatives of how to handle renewable sources for raw materials.

[0006] With this real necessity for sustainability, the market has brought the dilemma of how vulnerable and sensitive it is to migrate sources that once were used to feed people now to transportation sector. The most critical point about the redirection of resources is mainly related to the dimension of consumption to each sector. Taking USA as reference as one of the biggest consumption countries for vegetable oils, 22.9 million tons of vegetable oils were consumed in 2018, and the projection for 2026 could reach 32.9 million tons, according to Fortune Business Insight report. According to U.S. Energy Information Administration in 2021 distillate fuel consumption by the U.S. transportation sector, which is essentially diesel fuel, was about 142 million tons. For that matter, alternative sources of lipid matrix raw material that cannot be used for edible purposes are essential to compensate for such high volume for fuel sector while ensuring that sources for food will be kept within its real purpose.

[0007] Some examples of alternative lipid matrix sources, that are renewable, include Used Cooking Oil (UCO), Palm Oil Mill Effluent (POME), Animal Fats, Distilled Corn Oil, Brown and Yellow Grease, etc. The challenge for these sources is that the level of contaminants like phosphorus and other elements (Ca, Fe, K, Mg, K, Si) has a high impact for HVO process, due to the “poisoning” or deactivation of a catalyst in the hydrotreatment step. Current technologies available industrially can mitigate partially the content for the described contaminants, such as for instance, standard refining techniques including degumming and bleaching process. However, mitigation requires high spent of utility and chemicals, while still not being able to achieve the proper level required for HVO industry, which is around few milligrams of each element per kg of pre-treated oil / fat. A mass transference separation process, known in the field as FFA (free fatty acids) stripping, can be applied in a last step of physical refining combined with hydrolysis process as an alternative method to select only the lipid fraction containing almost pure FFA. The process follows the same refining techniques for degumming and bleaching, sometimes more than once, in order to lower the contaminants to a suitable level for the following steps. In the sequence, hydrolysis process takes place to separate the fatty acids from the glycerol, continuing to the column for the stripping process. It is not always possible to decrease the amount of the contaminants from the lipid matrix to reach the stripping column, so the solution has considerable limitations on flexibility. Still, even in the cases where the solution works, there is a relatively high investment for operational costs. Last but not least, the product obtained is close to 100% FFA, raising metallurgical concerns.

[0008] As previously mentioned, other side problems expected from alternative lipid matrix raw materials can be associated with concerns relating to high FFA-content and both organic and inorganic chlorides The higher the content for those components is, the more complex and expensive the metal alloy composition will be required to avoid problems in the refinery process. It is known that for inorganic chlorides, a simple washing step included in the degumming process may be sufficient to mitigate more than 90% of their initial content. EP2097496 discloses an example of a process dealing with the high FFA content mitigation. WO 2021 / 213991 discloses a purifying process in which contaminants, such as P, Na, K, Mg, Ca and Fe are removed by thermal treatment in combination with one or more standard refining technologies, and in which the thermal treatment does not lower the content of FFA. Further, US20140020282A1 discloses a method for biodiesel production, in which glycerolysis is used downstream of degumming and physical refining steps to convert FFA to single methyl ester (SME). Further prior art is disclosed by WO2023 / 239914. The document discloses hydrodeoxygenation of a feedstock by using polyol treatment in an esterification reactor to provide an esterification product. The reaction is performed in high temperature and low pressure.

[0009] However, despite technologies for purifying the low-quality renewable raw materials, there is still room for improvements. Especially, there is an increased desire to decrease the content of organic chlorine compounds in an efficient and economical way.

[0010] SUMMARY OF THE INVENTION

[0011] Even though there are available technologies for the purifying of lipid-matrix based feedstocks of difficult processability and / or low quality so that they obtain appropriate quality to be further used as a source of feedstock for biofuel, there is still a need to improve the purifying processes to reduce the content of organic chlorine compounds while the content of P, Na, K, Mg, Ca and Fe and FFA is additionally decreased in these feedstocks. There is currently no efficient and economic industrial technology available to significantly reduce the content of organic chlorines from the feedstocks. Conventional, standard techniques of refining cannot always deal with the additional problem with high free fatty acid (FFA)-content (>5%) in raw materials, which can bring complications due to the leaching of the mineral elements present in the material composition to the adsorbents used in a bleaching step. In such conditions, it is often necessary to choose what to mitigate by using bleaching process. In the art, there are thus various methods for purification of feedstock. However, feedstock that contains impurities in molecular structures with physical-chemical properties similar to the lipid matrix, may not be sufficiently purified by techniques known in the art to a level of impurities allowing it to be used as a source of fuel. Present invention solves this problem by the method as disclosed herein, thereby allowing use of a feedstock that would normally be seen as uneconomical or unsuitable for purification.

[0012] Thus, in view of the problems above, it is an objective with the present invention to provide a method for treating feedstocks containing impurities of a character that currently available technologies and methods in the field are not able to remove to a degree that is prescribed as an appropriate quality for further use as a source of biofuel or HVO production. The impurities in such feedstocks, even in relatively low concentrations, are not removed to target levels by solely using conventional and commercially available refining or conditioning, such as degumming, bleaching or both. However, the lipid-matrix based material treated according to the present method will, for example, be a suitable feedstock for specific hydrogenation processes yielding to high quality biofuel or renewable diesel. Consequently, the present technology permits the recycling of waste materials into a valuable high-quality fuel. The purified lipid-matrix based material may be suitable for other oleo-chemical processes.

[0013] The present invention thus relates to a method for treating a lipid matrix-based feedstock from renewable sources as defined in the appended claims. The method comprises the steps of: i. providing the lipid matrix-based feedstock comprising contaminants, ii. providing a polyol into the feedstock by: a. adding the polyol to the feedstock in an amount from 0.5 to 50% by weight of the feedstock, b. forming the polyol in the feedstock by chemical or enzymatic reaction, such as by enzymatic hydrolysis by adding water and an enzyme to the feedstock, or c. using both a) and b); and iii. polyol-conditioning the lipid matrix-based feedstock by reacting the provided polyol with the lipid matrix-based feedstock, iv. purifying the polyol-conditioned feedstock from the step by iii) by further refining techniques.

[0014] It has thus been surprisingly noted that by providing a polyol, such as glycerol, to the lipid-matrix based feedstock to initiate polyol-conditioning reaction upstream of using conventional refining techniques, such as acid conditioning, alkali conditioning, (full / partial) neutralization, enzymatic conditioning, water conditioning, separation, adsorption, and / or filtration, considerably reduces impurities in the lipid-matrix based feedstock.

[0015] The polyol-conditioning may be carried out until necessary or determined changes in the properties of the contaminants are obtained in the purifying step iv). Thus, feedback from the further refining techniques in step iv) may be used to alter the conditions in the polyol- conditioning step to obtain the targeted necessary properties.

[0016] In the method the conditions for the polyol-conditioning step may vary. The polyol- conditioning in the step iii) may be performed at a temperature from 100 to 300°C, or from 150 to 250°C, or from 180 to 220°C, or from 190 to 210°C, or about 200°C.

[0017] During the polyol-conditioning a residence time for the reaction may vary from 10 to 240 minutes, or from 20 to 200 minutes, or from 30 to 150 minutes, or from 30 to 120 minutes, or about 90 minutes.

[0018] The polyol concentration in the feedstock can vary from 1-50% or 5 to 30% by weight of the feedstock. The pressure conditions are preferably from 1-50 bara (absolute pressure), or from 5-15 bara. It has been surprisingly noted that the content of organic chlorine compounds can be considerably reduced when using pressurized conditions instead of vacuum. This is an unexpected huge advantage with the present process over the processes using vacuum conditions.

[0019] Generally, in the conditions above, it can be assured that reactions during polyol- conditioning take place in an optimized manner. Further, it has been noted that the content of undesired components can be decreased using pressurized conditions during the reaction. Especially, it has been surprisingly noted that the content of organic chlorine can be considerably decreased compared to methods in vacuum conditions. This is a great advantage, since it has been one of the big challenges in industry to provide low organic chlorine content in feedstocks of difficult processability.

[0020] The polyol-conditioning in the step iii) may be carried out until the properties of the contaminants are changed to a determined level and such that removal of the contaminants by separation can be performed. In this manner, the impurities may be effectively removed from the feedstock.

[0021] The method may comprise the step ii) b), which may comprise the steps of adjusting the water content of the feedstock to 1-10% by weight of the feedstock to provide an aqueous feedstock and adjusting the pH of the aqueous phase to an acidic range, such as pH from 4 - 6.5. The method may further comprise keeping the aqueous feedstock under stirring until enzymatic hydrolysis activity achieves minimum 150LCLU-SL / g of enzyme dosed. In this way it can be assured that sufficient amount of the polyol, such as glycerol, is formed in the reaction.

[0022] In the method, the surplus of the polyol formed / added in the previous steps and not used in the polyol-condition step, is collected and re-used. In this way the amount of process waste can be limited.

[0023] The method may comprise removing water and / or polyol by separation from the feedstock upstream or downstream of the polyol-conditioning step and / or downstream of the purifying step using conventional techniques. For example, the feedstock may have a lipid- matrix having a lower density than an aqueous phase in the feedstock. In this way the separation can be performed by means of centrifugal separation, such as by means of a highspeed separator or a decanter. The centrifugal separators provide effective separation of the different phases, whereby the purification may be further improved. Alternatively, static separators can be used.

[0024] The polyol-conditioned feedstock from the step iii) may be cooled to a temperature of 60-120°C, or to 60-80°C before or during the step iv). By the cooling it is for example possible to obtain improved separation.

[0025] The refining in the step iv) may comprise acid conditioning, alkali conditioning, full or partial neutralization, enzymatic conditioning, water conditioning, separation, adsorption, and / or filtration. These refining / purifying techniques are conventional and may be already present in many refineries. By including the upstream process of the present invention, the existing refining equipment may be maintained in the factory. Thus, the existing process needs not to be changed essentially, when the polyol-conditioning upstream process is added. This simplifies the modification of the process and reduces costs.

[0026] The refining in step iv) may comprise acid conditioning, which may comprise adding an acid, such as citric acid, phosphoric acid to the polyol-conditioned feedstock. Alternatively, the refining in step iv) may comprise alkali conditioning, which may comprise adding an alkali water solution, such as aqueous sodium hydroxide and / or potassium hydroxide, to the polyol- conditioned feedstock. The alkali conditioning with the alkali water solution addition may take place after the acid conditioning to neutralize stoichiometrically, fully or partially, the acid dosed. Further, the step iv) may comprise neutralizing stoichiometrically, fully or partially, free fatty acids (FFA) contained in the polyol-conditioned feedstock. According to a further example, the step iv) may comprise enzymatic conditioning. This may comprise adding a phospholipase enzyme, such as phospholipase A1 , or phospholipase C, to the polyol-conditioned feedstock. Additionally, or alternatively, the step iv) may comprise water conditioning, which may be performed by adjusting the water content of the polyol, acid, alkali, neutralization or enzyme conditioned feedstock, to a content of 0.05% to 10% by weight of the conditioned feedstock and separating the purified feedstock from the conditioned feedstock mixture. Further, the step iv) may comprise adsorption by using an adsorbent, such as bleaching earth or silica.

[0027] According to a variant, the polyol added in the step ii)a may comprise or consist of glycerol. The purity of the glycerol may be over 90%, or 92-97%.

[0028] The method may comprise the step ii) a) when the feedstock comprises an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm, a phosphorous content (P) of more than 5 ppm and a chloride in the organic form of more than 10 ppm.

[0029] The method may comprise the step ii) b) when the feedstock comprises an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm and a phosphorous content (P) of more than 5 ppm.

[0030] Further aspects of the invention are apparent from the dependent claims and the description.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] Further objects, features and advantages will appear from the following detailed description of several embodiments of the invention with reference to the drawings, in which:

[0033] Fig. 1 shows a flow scheme schematically showing the steps of the present method;

[0034] Fig. 2 shows a flow scheme in which the alternative of providing polyol by polyol addition is shown;

[0035] Fig. 3 shows a flow scheme in which the alternative of providing polyol by forming polyol by chemical or enzymatic reaction is shown;

[0036] The invention will be further explained in the following detailed description with reference to the appended drawings.

[0037] DETAILED DESCRIPTION

[0038] The present invention relates to a method of treating by purification of a lipid-matrix based feedstock, which after purification is suitable for use as a fuel.

[0039] By the “lipid-matrix based feedstock” is in this context meant a feedstock containing a lipid matrix, i.e. a matrix of any of a large group of organic compounds that comprise esters of fatty acids (lipids, such as oils, fats and waxes) or closely related substances (compound lipids, such as phospholipids or phenolic lipids), which are usually insoluble in water but soluble in alcohol and other organic solvents.

[0040] By “polyol” is meant an alcohol containing at least two hydroxyl groups.

[0041] By the term “polyol-conditioning” is in this context meant a reaction of the polyol with the feedstock containing the contaminants. During the reaction, the properties of the contaminants are changed. For example, the contaminants may be converted into molecules extractable into an aqueous phase. Alternatively, the contaminants may be converted to be suitable to be adsorbed. The polyol can be added or formed during enzymatic or chemical reactions and is subjected to the reaction with the contaminants. The reaction may occur at elevated temperatures, with a controlled residence time and pressure and with a concentration of polyol / s added, which lead to a change of the contaminant properties in the lipid matrix to a suitable chemical structure for removal with the process applied downstream. Due to the high complexity of the lipid matrix mainly in the feedstocks of difficult processability, besides partial glycerides and free fatty acid as main components, several species of the most various group of organic molecules such as alcohol, ketones and aldehydes influence the countless chemical mechanisms taking place during the polyol conditioning. Some examples are acid migration, esterification, oxidation, etc. It is believed that these reactions (but not limited to) are the mechanisms responsible for changing the contaminants molecular structure and making them suitable for removal with the process applied downstream.

[0042] By “refining techniques” or “purifying techniques” are in this context meant conventional refining techniques to remove contaminants or impurities from the oil or feedstock. These techniques comprise different types of conditioning processes such as acid conditioning, alkali conditioning, full or partial neutralization, enzymatic conditioning, water conditioning, separation, adsorption, and / or filtration.

[0043] Neutralization is a process where an alkali aqueous solution is used to neutralize partially, or the total amount of free fatty acids present in a feedstock, and in this process some contaminants are also extracted or made soluble and removable on the process downstream.

[0044] Acid, alkali, enzymatic and water conditioning are processes in which the lipid matrix is mixed with an aqueous solution of the respective chemicals or enzyme in order to extract, or make the contaminants present in the lipid matrix soluble and removable on the process downstream. These processes, or the combination of them, are also known as a degumming process. In the degumming processes gums comprising e.g. lecithin, phospholipids and metals are removed. The gums have the function of being emulsifiers, which may render oil with high viscosity and / or difficult to separate e.g. by centrifugal separation or by filtration. An example of a way to perform degumming is treatment with acid, such as citric acid. With respect to acids, if citric acid is used the acid may be used in a concentration of 0.02 - 1% by weight of the reacted feedstock from which water and glycerol have been removed. Optionally, the acid dosed can be partially neutralized with caustic solution. The partial neutralization can range stoichiometrically from 5 - 100%. Thus, after the acid addition, the oil may be treated with base to neutralize the oil. Alternatively, the oil may be treated with a chelating agent, such as EDTA. Additional methods of degumming may include membrane degumming and enzymatic degumming. In enzymatic degumming phospholipids are hydrolyzed. Thus, generally in degumming impurities are removed by the addition of acid, and / or alkali, and / or enzymes and water. The separation of impurities may be performed by gravitational separation by e.g. centrifugation. Optionally, a certain amount of water may be added to the feedstock. The water may be capable of forming a separate phase with the impurities present in the feedstock. The amount of water may be 0.05 wt% to 10 wt%, 0.1 wt% to 5 wt%, 0.2 wt%, 0.5 wt% based on the weight of the treated feedstock to which the water is added.

[0045] Further examples of conventional purifying technologies include adsorption technology, which involves the use of a bleaching clay, earth, silica, or any material with adsorbent properties which can adsorbs impurities, such as pigments, metal and metalloids complex from the oils. The adsorbent may be normally filtered from the oil after adsorption process. In the vegetable oil industry, the adsorption process with bleaching earth is known as bleaching process.

[0046] However, as mentioned above, the traditional purifying technologies may not be sufficient for purifying the oil if the feedstock is of low quality. For example, in the different conditioning approaches described as part of degumming, the centrifugation may become difficult or even impossible if the content of emulsifying compounds, such as phospholipids, hydrolyzed lipids, is high and / or if the feedstock has a high density or viscosity after traditional degumming and / or bleaching operations. These may result in poor phase separation and high losses of feedstock. In the very specific case where the contaminants are in a molecular structure with properties similar to the lipid matrix, such as organic complex molecules with high lipophilic and apolar properties, the process may also become impossible. In the adsorption process adsorbents with limited adsorbent capacity are used and high impurity feedstock generally may become uneconomical to purify. The present method aims to solve these problems. It has a further benefit of the possibility to skip bleaching process and the additional step of filtration, thus minimizing the entrained feedstock, consequently losses and generation of waste material, which brings a critical environmental concern.

[0047] The lipid-matrix based feedstock that is treated with the present method is usually of a quality that it can serve as fuel or be used in further processes such as e.g. catalytic cracking without containing levels of impurities that cause disturbances in the functionality of an engine or deteriorate catalysts. The purified feedstock may also be further processed into various chemicals, such as bulk chemicals (e.g. polymers, solvents, solvent components and lubricants) or specialty chemicals (e.g. cosmetics and pharmaceuticals). The feedstock is not aimed for use as feed or food.

[0048] The lipid-matrix based feedstock can comprise or consist of animal-based oils or fats, such as fish-based oils or fats, vegetable-based oils or fats such as e.g. sludge palm oil and used cooking oil or oil used in deep frying, microbial or algae oils, free fatty acids, used or spent lubrication oils, or lipids containing phosphorous and / or metals. The feedstock may comprise or consist of any lipid matrix containing contaminants, such as phosphorous, organic chlorines and / or metals. Low quality animal fats (LQAF), which are not accepted to catalytic hydrotreatment process and have very high N, PE, metals, phosphorus contents may be used as the feedstock. Further examples of feedstocks include rapeseed oil, canola oil, colza oil, tall oil, sunflower oil, soybean oil, hemp oil, olive oil, linseed oil, cottonseed oil, mustard oil, palm oil, arachis oil, castor oil, coconut oil, distilled corn oil, oil recovered from spent bleaching earth, acid oil from soapstock splitting, oil recovered from effluent, gutter or sewage oil (GSO), animal fats such as suet, tallow, poultry, brown grease, yellow grease, blubber, recycled alimentary fats, starting materials produced by genetic engineering, and biological starting materials produced by microbes such as algae and bacteria. Examples may further include tall oil pitch or the residual bottom fraction from tall oil distillation processes.

[0049] The feedstocks that may be purified according to the method of the present disclosure are thus low-quality feedstocks. For example, gutter and / or sewage oil (GSO) may contain high levels of oligomers and organic chlorine, besides high level of P contaminants in molecular structures, and these are not suitable to be removed with conventional techniques. Further, palm mill effluent oil (POME), which is a waste oil extracted from palm oil mill processes, may have a very high iron content, thereby rendering low quality to the oil. Further, low quality vegetable oil (LQVO), is a group of vegetable oils with high level of oxidation and hydrolysis. The high level of oxidation and hydrolysis may be rendered by for example bad practices in extraction or storage or may be caused by byproducts from chemically aggressive processes.

[0050] Further, used cooking oil (UCO), is a group of waste oil with the presence of inorganic chloride and organic chlorine, as well as a considerable level of oxidation and hydrolysis. Further, a blend of used cooking oil and acid oil (BLEND), is a group of waste oil with the presence of high content of inorganic chloride and organic chlorine, as well as a high level of oxidation and hydrolysis.

[0051] The contaminants or impurities present in the feedstock may be of various character or origin. The feedstock may be a mixture of any of the above-mentioned examples of feedstock, and thus the impurities present in the feedstock may be of various character or origin. The impurities are such that they may be harmful in the process, e.g. they may poison or deactivate catalysts used in any further processing of the feedstock downstream of the process of present invention. Such further processes may be e.g. catalytic cracking, thermo-catalytic cracking, catalytic hydro treatment, fluid catalytic cracking, catalytic ketonization, catalytic esterification, or catalytic dehydration. The impurities may be of metallic origin such as elementary metals, organic chlorines, or for example phosphorous compounds and may be generally elements known as catalyst poison, which impact directly on aggression to the metallurgy of equipment composition in the downstream processes. The impurities may contain metals, organic chlorines and phosphorus in the form of phospholipids, soaps, salts or other organic complex species. Metal impurities that may be present in the feedstock may be e.g. alkali metals or alkali earth metals, such as sodium or potassium salts or magnesium or calcium salts or any compounds of said metals.

[0052] As mentioned above, the contaminants may have properties which make them difficult to be removed by the conventional refining techniques. According to the present invention, to improve the purification of the lipid-matrix based feedstock, the material is subjected to a polyol- conditioning upstream of conventional refining techniques such as acid conditioning, alkali conditioning, full or partial neutralization, enzymatic conditioning, water conditioning, separation, adsorption, and / or filtration. The polyol-conditioning may be performed at a temperature from 100 to 300°C, or from 150 to 250°C, or from 180 to 220°C, or from 190 to 210°C, or about 200 °C. A residence time may vary greatly, and may be from 10 to 240 minutes, or from 20 to 200 minutes, or from 30 to 150 minutes, or from 30 to 120 minutes, or about 90 minutes. The polyol concentration may be from 1-50% or 5 to 30% by weight of the feedstock. Suitable, the polyol- conditioning is performed at pressure conditions from 1-50 bar or from 5-15 bar. The reaction may be performed in a pressure reactor. The pressure may be achieved at least partly as a result of the gas phase composition formed by the vaporized molecules at due temperature of the pressure, in the pressure reactor. According to the present disclosure a pressure reactor is used so that the pressure can be controlled in a desirable way. According to the present disclosure, the use of an esterification reactor is not required, since esterification / re- esterification is not a target in the present process.

[0053] Vacuum pressure conditions are normally from 100-2000 mbara, or from 500 to 1500 mbara, or from 700 to 1100 mbara, but even though undesirable contaminants can be reduced, the organic chlorine content are not sufficiently reduced in vacuum conditions.

[0054] The polyol-conditioned feedstock can be cooled to a temperature suitable for the separation process (ideally from 60° - 95°C), and the separation process may take place to separate the different phases, mainly composed of the target lipid matrix to be purified as a lighter phase and the polyol dosed / formed as a heavier phase.

[0055] Sufficient contact between an added substance and feedstock should be enabled by any suitable method, by mixing before or during heating the mixture. Mixing can be done e.g. by stirring. Stirring may be achieved by conventional means such as e.g. mechanical stirring. Stirring may be done at 100 rpm, or 300 rpm, or 500 rpm, or 1000 rpm.

[0056] Water may be separated from the feedstock before initiating the method of the present invention. The feedstock may be filtered or separated by gravitational or centrifugal separation.

[0057] Depending on the aimed catalytic process there is specific target purification level of feedstock that should be gained in feedstock purification. The level of impurities (metals, P, N, organic Cl) tolerated by aimed catalytic process depends on process type and configuration, catalyst type, catalyst recycle and regeneration process and should be defined separately for each process. Impurities are removed in the form of e.g. salts of phosphates, sulphates, or any chemical structure hydrophilic or suitable to be extracted in the water phase.

[0058] Removal of the separate phase may take place by any method suitable for the specific application. Such methods are, but not limited to, filtration, phase-phase separation, centrifugation or decantation. The separation may also take place by use of several different types of separation techniques.

[0059] By the present method in which the feedstock is conditioned with the polyol before the conventional refining techniques are applied, the final content of contaminants is much lower than by only using the conventional techniques. Reference is now made to the appended drawings. Fig. 1 shows the main steps of the method with two different approaches “Route A” and “Route B”. In the method of Fig. 1 , the lipid matrix-based feedstock as exemplified above is used as a starting material. According to the invention, before performing any traditional purifying step, a polyol is provided to the feedstock by adding it to the feedstock as shown by Route A or by forming polyol / s in the feedstock by chemical and / or enzymatic reaction as show in in Fig. 1. The provided polyol is then reacted with the lipid matrix-based feedstock via polyol- conditioning, which occurs at a determined residence time, temperature, concentration of the polyol and / or pressure. The residence time, temperature, concentration of the polyol and / or pressure can be pre-determined or adjusted during the reaction. After the polyol-conditioning, the reacted feedstock can be cooled. Phase separation in which a lipid phase and an aqueous phase containing the contaminants may be performed. The polyol-conditioned feedstock is then forwarded to the conventional refining / conditioning steps including one of more of filtration, acid conditioning, alkali conditioning, enzymatic conditioning, neutralization, water conditioning, adsorption and / or further separation. As a result of the method, a purified feedstock, from which contaminants are at least partially removed, is obtained.

[0060] Reference is now made to Fig. 2, in which an example of the Route A option of carrying out the present method according is shown in more detail. As already shown and described in connection with Fig. 1 , a lipid matrix -based feedstock is provided. In the next step, glycerol is added to the feedstock as the polyol. When adding the glycerol, it can be added in an amount from 0.5 to 50% by weight of the feedstock. Thereby a mixture of the feedstock and glycerol as the polyol is provided. The provided glycerol is reacted with the lipid matrix-based feedstock via polyol-conditioning at a determined residence time, temperature, concentration of the polyol, and / or pressure. The polyol-conditioning is carried out until necessary or targeted changes in the contaminant’s properties are obtained and observed on the purifying process downstream. The admixture of polyol and the lipid matrix-based feedstock may be cooled and can optionally be separated so as to remove water. In the shown example in Fig. 2, the polyol-conditioned feedstock is the further conditioned or refined by acid and alkali conditioning and by further separation step to remove contaminants to obtain the purified feedstock. The option of Route A is especially useable when the feedstock contains contaminants having an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm, a phosphorous content (P) of more than 5 ppm and / or a chloride content, in the organic form of more than 10 ppm. A more detailed example of the steps in process “Route A” is described below: o providing a lipid matrix-based feedstock, o adding to the feedstock glycerol as polyol to a concentration from 0.5 - 50w / w%, o heating the admixture, to a temperature of 100°C - 300°C, o keeping the admixture under stir until necessary changes in the contaminants properties are observed in the process downstream, o keep the admixture below atmospheric pressure, from 100-2000 mbara, or from 500 to 1500 mbara (comparative examples), or under positive pressure 1 - 50 bara, or 1 -15 bara where the pressure will be the result of the gas phase composition formed by the vaporized molecules at due temperature of the pressure, in the pressure reactor, o optionally removing the water formed, o cooling the mixture to a temperature of 70 - 120°C, o optionally separating the polyol from the mixture as a heavy phase to obtain the polyol-conditioned feedstock as the light phase, and, o applying to the polyol-conditioned feedstock acid conditioning process, and, o optionally applying an alkali conditioning process, to a stoichiometric neutralization of the acid dosed in h) from 5 - 100%, o adjusting the water content in the feedstock to 0.05% to 10% wt o separating the light phase with the acid / alkali conditioned feedstock from the mixture to obtain a purified feedstock or perform water conditioning and further separation of the heavy phase.

[0061] Alternatively, the process may be carried out by Route B, especially when the feedstock comprises an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm and a phosphorous content (P) of more than 5 ppm. Fig. 3 shows the main steps of the method option “Route B”. As already shown and described in connection with Fig. 1 , a lipid matrix-based feedstock is provided. In the next step, enzymatic lipase splitting reaction is initiated to form or create glycerol to the feedstock as the polyol. Thereby a mixture of the feedstock and glycerol as the polyol is provided. The provided glycerol is reacted with the lipid matrix-based feedstock via polyol-conditioning at a determined residence time, temperature, concentration of the polyol, and / or pressure. The polyol-conditioning is carried out until necessary or targeted changes in the contaminant’s properties are obtained and observed on the purifying process downstream. The admixture of polyol and the lipid matrix-based feedstock may be cooled and can optionally be separated so as to remove water. In the example shown in Fig. 3, the polyol-conditioned feedstock is then further conditioned or refined by acid and alkali conditioning and by further separation steps to remove contaminants to obtain the purified feedstock. A more detailed example of the steps in process “Route B” is described below: o providing a lipid matrix-based feedstock, o heating the admixture, to a temperature of 60°C - 80°C, o adjusting feedstock water content to a concentration of 1 - 10%, o if necessary, adjust the pH of water in the heavy phase to a range of 4.0 - 6.5 o adding to the feedstock a lipase enzyme to a concentration from 50 - 1200ppmw o keeping the admixture under stir, for 15 - 240 minutes to form glycerol as polyol o heating the admixture to a temperature of 100°C - 300°C, o keeping the admixture under stir for 15 - 240 minutes, o optionally removing the water formed, o cooling the mixture to a temperature of 70 - 120°C, o optionally separating polyol from the mixture as a heavy phase to obtain the polyol- conditioned feedstock as the light phase, and, o applying to the polyol-conditioned feedstock acid conditioning process, and o optionally applying an alkali conditioning process to a stoichiometric neutralization of the acid dosed from 5 - 100%, o adjusting the water content in the conditioned mixture to 0.05% to 10% wt., o separating the lighter phase with the conditioned lipid matrix-based feedstock from the mixture to obtain a purified lipid matrix-based feedstock or, repeating step of water conditioning and further separation of the heavy phase.

[0062] The effects of the invention are now further described in the following practical examples and in the Table 1 below.

[0063] Examples

[0064] The process of the present invention was compared to the performance of conventional refining techniques. The examples show that by the present method in which the feedstock is conditioned with the polyol before the conventional refining techniques are applied, the final content of contaminants is much lower than by only using the conventional techniques.

[0065] Enzymatic Splitting Hydrolysis Lipase (EzHLip) (Route B)

[0066] Feedstock was preheated to 65°C. 3.0 wt-%, by weight of the feedstock, of pure water was added at 65°C with the aim of adjust the pH on the aqueous heavy phase between 4.8 - 6.0. Mixing was performed for 15 minutes with mixer (800 rpm). Lipase enzyme was dosed until enzymatic hydrolysis activity achieves minimum 150LCLU-SL / g of enzyme dosed, and the reaction was kept under mixing (800 rpm) for 120 min. Treated blend was heated to 80°C and a small fraction was collected to analyze FFA. Glycerol was formed as polyol during the enzymatic hydrolysis.

[0067] Glycerol as Polyol-conditioning (GYolC) (Route A)

[0068] Feedstock was dosed with glycerol as polyol at 5, 15 and 30% w / w% of the weight of the feedstock. The mixture was heated in a 1 liter stirred pressure reactor to an example temperature of 200°C , and held for 30 - 120 min under mixing 800 rpm. Higher temperature of for example 250°C could be alternatively used. The pressure in the system was exerted the reactor by means of partial pressure of the gas molecules formed or by positive pressure promoted with an external gas in the headspace. Optionally vacuum suction can be applied with a vacuum system. Pressure range can vary from 400mbara to 50bara. Then the polyol- conditioned feedstock was obtained. The reactor was cooled to ca. 95 °C and opened. Polyol- conditioned feedstock and glycerol sludge were centrifuged (batch mode in laboratory) for 3 min at 3000 rpm. When centrifuged, oils and fat fractions were carefully separated above glycerolwater phase. The polyol-conditioned feedstock was analyzed for impurities.

[0069] Pre-Acid Conditioning (Pre AciC)

[0070] Feedstock was preheated to 70°C. 2000 ppmw (dry basis) citric acid (CA, 25% concentration) was added to the feedstock at 70 °C. After acid addition, the blend was mixed for 15 minutes by a mixer (800 rpm). 5 wt-% of pure water was added at 70°C. Mixing was performed for 30 minutes with the mixer (800 rpm). Treated blend was centrifuged (batch mode in laboratory) with 3000 rpm for 3 minutes at 70°C. Oil and fat fractions were carefully separated above gums-water phase and the pre-acid conditioned feedstock was obtained. The pre-acid conditioned feedstock was analyzed for impurities.

[0071] Post-Acid Conditioning (Post AciC)

[0072] Feedstock was preheated to 95°C. 1000 ppmw (dry basis) citric acid (CA, 25% concentration) was added to feed at 95 °C. After acid addition, blend was mixed for 15 minutes by mixer (800 rpm). 7 wt-% of pure water was added at 95°C. Mixing was performed for 15 minutes with mixer (800 rpm). Treated blend was centrifuged (batch mode in laboratory) with 3000 rpm for 3 minutes at 70 °C. Oil and fat fractions were carefully separated above gums- water phase and the pre-acid conditioned feedstock was obtained. The pre-acid conditioned feedstock was analyzed for impurities

[0073] Acid / alkali conditioning (AciC / AlkC)

[0074] Feedstock was preheated to 70 °C. 2000 ppmw citric acid (CA, 25% concentration) was added to feed at 70°C. After acid addition, the blend was mixed for 15 minutes by mixer (800 rpm). 5 wt-% of pure water was added at 70°C. Following the water, 70% of the acid was neutralized stoichiometrically with caustic (lye, concentration 4%). Mixing was performed for 30 minutes with mixer (800 rpm). Treated blend was centrifuged (batch mode in laboratory) with 3000 rpm for 3 minutes at 70°C. Oil and fat fractions were carefully separated above gums- water phase and the acid / alkali conditioned feedstock was obtained. The centrifuged oil was analyzed for impurities. Enzymatic Conditioning (EzC)

[0075] Feedstock was preheated to 80°C. 2000 ppmw citric acid (CA, 25% concentration) was added to feedstock at 80 °C. After acid addition, the blend was mixed for 15 minutes by mixer (800 rpm). 3.5 wt-% of pure water was added at 80°C. Following the water, 45% of the acid was neutralized stoichiometrically with caustic (lye, concentration 4%) with the aim of adjust the pH on the aqueous heavy phase between 3.8 - 4.2. Mixing was performed for 15 minutes with mixer (800 rpm). PLA1 enzyme was dosed in a concentration of 50 ppmw, and the reaction was kept under mixing (800 rpm) for 120 min. Treated blend was heated to 80°C and then centrifuged (batch mode in laboratory) with 3000 rpm for 3 minutes at 80°C. Oil and fat fractions were carefully separated above the aqueous gums-water phase and the enzymatic conditioned feedstock was obtained. The centrifuged oil was analyzed for impurities.

[0076] Adsorption (Ads)

[0077] Feedstock was preheated to 100°C. Citric Acid (CA, 25% concentration) was added to feed at 100°C. After acid addition, blend was mixed for 15 minutes by mixer (800 rpm). 800 mbara vacuum suction was applied to the reactor, and 2 wt-% bleaching earth was dosed. Reaction is kept for 30 minutes by mixer (800rpm). The vacuum suction was increased to 200mbara, and the reaction kept by mixer (800rpm). Treated oil is filtered in a Bunchner filter, with a filter paper of 12pm and the adsorbed oil was obtained. The adsorbed oil was analyzed for impurities.

[0078] Example 1 : Treatment of gutter / sewage oil (GSO) by conventional refining techniques, and polyol-conditioning

[0079] A sample of oil recovered from gutter / sewage (GSO) was used as a feedstock. The content of impurities in the feeds are shown below in Table 1.

[0080] GSO was treated by different approaches of conditioning as explained above, pre-acid conditioning (Pre AciC), where the pH of the heavy phase is relatively low and acid / alkali conditioning (AciC / AlkC) where the pH of the heavy phase is relatively higher. Enzymatic conditioning (EzC) was also used as treatment.

[0081] For experiments, “Route A” polyol-conditioning was applied and glycerol as polyol sludge was separated by centrifuge (batch mode in laboratory) followed by acid / alkali conditioning. All the process are treated with the same conditions of post-acid conditioning (PostAciC) and adorption (Ads), except for the paths withPolyol Conditioning, in which adsorption process was not necessary.

[0082] Pre-acid conditioning (PreAciC) and acid / alkali conditioning (AciC / AlkC) attempts result in unsatisfactory purification of P, Org. Cl, Fe, Ca even when adsorption process was used as complementary process. In the case of some elements, adsorption presents worse figures as result of leaching of elements from the bleaching earth used, due to high concentrations of FFA. Enzymatic conditioning show relatively better results for Fe, Ca, Mg, and P, but only with the aid of adsorption process, and still cannot address P and the other impurities to desired level. Polyol-conditioning process followed by acid / alkali conditioning resulted in a significantly better purification result already after the first separation process in all parameters, except for Na, which is mainly related to the caustic addition. When polyol- conditioning is performed with lower amounts of glycerol as polyol present, and shorter period of retention time, results of Fe, Ca, Mg, Al, Na, and P are not impacted, however, the ability to remove Org. Chloride is impacted. This is also observed in the experiments in “Route B” where Fe, Ca, Mg, Al, Na, and P are removed to desired target, however Org. Chloride is not fully removed when enzymatic splitting hydrolysis lipase is applied to create glycerol as polyol, and consequently perform the polyol-conditioning.

[0083] For experiments in “Route B”, the enzymatic splitting hydrolysis lipase was performed with the same conditions. Regarding the polyol-conditioning, for the experiment with 1000mbara, centrifuge separation was used to separate the glycerol as polyol sludge before the acid / alkali conditioning, whereas in the experiment with 800mbara the separation was not applied after the polyol-conditioning, only after the conventional refining technique acid / alkali conditioning. This resulted in a slightly better result for the first design of parameters described but maintain still the results within the target for market specification for the second set of parameters.

[0084] Table 1 Example 2: Treatment of used cooking oil and acid oil blend (BLEND) by conventional refining techniques, and polyol-conditioning comparing pressure vs vacuum

[0085] A sample of used cooking oil and acid oil blend (BLEND) was used as a feedstock. The content of impurities in the feedstock is shown below in Table 2.

[0086] BLEND was treated by different approaches of conditioning using the parameters described above, where the combination of standard refining techniques (AciC / AlkC + PostAciC + Ads) was compared with the pre-step of polyol conditioning with different temperatures and pressure. For experiments, “Route A” polyol-conditioning was applied followed by acid / alkali conditioning. All the processes were treated with the same conditions of post-acid conditioning (PostAciC) and adorption (Ads), except for the paths with Polyol Conditioning, in which adsorption process was not necessary.

[0087] Acid / alkali conditioning (AciC / AlkC) attempts result in unsatisfactory purification of P, Org. Cl, Fe, Ca even when adsorption process was used as complementary process. In the case of some elements, adsorption presents worse figures as result of leaching elements from the bleaching earth used, due to high concentrations of FFA. Polyol-conditioning process followed by acid / alkali conditioning resulted in a significantly better purification result already after the first separation process in all parameters, except for Na, which is mainly related to the caustic addition. It is also observed that the overall ability to remove organic chlorine is improved by using higher pressure compared to vacuum conditions.

[0088] Table 2

[0089] The invention is not limited to the embodiments described above and shown on the drawings but can be supplemented and modified in any manner within the scope of the invention as defined by the enclosed claims.

Claims

CLAIMS1 . A method for treating a lipid matrix-based feedstock from renewable sources, the method comprising the steps of: i. providing the lipid matrix-based feedstock comprising contaminants; ii. providing a polyol into the feedstock by: a. adding the polyol to the feedstock, b. forming the polyol in the feedstock by chemical or enzymatic reaction, such as by enzymatic hydrolysis by adding water and an enzyme to the feedstock, or c. using both a) and b); and iii. polyol-conditioning the feedstock by reacting the provided polyol with the feedstock; and iv. purifying the polyol-conditioned feedstock from the step by iii) by using further refining techniques.

2. The method according to claim 1 , wherein the polyol-conditioning in the step iii) is performed at a temperature from 100 to 300°C, or from 150 to 250°C, or from 180 to 220°C, or from 190 to 210°C, or about 200 °C, and / or at a residence time from 10 to 240 minutes, or from 20 to 200 minutes, or from 30 to 150 minutes, or from 30 to 120 minutes, or about 90 minutes, and / or with the polyol concentration from 1-50% or 5 to 30% by weight of the feedstock.

3. The method according to claim 1 or 2, wherein the polyol-conditioning in the step iii) is performed at pressure conditions from 1 - 50 bara, or from 5 - 15 bara.

4. The method according to any one of claims 1 to 3, wherein the polyol-conditioning in the step iii) is carried out until the properties of the contaminants are changed to a determined level and such that removal of the contaminants by separation can be performed.

5. The method according to any one of the preceding claims, wherein the method comprises the step ii) b) comprising the steps of: adjusting the water content of the feedstock to 1-10% by weight of the feedstock to provide an aqueous feedstock, and adjusting the pH of the aqueous phase to an acidic range, such as pH from 4 - 6.5; keeping the aqueous feedstock from step b) under stirring until enzymatic hydrolysis activity achieves minimum 150LCLU-SL / g of enzyme dosed.

6. The method according to any one of the preceding claims, wherein the surplus of the polyol formed / added in the step ii) a) and / or b) and not used in the step iii) is collected and re-used.

7. The method according to any one of the preceding claims, wherein the method comprises removing water and / or polyol by separation from the feedstock upstream or downstream of the step iii) and / or downstream the step iv).

8. The method according to any one of the preceding claims, wherein the separation is performed by means of centrifugal separation, such as by means of a high-speed separator or a decanter.

9. The method according to any one of the preceding claims, wherein the polyol- conditioned feedstock from the step iii) is cooled to a temperature of 60-120°C, or to 60- 80°C before or during the step iv).

10. The method according to any one of the preceding claims, wherein the refining in the step iv) comprises acid conditioning, alkali conditioning, full or partial neutralization, enzymatic conditioning, water conditioning, separation, adsorption, and / or filtration.

11. The method according to claim 10, wherein the refining in step iv) comprises acid conditioning, which comprises adding an acid, such as citric acid, phosphoric acid to the polyol-conditioned feedstock.

12. The method according to claim 10 or 11 , wherein the refining in step iv) comprises alkali conditioning, which comprises adding an alkali water solution, such as aqueous sodium hydroxide and / or potassium hydroxide, to the polyol-conditioned feedstock.

13. The method according to claim any one of the preceding claims 10-12, wherein the alkali conditioning with the alkali water solution addition takes place after the acid conditioning to neutralize stoichiometrically, fully or partially, the acid dosed.

14. The method according to any one of the preceding claims 10-13, wherein the step iv) comprises neutralizing stoichiometrically, fully or partially, free fatty acids (FFA) contained in the polyol-conditioned feedstock.

15. The method according to any one of the preceding claims 10-14, wherein the step iv) comprises enzymatic conditioning, which comprises adding a phospholipase enzyme, such as phospholipase A1 , or phospholipase C, to the polyol-conditioned feedstock.

16. The method according to any one of the preceding claims 10-15, wherein the step iv) comprises water conditioning, performed by adjusting the water content of the polyol, acid, alkali, neutralization or enzyme conditioned feedstock, to a content of 0.05% to 10% by weight of the conditioned feedstock, and separating the purified feedstock from the conditioned feedstock mixture.

17. The method according to any one of the preceding claims 10-16, wherein the step iv) comprises adsorption by using an adsorbent, such as bleaching earth or silica.

18. Method according to any one of the preceding claims, wherein the polyol added in the step ii) a comprises or consists of glycerol.

19. Method according to claim 18, wherein the purity of the glycerol is over 90%, or 92-97%.

20. Method according to any one of the preceding claims, wherein the method comprises the step ii) a) when the feedstock comprises an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm, a phosphorous content (P) of more than 5 ppm and a chloride in the organic form of more than 10 ppm.

21. Method according to any one of the preceding claims 1-19, wherein the method comprises the step ii) b) when the feedstock comprises an iron content (Fe) of more than 1 ppm, a sodium content (Na) of more than 1 ppm and a phosphorous content (P) of more than 5 ppm.

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