Process for depolymerizing lignocellulosic biomass

Abstract

Process for depolymerizing lignocellulosic biomass comprising the following steps: (a) subjecting the lignocellulosic biomass to depolymerization in the presence of at least one alcohol having from 1 to 5 carbon atoms, preferably from 1 to 2 carbon atoms, operating at a weight / weight (w / w) lignocellulosic biomass / alcohol ratio comprised between 0.1 and 1, preferably comprised between 0.15 and 0.8, in supercritical conditions, at a temperature comprised between 200°C and 300°C, preferably comprised between 220°C and 295°C, at a pressure comprised between 40 bar and 170 bar, preferably comprised between 50 bar and 150 bar, for a time comprised between 5 minutes and 150 minutes, preferably comprised between 10 minutes and 130 minutes, obtaining: (i) a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol and a solid phase comprising carbon residues ("char"), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass; (ii) optionally, a gaseous phase; (b) separating the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol from the mixture (i) obtained in step (a) obtaining: (iii) a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol; (iv) a solid phase comprising carbon residues ("char"), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass; (c) subjecting the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol (iii) obtained in the step (b) to purification obtaining: (v) depolymerized lignocellulosic biomass; (vi) at least one alcohol. The depolymerized lignocellulosic biomass obtained from the above-mentioned process can be advantageously used, for example, as an antioxidant agent or anti-UV agent in biofuels, which can be used as such, or mixed with other fuels in diesel engines for automotive or aviation. In addition, the depolymerized lignocellulosic biomass obtained from the above-mentioned process can be advantageously used, for example, as an antioxidant agent in bio-feedstocks such as vegetable oils and animal or vegetable fats, in order to slow down their rancidity during transport and storage.

Description

[0001] PROCESS FOR DEPOLYMERIZING LIGNOCELLULOSIC BIOMASS

[0002] DESCRIPTION

[0003] The present invention relates to a process for depolymerizing lignocellulosic biomass.

[0004] More specifically, the present invention relates to a process for depolymerizing lignocellulosic biomass comprising the following steps: (a) subjecting the lignocellulosic biomass to depolymerization in the presence of at least one alcohol operating in supercritical conditions, at specific temperature, pressure and time conditions; (b) separating the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol from the mixture obtained in step (a); (c) subjecting the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol obtained in step (b) to purification obtaining depolymerized lignocellulosic biomass and at least one alcohol.

[0005] The depolymerized lignocellulosic biomass obtained from the above- mentioned process can be advantageously used, for example, as an antioxidant agent or anti-UV agent, in particular as an antioxidant agent or anti-UV agent in biofuels which can be used as such, or mixed with other fuels in diesel engines for automotive or aviation. In addition, the depolymerized lignocellulosic biomass obtained from the above-mentioned process can be advantageously used, for example, as an antioxidant agent in bio-feedstocks such as vegetable oils and animal or vegetable fats, in order to slow down their rancidity during transport and storage.

[0006] The present invention also relates to a depolymerized lignocellulosic biomass having the specific characteristics reported below.

[0007] Furthermore, the present invention also relates to the use of said depolymerized lignocellulosic biomass as an antioxidant agent or anti-UV agent, in particular as an antioxidant agent or anti-UV agent in biofuels which can be used as such, or mixed with other fuels in diesel engines for automotive or aviation.

[0008] In addition, the present invention also relates to the use of said depolymerized lignocellulosic biomass as an antioxidant agent in bio-feedstocks such as, for example, vegetable oils and animal or vegetable fats. In general, biomass is defined as any substance with an organic, vegetable or animal matrix, that can be used for the production of agricultural soil improver or for energy purposes, for example, as a raw material for the production of biofuels and / or biocombustibles, or components that can be added to fuels and / or combustibles. Therefore, biomasses, in addition to being products cultivated specifically for energy purposes, are all products of agricultural and forestry cultivation, including residues from agricultural and forestry processing, agri-food product waste intended for human consumption or animal husbandry, residues, not chemically treated, from the wood and paper processing industry, all organic products resulting from the biological activity of animals and humans, such as those contained in municipal waste.

[0009] As mentioned above, biomass, among the different possibilities of use, can be a source of renewable energy alternative to the traditional fossil-based raw materials usually used for producing combustibles. For this purpose, lignocellulosic biomass is particularly useful.

[0010] Lignocellulosic biomass is a complex structure comprising three main components: cellulose, hemicellulose and lignin. Their relative quantities vary depending on the type of lignocellulosic biomass used. For example, in the case of plants, said quantities vary depending on the species and age of the plant.

[0011] Cellulose is the major constituent of lignocellulosic biomass and is generally present in quantities comprised between 30% by weight and 60% by weight with respect to the total weight of lignocellulosic biomass. Cellulose consists of glucose molecules (approximately 500 to 10000 units) joined together by a P-l,4-glucosidic bond. The establishment of hydrogen bonds between the chains results in the formation of crystalline domains that impart strength and elasticity to the plant fibres. In nature, it is only found in its pure state in annual plants such as cotton and flax, while in woody plants it is always accompanied by hemicellulose and lignin.

[0012] Hemicellulose, which is generally present in quantities comprised between 10% by weight and 40% by weight with respect to the total weight of lignocellulosic biomass, appears as a mixed, relatively short (10 to 200 molecules) and branched polymer, formed by both sugars with six carbon atoms (glucose, mannose, galactose) and sugars with five carbon atoms (xylose, arabinose). The presence of hemicellulose is responsible for a number of important properties of plant fibres, the main one being that it promotes the imbibition of said fibres when water is present, causing them to swell. Hemicellulose also has adhesive properties and, therefore, tends to cement or become corneous when it dehydrates, with the consequence that said plant fibres become stiff and are imbibed more slowly.

[0013] Lignin is generally present in quantities comprised between 10% by weight and 30% by weight with respect to the total weight of the lignocellulosic biomass. Its main function is to bind and cement together the various plant fibres so as to give compactness and strength to the plant, and it also provides protection against insects, pathogens, injuries and ultraviolet light.

[0014] From a circular economy perspective, lignocellulosic biomass represents a category of materials with high potential for the industrial- scale production of a wide range of products from renewable sources. This is a category of materials generated as by-products of large- volume processes such as those in the food and paper industry, as well as those generated by the agricultural sector, and are therefore generally available in abundance and at low cost. Furthermore, these materials do not compete with products cultivated for human food, although they do compete, at least partially, with products cultivated for animal feed and the use of cultivated land.

[0015] Lignocellulosic biomass can be classified into virgin biomass, waste biomass and biomass from energy crops. Virgin biomass includes all naturally occurring terrestrial plants such as, for example, trees, bushes, grass. Waste biomass is a low- value product from various industries such as, for example, agriculture, forestry, paper industry. Biomass from energy crops comes from the cultivation of plants that, as mentioned above, do not compete with crops for human consumption, with high yields of lignocellulosic biomass used as raw material specifically for the production of second-generation biofuels.

[0016] To date, there are lignocellulosic biomass conversion technologies that involve either a fractionation of the lignocellulosic biomass to obtain, for instance, fermentable sugars from the hydrolysis of cellulose and hemicellulose that can be subsequently used in the production of second-generation biofuels, in particular bioethanol, or catalytic or non-catalytic thermal processes to obtain crude bio-oil that must subsequently be refined. The lignin obtained from these processes is generally considered a secondary waste product and is disposed of, for example, by incineration.

[0017] For example, US patent application US 2010 / 330638 relates to a method for producing ethanol from a lignocellulosic biomass using a fed-batch system, said method comprising the steps of a) treating an aqueous solution of lignocellulosic biomass up to 15% [dry biomass weight / total mass weight (biomass plus water)] with a dilute aqueous solution of ammonium hydroxide at a temperature greater than 100°C, for a sufficient time to increase the surface area of the biomass for enzymatic hydrolysis; b) washing the treated biomass with water; c) removing at least 40% of the water from the treated and washed biomass; d) placing the dehydrated biomass in contact with a saccharification enzyme under conditions conducive to the production of fermentable sugars; e) grinding the biomass after step (a) and before step (d); f) repeating steps a) to e) up to two times; and g) placing the fermentable sugars in contact with a micro-organism capable of producing ethanol. The above-mentioned method is said to be able to optimise the hydrolysis of biomass to sugars and produce ethanol at high titres.

[0018] US patent application US 2016 / 273010 relates to a method for processing lignocellulosic biomass comprising: providing a lignocellulosic biomass and at least one solvent; providing and heating a mixer to a temperature comprised between 100°C and 300°C; adding the biomass and solvent to the mixer; mixing the biomass and solvent resulting in a slurry; and melt compounding the slurry under shearing and heating for a sufficient amount of time to cause the inter- and intra-polymeric bonds of the biomass to break down. Preferably the solvent is a polyhydric alcohol, more preferably glycerol. The above-mentioned process is said to be able to provide materials that can be converted into fermentable sugars with high yields, maintaining high molecular weights and non-condensed lignin that can be recovered with good yields. International patent application WO 2019 / 072386 relates to a method for processing lignocellulosic material, comprising:

[0019] 1) providing and optionally preparing a process stream A comprising lignocellulosic material;

[0020] 2) subjecting said process stream A comprising lignocellulosic material to a pulping step and a separation step, thus obtaining two separate process streams: at least one process stream A derived from cellulose, and at least one process stream A derived from lignin;

[0021] 3) further processing of said at least one process stream A derived from cellulose, optionally subjecting said process stream A derived from cellulose to one or more of the following sub-steps: washing, delignification, bleaching, chemical processing, paper or board manufacture or any combination thereof;

[0022] 4) subjecting said at least one process stream A derived from lignin to at least one isolation and / or purification step, thereby obtaining at least one process stream A comprising modified lignin-derived components;

[0023] 5) subjecting said at least one process stream A derived from lignin comprising modified lignin-derived components to a chemical decomposition step, wherein the chemical decomposition step comprises oxidative cracking, reductive cracking or electro-oxidation of said modified lignin-derived components, thereby resulting in at least one process stream A derived from lignin comprising lignin-derived low molecular weight aromatic compounds;

[0024] 6) subjecting at least one process stream A derived from lignin comprising modified lignin-derived compounds to an isolation and / or purification step, thereby obtaining at least process stream A derived from lignin comprising lignin-derived low molecular weight aromatic compounds.

[0025] The above-mentioned method is said to be able to enhance both cellulose and lignin.

[0026] International patent application WO 2008 / 144878 relates to a modular process for the fractionation of lignocellulosic raw material into different components by means of organic solvents (organosolv) and the subsequent processing of those components, the modular process comprising: a first treatment module comprising a series of steps for the reception, physical screening and physico-chemical decomposition of a lignocellulosic raw material by means of a separately supplied organic solvent, thereby extracting components from it and separating these components into a cellulosic solid fraction and a first liquid fraction; a second processing module comprising a second series of steps for producing ethanol for use as fuel and a plurality of lignin derivatives from said solid cellulosic fraction; a third treatment module comprising a third series of steps comprising at least a first step for isolating the first liquid fraction into a second solid fraction comprising a plurality of a second class of lignin derivatives and a first filtrate, a second step for separating the first filtrate into a third solid fraction comprising a plurality of a third class of lignin derivatives and a second filtrate, and a third step for isolating furfurals from said filtrate, a fourth step for recovering a portion of the organic solvent from said filtrate by distillation to obtain a first distillate, and a fourth treatment module comprising a fourth series of steps for separating the first distillate into at least one fraction containing acetic acid, a plurality of a fourth class of lignin derivatives, a monosaccharide sugar syrup and solid waste.

[0027] The above-mentioned method is said to be able to provide components that can be selectively processed, controlled and manipulated.

[0028] International patent application WO 2012 / 109241 relates to a method for producing Cx- compounds from biomass comprising:

[0029] (i) providing a stream of reagents comprising a first reagent and a second reagent, the first reagent comprising one or more molecules having general formula CxHyOz and an average ratio of oxygen to carbon of the first reagent comprised between 0.2 and 1.0 and wherein x = 2-12 carbon atoms and z = 1-12 oxygen atoms, the second reagent comprising one or more molecules having general formula CpHrOs and an average ratio of oxygen to carbon of the second reagent of 0.2 or less and wherein p = 2-7 carbon atoms and s = 0-1 oxygen atoms, wherein the number of carbon atoms in the stream of reagents deriving from the first reagent is greater than 10% of the total carbon atoms in the stream of reagents, and the number of carbon atoms in the stream of reagents deriving from the second reagent is greater than 10% of the total carbon atoms in the stream of reagents, and

[0030] (ii) catalytically reacting the stream of reagents with hydrogen in the presence of an acid condensation catalyst to produce a product stream comprising water and a plurality of Cx- compounds selected from the group consisting of Cx- alkanes, Cx- alkenes, Cx- cycloalkanes, Cx- cycloalkenes, Cx- alcohols, Cx- ketones, an aryl, a molten aryl, an oxygenated aryl, an oxygenated molten aryl, and a mixture thereof, wherein the acid condensation catalyst comprises an acid support or a heterogeneous acid catalyst comprising a metal selected from the group consisting of Pd, Pt, Cu, Co, Ru, Cr, Ni, Ag, an alloy thereof, and a combination thereof.

[0031] The above-mentioned process is said to be capable of converting biomass and biomass-derived raw materials into a high quantity of heavy hydrocarbons useful as jet fuels and diesel, or as heavy oils for lubricating applications and / or combustible oil.

[0032] International patent application WO 2021 / 209555 relates to a process for the production of bio-crude oil comprising the steps of:

[0033] (i) providing lignocellulosic biomass and

[0034] (ii) subjecting said biomass to thermochemical treatment at a temperature comprised between 250°C and 450°C for residence times comprised between 1 minute and 120 minutes, said biomass being in the form of a slurry formed with the recycled oil obtained from previous thermochemical treatment of similar biomasses to which a short-chain alcohol is added in an amount comprised between 2% and 150% of the dry weight of the slurry, wherein the ratio of biomass to recycled oil is comprised between 1 : 1 and 1 :5 w / w and the ratio of biomass to added alcohol is comprised between of 1 :9 and 5: 1 w / w.

[0035] The above-mentioned process is said to be able to reduce the formation of carbon residues (“char”) and improve the yield of crude bio-oil.

[0036] Japanese patent application JP 2001 / 205070 relates to a process for obtaining a biomass-derived composition, said process comprising treating one, two or more components selected from the group consisting of lignocellulosic biomass, cellulosic biomass, nitrogen-containing polysaccharides and protein-based biomass in one or more organic solvents under supercritical or subcritical conditions. Preferably, the organic solvent used is an alcohol, more preferably methanol. The above-mentioned process is said to be able to provide a biomass composition in a simple and effective manner by limiting the formation of insoluble products in the solvent used.

[0037] The above-mentioned lignocellulosic biomass depolymerization processes mainly involve a fractionation of the lignocellulosic biomass in order to obtain, for example, fermentable sugars generally used for producing ethanol and lignin, which is generally discarded, or thermal processes, catalytic or non-catalytic, in order to obtain crude bio-oil, which must be further processed before being used as fuel. None of the above processes describes the possibility of obtaining depolymerized biomass that can be used, as such, as an additive, in particular as an antioxidant agent or anti-UV agent.

[0038] The Applicant was faced with the problem of finding a simple and versatile process for the depolymerization of lignocellulosic biomass that does not involve fractionation of the lignocellulosic biomass, and / or use of catalysts, and / or further processing of the final product obtained.

[0039] The Applicant has now found a process for the depolymerization of lignocellulosic biomass that allows depolymerized lignocellulosic biomass to be obtained that can be used, as such, as an additive, in particular as an antioxidant agent or anti-UV agent. In particular, the Applicant has found a process for the depolymerization of lignocellulosic biomass comprising the following steps: (a) subjecting the lignocellulosic biomass to depolymerization in the presence of at least one alcohol operating under supercritical conditions, at specific temperature, pressure and time conditions; (b) separating the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol from the mixture obtained in step (a); (c) subjecting the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol obtained in step (b) to purification obtaining depolymerized lignocellulosic biomass and at least one alcohol.

[0040] There are numerous advantages to be gained from the above-mentioned process. For example, the above-mentioned process allows: high yields of depolymerized lignocellulosic biomass to be obtained (i.e. yields comprised between 25% and 90% by weight with respect the total weight of the lignocellulosic biomass subjected to depolymerization); depolymerization to be carried out at temperatures not exceeding 300°C; in the case of obtaining a gaseous phase, a lower gas yield to be obtained [mainly consisting of a mixture of hydrocarbons with 1 to 4 carbon atoms and, to a lesser extent, other gases, for example, carbon monoxide (CO)] (gas yield less than or equal to 8% by weight with respect to the total weight of the lignocellulosic biomass subjected to depolymerization); the solvent, i.e. the alcohol used, at the depolymerization step, to be recycled, reducing losses of solvent; low molecular weight depolymerized lignocellulosic biomass to be obtained [i.e. weight average molecular weight (Mw) less than or equal to 1200 and number average molecular weight (Mn) less than or equal to 500 Daltons], Moreover, due to the lower or absent gas yield, the possibility of operating at high solid (i.e. biomass) / alcohol weight (w / w) ratios, the recycling of the alcohol, and the specific temperature and time conditions, the above-mentioned process is easily scalable at industrial level.

[0041] In addition, the above-mentioned process makes it possible to obtain depolymerized lignocellulosic biomass that can be advantageously used, for example, as an antioxidant agent or anti-UV agent in biofuels that can be used as such, or mixed with other fuels in diesel engines for automotive or aviation. In addition, the depolymerized lignocellulosic biomass obtained from the above- mentioned process can be advantageously, for example, as an antioxidant agent in bio-feedstocks such as vegetable oils and animal or vegetable fats, in order to slow down their rancidity during transport and storage.

[0042] Therefore, the present invention relates to a process for depolymerizing lignocellulosic biomass comprising the following steps:

[0043] (a) subjecting the lignocellulosic biomass to depolymerization in the presence of at least one alcohol having from 1 to 5 carbon atoms, preferably from 1 to 2 carbon atoms, operating at a weight / weight (w / w) lignocellulosic biomass / alcohol ratio comprised between 0.1 and 1, preferably comprised between 0.15 and 0.8, in supercritical conditions, at a temperature comprised between 200°C and 300°C, preferably comprised between 220°C and 295°C, at a pressure comprised between 40 bar and 170 bar, preferably comprised between 50 bar and 150 bar, for a time comprised between 5 minutes and 150 minutes, preferably comprised between 10 minutes and 130 minutes, obtaining:

[0044] (i) a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol and a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass;

[0045] (ii) optionally, a gaseous phase;

[0046] (b) separating the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol from the mixture (i) obtained in the step (a) obtaining:

[0047] (iii) a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol;

[0048] (iv) a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass;

[0049] (c) subjecting the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol (iii) obtained in the step (b) to purification obtaining:

[0050] (v) depolymerized lignocellulosic biomass; (vi) at least one alcohol.

[0051] For the purpose of the present description and following claims, the definitions of the numeric ranges always include the extremes unless specified otherwise.

[0052] For the purpose of the present description and following claims, the term “comprising” also includes the terms “which essentially consists of’ or “which consists of’.

[0053] In accordance with a preferred embodiment of the present invention, said lignocellulosic biomass can be selected, for example, from: plants specifically cultivated for energy use such as, for example, miscanthus, switchgrass (Panicum virgatuni), common reed (Arundo donctx plants not specifically cultivated for energy use such as sorghum (for example, sorghum fibre); scraps, residues and waste products from agriculture, such as, for example, guayule, maize (for example, maize stalks, maize cobs), soybean, cotton, flax, rapeseed, wheat (for example, wheat straw), rice (for example, rice straw, rice hulls, rice husk), sugar cane (for example, sugar cane straw, sugar cane bagasse), palm (for example, palm leaves, palm trunks, palm mibrids, palm empty fruit bunches); scraps, residues and waste products from forestry, silviculture, or wood processing such as, for example, fir, poplar, alder, birch; scraps from agri-food products intended for human consumption or animal husbandry; residues, not chemically treated, from the paper industry; waste from separate collection of municipal solid waste (for example, municipal vegetable waste, paper); algae such as, for example, microalgae or macroalgae, in particular macroalgae.

[0054] In accordance with a further preferred embodiment of the present invention, said lignocellulosic biomass can be selected, for example, from waste (oilcakes) (“oilseed pressing panel cakes” or “oilseed squeezing panel cakes”) deriving from the pressing of seeds of plants such as, for example, camelina, brassica, soybean, sunflower, canola, safflower, flax, Hevea, castor, cotton, Crambe.

[0055] It should be noted that when using oilcakes, the depolymerized lignocellulosic biomass also comprises fatty acid esters [for example, fatty acid methyl esters (FAME)]. Said fatty acid esters can possibly be recovered from said depolymerized lignocellulosic biomass by processes known in the art such as, for example, filtration, decantation, centrifugation, preferably by filtration.

[0056] In accordance with a preferred embodiment of the present invention, prior to undergoing said depolymerization step (a), said lignocellulosic biomass can be subjected to a preliminary grinding process. Preferably, said lignocellulosic biomass can be ground to a particle diameter comprised between 0.05 mm and 2.5 mm, more preferably comprised between 0.08 mm and 2 mm. Particles with a diameter of less than 2 mm are particularly preferred.

[0057] In accordance with a preferred embodiment of the present invention, in said depolymerization step (a) said at least one alcohol can be selected, for example, from methanol, ethanol, propanol, butanol, pentanol, or mixtures thereof; preferably from methanol, ethanol, or mixtures thereof.

[0058] It should be noted that, for the purpose of the process of the present invention, said at least one alcohol used in depolymerization step (a) can be either of synthetic origin or of bio-origin (bio-alcohol).

[0059] The optional gaseous phase (ii), which can be obtained in the depolymerization step (a) of the aforesaid process, is generally less than or equal to 8% by weight with respect to the weight (dry weight) of the starting biomass. Said gaseous phase consists mainly of a mixture of hydrocarbons having 1 to 4 carbon atoms and, to a lesser extent, other gases [for example, carbon monoxide (CO)]. This gaseous phase, after separation, which can be carried out for example by depressurization of the pressure vessel in which said depolymerization step (a) is carried out, before the mixture (ii) obtained in said depolymerization step (a) is sent for separation, is generally sent for further treatment in order to enhance its combustible organic component.

[0060] In accordance with a preferred embodiment of the present invention, said separation step (b) can be carried out, for example, by filtration, decantation, centrifugation.

[0061] In accordance with a preferred embodiment of the present invention, the solid phase (iv) comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass can be subjected to a step (d) of purification and separation, obtaining:

[0062] (vii) a liquid phase consisting of non-depolymerized lignocellulosic biomass;

[0063] (viii) a solid phase comprising carbon residues (“char”) and, optionally, non- depolymerized lignocellulosic biomass.

[0064] In accordance with a preferred embodiment of the present invention, in said step (d) the purification can be carried out by washing with at least one alcohol, preferably with at least one alcohol used in the depolymerization step (a), more preferably methanol, ethanol, or mixtures thereof.

[0065] In accordance with a preferred embodiment of the present invention, in said step (d) the separation can be carried out by filtration, decantation, centrifugation, preferably by filtration.

[0066] At the end of step (d) of purification and separation: the solid phase (viii) comprising carbon residues (“char”) and, optionally, non-depolymerized lignocellulosic biomass, can be dried, for example, in an oven, so as to remove the residual alcohol that can be recycled to the depolymerization step (a); the liquid phase consisting of depolymerized lignocellulosic biomass can be combined with the liquid phase (iii) comprising depolymerized lignocellulosic biomass and at least one alcohol obtained in the separation step (b) and the whole can be sent to the purification step (c).

[0067] In accordance with a preferred embodiment of the present invention, said purification step (c) can be carried out by vacuum distillation.

[0068] At the end of the purification step (c), the alcohol (vi) (i.e. pure regenerated alcohol) can be fed to the depolymerization step (a), while the depolymerized lignocellulosic biomass (v) comprising monomers and oligomers deriving from the three components of the lignocellulosic biomass (i.e. cellulose, hemicellulose and lignin) can be used as such.

[0069] As mentioned above, the present invention also relates to the depolymerized lignocellulosic biomass obtained by the above-mentioned process.

[0070] Accordingly, further subject matter of the present invention is a depolymerized lignocellulosic biomass free of fatty acid esters, having the following features: weight average molecular weight (Mw) less than or equal to 1200 Dalton, preferably comprised between 150 Dalton and 1000 Dalton, even more preferably comprised between 200 Dalton and 900 Dalton; number average molecular weight (Mn) less than or equal to 500 Dalton, preferably comprised between 80 Dalton and 400 Dalton, more preferably comprised between 100 Dalton and 300 Dalton; percentage variation between the H / C ratio of the depolymerized lignocellulosic biomass and the H / C ratio of the starting lignocellulosic biomass equal to at least 30% more, preferably comprised between 35% more and 250% more, even more preferably comprised between 50% more and 230% more, with respect to the H / C ratio of the starting lignocellulosic biomass; percentage variation between the H / O ratio of the depolymerized lignocellulosic biomass and the H / O ratio of the starting lignocellulosic biomass equal to at least 40% more, preferably comprised between 45% more and 500% more, even more preferably comprised between 60% more and 450% more, with respect to the H / O ratio of the starting lignocellulosic biomass; percentage variation between the O / C ratio of the depolymerized lignocellulosic biomass and the O / C ratio of the starting lignocellulosic biomass equal to at least 20% less, preferably comprised between 25% less and 250% less, even more preferably comprised between 30% less and 200% less, with respect to the O / C ratio of the starting lignocellulosic biomass. Further subject matter of the present invention is also a depolymerized lignocellulosic biomass comprising fatty acid esters, having the following features: weight average molecular weight (Mw) less than or equal to 1200 Dalton, preferably comprised between 150 Dalton and 1000 Dalton, even more preferably comprised between 200 Dalton and 900 Dalton; number average molecular weight (Mn) less than or equal to 400 Dalton, preferably comprised between 50 Dalton and 390 Dalton, more preferably comprised between 60 Dalton and 350 Dalton; percentage variation between the H / C ratio of the depolymerized lignocellulosic biomass and the H / C ratio of the starting lignocellulosic biomass equal to at least 2% less, preferably comprised between 4% less and 200% less, even more preferably comprised between 6% less and 180% less, with respect to the H / C ratio of the starting lignocellulosic biomass; percentage variation between the H / O ratio of the depolymerized lignocellulosic biomass and the H / O ratio of the starting lignocellulosic biomass equal to at least 5% less, preferably comprised between 10% less and 200% less, even more preferably comprised between 20% less and 150% less, with respect to the H / O ratio of the starting lignocellulosic biomass; percentage variation between the O / C ratio of the depolymerized lignocellulosic biomass and the O / C ratio of the starting lignocellulosic biomass equal to at least 30% more, preferably comprised between 35% more and 350% more, even more preferably comprised between 40% more and 280% more, with respect to the O / C ratio of the starting lignocellulosic biomass.

[0071] As mentioned above, the present invention relates to the use of depolymerized lignocellulosic biomass as an antioxidant agent or anti-UV agent.

[0072] Accordingly, a further subject matter of the present invention is the use of depolymerized lignocellulosic biomass as an antioxidant agent or anti-UV agent, preferably as an antioxidant agent or anti-UV agent in bio-fuels that can be used as such, or mixed with other fuels in diesel engines for automotive or aviation.

[0073] Further subject matter of the present invention is also the use of depolymerized lignocellulosic biomass as an antioxidant agent in bio-feedstocks such as, for example, vegetable oils and animal or vegetable fats. The present invention will now be illustrated in greater detail through an embodiment with reference to Figure 1 reported below.

[0074] Figure 1 depicts an embodiment of the process according to the present invention. For this purpose, lignocellulosic biomass (1) (for example, fir sawdust) is subjected to a depolymerization step (2) in the presence of at least one alcohol (for example, methanol, ethanol), obtaining an optional gaseous phase (3) and a mixture (4) comprising a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol, and a solid phase comprising carbon residue (“char”) and optionally non-depolymerized lignocellulosic biomass. Said mixture (4) is sent to a separation step (5) (for example, by filtration) obtaining a solid phase (6) comprising carbon residue (“char”), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass, and a liquid phase (7) comprising depolymerized lignocellulosic biomass and at least one alcohol {said depolymerized lignocellulosic biomass optionally comprising fatty acid esters [for example, fatty acid methyl esters (FAME)]}. The solid phase (6) is subjected to purification and separation (8) obtaining a liquid phase consisting of depolymerized lignocellulosic biomass (10) which can be combined with the liquid phase (7) comprising depolymerized lignocellulosic biomass and at least one alcohol {said depolymerized lignocellulosic biomass optionally comprising fatty acid esters [for example, fatty acid methyl esters (FAME)]} and a solid phase comprising carbon residues (“char”) and optionally non-depolymerized lignocellulosic biomass (9) that can be dried in an oven to remove all alcohol that can subsequently be recycled to the depolymerization step (2) (not shown in Figure 1). The liquid phase (7), after being combined with the liquid phase (10), is sent to a purification stage (11) obtaining at least one alcohol (13) which is recycled to the depolymerization step (2) and depolymerized lignocellulosic biomass (12).

[0075] In order to better understand the present invention and to put it into practice, some illustrative and non-limiting examples thereof are reported below.

[0076] Analysis and characterization methods

[0077] The analysis and the characterization methodologies reported below were used. Determination of the molecular weight

[0078] The depolymerized lignocellulosic biomass obtained in the following examples was subjected to molecular weight determination by gel permeation chromatography (GPC) on an Agilent 1100 GPC using two PFG M (PSS) columns connected in series with an Agilent 1100 VWD / UV detector operating at wavelengths comprised between 200 nm and 300 nm, connected in turn to an RI detector, with hexafluoro-2-propanol (HFIP) eluent. The depolymerized lignocellulosic biomass samples obtained in the examples reported below were diluted in hexafluoro-2-propanol (HFIP) at a concentration of approximately 5 mg / mL. The samples were then filtered on 0.2 nm polytetrafhiroethylene (PTFE) filters before being inserted for analysis. The analysis was carried out at a flow rate of 1 mL / min, at 40°C, for approximately 40 minutes.

[0079] The weight-average molecular weight (Mw), number-average molecular weight (Mn) and polydispersity index (i.e. the Mw / Mnratio) were assessed by means of polyethylene terephthalate (PET) standards.

[0080] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the depolymerized lignocellulosic biomass samples obtained in the examples reported below were determined considering a range of reference molecular weights comprised between 10° and 104.

[0081] Determination of H / C, H / O and O / C ratios

[0082] For this purpose, the elemental analysis CHNS(O) was performed using an ICP-OES analyser (ICAP 6500 DV Thermo Fisher Scientific, Waltham, MA, USA). This analysis allows the amounts of carbon (C), hydrogen (H), nitrogen (N), sulphur (S) and oxygen (O) present in a sample to be determined.

[0083] After thoroughly washing with ethanol and drying all the instruments, the following steps were taken.

[0084] The sample to be analysed (2 mg) was placed in a tin crucible which was then closed to ensure that the sample was well sealed inside. The crucible was then placed in the above-mentioned elemental analyser and, using the software connected to it, the percentages of C, H, N and S were obtained. From these values, the H / C, H / O and O / C ratios were obtained. EXAMPLE 1

[0085] Production of depolymerized lignocellulosic biomass

[0086] 30 g of fir sawdust (particle diameter < 2 mm) and 150 g of methanol [lignocellulosic biomass / methanol ratio (w / w) equal to 0.2] were placed in a 500 ml reactor: the whole was kept, under stirring, at 250°C, 94 bar, for 120 minutes obtaining a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and methanol and a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and non-depolymerized lignocellulosic biomass.

[0087] The above-mentioned mixture was subjected to separation by filtration, obtaining a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass, and non-depolymerized lignocellulosic biomass (73.5 g) and a liquid phase comprising depolymerized lignocellulosic biomass and methanol (106.5 g).

[0088] Subsequently, the above-mentioned solid phase was subjected to purification and separation. For this purpose, said solid phase was placed in a 250 ml beaker, equipped with a magnetic stirrer, and 100 g of pure methanol were added: the whole was kept, under stirring, at room temperature (25°C) for 15 minutes. At the end, the obtaining mixture was separated by filtration twice obtaining a liquid phase consisting of depolymerized lignocellulosic biomass (100 g) which was subsequently combined with the aforementioned liquid phase comprising depolymerized lignocellulosic biomass and methanol, and a solid phase comprising carbon residue (“char”) and non-depolymerized lignocellulosic biomass which was dried in an oven, at 85°C and 10 mbar, for 10 hours in order to completely remove the residual methanol: the amount of final dried solid was approximately 22 g.

[0089] The liquid phase comprising depolymerized lignocellulosic biomass and methanol (206.5 g) was subjected to evaporation by Rotavapor operating at 650 mbar and 85°C, for 30 minutes, obtaining a depolymerized lignocellulosic biomass (approx. 8 g - yield 26.67%) and methanol (198.5 g), which can be recycled to the depolymerization step.

[0090] The depolymerized lignocellulosic biomass was subjected to molecular weight and H / C, H / O and 0 / C ratios determination, operating as described above.

[0091] The results obtained were as follows: weight average molecular weight (Mw) 700 Daltons; number average molecular weight (Mn) 270 Dalton;

[0092] H / C ratio equal to 0.18 (starting lignocellulosic biomass H / C ratio equal to 0.09);

[0093] H / O ratio equal to 0.35 (starting lignocellulosic biomass H / O ratio equal to 0.09);

[0094] O / C ratio equal to 0.52 (starting lignocellulosic biomass O / C ratio equal to 0.98).

[0095] EXAMPLE 2

[0096] Production of depolymerized lienocellulosic biomass

[0097] 30 g fir sawdust (particle diameter < 2 mm) and 150 g of ethanol [lignocellulosic biomass / ethanol ratio (w / w) equal to 0.2] were placed in a 500 ml reactor: the whole was kept, under stirring, at 250°C, at 72 bar, for 120 minutes obtaining a gaseous phase (about 0.9 g) which was removed by depressurization and a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and ethanol and a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and non-depolymerized lignocellulosic biomass.

[0098] The above-mentioned mixture was subjected to separation by filtration, obtaining a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass, and non-depolymerized lignocellulosic biomass (44.1 g) and a liquid phase comprising depolymerized lignocellulosic biomass and ethanol (135 g).

[0099] Subsequently, the above-mentioned solid phase was subjected to purification and separation. For this purpose, said solid phase was placed in a 250 ml beaker, equipped with a magnetic stirrer, and 100 g of pure ethanol were added: the whole was kept, under stirring, at room temperature (25°C) for 15 minutes. At the end, the obtained mixture was separated by filtration twice obtaining a liquid phase consisting of depolymerized lignocellulosic biomass (100 g) which was subsequently combined with the above-mentioned liquid phase comprising depolymerized lignocellulosic biomass and ethanol, and a solid phase comprising carbon residue (“char”) and non-depolymerized lignocellulosic biomass which was dried in an oven, at 85°C and 10 mbar, for 10 hours in order to completely remove the residual ethanol: the amount of final dried solid was approximately 22 g.

[0100] The liquid phase comprising depolymerized lignocellulosic biomass and methanol (235 g) was subjected to evaporation by Rotavapor operating at 650 mbar and 85°C, for 30 minutes, obtaining a depolymerized lignocellulosic biomass (approx. 7 g - yield 23.33%) and ethanol (228 g), which can be recycled to the depolymerization step.

[0101] The depolymerized lignocellulosic biomass was subjected to molecular weight and H / C, H / O and O / C ratios determination, operating as described above.

[0102] The results obtained were as follows: weight-average molecular weight (Mw) 780 Daltons; number-average molecular weight (Mn) 250 Dalton;

[0103] H / C ratio equal to 0.18 (starting lignocellulosic biomass H / C ratio equal to 0.09);

[0104] H / O ratio equal to 0.35 (starting lignocellulosic biomass H / O ratio equal to 0.09);

[0105] O / C ratio equal to 0.53 (starting lignocellulosic biomass O / C ratio equal to 0.98).

[0106] EXAMPLE 3

[0107] Production of depolymerized lignocellulosic biomass

[0108] 60 g of camelina oilcakes (particle diameter < 2 mm) and 120 g of methanol [lignocellulosic biomass / methanol ratio (w / w) equal to 0.5] were placed in a 500 ml reactor: the whole was kept, under stirring, at 250°C, at 90 bar, for 120 minutes obtaining a gaseous phase (about 2.64 g) which was removed by depressurisation and a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and methanol, said depolymerized lignocellulosic biomass comprising fatty acid methyl esters (FAMEs) and a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and non-depolymerized lignocellulosic biomass.

[0109] The above-mentioned mixture was subjected to separation by filtration, obtaining a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass, and non-depolymerized lignocellulosic biomass (45 g) and a liquid phase comprising depolymerized lignocellulosic biomass and methanol, said depolymerized lignocellulosic biomass comprising fatty acid methyl esters (FAME) (150 g).

[0110] Subsequently, the above-mentioned solid phase was subjected to purification and separation. For this purpose, said solid phase was placed in a 250 ml beaker, fitted with a magnetic stirrer, and 100 g of pure methanol was added: the whole was kept, under stirring, at room temperature (25°C) for 15 minutes. At the end, the obtained mixture was separated by filtration twice obtaining a liquid phase consisting of depolymerized lignocellulosic biomass (100 g) which was subsequently combined with the above-mentioned liquid phase comprising depolymerized lignocellulosic biomass, methanol and fatty acid methyl esters (FAME) and a solid phase comprising carbon residue (“char”) and nondepolymerized lignocellulosic biomass which was dried in an oven, at 85°C and 10 mbar, for 10 hours in order to completely remove the residual methanol: the amount of final dried solid corresponds to about 22 g.

[0111] The liquid phase comprising depolymerized lignocellulosic biomass and methanol, said depolymerized lignocellulosic biomass comprising fatty acid methyl esters (FAME) (250 g) was subjected to evaporation by Rotavapor operating at 650 mbar and 85°C for 30 minutes, obtaining a depolymerized lignocellulosic biomass comprising fatty acid methyl esters (FAME) (approx. 47.5 g - yield 56.2%) and methanol (202.5 g), which can be recycled to the depolymerization step.

[0112] The depolymerized lignocellulosic biomass comprising fatty acid methyl esters (FAME) was subjected to molecular weight and H / C and H / O ratios determination, operating as described above.

[0113] The results obtained were as follows: weight-average molecular weight (Mw) 790 Daltons; number-average molecular weight (Mn) 90 Dalton; H / C ratio equal to 0.13 (starting lignocellulosic biomass H / C ratio equal to 0.14);

[0114] H / O ratio equal to 0.10 (starting lignocellulosic biomass H / O ratio equal to 0.27);

[0115] O / C ratio equal to 1.34 (starting lignocellulosic biomass O / C ratio equal to 0.52).

[0116] EXAMPLE 4

[0117] Determination

[0118] For this purpose, a commercial, antioxidant-free, food-grade sunflower oil was used and comparative tests were carried out as follows.

[0119] In a 10 ml flask, under magnetic stirring, at a temperature of 35°C, the following was added to the sunflower oil: commercial antioxidant butylated hydroxytoluene (BHT - Merck) at 0.3% by weight with respect to the total weight of the sunflower oil (Sample B); depolymerized lignocellulosic biomass obtained in Example 2 at a concentration equal to 1% by weight with respect to the total weight of the sunflower oil (Sample A).

[0120] For comparison purposes, Sample C consisting of commercial food-grade sunflower oil, free of antioxidants as is, is also shown in Figure 2.

[0121] Next, after placing the flask in a silicon bath and topping it with a condenser, a (previously calibrated) oxygen-sensitive probe was inserted: the whole was kept under magnetic stirrer, the temperature was brought to 130°C, and the consumption of oxygen due to the auto-oxidation of the sunflower oil was then measured by means of said oxygen-sensitive probe.

[0122] In Figure 2 [the abscissa shows the time in seconds (s); the ordinate shows the percentage (%) of oxygen (O2) present in the test atmosphere], it can be seen how the addition of the depolymerized lignocellulosic biomass obtained in Example 2 increases the oxidation time of the sunflower oil.

[0123] EXAMPLE 5

[0124] Determination of antioxidant

[0125] The depolymerized lignocellulosic biomass obtained in Example 2 and Example 3 was compared with a commercial antioxidant [butylhydroxytoluene (BHT - Merck)] using the Rancimat Test in accordance with EN 15751-2014 standard: said test determined the oxidation stability of the depolymerized lignocellulosic biomass by measuring the induction period up to a maximum of 48 hours.

[0126] For this purpose, a sample was prepared by mixing commercial food-grade soybean oil with the depolymerized lignocellulosic biomass obtained in Example 2 and Example 3 so as to have a concentration of depolymerized lignocellulosic biomass at 1% by weight with respect to the total weight of the soybean oil (Sample A and B). The sample thus prepared was inserted into the Rancimat apparatus (Metrohm Herisau Switzerland).

[0127] Subsequently, a stream of purified air was passed through the sample previously heated to 110°C. During the oxidation process, the volatile compounds formed pass, together with the air, into a flask containing demineralized water and a conductivity electrode: said conductivity electrode allows to measure the end of the induction period, which is marked by a rapid increase in conductivity due to the dissociation of the volatile carboxylic acids absorbed in the water.

[0128] For comparison purposes, the following samples were prepared by mixing commercial antioxidant-free food-grade soybean oil with: commercial antioxidant butylated hydroxytoluene (BHT - Merck) so that the concentration of butylated hydroxytoluene (BHT) is equal to 0.3% by weight with respect to the total weight of the soybean oil (Sample C); depolymerized lignocellulosic biomass obtained in Example 2 so that the concentration of depolymerized lignocellulosic biomass is equal to 1% by weight with respect to the total weight of soybean oil (Sample A); depolymerized lignocellulosic biomass obtained in Example 3 so that the concentration of lignocellulosic biomass is equal to 1% by weight with respect to the total weight of soybean oil (Sample B).

[0129] For comparison purposes, Sample D consisting of commercial food-grade soybean oil was also shown in Figure 3.

[0130] The samples prepared as described above were placed in the Rancimat apparatus (Metrohm Herisau Switzerland) and the antioxidant power was determined by operating as described above. The results obtained are shown in Figure 3.

[0131] From the data shown in Figure 3 [the abscissa shows the samples; the ordinate shows the average induction time in hours (h)], it can be inferred that the depolymerized lignocellulosic biomass obtained in Example 2 and Example 3 at 1% by weight in soybean oil exhibits antioxidant activity comparable to the commercial antioxidant butylhydroxytoluene (BHT - Merck) at 0.3% by weight in soybean oil.

Claims

CLAIMS1. Process for depolymerizing lignocellulosic biomass comprising the following steps:(a) subjecting the lignocellulosic biomass to depolymerization in the presence of at least one alcohol having from 1 to 5 carbon atoms, preferably from 1 to 2 carbon atoms, operating at a weight / weight (w / w) lignocellulosic biomass / alcohol ratio comprised between 0.1 and 1, preferably comprised between 0.15 and 0.8, in supercritical conditions, at a temperature comprised between 200°C and 300°C, preferably comprised between 220°C and 295°C, at a pressure comprised between 40 bar and 170 bar, preferably comprised between 50 bar and 150 bar, for a time comprised between 5 minutes and 150 minutes, preferably comprised between 10 minutes and 130 minutes, obtaining:(i) a mixture comprising a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol and a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, nondepolymerized lignocellulosic biomass;(ii) optionally, a gaseous phase;(b) separating the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol from the mixture (i) obtained in the step (a) obtaining:(iii) a liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol;(iv) a solid phase comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, non-depolymerized lignocellulosic biomass;(c) subjecting the liquid phase comprising depolymerized lignocellulosic biomass and at least one alcohol (iii) obtained in the step (b) to purification obtaining:(v) depolymerized lignocellulosic biomass;(vi) at least one alcohol.

2. Process for depolymerizing lignocellulosic biomass according to claim 1, wherein said lignocellulosic biomass is selected from: plants specifically cultivated for energy use such as miscanthus, switchgrass (Panicum virgatum), common reed (Arundo donctx plants not specifically cultivated for energy use such as sorghum; scraps, residues and waste products from agriculture, such as, guayule, maize, soybean, cotton, flax, rapeseed, wheat, rice, sugar cane, palm; scraps, residues and waste products from forestry, silviculture, or wood processing such as fir, poplar, alder, birch; scraps from agri-food products intended for human consumption or animal husbandry; residues, not chemically treated, from the paper industry; waste from separate collection of municipal solid waste; algae such as microalgae or macroalgae, in particular macroalgae.

3. Process for depolymerizing lignocellulosic biomass according to claim 1, wherein said lignocellulosic biomass is selected from waste (oilcakes) (“oilseed pressing panel cakes” or “oilseed squeesing panel cakes”) deriving from the pressing of seeds of plants such as camelina, brassica, soybean, sunflower, canola, safflower, flax, Hevea, castor, cotton, Crambe.

4. Process for depolymerizing lignocellulosic biomass according to any one of the preceding claims, wherein before being subjected to said depolymerization step (a), said lignocellulosic biomass is subjected to a preliminary grinding process, preferably, said lignocellulosic biomass is ground until obtaining particles having a diameter between 0.05 mm and 2.5 mm, more preferably between 0.08 mm and 2 mm, more preferably particles having a diameter of less than 2 mm.

5. Process for depolymerizing lignocellulosic biomass according to any one of the preceding claims, wherein in said step (a) of depolymerization said at least one alcohol is selected from methanol, ethanol, propanol, butanol, pentanol, or mixtures thereof; preferably from methanol, ethanol, or mixtures thereof.

6. Process for depolymerizing lignocellulosic biomass according to any one ofthe preceding claims, wherein said step (b) of separation is carried out by filtration, decantation, centrifugation, preferably by filtration.

7. Process for depolymerizing lignocellulosic biomass according to any one of the preceding claims, wherein the solid phase (iv) comprising carbon residues (“char”), depolymerized lignocellulosic biomass and, optionally, nondepolymerized lignocellulosic biomass is subjected to a step (d) of purification and separation obtaining:(vii) a liquid phase consisting of non-depolymerized lignocellulosic biomass;(viii) a solid phase comprising carbon residues (“char”) and, optionally, nondepolymerized lignocellulosic biomass.

8. Process for depolymerizing lignocellulosic biomass according to claim 7, wherein in said step (d) the purification is carried out by washing with at least one alcohol, preferably with at least one alcohol used in the depolymerization step (a), more preferably methanol, ethanol, or mixtures thereof.

9. Process for depolymerizing lignocellulosic biomass according to claim 7 or 8, wherein in said step (d) the separation is carried out by filtration, decantation, centrifugation, preferably by filtration.

10. Process for depolymerizing lignocellulosic biomass according to any one of the preceding claims, wherein said step (c) of purification is carried out by vacuum distillation.

11. Depolymerized lignocellulosic biomass free of fatty acid esters, having the following features: weight average molecular weight (Mw) less than or equal to 1200 Dalton, preferably comprised between 150 Dalton and 1000 Dalton, even more preferably comprised between 200 Dalton and 900 Dalton; number average molecular weight (Mn) less than or equal to 500 Dalton, preferably comprised between 80 Dalton and 400 Dalton, more preferably comprised between 100 Dalton and 300 Dalton; percentage variation between the H / C ratio of the depolymerized lignocellulosic biomass and the H / C ratio of the starting lignocellulosic biomass equal to at least 30% more, preferably comprised between 35% moreand 250% more, even more preferably comprised between 50% more and 230% more, with respect to the H / C ratio of the starting lignocellulosic biomass; percentage variation between the H / O ratio of the depolymerized lignocellulosic biomass and the H / O ratio of the starting lignocellulosic biomass equal to at least 40% more, preferably comprised between 45% more and 500% more, even more preferably comprised between 60% more and 450% more, with respect to the H / O ratio of the starting lignocellulosic biomass; percentage variation between the O / C ratio of the depolymerized lignocellulosic biomass and the O / C ratio of the starting lignocellulosic biomass equal to at least 20% less, preferably comprised between 25% less and 250% less, even more preferably comprised between 30% less and 200% less, with respect to the O / C ratio of the starting lignocellulosic biomass.

12. Depolymerized lignocellulosic biomass comprising fatty acid esters, having the following features: weight average molecular weight (Mw) less than or equal to 1200 Dalton, preferably comprised between 150 Dalton and 1000 Dalton, even more preferably comprised between 200 Dalton and 900 Dalton; number average molecular weight (Mn) less than or equal to 400 Dalton, preferably comprised between 50 Dalton and 390 Dalton, more preferably comprised between 60 Dalton and 350 Dalton; percentage variation between the H / C ratio of the depolymerized lignocellulosic biomass and the H / C ratio of the starting lignocellulosic biomass equal to at least 2% less, preferably comprised between 4% less and 200% less, even more preferably comprised between 6% less and 180% less, with respect to the H / C ratio of the starting lignocellulosic biomass; percentage variation between the H / O ratio of the depolymerized lignocellulosic biomass and the H / O ratio of the starting lignocellulosic biomass equal to at least 5% less, preferably comprised between 10% less and 200% less, even more preferably comprised between 20% less and 150% less,with respect to the H / O ratio of the starting lignocellulosic biomass; percentage variation between the O / C ratio of the depolymerized lignocellulosic biomass and the O / C ratio of the starting lignocellulosic biomass equal to at least 30% more, preferably comprised between 35% more and 350% more, even more preferably comprised between 40% more and280% more, with respect to the O / C ratio of the starting lignocellulosic biomass.

13. Use of the depolymerized lignocellulosic biomass as an antioxidant agent or anti-UV agent, preferably as an antioxidant agent or anti-UV agent in biofuels which can be used as such, or mixed with other fuels in diesel engines for automotive or aviation.

14. Use of the depolymerized lignocellulosic biomass as antioxidant agent in biofeedstocks such as vegetable oils and animal or vegetable fats.

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