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BR-112021010998-B1 - PROCESS FOR TREATMENT AT ACIDIC OR NEUTRAL PH IN A TREATMENT REACTOR OF LIGNOCELLULOSIC BIOMASS AND INSTALLATION FOR CARRYING OUT THIS PROCESS

BR112021010998B1BR 112021010998 B1BR112021010998 B1BR 112021010998B1BR-112021010998-B1

Abstract

PROCESS FOR CLEANING A TREATMENT REACTOR FOR LIGNOCELLULOSIC BIOMASS. The present invention relates to a treatment process at acidic or neutral pH in a treatment reactor (4) for lignocellulosic biomass (P), said process comprising a continuous cleaning phase of the reactor, which comprises the introduction of a basic aqueous solution (EB) into said reactor containing the biomass being treated.

Inventors

  • MERIEM BOURAS GALINIE
  • Caroline Aymard
  • OLIVIER CARNNOT

Assignees

  • INSTITUT NATIONAL DE LA RECHERCHE POUR L'AGRICULTURE, L'ALIMENTATION ET L'ENVIRONNEMENT
  • AGRO INDUSTRIES RECHERCHE ET DEVELOPPEMENT
  • IFP Energies Nouvelles

Dates

Publication Date
20260310
Application Date
20191213
Priority Date
20181221

Claims (16)

  1. 1. Treatment process at acidic or neutral pH in a treatment reactor (4) of a lignocellulosic biomass (P), said process characterized by comprising a continuous cleaning phase of the reactor, comprising the introduction of a basic aqueous solution (EB) into said reactor containing the biomass being treated, the base concentration of the basic aqueous solution (EB) being adjusted so as to increase the pH of the biomass (P) entering the reactor (4) from an acidic pH range between 0.5 and 3 to a basic pH range between 8 and 14.
  2. 2. Process according to claim 1, characterized in that the aqueous basic solution (EB) is heated before introduction into the treatment reactor (4), notably to a temperature of at least 40°C, notably at least 80°C.
  3. 3. Process according to previous claim 1 or 2, characterized in that the introduction of the basic solution into the treatment reactor (4) is carried out in said reactor, the internal volume of which is at a temperature of at least 120°C, notably at least 140°C.
  4. 4. Process according to any of the preceding claims, characterized in that the cleaning phase of the treatment reactor (4) with the basic solution (EB) has a duration between 15 minutes and 8 hours, notably between 1 and 3 hours.
  5. 5. Process according to any of the preceding claims, characterized in that, in the cleaning stage of the treatment reactor (4), the residence time in said reactor of the biomass (P) impregnated with aqueous basic solution (EB) is between 5 and 15 minutes.
  6. 6. Process according to any of the preceding claims, characterized in that, in the cleaning phase of the treatment reactor (4), the flow rate of the aqueous basic solution (EB) at the inlet of said reactor is regulated in such a way that the dry matter content DM of the biomass (P) decreases as it passes through the reactor, from a value of 30 to 60% DM, notably 50% DM, to a value of 15 to 25% DM, notably 20% DM.
  7. 7. Process according to any of the preceding claims, characterized in that the concentration of the aqueous basic solution (EB) is regulated so as to increase the pH of the biomass (P) entering the reactor (4) from an acidic pH range close to 3, to a basic pH close to 13.
  8. 8. Process according to any of the preceding claims, characterized in that the continuous cleaning phase of the treatment reactor (4) is carried out according to a given frequency and/or when a limit value of a physical-chemical or rheological characteristic of the reaction medium in said reactor is exceeded.
  9. 9. Process according to any of the preceding claims, characterized in that one of the physical, chemical or rheological characteristics or the nature of the biomass (P) feeding the treatment reactor (4) is changed during at least part of its cleaning phase.
  10. 10. Process according to any of the preceding claims, characterized in that the treatment is a steam explosion cooking, and in that the heat of the steam (V) at the outlet of a separation device (5) disposed at the outlet of the treatment reactor (4) is thermally exhausted, at least in part, by recovery via a heat exchanger, to heat the aqueous solution or solutions (E, EA, EB) used in said process, the portion of steam (V) that is condensed, notably via a condenser, being preferably recycled as a water supply.
  11. 11. Process according to any of the preceding claims, characterized in that the biomass (P) is impregnated with an aqueous acidic solution (EA) in an impregnation reactor (3) before its introduction into the treatment reactor, which is a pretreatment reactor (4).
  12. 12. Process according to any of the preceding claims, characterized in that, during at least part of the continuous cleaning phase of the treatment reactor (4), the acid content of the aqueous acid solution (EA) placed in contact with the biomass during its prior impregnation in the impregnation reactor (3) is reduced or suppressed.
  13. 13. Process according to claim 11, characterized in that, during at least part of the continuous cleaning phase of the treatment reactor (4), the acidic aqueous solution (EA) placed in contact with the biomass (P), during its prior impregnation in the impregnation reactor (3), is replaced by a basic aqueous solution (EB), notably the same one that is injected during said phase into the treatment reactor (4), or by a neutral pH aqueous solution (E).
  14. 14. Process according to any one of claims 1 to 10, characterized in that several, notably two impregnation reactors (3, 3’) are used in parallel to impregnate the biomass (P) with an aqueous solution before its introduction into the pretreatment reactor, a first impregnation reactor (3) being fed with an acidic aqueous solution (EA) or with a neutral pH aqueous solution (E), and a second impregnation reactor (3’) being fed with a basic aqueous solution (EB), the two reactors (3, 3’) operating alternately, the second reactor (3’) being operational during at least part of the cleaning phase of the pretreatment reactor (4).
  15. 15. Process according to any of the preceding claims, characterized in that a separation is carried out between biomass (P) and the aqueous phase in liquid or vapor form at the outlet of the pretreatment reactor (4) by a separation device (5), and that the cleaning phase comprises, after the introduction of the basic aqueous solution (EB) into the pretreatment reactor (4), at least one rinse of the separation device by an aqueous solution (E), notably between 1 and 10 successive rinses.
  16. 16. Installation for carrying out the process according to any of the preceding claims, characterized in that it comprises, from upstream to downstream, an impregnation reactor (3) for lignocellulosic biomass (P) in fluid connection with a tank (1) for preparing an acidic (EA) or neutral (E) aqueous solution, a treatment reactor which is a pre-treatment reactor (4) for the impregnated biomass, in fluid connection with a tank for preparing a basic aqueous solution (EB), and a separation device (5) which is associated with rinsing means by an aqueous solution (E).

Description

Technical field [001] The invention relates to a process for treating lignocellulosic biomass to produce second-generation (2G) sugar juices. These sugar juices can be used to produce other products via biochemical means (e.g., alcohols such as ethanol, butanol or other molecules, or solvents such as acetone, etc.). This process comprises different stages, of which generally three stages are liquor preparation, impregnation of the biomass for this liquor, and pre-treatment of the impregnated biomass for cooking, notably by steam explosion. State of the art [002] Lignocellulosic biomass represents one of the most abundant renewable resources on Earth. Substrates considered are very varied, including lignite substrates, such as different woods (hardwood and softwood), by-products from agriculture (wheat straw, corn stalks, etc.), or other agri-food, paper, etc. industries. [003] The biochemical transformation process of lignocellulose into 2G sugar juice notably comprises a pre-treatment step and an enzymatic hydrolysis step using an enzymatic cocktail. These processes also often include an impregnation step before pre-treatment. The sugar juices resulting from hydrolysis are then treated, for example, by fermentation, and the process may also include separation steps and/or a purification step of the final product. [004] Lignocellulosic biomass is composed of three polymers: cellulose (35 to 50%), which is a polysaccharide essentially composed of hexoses; hemicellulose (20 to 30%), which is a polysaccharide essentially composed of pentoses; and lignin (15 to 25%), which is a polymer with a complex structure and high molecular weight, composed of aromatic alcohols linked by ether bonds. These different molecules are responsible for intrinsic properties of the plant cell wall and are organized in a complex network. [005] Among the three basic polymers that make up alignocellulosic biomass, cellulose and hemicellulose are two that allow the production of 2G sugary juices. [006] Most of the time, hemicellulose is mostly broken down into monomeric sugars and oligomers during pretreatment, and cellulose is converted into glucose by enzymatic hydrolysis. However, access to crude cellulose in the native substrate remains difficult for enzymes to access, hence the need for pretreatment. This pretreatment allows modifying the physicochemical properties of lignocellulosic in order to improve the accessibility of cellulose to enzymes and its reactivity to enzymatic hydrolysis. [007] There are numerous technologies relevant to the invention for carrying out this pretreatment, which will be grouped below under the generic term "cooking", consisting of heating the biomass to a high temperature for a defined duration. Notably known are acid cooking, in which the biomass is contacted with an acidic solution before/during cooking, and alkaline cooking, in which the biomass is contacted with a basic solution before/during cooking. Also known is cooking (acid, alkaline or without impregnation) called "steam explosion", in which the biomass is subjected to water vapor under pressure. [008] There are also pretreatment processes called "organosolvent pulping" according to English terminology (or organosolvent treatment). This latter process refers to a pretreatment in the presence of one or more organic solvents and usually water. The solvent can be an alcohol (ethanol), an acid such as acetic acid, formic acid, or even acetone, and even a mixture of these compounds. Organosolvent pulping processes lead to at least partial solubilization of lignin, and partial solubilization of hemicelluloses. Then we have two streams at the outlet: the substrate pretreated with residual cellulose, hemicellulose and lignin, and the solvent phase containing the solubilized lignin and a portion of the hemicelluloses. There is usually a solvent regeneration step, which allows the extraction of a lignin stream. Certain organosolvent pulping treatments (notably with ethanol) can be stopped by the addition of a strong acid (such as H2SO4). One could also consider contacting the biomass with the solvent via an impregnation reactor before the cooking phase, or contacting the biomass with the acid catalyst before performing an "organo-pulping" cooking process. [009] Different configurations are reported, for example, in the document "Production of bioethanol from lignocellulosic materials via the biochemical pathway: A review", M. Balat, Energy Conversion and Management 52 (2011) 858-875), or in the document "Bioethanol production from agricultural wastes: an overview", No. Sarkar, S. Kumer Ghosh, S. Bannerjee, K. Aikat, Renewable Energy 37 (2012) 19-27). [0010] One of the most effective pretreatments is steam explosion cooking, mentioned above, as it allows for almost complete hydrolysis of hemicellulose and a significant improvement in the accessibility and reactivity of cellulose to enzymes. This pretreatment can be preceded/followed by other treatment(