Method for production of levulinic acid

Description

1 / 19 METHOD FOR PRODUCING LEVULINIC ACID TECHNICAL FIELD

[01] This patent application relates to a process for the production of levulinic acid. More particularly, this patent application relates to a method for the production of levulinic acid from technical lignin. BACKGROUND OF THE INVENTION

[02] Levulinic acid, also known as 4-oxopentanoic acid, is a white crystalline solid, soluble in water and polar organic solvents. It is relatively stable with respect to other chemical reactions under hydrolysis conditions. Levulinic acid is used as a precursor in pharmaceuticals, plasticizers, and various other additives. Processes have been developed to produce it from wood, cellulose, starch, or glucose.

[03] Technical lignin refers to the byproducts obtained as a result of the delignification process of lignocellulosic biomass. Traditionally, technical lignin is obtained as a byproduct of paper mills. Technical lignin is highly recalcitrant by nature and currently has no other use except burning to generate heat, which is primarily a waste management strategy. Thus, there is an urgent need to develop a process to valorize it and develop high-value products in a biorefinery to improve the sustainability of biofuels. One of the main objectives of the present invention is to valorize technical lignin for value-added or biochemical products.

[04] US patent 3258481 describes a process for producing levulinic acid from bagasse, sawdust, waste paper, starch, corn cobs, sucrose or molasses using a Petition 870230032893, dated 04 / 19 / 2023, page 9 / 35 2 / 19 Strong acid catalyst (hydrochloric acid, sulfuric acid, phosphoric acid, para-toluenesulfonic acid and hydrobromic acid). acid). In which, the exothermic heat recycling containing vapors and volatile HCl, washing liquor (from washing solids containing levulinic acid) and lactones, claiming high yield of yellow-colored levulinic acid. The recycling was done through a preheater and is a multi-pot reaction (operating conditions: 1-5% w / v acid, temperature 150-250°C, 1s-3h).

[05] Document US4897497 describes a process in which a continuous two-reactor system produces furfural and levulinic acid from lignocellulose (hardwood) at 5-25% solids. Furfural and lignin from the first reactor (operating conditions: 110% w / v acid, temperature 180-265°C) are collected before entering the second reactor (operating conditions: 1-15% w / v acid, temperature 130-250°C, 1-60 min). The yields of furfural and levulinic acid were > 75% and > 55%, respectively, which theoretically can be derived.

[06] Document WO2014 / 087015 describes that washing with a steam condensate (obtained by vaporizing the raffinate directly after centrifugation) results in higher levulinic acid yields compared to washing with normal water. Furthermore, it describes that washing with an aqueous phase (other than the organic solvent during extractions) results in a less compressible filter cake. Washing first with an aqueous phase and subsequently with a steam condensate results in even higher levulinic acid yields.

[07] Document US9174909 describes a 2-stage process in which the first stage extracts pentosans while the second Petition 870230032893, dated 04 / 19 / 2023, p. 10 / 35 3 / 19 converts hexosans to LA. The goal of both steps is to protect pentosans while simultaneously reducing humins.

[08] Document US3065263 describes a process where three series of ten cyclic digestions were performed for residence times of 15, 30 and 60 minutes, under operating conditions: 4-10% w / v acid, 6-10% recycled levulinic acid, temperature of 140-200°C, 5-60 min). Total solids were 1-15% by weight.

[09] Document US5608105 describes another biofine process featuring a continuous two-reactor system in which hydroxylmethylfurfural from the first reactor (operating conditions: 1-5% w / v acid, temperature 210-230°C, 13-25 seconds) enters the second reactor (operating conditions: 3-7.5% w / v acid, temperature 195-215°C, 15-60 minutes) to produce levulinic acid.

[010] Liu et al, 2020 discussed the state of the art of the mechanism, pretreatment and catalytic systems for levulinic acid production from cellulose, lignocellulosic biomass and industrial production status. The authors disclose a method for producing levulinic acid from expensive substrates such as pure sugars (glucose, fructose), expensive carbohydrates (starch, cellulose) and “cellulose-rich, low-lignin” feedstock / biomass (flour, pulp, paper, miscanthus, cotton, bagasse, etc.). These substrates are composed of more than 60% sugars / carbohydrates and few of them are 100% sugars.

[011] Tat Boonyakarn et al., 2019 disclose a catalyst system for converting cellulose into levulinic acid.

[012] Document CN101648863 discloses a method for preparing levulinic acids using straw biomass. Petition 870230032893, dated 04 / 19 / 2023, page 11 / 35 4 / 19

[013] Document CN104402722A discloses a method for alcoholysis of lignocellulose biomass for the preparation of levulinate and furan derivatives. None of the previously cited arts provides a simple “one-pot” method for producing levulinic acid from high lignin content (35-40%) and high ash content (30-45%) containing residues, technical lignin. OBJECTIVES

[014] The main objective of the present invention patent is to develop a process for producing high-value levulinic acid from technical lignin.

[015] Another objective of the present invention is to provide a catalyst comprising a combination of mineral acid and Lewis acid optimized to produce levulinic acid from technical lignin.

[016] Yet another objective of the present invention is to provide an economical process for obtaining improved yield of levulinic acid on high solids load cellulose substrate. In order to overcome the aforementioned disadvantages of conventional processes, the present invention provides a method in which levulinic acid is produced from technical lignin, which is a residue.

[017] The process of the present invention patent is advantageous in relation to existing processes, as it provides a process for valorizing technical lignin to produce high-value levulinic acid. This residue has no other use except incineration as a waste management practice.

[018] Thus, the present invention patent provides an economical and environmentally friendly process for the production of levulinic acid from technical lignin. Furthermore, the present process Petition 870230032893, dated 04 / 19 / 2023, page 12 / 35 5 / 19 enables the purification of cellulose from technical lignin waste using an optimized combination of formic acid and technical alcohol at high temperature (160-180°C) for 30-60 minutes at autogenic pressure (15-20 bar). Furthermore, the synergistic combination of a mineral acid and Lewis acid as a catalyst results in high yields of levulinic acid (65%) compared to methods disclosed in the prior art (30-40%).

[019] The method of the present invention patent works with high total solids (20-25%) compared to 5-10% available in the state of the art. Furthermore, high-purity levulinic acid (88%) is produced by the method of the present invention patent. The method of the present invention patent provides an optimized process with reduced generation of biochar / humins and without any other byproduct formation, such as furfurals, HMF, aldehydes, etc., to aid in simple and low-cost downstream processing. In view of the above, the process of the present invention patent is an economical process for the production of levulinic acid using inexpensive residual technical lignin.

[020] The process of the present invention patent allows the use of technical lignin, a residual residue, for the production of levulinic acid in high solids loads and allows the valorization of technical lignin. SUMMARY

[021] The present invention relates to a process for the production of levulinic acid. Consequently, the present invention provides a simple one-pot process for producing levulinic acid from technical lignin. In a preferred aspect, the technical lignin is recovered from the 2G biorefinery after production and distillation. Petition 870230032893, dated 04 / 19 / 2023, page 13 / 35 6 / 19 of ethanol.

[022] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin, said process comprising: a) Treat technical lignin with a combination of formic acid and technical alcohol in a high-pressure reactor to obtain cellulose and lignin; b) subject the cellulose from step a) to treatment with a catalyst to obtain a paste; c) Centrifuge the paste followed by mixing the liquid fraction containing levulinic acid with a solvent to obtain an organic mixture and an acidic aqueous liquid residue; d) evaporate the solvent from the organic mixture to obtain levulinic acid; and e) recycle the acidic aqueous liquid residue from step c) and the solvent from step d) for the next extraction and purification step of levulinic acid;

[023] wherein technical lignin comprises 10-25% cellulose, 0-5% hemicellulose, 25-55% lignin and 20-50% ash content.

[024] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the combination of formic acid and technical alcohol is present in a 1:1 ratio.

[025] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the high-pressure reactor (HPR) is operated at a temperature of 160-180°C and wherein the technical lignin is treated with a combination of formic acid and Petition 870230032893, dated 04 / 19 / 2023, page 14 / 35 7 / 19 technical alcohol for 1 hour.

[026] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the catalyst comprises a combination of mineral acid and Lewis acid.

[027] In one embodiment of the present invention patent, a process is provided for the production of levulinic acid from technical lignin as described in this document, in which the cellulose is subjected to catalytic treatment at a temperature of 80-200°C for 30-60 minutes.

[028] In one embodiment of the present invention patent, a process is provided for the production of levulinic acid from technical lignin as described in this document, wherein the solvent is selected from the group comprising dichloromethane, diethyl ether and ethyl acetate.

[029] In one embodiment of the present invention patent, a process is provided for the production of levulinic acid from technical lignin as described in this document, wherein the liquid fraction containing levulinic acid and the solvent in step c) are present in the ratio of 1:3.

[030] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described herein, wherein the levulinic acid is produced as 71% of the theoretical yield.

[031] In one embodiment of the present invention, a process is provided for the production of levulinic acid from technical lignin as described in this document, wherein the technical alcohol comprises 85% ethanol, 5% acetic acid, 5% acetaldehyde and Petition 870230032893, dated 04 / 19 / 2023, page 15 / 35 8 / 19 water 5%.

[032] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; and wherein the Lewis acid is selected from the group consisting of aluminum chloride, ferric chloride and chromium chloride.

[033] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described herein, wherein 10-30% w / v of solid cellulose filler is used in step b) of the process.

[034] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the catalyst is a combination of sulfuric acid and ferric chloride added at a concentration of 4% (v / v) in 1 L HPR at 200°C.

[035] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the process produces 34.7-65.1% by weight of levulinic acid with 88% purity.

[036] These and other characteristics, aspects and advantages of the present subject will be better understood with reference to the following description. This summary is provided to present a selection of concepts in a simplified way. BRIEF DESCRIPTION OF THE FIGURES

[037] The following figures are part of this descriptive report and are included to further illustrate aspects of the present patent. Petition 870230032893, dated 04 / 19 / 2023, page 16 / 35 9 / 19 of invention. The invention patent can be better understood by reference to the figures in combination with the detailed description of the specific embodiments presented herein.

[038] Figure 1 is a graphical representation of the chemical composition of technical lignin comprising cellulose, hemicellulose, lignin and ash content.

[039] Figure 2 is a schematic representation of the mass balance of cellulose extraction from lignin using a combination of formic acid and alcohol.

[040] Figure 3 represents the NMR characterization of levulinic acid using 13C to determine the purity of levulinic acid produced by the present method. DETAILED DESCRIPTION OF THE INVENTION

[041] Those skilled in the art will be aware that the present invention is subject to variations and modifications beyond those specifically described. It should be understood that the present invention includes all such variations and modifications. The invention also includes all process steps, product features, referred to or indicated in this descriptive report, individually or collectively, and any and all combinations of any one or more of these steps or features.

[042] For convenience, before the further description of the present invention, some terms employed in the descriptive report and examples are collected here. These definitions should be read in the light of the remainder of the invention and understood as by one skilled in the art. The terms used in this document have the meanings recognized and known by those skilled in the art; however, for convenience and completeness, specific terms and their meanings are Petition 870230032893, dated 04 / 19 / 2023, p. 17 / 35 10 / 19 presented below.

[043] The articles a, an and the are used to refer to one or more of (that is, at least one) of the grammatical object of the article.

[044] The terms comprise and comprising are used in an inclusive, open sense, meaning that additional elements may be included. It is not intended to be interpreted as “consists only of”.

[045] Throughout this descriptive report, unless the context requires otherwise, the word comprehend and variations such as comprehend and comprehending, will be understood as implying the inclusion of a stated element or step or group of elements or steps, but not the exclusion of any other element or step or group of elements or steps.

[046] The term including is used to mean including, but not limited to. “Including” and “including, but not limited to” are used interchangeably.

[047] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning commonly understood by one skilled in the art to which this invention patent pertains. Although any methods and materials similar or equivalent to those described in this document may be used in the practice or testing of the invention patent, the preferred methods and materials are now described. All postings mentioned herein are incorporated herein by reference.

[048] This invention patent should not be limited in scope by the specific embodiments described herein, which are intended for illustrative purposes only. Functionally equivalent products and methods are clearly within the scope of Petition 870230032893, dated 04 / 19 / 2023, p. 18 / 35 11 / 19 invention patent, as described in this document.

[049] Technical lignin is primarily derived from lignocellulosic biomass. Traditionally, technical lignin is obtained as a byproduct of paper mills. In a preferred aspect of the present invention, the residue generated after distillation and recovery of ethanol is referred to as 2-G biorefinery residue or technical lignin. The technical lignin obtained after enzymatic hydrolysis, fermentation, and distillation was stored in a cool, dry place immediately after air drying for the study. Technical lignin, being of a highly recalcitrant nature, has no other use except for burning in a boiler to generate heat and energy. However, this is generally considered a waste management practice rather than a valuable or economically lucrative proposition for 2G ethanol production technology.

[050] The chemical composition of the technical lignin was determined, organosolv extraction of cellulose, catalyst screening, catalyst concentration optimization, synergistic catalysis was determined, and the levulinic acid production process was optimized on a 2 kg scale. The technical lignin used in the process of the present invention comprises 10-25% cellulose, 0-5% hemicellulose, 25-55% lignin, and 20-50% ash content.

[051] In one aspect, the present invention relates to a process for the production of levulinic acid from technical lignin. Consequently, the present invention provides a simple one-pot process for producing levulinic acid from technical lignin.

[052] In one embodiment, the present invention patent provides a process for producing levulinic acid from technical lignin, the Petition 870230032893, dated 04 / 19 / 2023, page 19 / 35 12 / 19 referred process comprising: a) treatment of technical lignin with a combination of formic acid and technical alcohol in a high-pressure reactor to obtain cellulose and lignin; b) subjecting the cellulose from step a) to treatment with a catalyst to obtain a paste; c) centrifugation of the paste followed by mixing the liquid fraction containing levulinic acid with a solvent to obtain an organic mixture and an acidic aqueous liquid residue; d) evaporation of the solvent from the organic mixture to obtain levulinic acid; e) recycling the acidic aqueous liquid residue from step c) and the solvent from step d) for the next step of extraction and purification of levulinic acid; wherein the technical lignin comprises 10-25% cellulose, 0-5% hemicellulose, 25-55% lignin and 20-50% ash content.

[053] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the combination of formic acid and technical alcohol is present in a 1:1 ratio.

[054] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the high-pressure reactor (HPR) is operated at a temperature of 160-180°C and wherein the technical lignin is treated with a combination of formic acid and technical alcohol for 1 hour.

[055] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the catalyst comprises a combination of mineral acid and Lewis acid.

[056] In one embodiment of the present invention patent, it is Petition 870230032893, dated 04 / 19 / 2023, page 20 / 35 13 / 19 provides a process for producing levulinic acid from technical lignin as described in this document, in which cellulose is subjected to catalytic treatment at a temperature of 80-200°C for 30-60 minutes.

[057] In one embodiment of the present invention patent, a process is provided for the production of levulinic acid from technical lignin as described in this document, wherein the solvent is selected from the group comprising dichloromethane, diethyl ether and ethyl acetate.

[058] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin as described herein, wherein the liquid fraction containing levulinic acid and the solvent in step c) are present in the ratio of 1:3.

[059] In one embodiment of the present invention patent, a process is provided for producing levulinic acid from technical lignin, as described herein, wherein the levulinic acid is produced as 71% of the theoretical yield.

[060] In one embodiment of the present invention, a process is provided for the production of levulinic acid from technical lignin as described herein, wherein the technical alcohol comprises 85% ethanol, 5% acetic acid, 5% acetaldehyde and 5% water.

[061] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described herein, wherein the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; and wherein the Lewis acid is selected from the group consisting of aluminum chloride, ferric chloride and chromium chloride.

[062] In one embodiment of the present invention patent, it is Petition 870230032893, dated 04 / 19 / 2023, page 21 / 35 14 / 19 provided a process for producing levulinic acid from lignin using a technique as described herein, in which 10-30% w / v of solid cellulose feedstock is used in step b) of the process.

[063] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the catalyst is a combination of sulfuric acid and ferric chloride added at a concentration of 4% (v / v) in 1 L HPR at 200°C.

[064] In one embodiment of the present invention, a process is provided for producing levulinic acid from technical lignin as described in this document, wherein the process produces 34.7-65.1% by weight of levulinic acid with 88% purity.

[065] Although the object has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. EXAMPLES

[066] The invention patent will now be illustrated with working examples, which are intended to illustrate the operation of the invention patent and are not intended to be restrictive so as to imply any limitations on the scope of the present invention patent. Unless defined otherwise, all technical and scientific terms used in this document have the same meaning as commonly understood by one skilled in the art to which this invention patent pertains. Although methods and materials similar or equivalent to those described in this document may be used in the practice of the disclosed methods, exemplary methods, devices and materials are described in this document. It should be understood that this invention patent is not limited to particular methods and conditions. Petition 870230032893, dated 04 / 19 / 2023, page 22 / 35 15 / 19 experimental cases are described, as such methods and conditions may vary.

[067] Example 1: Compositional Analysis

[068] The technical lignin used in the process of the present invention was purchased from a local supplier on a non-commercial basis for research purposes. The chemical composition of the technical lignin was determined by the NREL protocol (NREL / TP-510-42618). The concentration of sugar and inhibitors in the liquid hydrolysates was measured by HPLC following NREL LAP as described in Kapoor et al., 2017, using the Bio-Rad Aminex HPX-87H column coupled with a refractive index (RI) and Photodiode Array Detector (PDA) at a flow rate of 0.6 ml / min at a column temperature of 50°C. The mobile phase was 0.005 N H2SO4. The chemical composition of the technical lignin and its values ​​vary depending on the raw material, processing, and industry. The chemical composition of the technical lignin is shown in Figure 1 of the present invention. Based on the results obtained, it was observed that technical lignin comprises 10-25% cellulose, 0-5% hemicellulose, 25-55% lignin, and 20-50% ash.

[069] Example 2: Extraction of cellulose from technical lignin.

[070] Cellulose is extracted from technical lignin by an optimized organosolv processing using a combination of formic acid and technical alcohol in a 1:1 ratio, in a high-pressure reactor at 160-180°C for 1 hour. The chemical composition of the technical alcohol obtained in the ethanol production unit is shown in Table 1 below. Petition 870230032893, dated 04 / 19 / 2023, page 23 / 35 16 / 19

[071] Table 1: Chemical composition of technical alcohol No. Component Content (%) 1 Ethanol 85.0% 2 Water 5.0% 3 Acetic acid 5.0% 4 Acetaldehyde 5.0%

[072] The optimization of solvents for the organosolv process was carried out by evaluating different solvent combinations, as shown in Table 2 below.

[073] Table 2. Evaluation of formic acid in combination with ethanol / technical alcohol for lignin solubilization No.S. Solvent Temperature (°C) Pressure (Bar) Time (min) Solubility (%) Observation 1 Formic acid 160 6 60 18.2 Low solubility 2 Formic acid + ethanol (1:1) 160 11 60 28.62 High solubility with low ash content 3 Formic acid + alcohol (1:1) 160 9 60 36.8 High solubility with low ash content 4 Formic acid + water 160 6 60 11.3 Low solubility 5 Formic acid + acetic acid 160 6 60 14.1 Low solubility 6 Formic acid + acetaldehyde 160 6 60 12.4 Low solubility 7 Formic acid + ethanol + water + acetic acid + Acetaldehyde 160 9 60 36.0 High solubility with low ash content

[074] Based on the results obtained in Table 2, it was shown that the Petition 870230032893, dated 04 / 19 / 2023, page 24 / 35 17 / 19 Formic acid + alcohol (technical alcohol) in a 1:1 ratio recovers a high quantity of lignin compared to other solvent combinations. Therefore, formic acid + alcohol (1:1) is selected and used in the subsequent steps of the process of the present invention patent.

[075] Example 3: Lignin cellulose extraction using organosolv technology [temperature optimization (120-200oC)]

[076] Based on extensive screening, a solvent mixture was evaluated for the extraction of cellulose from technical lignin, namely, formic acid:alcohol. Different combinations of formic acid:alcohol were evaluated, as shown in Figure 2 of the present invention patent, and it was found that high recovery of cellulose (92%) and lignin (67.6%) was obtained at 160 °C with formic acid:alcohol, as shown in Table 3 below.

[077] Table 3. Temperature optimization for maximum lignin recovery from cellulose using formic acid: alcohol HRP Treatments Temperature / Time Total Lignin Recovery (%) Total Cellulose Recovery (%) 120°C / 1h 32.8 98.1 140°C / 1h 45.2 96.4 160°C / 1h 67.6 92.0 180°C / 1h 61.7 89.7 190°C / 1h 57.1 87.6 200°C / 1h 52.1 83.8

[078] Example 4: Catalyst screening and concentration optimization

[079] Catalyst screening for levulinic acid production was performed using organosolv cellulose as a substrate at 200°C for 3 hours. It showed that a synergistic combination of strong mineral acid (H2SO4, HCl, HNO3 and H3PO4) and weak Lewis acid (AlCle, FeCfe, CrCh) is ideal for levulinic acid production. The study was conducted in Petition 870230032893, dated 04 / 19 / 2023, page 25 / 35 18 / 19 L HPR at 200°C under autogenous pressure. Levulinic acid was measured for each reaction by HPLC after appropriate dilution of the samples using a Bio-Rad Aminex HPX-87H column coupled to a refractive index (RI) and photodiode array (PDA) detector at a flow rate of 0.6 ml / min and a column temperature of 50°C. The mobile phase was 0.005 N H2SO4.

[080] Based on the results obtained, it was indicated that H2SO4 provides optimum yields of 66%, followed by H3PO4 producing ~ 50% levulinic acid in combination with FeCh, as shown in table 4 below.

[081] Table 4. Catalyst screening and concentration optimization Us. Substrate Solvent / Catalyst levulinic acid 1 Cellulose organosolv 1% H2SO4 17.6 2 2% H2SO4 20.7 3 3% H2SO4 32.5 4 2% AICI3 3.4 5 2% FeCIs 18.3 6 2% CrCI3 16.5 7 2% H2SO4+2% AICI3 40.4 8 2% H2SO4+2% CrCI3 43.3 9 2% H2SO4+2% FeCIs 49.6 10 4% H2SO4+4% FeCIs 65.6 11 4% HCL+ 4% FeCIs 37.5 12 4% HNO3 + 4% FeCIs 3.3 13 4% H3PO4+ 4% FeCIs 49.3 14 5% H2SO4+ 5% FeCIs 56.2 15 8% H2SO4+ 8% FeCIs 56.7 16 10% H2SO4+ 10% FeCIs 57.3

[082] Example 5: Production of levulinic acid in different solid loads

[083] Levulinic acid production was studied in different solid feedstocks (10-30%, w / v) of organosolv cellulose recovered from technical lignin. Catalysts (H2SO4 & FeCh) were added at a concentration of 4% (v / v) in 1 L of HPR (200°C). Yields Petition 870230032893, dated 04 / 19 / 2023, page 26 / 35 19 / 19 were 65.1%, 62.6%, and 34.7% at total solids loadings of 10%, 20%, and 25%, respectively, as shown in Table 5 below. Levulinic acid yields decreased at higher solids loadings (i.e., above 20%) due to high viscosity and mass transfer issues. Thus, 20% (w / v) was indicated as the optimum loading for both substrates. As there was no free-flowing fluid with a 30% total solids loading, the reaction could not be carried out (therefore, there is no data with 30% TS).

[084] Table 5: Levulinic acid production in different solid loads No.S. Substrate Solid Fillers (%) Levulinic Acid (%) 1 Organosolvable Cellulose 10 65.1 2 20 62.6 3 25 34.7 4 30 No reaction

[085] Example 6: Downstream processing by solvent recycling

[086] After the production of levulinic acid in the reactor, the slurry is recovered and solid-liquid separation is performed by centrifugation. The liquid containing levulinic acid is mixed with a selected solvent, such as dichloromethane or diethyl ether or ethyl acetate, in a 1:3 ratio. The levulinic acid is preferably distributed in the organic solvent layer, which is extracted using a separatory funnel, and the acidic aqueous liquid residue is processed separately. The solvent was evaporated from the organic mixture using a rotary evaporator to recover high-purity (88%) levulinic acid, and the solvent is recycled for the next round of levulinic acid extraction and purification, as shown in Figure 3 of the present invention. Petition 870230032893, dated 04 / 19 / 2023, page 27 / 35

Claims

1 / 2 CLAIMS 1. Process for producing levulinic acid from technical lignin, characterized by comprising the steps of: a) treating technical lignin, comprising 10-25% cellulose, 0-5% hemicellulose, 25-55% lignin and 20-50% ash content, with a combination of formic acid and technical alcohol in a high-pressure reactor to obtain cellulose and lignin; b) subjecting the cellulose from step (a) to treatment with a catalyst to obtain a paste; c) centrifuging the paste followed by mixing the liquid fraction containing levulinic acid with a solvent to obtain an organic mixture and an acidic aqueous liquid residue; d) evaporating the solvent from the organic mixture to obtain levulinic acid; (ee) optionally recycle the acidic aqueous liquid residue from step (c) and the solvent from step (d) for the next round of levulinic acid extraction and purification wherein the technical alcohol comprises 85% ethanol, 5% acetic acid, 5% acetaldehyde and 5% water.

2. Process according to claim 1, characterized in that the combination of formic acid and technical alcohol is present in a 1:1 ratio.

3. Process according to claim 1, characterized in that the high-pressure reactor (HPR) is operated at a temperature of 160-180°C, and in which technical lignin is treated with a combination of formic acid and technical alcohol for 1 hour.

4. Process according to claim 1, characterized in that the catalyst consists of a combination of mineral acid and Lewis acid. Petition 870250114558, dated 12 / 12 / 2025, page 11 / 14 2 / 2 5. Process according to claim 1, characterized in that the cellulose is subjected to catalytic treatment at a temperature of 80-200°C for 30-60 minutes.

6. Process according to claim 1, characterized in that the solvent is selected from the group consisting of dichloromethane, diethyl ether and ethyl acetate.

7. Process according to claim 1, characterized in that the liquid fraction containing levulinic acid and the solvent of step c) are present in a ratio of 1:

3.

8. Process according to claim 1, characterized in that the levulinic acid has a yield of 71% of the theoretical yield.

9. Process according to claim 1, characterized in that the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; and in that the Lewis acid is selected from the group consisting of aluminum chloride, ferric chloride and chromium chloride.

10. Process according to claim 1, characterized in that 10-30% w / v of solid cellulose feedstock is used in step b) of the process.

11. Process according to claim 1, characterized in that the catalyst is a combination of sulfuric acid and ferric chloride added at a concentration of 4% (v / v) in 1 L HPR at 200°C.

12. Process according to claim 1, characterized in that the process produces 34.7-65.1% by weight of levulinic acid with 88% purity. Petition 870250114558, dated 12 / 12 / 2025, page 12 / 14

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