WO2017174098A1 - Procédé de production de composés aromatiques de bas poids moléculaire dérivés de la lignine - Google Patents

Procédé de production de composés aromatiques de bas poids moléculaire dérivés de la lignine Download PDF

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Publication number
WO2017174098A1
WO2017174098A1 PCT/EP2016/000575 EP2016000575W WO2017174098A1 WO 2017174098 A1 WO2017174098 A1 WO 2017174098A1 EP 2016000575 W EP2016000575 W EP 2016000575W WO 2017174098 A1 WO2017174098 A1 WO 2017174098A1
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Prior art keywords
lignin
derived
optionally substituted
molecular weight
compound
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PCT/EP2016/000575
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English (en)
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Krawczyk NASTARAN
Möller ALEXANDER
Peter Geigle
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Cmblu Projekt Ag
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Priority to PCT/EP2016/000575 priority Critical patent/WO2017174098A1/fr
Priority to US16/091,436 priority patent/US11008284B2/en
Priority to AU2017246494A priority patent/AU2017246494B2/en
Priority to CA3017991A priority patent/CA3017991A1/fr
Priority to JP2019503619A priority patent/JP2019516781A/ja
Priority to KR1020187032231A priority patent/KR20180134369A/ko
Priority to CN201780022496.4A priority patent/CN109072089B/zh
Priority to JP2019503620A priority patent/JP7050747B2/ja
Priority to MYPI2018703302A priority patent/MY191139A/en
Priority to CN201780022306.9A priority patent/CN109072088B/zh
Priority to AU2017246493A priority patent/AU2017246493A1/en
Priority to CA3017989A priority patent/CA3017989A1/fr
Priority to BR112018069113-5A priority patent/BR112018069113B1/pt
Priority to BR112018069518A priority patent/BR112018069518A8/pt
Priority to EP17716793.9A priority patent/EP3440158A1/fr
Priority to PCT/EP2017/000462 priority patent/WO2017174207A1/fr
Priority to PCT/EP2017/000461 priority patent/WO2017174206A1/fr
Priority to US16/091,437 priority patent/US11225756B2/en
Priority to KR1020187032226A priority patent/KR20180133888A/ko
Priority to EP22203648.5A priority patent/EP4180504A3/fr
Priority to EP22203539.6A priority patent/EP4180503A1/fr
Priority to EP17716792.1A priority patent/EP3440157A1/fr
Publication of WO2017174098A1 publication Critical patent/WO2017174098A1/fr
Priority to ZA2018/06214A priority patent/ZA201806214B/en
Priority to ZA2018/06216A priority patent/ZA201806216B/en
Priority to US17/177,567 priority patent/US11773537B2/en
Priority to JP2021142062A priority patent/JP2022000431A/ja
Priority to AU2023202814A priority patent/AU2023202814A1/en
Priority to US18/197,415 priority patent/US20230304221A1/en

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal

Definitions

  • the present invention relates to the field of efficientlyzing lignin-comprising material, typically a by-product of pulping processes.
  • the present invention provides a method for producing low molecular weight aromatic lignin-derived compounds.
  • the inventive method comprises the steps of providing modified lignin-derived components obtainable from a pulping process and subjecting the same to a decomposition step comprising cracking and oxidizing or reducing by means of a catalyst or by electrooxidation. After purification and optional annulation, the obtained low molecular weight aromatic lignin-derived compound is preferably further oxidized to a redox active compound, such as a monocyclic or bicyclic hydroquinone and/or quinone compound, and optionally further derivatized.
  • the present invention relates to compounds obtainable by the inventive method, to an assembly for carrying out the inventive method, and to a method to implement said assembly in a state-of-the-art pulp and/or paper manufacturing plant.
  • Lignin is among the most abundant naturally occurring organic materials together with cellulose and chitin ⁇ Sitte et al. 2002; S. 353-356). In total, lignin constitutes about 30% of non-fossil organic carbon and 20-35% of the dry mass of wood ⁇ W. Boerjan et al. (2003). "Lignin biosynthesis”. Ann. Rev. Plant Biol. 54 (I): 5 9-549). Generally, the term "lignin” denominates phenolic macromolecules, which are composed of different monomeric building blocks. They are rigid biopolymers, which are part of plant cell walls and cause lignification of plant cells. About 20-30% of the dry mass of plants consists of lignin.
  • lignin is covalently linked to hemicellulose and, therefore, crosslinks plant polysaccharides, conferring mechanical strength to the cell wall and, thus, to the plant as a whole ⁇ Chabannes, M.; et al. (2001).
  • "In situ analysis of lignins in transgenic tobacco reveals a differential impact of individual transformations on the spatial patterns of lignin deposition at the cellular and subcellular levels". Plant J. 28 (3): 271-282). Therefore, height increment of plants requires lignin.
  • Any chemical pulping applied aims to dissolve and remove lignin and hemicellulose and to liberate wood cellulose fibers.
  • (some) hemicellulose is also degraded in the process (Brannva/I, 2009 Overview of pulp and paper processes, in: Ek, M., Gellerstedt, G, Henriksson, G, (Eds.), Pulp and paper chemistry and technology, Volume 2, Pulping chemistry and technology. Walter de Gruyter, Berlin, Germany).
  • Sulfite pulping by the sulfite process pre-dates the Kraft process, but has largely been replaced by the Kraft process due to increased cellulose fiber strength resulting from the Kraft process.
  • lignin oversupply is a common phenomenon, e.g., in state-of-the-art Kraft pulping plants, as such plants have become more energy efficient. Meanwhile, less lignin is required as energy source to operate such a plant (J- Lora, 2008.
  • Lignin material typically obtained as by-product of the pulping processes for example, Kraft lignin or lignosulfonate is composed of numerous complex lignin derivatives.
  • lignosulfonates are yielded from the pulping liquor of the sulfite process (sulfite pulping), or may be produced by so-called postsulfonation of lignin-derived polymers obtained by the Kraft process (sulfate pulping).
  • modified lignin-derived components such as lignosulfonates
  • lignosulfonates are primarily employed as dispersants and binders in construction, mining and agricultural industries.
  • the largest dispersant use of lignosulfonates is its admixture for concrete, whi le copper mining, carbon black and coal represent its most prominent applications as binder.
  • Demand in downstream markets is greatly influenced by the overall economic. Consumption of lignosulfonates is predicted by some experts to grow moderately at an average annual rate of about 2.5% until end of 201 6. However, competing products are likely to reduce lignosulfonate's demand.
  • the object underlying the present invention is solved according to a first aspect by the method of claim 1 comprising preferably steps (A) to (F).
  • the present invention refers to low molecular weight lignin derived compounds, which are obtainable by a method according to the first aspect.
  • the present invention is directed to an assembly, which allows to carry out steps (C) to (F) of the inventive method.
  • the present invention is directed to a method for producing at least one low molecular weight aromatic lignin-derived compound, wherein the method comprises the provision of lignocellulosic material (step A).
  • the lignocellulosic material is preferably chopped.
  • Such material is subjected to a pulping process in subsequent step (B).
  • step (C) the pulp obtained in step (B) is separated in a pulp separating step from the process stream obtainable from the pulping process in step (B), to provide a substantially pulp-free process stream.
  • That substantially pulp-free process stream comprises modified lignin-derived components, hemicellulose, inorganic material, such as reactive agents.
  • the essentially pulp-free process stream which contains the modified lignin-derived components, may be provided as one single process stream or may be partitioned in at least two (partial) process streams.
  • the fraction of modified lignin-derived components comprised either (alternative D.1 ) in the process stream provided by step (C) or (alternative D.2) in at least one of the at least two (partial) process streams provided by step (C) is isolated from the process stream(s) and its/their other components (e.g. hemicellulose and/or hydrolysis products thereof).
  • step (E) the isolated fraction of modified lignin-derived components of step (D) is subjected to chemical decomposition by step (E), wherein chemical decomposition step (E) may be carried out by either (alternative E.1 ) cracking and oxidizing the modified lignin-derived components in the presence of a homogeneous catalyst comprising a metal or a metalloid component.
  • chemical decomposition step (E) may be enabled (by alternative E.2) by cracking and reducing the modified lignin-derived components in the presence of a heterogeneous catalyst comprising a metal or a metalloid component.
  • the modified lignin-derived components may be subjected to electrooxidation, preferably in alkaline or acidic solution.
  • the inventive method is characterized by its final step (F), wherein the resulting lignin-derived products provided by step (E) are subjected to an isolation step.
  • the target compounds i.e. low molecular weight aromatic lignin-derived compounds
  • the target compounds may be purified by isolation from, e.g., higher molecular weight aromatic lignin components and/or preferably from other non-lignin-derived residual components, including e.g. inorganic reactive agents.
  • the present invention is based on the unprecedented combination of state-of-the-art large-scale pulp and/or paper manufacturing processes as source of enormous quantities of modified lignin-derived components representing by-products of such processes.
  • the inventive method comprises conversion or decomposition of said modified lignin-derived components (as by-products of the pulping process (step (B)) to low molecular weight lignin- derived compounds and their subsequent isolation, i.e. by a purification step from residual material.
  • Said method yields low molecular lignin-derived compounds, preferably low molecular weight aromatic lignin-derived compounds. They are preferably of low polydispersity due to the method's final purification step (F).
  • the present i nvention provides a method for the production of at least one low molecular weight aromatic lignin-derived compound, preferably of low polydispersity.
  • Said low polydispersity may essential ly be achieved by at least one isolation step (F), e.g. by filtration or extraction, to isolate the desired modified lignin-derived products resulting from decomposition in step (E).
  • isolation step (F) e.g. by filtration or extraction
  • the present invention refers to an inventive method al lowing to provide products resulti ng from reaction steps (A) to (F) and, optionally, from further downstream steps.
  • the method uses a renewable and abundant source of lignocel lulosic material as starti ng material.
  • the product resulting from reaction steps (A) to (F) is by itself commercially exploitable.
  • the product resulting from step (F) is further derivatized to produce compounds of characteristic nature, e.g. redox active compounds, which may be advantageously and versati lely used.
  • ligni n is generally understood herei n as wood-derived heterogeneous phenolic macromolecule or, rather, a group of phenolic macromolecules of plant origin, which is or are composed of different monomeric bui lding blocks. Hence, it is understood to be a natural copolymer. More specifical ly, ligni n may be generally defined as an amorphous three- dimensional polymer, which is mainly and natural ly composed of phenol ic bui lding blocks. Lignin in its "native" state, i.e.
  • Lignin typically comprises p-coumaryl, coniferyl and sinapyl alcohol as the phenolic bui lding blocks, which are l i nked (randomly) with ether (C-O-C) bonds, such as " ⁇ - ⁇ -4", "4-0-5" and, to a less frequent extent, "1 -0-4".
  • C-C linkages may occur in natural lignin, such as "5-5", “ ⁇ -5", “ ⁇ - ⁇ ” and “ ⁇ -1 ", amongst which the "5-5" l inkage is most frequently seen C-C l inkage, i n particular in softwood, such as spruce.
  • Typical li nkages as " ⁇ - ⁇ -4", "4-0-5" and "5-5" are depicted in the following:
  • a “building block” as used herein may preferably be understood as an organic moiety, which comprises at least one bond to covalently link said building block to another building block of the same or different chemical structure to form a plurality of covalently associated building blocks.
  • a building block according to the present invention is a "phenolic building block", i.e. any moiety comprising a six-membered aromatic ring, covalently functionalized by at least one hydroxyl group (-OH).
  • the lignin "building block” is typically characterized by a monocyclic, typically an aromatic moiety, with the monocycle typically being substituted at at least one position.
  • each lignin building block exhibits a carbocyclic monocycle with one or two substituents acting as linkers to another building block and one or two substituents, which do not exhibit any linking function.
  • a building block in the context of the present invention corresponds to a "monomer”.
  • a "dimer” as used herein typically comprises two such bui lding blocks covalently linked.
  • the dimer is typically characterized by two isolated monocyclic moieties covalently linked by a linker group or by a bond (biphenylic ring system). Biphenylic ring systems (as characteristic moiety of dimers) occur with lower frequency in plant lignin, in some plants (e.g. in spruce) with higher frequency.
  • any such dimeric compounds belong to the class of bicycles.
  • a larger plurality of any such covalently connected or linked building blocks forms typically the larger 3-dimensional lignin structure.
  • a "polymer” refers to a natural lignin molecule as it occurs in plants, e.g. as part of lignocellulosic material.
  • the lignin polymer is typically a copolymer of distinct building blocks.
  • Natural lignin's "building block” corresponds to a "monomer”. Accordingly, a building block typically is a (repeating) structural part of the natural polymer lignin.
  • the (phenolic) building block has typically 9 carbon atoms (Cg) or, less frequently seen, 8 carbon atoms (C8).
  • the building blocks have a molecular weight of about 1 30 to 300 Da, preferably of 1 50 to 250 Da, more preferably of 1 60 to 1 90 Da.
  • their basic monomeric C or Cs structure is not altered in the course of the natural lignin modifying process by e.g. pulping.
  • the "modified lignin-derived component" is a lignin molecule, which underwent a pulping process, such as "Kraft lignin" or "lignosulfonate".
  • a "modified lignin-derived component” typically has a lower molecular weight than natural lignin, from which it is derived. However, the "modified lignin-derived component” is larger than the monomeric or dimeric target compound, preferably having a molecular weight of at least 1 .000 Da.
  • the nature (and the actual molecular weight) of the "modified lignin-derived component” may vary largely depending, e.g., on the starting material, on the (pulping) method, by which the modified lignin-derived component is obtained, and on the reaction conditions applied by the inventive method. However, it is common to the modified lignin- derived components that they are composed of Ce or Cg building blocks after, e.g., a pulping process, as they occur in natural lignin.
  • lignin-derived components such as products of the pulping process
  • the pulping process provides a larger variety of lignin-derived components, which may typically contain from 8 to 1 50 building blocks.
  • lignin-derived components of the same number of building blocks are also diverse in terms of their chemical nature, as they reflect individual portions of the heterogeneous natural lignin polymer. That chemical and structural heterogeneity of lignin-derived material obtained from e.g. the pulping process traditionally impeded the preparation of homogeneous and/or high quality products by prior art methods, such that adequate economic exploitation of lignin-derived material was difficult to achieve in the art.
  • Pulping processes typically yield "modified" lignin-derived components based on Ce or Cg building blocks, wherein some or all of the building blocks may be modified. Modifications preferably occur at the linking groups of those building blocks of natural lignin, which are dissociated by the pulping process, and/or at substitution sites of the bui lding blocks, in particular at the aromatic ring system of a building block, e.g. by side chain modification or e.g. by sulfonation. Accordingly, the molecular weight of the modified building blocks of lignin-derived components may typically be slightly higher than the molecular weight of the building blocks of the natural lignin polymer.
  • the method according to a first aspect of the present invention comprises by its step (A) the provision of lignocellulosic material of plant origin as starting material.
  • “Lignocellulosic material” understood to be the starti ng material for the method of the present invention, may be provided as any form of plant biomass, which natural ly comprises cel lulose, l ignin and hemicel lulose.
  • cel lulose a polysaccharide consisting of a linear chain of several hundred to many thousands of ⁇ (1 ⁇ 4) linked D-glucose units
  • hemicel lulose typically forms a scaffold of fibers together with hemicel lulose.
  • Hemicellulose is any of several heteropolymeric polysaccharides, which include xylan, glucuronoxylan, arabi noxylan, glucomannan, and xyloglucan. It is typically present along with cellulose in almost all plant cel l walls. In contrast to cel lulose, hemicel lulose usual ly has a random, amorphous structure with little strength.
  • Said lignocel lulosic material typical ly is the starting material for any pulpi ng process with the object to obtain "pulp".
  • Pulp is understood herein to essential ly comprise a mixture of (preferably pure) cel lulosic fibrous material, which does not contai n ligni n or ligni n-derived components or contains only minor residual amounts of lignin components.
  • Said l ignocellulosic material may be derived from any appropriate plant origin, e.g. wood, fiber crops or waste paper origin. In case waste paper is used as starting material for the inventive method, such waste paper is typically of lower paper qual ity, such as newspaper paper.
  • Non-wood fiber sources may be employed by the inventive method as wel l (as far as it is for global pulp production), for a variety of reasons, i ncluding seasonal avai labil ity, problems with chemical recovery, brightness of the pulp etc.
  • Non-wood pulp processing usually, usual ly requires more water and energy than wood pulp pressing.
  • Lignocel lulosic material of known and invariant character is preferred, such that the inventive method's downstream products remain essentially unaltered, preferably provided in the form of chopped lignocel lulosic material, e.g. in the form of wood chips.
  • chopped lignocel lulosic material is understood - by the present invention - to be advantageously mechanical ly processed starti ng from plant material of natural origin, such that it is chopped to smal ler pieces.
  • Said lignocellulosic material is typical ly processed by any form of grindi ng, crushing and/or mi l li ng, which results i n smaller pieces of the lignocellulosic material, i.e.
  • the chopped lignocellulosic material which is preferred i n the context of the present invention. It may be preferred to employ lignocellulosic material with a lignin content of at least 1 5%, more preferred of at least 20%, most preferred of 20 to 35%.
  • the lignocellulosic material according to the present invention is preferably provided in the form of woodchips.
  • Woodchips are understood as a medium-sized solid material made by cutting, or chipping, larger pieces of wood. Characteristic values (such as water content, ash content, particle size distribution, bulk density, nitrogen content, chlorine content) are preferably chosen such that they fulfil generally accepted provisions, such as the European Standard EN 14961 . Wood chips as typically used for chemical pulping processes are preferably used for the inventive method as well as they are usually relatively uniform in size and substantially free of bark. The optimum size may vary with the wood species. Preferred sizes of the main fraction are about 3 to 45 mm with a fine fraction, defined as particles below 1 mm, of preferably less than 5%.
  • the inventive method comprises by its step (B) processing of the lignocellulosic (starting) material, which is preferably chopped, by a pulping process.
  • a "pulping process” is understood in the context of the present invention as process of chemically and/or mechanically disjoining cellulose fibers from other constituents of the lignocellulosic starting material of the pulping process, such as any wood, fiber crops or waste paper. Said pulping process generally yields pulp. Pulp is - in contrast to a processes for the manufacturing of pulp- the by-product (reflecting the essentially cellulosic fraction) of the present inventive method.
  • Distinct pulping processes may be used as a matter of choice to provide feedstocks for obtaining the lignin-derived components intermediates of the method of the present invention. These processes may preferably be those overly used in the pulp and paper industries (i.e., Kraft or sulfite process) or other feedstocks such as organosolv. Each process type has its advantages and disadvantages.
  • the choice of the employed pulping process as step (B) of the inventive method may depend on the type of lignin-derived components, which is envisaged as intermediate before decomposition and eventual further derivatization.
  • modified lignin-derived components obtainable as "by-product" of the chosen pulping process may be employed for further processing (e.g. derivatization) by downstream reactions of the inventive method.
  • the choice of the pulping process may thereby determine the target compounds obtainable by the inventive method.
  • the Kraft process is by far the most prevalent pulping process worldwide. It is typically a high pH pulping process in aqueous solution containing one or more of salt or non-salt agents selected from sulfide, sulfhydryl and polysulfide. It usually further comprises a sulfate salt.
  • the Kraft process is versatile in terms of the lignocellulosic starting material, which is treated in aqueous solution at elevated temperature and pressure. It is energy efficient and recycles most of the employed reactive agents, such as reactive agents required for the pulping process. Said process yields "Kraft lign in".
  • the modified lignin-derived components have a molecular weight of about 2.000 to 5.000 Da, preferably 2.000 to 3.000 Da. They may be components of the natural 3-D lignin polymers, potentially further chemically functionalized.
  • the sulfite process may be employed, which is the second most prevalent pulping process worldwide. It is typically a low pH pulping process in aqueous solution containing one or more of salt or non-salt agents exhibiting one or more of sulfite or bisulfite groups or anions.
  • the lignocellulosic starting material is treated in aqueous solution at elevated temperature and pressure. The process yields "lignosulfonate", which is more water-soluble than "Kraft lignin”.
  • Sulfite pulping is generally less destructive than Kraft pulping, i.e. the natural lignin polymer is degraded to modified lignin-derived components being larger than the corresponding components in Kraft pulping.
  • lignosulfonate typically has a molecular weight of about 3.000 to 100.000 Da, preferably 5.000 to 20.000 Da.
  • the “organosolv process” is typically carried out by treatment of wood or bagasse with various organic solvents.
  • “Bagasse” is the fibrous residue that remains once plant material (such as sugar cane) has been crushed and juice or sap have been extracted.
  • the “Alcell process” is one of the most commonly applied organosolv processes. It finally involves dissolution of lignin in either ethanol or ethanol/water mixtures. The advantage of the organosolv process is that it allows to automatically generate separate process streams of cellulose, hemicelluloses, and lignin.
  • organosolv process typically yields organosolv lignin as the modified lignin-derived components, which may be employed in further downstream reaction steps of the present invention. It is therefore typically low in its sulfur content. It has a low molecular weight of about 1 .000 to 2.000 Da. It is typically also of higher purity than the lignin-derived components obtained from other pulping processes.
  • a disadvantage of the organosolv process are the costs of solvent recovery.
  • Another pulping process which may be employed by the present invention, is the "steam explosion process" involving steam impregnation under pressure followed by rapid pressure release, which separates the lignocellulosic constituents. Covalent linkages of 3D lignin are ruptured as well, such that a complex mixture of lignin derived fragments is obtained.
  • wood or bagasse is exposed to steam at overpressure and elevated temperature, such as a total pressure of 1 .38 to 3.45 MPa and a temperature from about 453 to 503 K for about 1 -20 min before rapid pressure release.
  • the molecular weight distribution of the lignin fragments obtained by the steam explosion process is typically similar to the organosolv process.
  • Pyrolysis of lignocellulosic material (as a further alternative of step (B)) generally leads to pyrolyzed lignin-derived fragments, which may also be considered as modified lignin-derived components to be employed by the present invention.
  • the pyrolysis process typically involves relatively high temperatures, typically at least 600 K, such as between 720 and 750 K. No waste other than flue gas and ash is produced by that process, whereas increased energy consumption is required to fuel the process.
  • Pyrolysis lignin exhibits structural characteristics significantly different from other "pulping processes". It involves C8- rather than C9 building blocks, potentially allowing for unique downstream reactions according to the present invention. Thereby, specific aromatic hydrocarbons are made avai lable as target compounds, which are not avai lable via other processes.
  • step (B) Several other methods for isolating (modified) l ignin from wood or plant biomass or starting material are described in the art as well, including the "ammonia fiber explosion” (AFEX) process and the “hot water process”, which may also be employed as step (B).
  • AFEX ammonia fiber explosion
  • step (B) the "di lute acid process” as a further option for step (B) of the inventive method may ensure effective separation of lignin from other biomass components. It may, however, provide lower yields. Corrosion of equipment (due to the acidic environment) may also be an issue.
  • the "alkaline oxidation process” may use 0 2 or H2O2 to degrade lignin. However, the process may suffer from slower delignification rates.
  • the di lute acid process and alkaline oxidation process may both provide modified ligni n-derived components with simi lar molecular weight (distributions) as organosolv l ignin.
  • the inventive method comprises by its step (C) the step of separati ng pulp obtained by step (B) from the process stream obtai nable from step (B) (and, thereby, from the envisaged modified lignin-derived components) in a pulp separating step.
  • step (B) is converted to (i) a substantial ly cel lulose-free stream with enriched fractions of modified l igni n-derived components, hemicel lulose and/or fragments of any thereof, and (i i) pulp, which is understood herei n to essentially comprise a mixture of (enriched) cel lulose fibrous material .
  • the pulp fraction may be separated by step (C) as dry matter or as a pulp contai ning stream.
  • the pulp or pulp containing stream is further processed according to state- of-the-art technologies for, e.g., manufacturi ng paper.
  • the stream(s) contai ning the fraction of modified lignin-derived components is subjected to step (D) of the inventive method.
  • a "stream” or “process stream” is general ly understood as a liquid medium comprising i ntermediates of the i nventive method resulti ng from the preceding method step, which serve as starti ng (process) material for the subsequent method step.
  • the stream includes its components dissolved, suspended or dispersed in said l iquid medium. Distinct fractions of the (process) stream may be obtai ned reflecti ng components of homogenous nature, which may be isolated by fractionation from the process stream.
  • a "fraction” may represent a part of a whole or, more generally, any number of (equal) parts.
  • a fraction is understood herein to be a part of a (process) stream according to the present i nvention, which typical ly comprises at least two different fractions.
  • different fractions may be organic matter comprising (residual) cellulosic material and non-cel lulosic material such as modified lignin-derived components (e.g. Kraft lignin or lignosulfonate) and hemicelluloses.
  • fractions of a stream according to the present invention may be inorganic reactive agents, which are required to run the process, e.g. inorganic buffer salts.
  • the solvent usually is an aqueous solvent/dispersant from the pulping process, which may be diluted or concentrated in the steps following step (B), which is herein understood to form a part of the total dry mass carried in the stream according to the present invention.
  • a particularly important fraction of the stream in the context of the present invention is the fraction of modified lignin-derived components.
  • lignin-derived material has the broadest meaning with regard to any lignin, which underwent one or more process steps, from process step (B) onwards, according to the present invention.
  • a "derived” material has to be understood as a chemical derivative according to the present invention.
  • a lignin-derived material may be of any molecular weight smaller than the natural lignin polymer, including a small molecule, i.e. a low molecular weight compound as used herein.
  • both "modified lignin- derived components” and “lignin-derived compounds” according to the present invention are lignin-derived material.
  • a "modified lignin-derived component” has to be understood in the context of the present invention as a lignin molecule, which underwent a pulping process according to step (B) of the inventive method. Thereby, it may be modified with regard to, for example, molecular weight and/or solubility in water. Typically, intramolecular bonds such as ether bonds are broken up within the lignin. Thus, the macromolecule usually shrinks in size, i.e. in molecular weight.
  • a "native" lignin molecule starting material i.e. a lignin, which is not (yet) modified by a pulping process, typically is larger than modified lignin-derived components.
  • modified lignin-derived components are, for example, Kraft lignin and lignosulfonate, but also other lignin derivatives resulting from further pulping processes are comprised in the context of the present invention, such as organosolv lignin.
  • organosolv lignin may be, for example, soda pulping, which is generating soda lignin, processes involving organic solvents such as organosolv providing organosolv lignin and even less frequent processes such as the steam explosion process or the ammonia fiber explosion process and the hot water process providing respective modified l ign in.
  • modified lignin-derived components are typically used herein to refer to lignin derivatives in contrast to a low molecular weight lignin-derived compound, which is a preferred product of the i nventive method.
  • a (chemical) "derivative” is typical ly a compound that is derived from a simi lar compound by a chemical reaction.
  • a derivative may be understood herein as a compound that can be imagined to arise from another compound, if one atom or group of atoms is replaced with another atom or group of atoms, or the term may be understood as a structural analog.
  • structural analogue is generally common in organic chemistry.
  • modified l ignin-derived components as used herein are present as a fraction of a (process) "stream".
  • a stream may comprise residual or waste material and the solvent and/or dispersant from which the i ntermediate of interest is preferably isolated.
  • the solvent and/or dispersant accounts for at least 50% (w/w) of the total weight of material forwarded as a "stream” to the next method step, or at least 60% (w/w), or at least 70% (w/w), or at least 80% (w/w), or at least 90% (w/w), or at least 95% (w/w).
  • the solvent and/or dispersant is typically an aqueous medium, but may alternatively be an organic solvent, dependi ng on the pu lping process.
  • the stream flows unidirectionally, from the preceding method step to the more downstream method steps. Valves, pumps and/or gravity- assisted means may typical ly be employed to faci litate the required flow of the stream downwards to the final step of the method of the present invention.
  • the inventive method comprises step (C) for separating the pulp from the process stream from the pulping step (B).
  • step (C) for separating the pulp from the process stream from the pulping step (B).
  • the lignin in the lignocel lulosic material is broken into smaller molecules, which are more soluble i n the pulping liquid.
  • Cel lulose is degraded to a minor degree, although individual cellulose fibers may detach from the chopped lignocellulosic material during the pulpi ng process and dissolve in the pulping liquid than natural l igni n.
  • residual cel lulosic scaffold remains.
  • cellulose fibers are also present i n the l iquid in dispersed form, i .e. not in the larger scaffold structure of fibers-
  • step (C) of the inventive method preferably both the scaffold and the dispersed cellulose fibers are separated from the process stream.
  • a preferred embodiment of separating the cellulose which is present i n the scaffolds is "blowing" the cel lulose scaffold of the chopped lignocellulosic material, which underwent the pulping of step (B), into a collection tank ("blow tank”).
  • the residual cellulosic scaffolds may be blown into a blow tank that usually operates at atmospheric pressure. This blowing typically releases steam and volatiles.
  • Volatiles are understood herein as organic chemicals that have a high vapor pressure at ordinary room temperature. Typically, they are characterized by an individual odor.
  • the volatile fraction may be condensed and collected. When employing "northern softwoods" as the starting material for the present invention, the volatile fraction typically encompasses raw turpentine.
  • the pulp separation in step (C) may preferably further comprise to separating cellulose from the liquid, which was not blown out as part of the blown out residual cellulosic scaffold, e.g. the dispersed cellulose fibers.
  • the pulp separation according to step (C) may encompass distinct sieves or screens and/or centrifugal separation.
  • the sieves are typically arranged in a multistage cascade-like assembly. By such an arrangement, considerable amounts of pulp is preferably captured, and thus, separated from the process stream containing the fraction of interest according to the inventive method, i.e. the fraction of modified lignin-derived components.
  • the process stream may also undergo one or more washing steps to separate pulp.
  • (residual) dispersed cellulose fibers are separated from the process stream.
  • a pulp mill encompasses 3-5 washing stages in series.
  • Pulp washing as used herein is typically carried out by pulp washers using counter- current flow in between two subsequent stages such that the pulp moves in the opposite direction to the flow of washing water. While the washing water becomes a part of the process stream comprising the target modified lignin according to the present invention, cellulose is effectively separated and ready for conventional use such as paper production.
  • Various techniques may be involved in pulp washing, such as thickening / dilution, displacement and diffusion.
  • the washing equipment may comprise, for example, pressure diffusers, atmospheric diffusers, vacuum drum washers, drum displacers and wash presses.
  • Said separation step or steps may provide a substantial ly pulp-free process stream as a result of step (C).
  • Said pulp-free stream which is herein forwarded for its further processing in step (D), is commonly designated as "black liquor” (due to its color), when applying the Kraft process or "brown liquor", when applying the sulfite process in step (B). It typically comprises modified lignin-derived components and random fragments thereof (i.e. lignin-derived molecules formed during the pulping process, but having a lower molecular weight than the typical modified lignin-derived components) and hydrolysis products of hemicellulose.
  • Hemicellulose is typically hydrolyzed in any pulping process, e.g. in acidic or alkaline medium, yielding smaller pieces of hemicellulose such as poly- or oligosaccharide fragments or even mono- or disaccharides thereof, which are all usually dissolved in the pulping liquid and/or the process stream.
  • (in)organic salts as residual components of the reactive agents used for the pulping process may be comprised in the essentially pulp-free process stream, such as sodium carbonate and/or sodium sulfate.
  • step (D) of the inventive method the fraction of modified lignin-derived components is isolated from the above components of the essentially pulp-free process stream obtainable from step (C).
  • the process stream of step (C) entering to step (D) may be provided by either one single stream (according to alternative D.1 ) or as at least two streams (according to alternative (D.2)).
  • two or more (partial) streams according to alternative D.2), it may be controlled, which amount of the modified lignin-derived components is further processed according to the inventive method.
  • stream separation in alternative (D.2) is a tool to fine tune the inventive method when determining its flow rate and turnover of the process.
  • each process stream may have a flow rate corresponding to one third of the flow rate of the stream.
  • one or two partial streams may have a flow rate higher or lower than the third stream, provided that the sum of the flow rates of the partial streams preferably equals the flow rate of the initial stream.
  • modified lignin- derived components comprised in all partial streams may be simultaneously supplied to (conventional) combustion as an energy source, to further processing according to the inventive method and, e.g., to storage facilities, e.g. a container.
  • said stream division may provide a "buffer capacity" depending on the status of the plant and the turnover of the method as a whole, which adds versatility and efficiency to the method, preferably without generating extra waste.
  • Dividing the stream for further processing according to step (D.2) may be carried out by technical means known in the field of fluid process technology.
  • the dividing means are adjustable in such a way, that defined portions of the stream of step (C) may be mechanically divided into two or more, three or more or four or more partial streams.
  • the means for dividing may be selected from a flap, hatch, clack, lid, valve, damper or shutter or a combination thereof. Said means may operate electrically and/or hydraulically.
  • the stream may be divided into partial streams by vacuum and/or pressurized gas, i.e. portions of the stream may be sucked or blown into two or more passages.
  • a passage is understood as any form of duct, which passes the respective stream to its next stage.
  • the dividing means and/or of the passages conducting the partial process streams are typically made of non-corroding metal, preferably coated or non-coated stainless steel.
  • step (D) of the inventive method all or a portion of the fraction of modified lignin-derived components is isolated from the one (alternative (D.1 )) or from at least one of at least two process streams (alternative (D.2)).
  • isolation of the fraction of modified lignin-derived components from the single process stream may be controlled by the isolation means applied, e.g. by the parameters applied (e.g. the amount of precipitation agent, pH, extraction or filtration characteristics, which define the setting in step (D.1 ).
  • step (D.1 ) is less flexible than step (D.2) and requires more complex controlling efforts.
  • step (D.2) isolation of the fraction of modified lignin-derived components is applied to one or more of the partial streams provided at the stage of step (C). Isolation, i.e. controlled removal of the fraction of modified lignin-derived components from the process stream(s) may alternatively be applied to all partial process streams, if required.
  • the essentially pulp-free process stream provided by step (C) is divided into two partial process streams, with one of them subjected to isolation of the fraction of modified lignin-derived components from the process stream and the other partial process streams being used for combustion and/or other uses.
  • the fraction of modified lignin-derived components may be isolated from the solvent and/or dispersant of the process stream, such that the fraction of modified lignin- derived components may be obtained as dry matter. It may then be re-dissolved in a suitable solvent or dispersed in a suitable dispersant, e.g. an aqueous solvent or dispersant, to be further processed in the subsequent method step.
  • a suitable solvent or dispersed in a suitable dispersant e.g. an aqueous solvent or dispersant
  • the fraction of modified lignin-derived components may be enriched, e.g. by reducing the solvent and/or dispersant content of the fraction of modified lignin-derived components, such that a concentrated solution or dispersion is provided.
  • Isolation of step (D) may be carried out by any appropriate means employed in the field of solid-fluid or fluid-fluid separation.
  • the isolation may, for example, involve filtration, extraction, counter current flow separation and precipitation.
  • Any technology may be used according to step (D) of the invention to control the amount of isolated modified lignin-derived components, which may then be subjected to further processing. Whether filtration is applied by step (D) or not may depend on whether the modified lignin- derived components are dissolved in the fluid phase or suspended as solid components.
  • Filtration is preferably used for separation of suspended or dispersed solid, i.e. preferably dispersed particles of a size of about > 1 pm. By filtration, oversize solid particles are typically retained by the membrane with the yield depending on the character of the modified lignin components, their particle size and the filter's cut off.
  • Frtration is hereby understood as a physical purification or enrichment method involving membrane technology by permeable membranes.
  • Membranes are characterized by their nominal pore size. It typically describes the maximum pore size distribution.
  • the "cut-off” is typically used as the parameter to characterize separation properties of membrane- associated filtration.
  • the exclusion limit or “cut-off” of the membrane is usually specified in the form of NMWC (nominal molecular weight cut-off, or MWCO, molecular weight cut off, with units in Dalton). It is commonly defined as the minimum molecular weight of a globular molecule that is retained to 90% by the membrane.
  • the MWCO of the membrane should be at least 20% lower than the molecular weight of the molecule that is to be separated.
  • a 1 kDa filter is suitable to let pass a small molecule with a molecular weight of, e.g., 500 Da, while the larger modified lignin-derived components of a molecular weight of, e.g., 2.000 Da are not able to pass.
  • fi ltration is used herein to isolate, in step (D), the dispersed or suspended modified lignin-derived components obtained in step (B).
  • the filter cut-off is set in such a way, that it is suitable to discriminate the molecular weight of the target modified lignin-derived components and of other components in the process stream.
  • the other components may be larger (e.g. residual natural lignin and/or fragments thereof having a higher molecular weight than the modified lignin-derived components) or smaller (e.g. reactive agents of the pulping process, hydrolyzed hemicellulose) than the target components. If the target modified lignin- derived components are of a larger molecular weight than all other components in the process stream, the filter is selected to have a cut off such that the target components are typically retained in the filter. Otherwise, if other components are larger -in terms of molecular weight- than the modified lignin-derived components, the cut-off may typically be selected such that the target components may typically be found in the filtrate.
  • the filtration in isolation step (D) may be a combination of (different) filtration steps.
  • the cut off of the filter is selected to be higher than the molecular weight of the modified lignin-derived components. Accordingly, other components with a higher molecular weight are kept in the filter and the modified-lignin-derived components remain in the filtrate, i.e. in the residual process stream.
  • the residual process stream may be subjected to a second filtration, wherein the cut-off is selected to be lower than the molecular weight of the modified lignin-derived components. Accordingly, the target modified lignin-derived components are reained in the filter and, thereby, isolated from the residual process stream.
  • the target components may be obtained as dry matter and may subsequently be dissolved for further processing.
  • filtration may be very preferred to separate Kraft lignin from lignin-derived material of higher molecular weight, such as non-modified or re- polymerized lignin-derived material or other debris in step (D).
  • extraction is typically a separation process comprising the separation of a target substance from its environment. It may include liquid-liquid extraction and/or solid phase extraction. Extraction may use two immiscible phases to separate dissolved modified lignin- derived components from the original phase into another. By extraction, organic compounds are extracted by an organic solvent from the aqueous phase.
  • Common solvents for extraction are classified by their polarity from ethyl acetate (lowest polarity) to water (highest polarity): ethyl acetate ⁇ acetone ⁇ ethanol ⁇ methanol ⁇ acetone:water (7:3) ⁇ ethanol:water (8:2) ⁇ methanol :water (8:2) ⁇ water, in the order of the Hildebrand solubility parameter.
  • the solution containing the extracted fraction i.e. the components
  • Kraft lignin may be extracted by step (D) from the process stream, it less soluble in an aqueous medium than in appropriate organic solvents (such as methanol, ethanol, acetone and aqueous mixtures thereof known in the art).
  • organic solvents such as methanol, ethanol, acetone and aqueous mixtures thereof known in the art.
  • Alternative extraction techniques may include supercritical carbon dioxide extraction, ultrasonic extraction, heat reflux extraction, microwave-assisted extraction, instant controlled pressure drop extraction (DIC), and perstraction. Amongst them, perstraction may be preferred.
  • “perstraction” includes two liquid phases, with only one phase including a solvent for extraction. Perstraction may advantageously be more gentle, faster and cheaper than traditional biphasic extraction techniques.
  • “Stripping” may be employed as another gentle extraction alternative, which allows the fraction of modified lignin-derived components may be isolated from the process stream.
  • “Stripping” is generally a physical separation process, wherein one or more components are removed from a liquid stream by a vapor stream. In industrial applications, the liquid and vapor streams may be employed co-currently or flow countercurrent.
  • Stripping is usually carried out in either a packed or trayed column.
  • Isolation of the fraction of modified lignin-derived components in step (D) may generally be achieved by countercurrent flow, with the flow forwarded in opposite directions.
  • concentration of dissolved modified lignin-derived components along the concentration gradient may be envisaged.
  • the counter-current exchange method may maintain the gradient of the two flows essentially stable for the entire contact zone. Hence, countercurrent flow is particularly suitable to isolate dissolved modified lignin-derived components and may be less preferred for dispersed modified lignin-derived components.
  • precipitation may be employed as an isolation method to allow a solid fraction to be isolated from solution. Precipitation may also be employed to control the amount of precipitated modified lignin (within a given time window) by the choice of the added amount of precipitation agent and/or the pH. Preferably, precipitation of step (D) may be conducted by means of the addition of a cation, preferably a di- or multivalent cation, most preferably of calcium. The remainder of modified lignin-derived components, which are not further employed by the present invention, may be channeled to the paper manufacturing process or may serve for other applications such as energy provision, or may be stored for later use or may be discarded.
  • Precipitation in step (D) may be in particular preferred for lignosulfonate or, equivalently, for sulfonated Kraft lignin.
  • Precipitation by pH is less preferred, e.g. for lignosulfonate, as it is generally soluble in water over the entire pH range and may not be readily isolated by pH modification.
  • precipitation by calcium salt addition may be preferred.
  • excess lime i.e. a calcium-containing inorganic material, in which carbonates, oxides and hydroxides typically predominate
  • This process is generally known as Howard process. It is the most straight-forward recovery method known.
  • lignosulfonate typically, up to 95% of the stream's lignosulfonate may be isolated by precipitation.
  • Modified lignin resulting from the Kraft process (“Kraft lignin”) may be sulfonated in step (B) and thereafter subjected to, e.g., lime precipitation.
  • step (E) of the inventive method the isolated fraction of modified lignin-derived components of step (D) is subjected to a chemical (and optionally physical) decomposition step.
  • the reaction may allow to convert the fraction of modified lignin-derived components of higher molecular weight to lower molecular weight compounds characterized by structural elements or units of the initial lignin polymer.
  • Step (E) corresponds to a decomposition reaction of the modified lignin-derived components resulting in a heterogeneous ensemble of preferably low molecular weight compounds of typically aromatic nature.
  • Chemical decomposition comprises (alternative E.1 ) cracking and oxidizing the modified lignin-derived components isolated in step (D).
  • Such decomposition is carried out in the presence of a homogeneous metal ion-based or a metalloid-based catalyst.
  • step (E.2) cracking and reducing is applied to decompose the modified lignin-derived components in the presence of a heterogeneous metal ion-based or metalloid-based catalyst.
  • step (E.3) said step is characterized by electro-oxidation of the modified lignin-derived components in alkaline or acidic solution.
  • Chemical decomposition is typically understood as the provision of a plurality of lower molecular weight compounds by chemical and/or physical degradation of higher molecular weight starting material. Typically, such a reaction yields compounds comprising fragments or moieties of the higher molecular weight starting material.
  • Chemical decomposition may be studied by chemical analysis, e.g. by mass spectrometry, gravimetric analysis, and thermogravimetric analysis.
  • decomposition according to the inventive method is carried out by catalytic reaction, or alternatively, electrolytically.
  • Thermal decomposition may be employed as well according to the invention, but is less preferred, as it usually yields an even broader spectrum of diverse low molecular weight lignin-derived compounds.
  • a larger fraction of these compounds following decomposition is of aromatic nature reflecting aromatic ring systems of the building blocks of the natural lignin polymer provided in step (A).
  • Decomposition may result in a heterogeneous ensemble of lignin-derived products comprising (modified) lignin-derived building blocks, i.e. "monomers” or “dimers", preferably biphenylic dimers.
  • the resulting modified lignin-derived products herein essentially consist of monomers and dimers, i.e. the resulting lignin-derived products of step (E) do preferably not comprise larger (oligomeric) modified lignin-derived fragments but only modified lignin- derived monomers and dimers.
  • a suitable catalyst e.g. in a cracking and oxidizing/reducing reaction
  • "cracking” describes any type of molecular dissociation under the influence of, e.g., heat, catalysts, electric currents and/or solvents.
  • Cracking of the isolated fraction of modified lignin-derived components, e.g. lignosulfonates, is understood as the reaction underlying the decomposition or decomposition of step (E.1 ) or (E.2). Cracking kinetics and the products of that reaction are typically dependent on the temperature and/or the catalysts applied. In addition, the ensemble of products resulting from cracking is dependent on the nature of the lignin-derived fraction used as starting material for the decomposition reaction. Accordingly, the fraction of modified lignin-derived components, e.g.
  • Kraft lignin or lignosulfonate may be subjected by step (E) to a catalytic reaction at a temperature significantly lower than pyrolytic temperature or to electric current, preferably by electro-oxidation.
  • Oxidation is involved in the decomposition reaction according to step (E.1 ).
  • oxidation refers to any reaction, which includes loss of electrons. More specifically, the term refers to the introduction oxygen-containing functional groups, e.g. a hydroxy I group.
  • aromatic ring systems are typically functional ized by an oxygen-containing functional group and/or by the substitution of a hydroxyl group by an oxo group. Oxidation is typically achieved by an oxidizing agent.
  • An oxidizing agent may - more generally - correspond to any chemical species that removes electron(s) from another species. More specifically, it transfers (electronegative) oxygen to a substrate.
  • Catalysis is involved in step (E.1 ) and (E.2). It typically allows to enhance the kinetics of a chemical reaction by the presence of a catalyst lowering the activation energy.
  • Preferred catalysts for oxidizing of the (modified) lignin-derived components in step (E.1 ) are catalysts comprising metal ions, such as salts with catalytically active cations, or coordination (metal or metalloid) complexes.
  • a "coordination complex” is typically known in chemistry to consist of a central atom, which may be a metallic or metalloid atom, e.g. a metal ion or a metalloid ion. It is called the coordination center.
  • the surrounding sphere of bound molecules or ions is known as ligands or complexing agents.
  • catalysts may be of metalloid character including coordination complexes, with a metalloid atom as the coordination center, such as boron.
  • catalysts used according to step (E.1 ) are homogeneous catalysts, but may also be heterogeneous catalysts.
  • homogeneous catalysis is based on catalytic reactions with the catalyst being in the same phase as the reactant(s). More specifically, a homogeneous catalyst is dissolved for catalysis in the solution.
  • step (E.2) the fraction of modified lignin-derived components is reduced, typically by addition of a reducing agent.
  • a "reducing agent” is understood as an agent which "donates" electron(s) to another chemical species (electron donor).
  • the catalyst typically employed by step (E.2) is a heterogeneous catalyst, which is defined as a catalyst provided in another phase, typically in solid or gaseous phase, than the reactant(s), which are typically provided in solution.
  • a homogeneous catalyst may, however, alternatively be employed.
  • the modified lignin-derived components are typically provided in solution and the catalyst is usually provided as solid matter.
  • heterogeneous catalysis provides the advantage that reaction products may readi ly be separated from the catalyst component.
  • heterogeneous catalysts are usually more stable and decompose more slowly than homogeneous catalysts. They may be recycled.
  • step (E.3) "electro-oxidation” is understood as oxidation at the surface of an electrode and/or i n an electrical (electrochemical) cell.
  • any such electrical cel l employed by step (E.3) is a single galvanic cell or a flow cel l.
  • a flow cell is characterized by the ionic solution (electrolyte) passing continuously or batch-wise through the cell. The ionic solution is typical ly stored in separate storage tanks.
  • the method of the invention comprises by its step (F) an isolation step, wherei n the desired low molecular weight aromatic l igni n-derived compounds are separated from (residual) higher molecular weight aromatic lignin-derived components and/or other non- l igni n-derived residual components, which have not been decomposed or decomposed to a less significant degree, or which have adversely re-polymerized.
  • Decomposition reactions are avoided by step (E) of the i nventive method, which are characterized by reaction conditions, which bear the risk of re-polymerization of the lignin-derived material to be decomposed.
  • any such by-products may stil l result from step (E), which need to be eliminated downstream of the i nventive method.
  • Components other than the desired target lower molecular weight aromatic lignin-derived compounds are either discarded, e.g. for combustion, or recycled by another step of decomposition (e.g. a second decomposition reaction accordi ng to step (E)).
  • the target compound of the inventive method is a low molecular weight aromatic lignin- derived compound.
  • a "lignin-derived low molecular aromatic weight compound” is preferably a molecule, which corresponds or is derived from a (monomeric) bui lding block of natural ligni n or is a homo- or heterodimer of such (monomeric) buildi ng blocks.
  • Such target compounds are derived from natural ligni n via its modification resulting from step (B) ("pulping"), which provides the fraction of modified lignin-derived components as intermediates of the inventive method.
  • a decomposition step (E) provides low molecular weight target compounds.
  • aromatic refers to a compound, which fulfi ls the criterion of aromaticity - as it is general ly defined i n the art.
  • aromatic is typical ly used to describe a cyclic, i .e. ring-shaped, and planar system that exhibits increased stabi lity as compared to l inear, i .e. l i ne-shaped, molecules with the same number of atoms.
  • stabi lity the aromatic system is less prone to react under conventional conditions.
  • aromaticity In terms of the electronic nature of the molecule, aromaticity describes a conjugated system usually described by alternating single and double bonds within the ri ng system. This configuration typically al lows for the electrons in the molecule's pi system to be delocalized around the ring, increasing the molecules' stabi lity.
  • the most commonly encountered aromatic system in organic chemistry are benzene and its derivatives.
  • the model description for benzene typically consists of two resonance forms, which corresponds to the double and single bonds superimposing to produce six one-and-a-half bonds. Benzene is more stable by its charge derealization than is to be expected.
  • Non-carbocyclic and/or non-hexacyclic aromatic systems understood to be aromatic as wel l, if they fulfi l the aromaticity rules, such as heterocyclic aromatic compounds, di- tri- and tetracyclic compounds and compounds having any n-membered rings such as 5-membered rings. Any aromatic functional group may be designated as "aryl group”.
  • Aromatic compounds are commonly isolated i n the art from petroleum or its refined fractions.
  • aromatic target compounds of the inventive method comprise carbocyclic benzene or its benzene derivatives, such as phenolic derivatives. While compounds essentially comprisi ng benzene-derived aromatic ring systems and its derivatives are preferred, aromatic target compounds comprisi ng biphenylic, bi- and multicyclic (annulated) aromatic systems may likewise be envisaged.
  • a low molecular weight lignin-derived aromatic compound envisaged to be isolated by step (F) is preferably an aromatic compound, which typically exhibits a molecular weight of less than 1 .000 Da, preferably less than 700 Da, more preferably less than 500 Da, most preferably of about 1 00 to 500 Da, e.g. 200 to 400 Da. It typical ly has a size in the order of 1 0 "9 m or less.
  • such low molecular weight aromatic lignin-derived compound is based on a monomer or, alternatively, a homo- or heterodimer of the polymeric natural lignin which may have been modified in the pulpi ng process of step (B) of the i nventive method.
  • “Monomers” essential ly correspond to the (repetitive) bui ldi ng blocks of polymeric natural lignin.
  • a “monomer” may be any bui ldi ng block of the natural lignin polymer, which may be modified in step (B).
  • "Monomers” of the natural lignin polymer are typically of aromatic nature (e.g. contain an aromatic ring system), but may be diverse in terms of their specific chemical character.
  • the target compound comprises one single benzene-derived (substituted) aromatic ri ng system.
  • the low molecular weight aromatic lignin-derived compound i.e.
  • step (F) typically a monomer comprising one aromatic ring system or a dimer comprising typically two (non-annulated) aromatic rings, shall be isolated in step (F) from other components resulting from decomposition of step (E), e.g. fragments other than the monomeric or dimeric target compounds, by appropriate techniques.
  • “Fragments” of the modified lignin-derived components are typically larger in molecular weight than the monomeric or dimeric target compounds, but have typically a lower molecular weight than the modified lignin-derived components obtained by step (B) as intermediates of the inventive method.
  • Such fragments are typically not understood to be low molecular weight target compounds of the inventive method. Instead, they may comprise or they are tri- or n-mers of the bui lding blocks of the modified lignin-derived components.
  • Such fragments resulting from the decomposition step are typically oligomers being of smaller molecular weight than the modified lignin-derived components obtainable in the pulping process of step (B). However, such fragments may vary significantly in size and in their molecular weight, as the lignin-derived components vary.
  • step (F) monomeric or dimeric target compounds (obtained from the decomposition reaction of, e.g. lignosulfonate, by step (E)) are isolated from the other fragments of the decomposition step (E).
  • the monomeric or dimeric target compounds to be isolated are typically monocyclic phenolic derivatives or encompass two such monomeric moieties each containing individual (non-annulated) phenolic ring systems, respectively.
  • the ring systems may be directly connected by a bond.
  • two monomeric moieties containing an aromatic ring system each may be connected by a linker group, e.g.
  • an aliphatic linker group to form a homo- or heterodimer, typically a heterodimer.
  • a heterodimer exhibits two aromatic ring systems with individual (distinct) substitution patterns.
  • the dimer may represent the basic chemical structure of two (substituted) aromatic ring systems directly linked by a bond to form a bi-phenylic ring system.
  • the monomeric or dimeric compounds isolated by step (F) may be further modified according to the present invention. They may e.g. be oxidized or chemically modified by other reactions, which may result in modified substitution patterns or modified ring structure, e.g. result in annulated ring systems, e.g. result in naphthalene or anthracene-derived compounds.
  • the low molecular weight compounds isolated by step (F) may be subjected to other chemical reactions and may thereby comprise functional groups or aromatic ring systems not occurring in the modified lignin-derived components obtained by step (B).
  • lignin-derived compounds may, e.g., be of higher or lower oxidation state, they may contain functional groups not occurring in natural lignin at all, and/or they may exhibit bi-, tri-, tetra- or pentacyclic (annulated) aromatic ring systems.
  • Either low molecular weight aromatic lignin-derived compounds isolated by step (F) or their derivatization products may serve for commercial application, e.g. as redox-active compounds or for any other use.
  • any lignocellulosic material from whatever plant may be employed in the inventive method.
  • the lignocellulosic starting material of the method provided according to step (A) may preferably be based on wood of low silica and resin content, more preferably based on "northern woods", even more preferably based on the group consisting of beech, pine, birch, eucalyptus and spruce, most preferably based on beech.
  • the lignocellulosic starting material of the method provided according to step (A) is preferably provided as chopped material, more preferably in the form of woodchips.
  • the Kraft process which may be employed as step (B) of the inventive method, may consume a wider range of fiber sources than most of the other pulping processes, which may alternatively be used by the present invention (such as the sulfite process). Accordingly, the Kraft process is typically operable with all types of wood, from whatever plant, including more resinous wood species (like southern pine), and even non-wood species, like bamboo and kenaf.
  • the pulping process of step (B) may be selected from the group consisting of Kraft process, sulfite process, organosol v process, and lignin pyrolysis process.
  • Other processes for separating lignin and cellulose components from lignocellulosic starting material may also be used for the reaction of step (B) to arrive at a (modified) lignin-derived fraction.
  • the Kraft process or, alternatively, the sulfite process are preferred as step (B) for the method of the invention.
  • the Kraft process may be carried out as alternative (B.1 ) according to the inventive method.
  • the Kraft process may comprise the sub-steps of (a) optionally pre-steaming the (preferably chopped) lignocellulosic material, wherein the (preferably chopped) lignocellulosic material is advantageously wetted and preheated with steam, (b) adding (preferably chopped) lignocellulosic material to an aqueous alkaline solution comprising Kraft pulping agents, one or more of the agents preferably selected from the group consisting of a sulfide salt, a sulfhydryl compound or salt, and a polysulfide salt (and, typically, at least one sulfate salt is additionally comprised by the alkaline solution as well), (c) cooking the (preferably chopped) lignocellulosic material, which is provided (e.g.
  • lignocellulosic material suspended and/or dispersed)) in said aqueous alkaline solution, and (d) optionally sulfonating the lignocellulosic material in the presence, e.g. of sulfuric acid solution and/or sulfur trioxide.
  • the sulfite process is referred to as alternative method step (B.2).
  • the sulfite process may comprise the sub-steps of (a) optionally pre-steaming the (preferably chopped) lignocellulosic material, wherein the (preferably chopped) lignocellulosic material is advantageously wetted and preheated with steam, (b) adding the (preferably chopped) lignocellulosic material to an aqueous, preferably acidic solution comprising a sulfite and/or bisulfite salt, and (c) cooking the (preferably chopped) lignocellulosic material, which is provided (e.g. dispersed or and/or suspended) in said aqueous, preferably acidic, solution.
  • step (B) of the inventive method comprises a process as it may be commonly practiced as an initial step in pulp and/or paper manufacturing.
  • both the Kraft process (step B.1 ) and the sulfite process (step B.2) are widely known from the afore-mentioned applications and are applied accordingly by the inventive method. They allow to separate cellulosic fibrous material (pulp), which is the target material in the production of pulp and/or paper, from other non-cellulosic wood components, in particular lignin or, rather, the lignin-derived components.
  • pulp is neither a target product nor an intermediate.
  • the target of step (B) is the provision of lignin as the other major wood component, preferably in its modified, advantageously soluble form ("modified lignin-derived components").
  • modified lignin-derived components such as “Kraft lignin”, “sulfonated Kraft lignin” or “lignosulfonate”, upon separation of the cellulose fraction, as an intermediate of the inventive method.
  • the "pulp and/or paper manufacturing process” is typically a commercially established process for the production of pulp and/or paper in a pulp and/or paper manufacturing plant.
  • pulp is generally understood to essentially comprise preferably (enriched) cellulosic fibrous material prepared from, for example, wood, fiber crops or waste paper.
  • a pulping process provides the preferably pure cellulosic fibrous material (pulp). Being typical ly in the form of fibers, pulp is usually not dissolved, but dispersed or suspended in the liquid employed in the pulping process. Due to its fibrous form, pulp is typically separated by step (C) of the inventive method as fibrous material, preferably by mechanical means, such as sieves and/or centrifuges, from the method's process stream, which contains the (preferably dissolved, suspended and/or dispersed) fraction of lignin-derived material and which is further processed by step (D).
  • the objective of any pulp and/or paper manufacturing process is to allow disintegration of wood into fibrous cellulosic material, lignin and hemicellulose products. This is achieved by breaking covalent bonds of 3-dimensional polymeric lignin macromolecules. Carbon to carbon (C-C) bonds are more stable than oxygen - carbon bonds (C-O) under conditions typically applied for bond breaking by the "cooking" sub-step (c) of the inventive method. Thus, cleavage of oxygen - carbon bonds is the most prevalent and important reaction in any typical pulping process described herein as step (B).
  • any such reaction of step (B) produces modified products characterized by phenolic hydroxyl groups due to cleavage of natural lignin's aryl-alkyl-ether bonds.
  • the modified lignin-derived components as modified products of the pulping process i.e. "the modified lignin-derived components" are of lower molecular size than the polymeric lignin starting material (natural lignin).
  • lignin-derived polymers are usually more soluble or dispersible than natural lignin in the process stream leaving the pulping process of step (B). From that process stream non-dissolved or non-dispersed pulp, which usually is the target product of any commercial pulping process, may readily be separated from dissolved and/or suspended modified lignin-derived components (as realized by step (C) of the inventive method).
  • the present invention is characterized by the advantage that it may readily employ by its step (B) existing plants for pulp production. It is characterized by enabling commercial use of lignin (in the art typically regarded as the major undesired by-product of pulp production), which has essentially not yet been made accessible for other applications than as energy source. If required, the present invention may also use a smaller portion of the lignin-derived fraction of step (C) as energy source either for the pulp production or for further downstream steps.
  • the present invention is, however, unprecedented, as it enables lignin (as abundantly available and renewable natural material) to become the starting material for the provision of a large diversity of organic compounds usable for a broad spectrum of applications. Some of them have been so far made avai lable in the art by the methods of petroleum chemistry only.
  • the Kraft process according to step (B.1 ) is typical ly a higher pH pulping process i n the presence of an aqueous solution containing one or more of salt or non-salt agents selected from the group consisting of sulfide, sulfhydryl and polysulfide.
  • salt or non-salt agents selected from the group consisting of sulfide, sulfhydryl and polysulfide.
  • One or more sulfate salt(s) is/are typical ly added as well.
  • preferably chopped lignocellulosic material such as woodchips
  • preferably chopped lignocel lulosic material is wetted and heated, which typically renders it more susceptible to adsorb treatment solutions as appl ied by subsequent sub-step (b).
  • Cavities of fresh wood are filled with fluids and/or air.
  • Steam pre-treatment causes the air to expand.
  • About 25% of the air and/or other fluids naturally occupying the cavities is thereby expel led from these cavities.
  • the optional ly pre-treated, i.e. pre-steamed and pre-heated, preferably chopped l ignocellulosic material is treated, preferably at elevated temperatures, with an aqueous alkal ine solution ("treatment solution").
  • the lignocellulosic material is added to the treatment solution.
  • Said solution typical ly comprises at least one chemical ly reactive agent for the Kraft process to operate.
  • the treatment solution may be a liquor known i n the art as "white liquor”.
  • the employed reactive agents may adjust the pH and/or provide nucleophi lic sulfide (S 2 ⁇ ) and/or bisulfide (HS " ) ions and/or moieties.
  • said treatment solution comprises a mixture of chemically reactive agents generally used for Kraft pulping to provide nucleophi lic sulfide and/or bisulfide ion or moiety for rupturing the embedment of lignin in the cellulose scaffold of natural lignin.
  • the reactive sulfur containing agents are usually provided as (dissolved) salts, but they may also be provided as non-salt agents, e.g. as (dissolved) organic compounds, which comprise one or more sulphur or sulphur-based chemical functionalities.
  • any suitable reactive agent known in the art for use in the impregnation and cooking step of the Kraft process may be employed accordi ng to the present i nvention.
  • further agents added to the solution in step (B) in lower amounts are typical ly one or more of sodium carbonate, sodium sulfate, sodium thiosulfate, sodium chloride, and calcium carbonate.
  • the preferably chopped lignocel lulosic material is typically initial ly saturated with the aqueous alkal ine solution, e.g. with the fresh ("white l iquor") treatment solution or with its recycled equivalent (“black liquor”).
  • the step is preferably designated as the "impregnation step", which may be performed before the chopped lignocellulosic material is forwarded to the vessel for the cooking process (sub-step (c)) to occur within the vessel.
  • the preferably chopped lignocellulosic material is typically not exposed to elevated temperatures (corresponding to the cooking temperature), but just "pre-treated". Accordingly, the material is not or only gently heated for that pre- treatment step.
  • Additional reactive agents may be added to the treatment solution to improve the Kraft impregnation of e.g. the employed wood chips with the cooking liquor.
  • Anthraquinone may be used as such an additive. It typically acts as a redox catalyst by oxidizing cellulose and reducing lignin. It protects cellulose from its degradation and makes the lignin component of the starting material more water-soluble.
  • an emulsion breaker may be added in an optional soap separation step to expedite and improve the separation of soap from the cooking liquors by flocculation, once they have been used. Soap, such as rosin soap, generally forms as by-product of the Kraft process. The soap typically floats at the surface of the aqueous liquid and has to be skimmed off.
  • the collected soap may be further processed to tall oil.
  • defoamers may be employed to remove eventually formed foam and foster the pulp production process. Drainage of washing equipment gives cleaner pulp.
  • Dispersing agents, detackifiers and/or complexing agents preferably allow to keep the process vessels cleaner and to reduce the number of maintenance operations.
  • Fixation agents may be used to allow finely dispersed material to be deposited on the fibers, thereby allowing such material to be readily eliminated.
  • aqueous alkaline solution used for impregnation may be applied for the cooking step as well.
  • the aqueous alkaline solution (treatment solution) used for impregnation in sub-step (b) in the Kraft process - and likewise the corresponding aqueous acidic solution for the sulfite process - is defined as "cooking liquor” in sub-step (c).
  • the treatment solution or "cooking liquor” preferably penetrates into the capillary structure of the chopped lignocellulosic material, such that initial reactions with the wood components start at low temperature conditions.
  • step (B.1 ) of the inventive method the pre-treated (impregnated) preferably chopped lignocellulosic material is cooked in said aqueous alkaline treatment solution as required.
  • the cooking period may depend on the reaction conditions, i.e. the pH, pressure and temperature, and may further depend on the type and strength of the employed chopped lignocellulosic material.
  • the material is cooked for several hours, e.g. 3 to 9 hours.
  • the Kraft process breaks natural lignin's internal ether bonds by nucleophilic attack of sulfide (S 2 " ) and/or bisulfide (HS " ) ions or moieties.
  • S 2 " sulfide
  • HS " bisulfide
  • the function of sulfide in the Kraft process may be two-fold: It may promote and accelerate the cleavage of ether bonds between neighboring building blocks of lignin's 3-dimensional polymeric structure and it reduces the extent of undesirable condensation.
  • the modified lignin-derived components obtained from sub-step (c) of step (B.1 ) are commonly known as "Kraft lignin". These components are essentially unsulfonated or at least less sulfonated than "lignosulfonate” resulting from the sulfite process. Typically, they are more soluble in aqueous alkaline solution, preferably at a pH of greater than about 9 and reasonably soluble in strongly polar organic solvents.
  • the average molecular weight of the lignin-derived components is generally between 1 .000 and 4.000 Da, preferably 2.000 to 3.000 Da.
  • the average component of that lignin-derived fraction comprises about 1 0 to 35 building blocks, preferably 10 to 25 building blocks, and thus, may have a "polymerization degree" of 10 to 35, preferably 1 0 to 25.
  • the lignin-derived material typically exhibits a polydispersity of between 2 and 4, although it can be as high as 8 or 9. Material of such higher values of polydispersity may be typically employed for industrial grade applications, but does usually not allow its subsequent exploitation as basic material for the provision of a larger variety of organic target compounds as envisaged by the invention. Accordingly, polydispersity of the material obtained by sub-step (c) should not go beyond 6, preferably should be less than 5 or from 2 to 5.
  • a "molecular formula" of C9H8.502.i So.i(OCH 3 )o.8(C02H)o.2 was previously reported for softwood Kraft lignin. About 4% by weight is typically free phenolic hydroxyl. ⁇ Lebo, S.E. et al, Lignin, Kirk-Othmer Encyclopedia of Chemical Technology, p. 18 of on-line version, (200 ⁇ ), John Wiley & Sons, Inc.). Kraft process-derived modified lignin-derived components typically also comprise biphenylic moieties, in particular when using lignocellulosic starting material being of spruce origin. Hence, spruce may be the preferred starting material for the inventive method, if dimeric biphenylic target products are desired.
  • sub-step (d) may optionally be added to step (B. I ). That sub-step is preferably a sulfonation step.
  • sulfonating agents known in the art, such as a solution of preferably concentrated sulfuric acid, may be added.
  • Aliphatic side chains are typical ly sulfonated, e.g. by the introduction of sulfonyl moieties as substituents of side chains of Kraft lignin. Sulfonation may occasional ly also affect the aromatic rings of the Kraft ligni n components.
  • sulfonated modified lignin By sulfonation of Kraft l igni n, sulfonated modified lignin is obtained, which is herei n understood as "sulfonated Kraft lignin".
  • sulfonation of sub-step (d) confers i ncreased solubi l ity and surfactant properties to Kraft lignin.
  • "Sulfonated Kraft ligni n” shares characteristic structural or functional properties with “lignosulfonate” of the sulfite process, such as water solubi lity over a broader pH range. Both, Kraft process-derived “sulfonated Kraft lignin” and sulfite process-derived "l ignosulfonate” are referred to as “sulfonated l ignin”.
  • Kraft process-derived "sulfonated Kraft ligni n" and sulfite process-derived “lignosulfonate” are generated under distinct chemical conditions resulting in structural distinct l igni n-derived compositions.
  • the average molecular weight of components of "sulfonated Kraft ligni n” is typically lower than the average molecular weight of components of "lignosulfonate” resulting from the sulfite process. Accordingly, the molecular weight of the components of sulfonated Kraft l ignin may typically be about 1 .000 to 4.500 Da, preferably 2.500 to 3.500 Da.
  • sulfonated Kraft lignin may be recovered, e.g., by water removal or by precipitation, e.g. with excess l ime, as calcium lignosulfonates.
  • sulfonation confers improved water solubi l ity properties to Kraft ligni n, it makes such sulfonated lignin-derived material easier to separate in an aqueous environment from insoluble cellulosic material .
  • additional sulfonation step (d) (which may also be designated as "postsulfonation" for Kraft lignin) is therefore typically beneficially applied.
  • Sulfonation sub-step (d) of the Kraft process (B.1 ) is preferably carried out at a temperature below 300°C, more preferably below 200°C.
  • Such elevated temperatures preferably ensure both sufficiently high yields of sulfonated reaction products, whi le it avoids premature, i.e. uncontrolled thermal degradation of the l igni n-derived Kraft lignin material.
  • aromatic lignin-derived components remai n i ntact (without uncontrolled degradation) for their further processing towards the i nventive method's target compounds.
  • Low molecular weight monomeric or dimeric target compounds are obtained by well-controlled decomposition of the modified lignin-derived components in downstream method step (E), fol lowed by subsequent isolation (purification) i n step (F).
  • the largest portion of modified ligni n-derived components possible resulting from step (B) shall be made avai lable for control led decomposition in downstream step (E). Otherwise, the yield of the target compound would be unfavorably reduced.
  • the preferably chopped lignocellulosic material may be subjected to the sulfite process comprising the sub-steps of (a) optional ly pre-steaming the chopped lignocellulosic material, wherein the preferably chopped lignocellulosic material is wetted and preheated with steam, (b) providi ng an aqueous, preferably acidic solution comprisi ng sulfite and/or bisulfite, and (c) cooking the preferably chopped lignocel lulosic material in said aqueous, preferably acidic solution.
  • the sulfite process employed by step (B.2) of the invention is another pulping process.
  • the resulting sol id cellu lose fibers are obtained by using salts of sulfurous acid to separate the lignin fraction from natural l ignocellulosic starting material, such as wood chips, e.g. in digesters preferably operating at larger pressure.
  • the salt anions used in the pulping process may either be sulfites (SO3 2 ), and/or bisulfites (HSCV), dependi ng on the pH . At lower pH, i .e. under stronger acidic conditions, such as less than pH 2.5, the sulfite is typically provided as HSO 3 " .
  • Counter cations may be sodium (Na + ), calcium (Ca 2+ ), potassium (K + ), magnesium (Mg 2+ ) or ammonium (NH 4 + ).
  • Particularly divalent (e.g. earth alkali) cations, such as calcium and/or magnesium, may be used as the counter cation.
  • the preferred salt is calcium bisulfite, which may advantageously be employed, if the selected pH value for the sulfite process is 2.5 or less.
  • Higher pH sulfite pu lping (at a pH above pH 2.5 or, more specifical ly, above pH 4) general ly employs monovalent ions, such as sodium or ammonium, as counter cations.
  • Sulfite pulpi ng is preferably carried out under acidic conditions, preferably at a pH below 5, preferably from pH 1 .5 to 5 or 1 .5 to 4.
  • the (acidic) pH may be adapted depending on the nature of the counter cation for the sulfite (bisulfite) anion. However, it is not excluded that sulfite pulpi ng may be carried out over a wider pH range, including alkaline conditions of about pH 7 to1 2.
  • the aqueous, preferably acidic sulfite and/or bisulfite containing solution used as "pulping liquor" for the sulfite process may be provided as follows: Sulfur may be oxidized (burnt) with the stochiometrically adequate amount of oxygen to yield sulfur dioxide. Sulfur dioxide is preferably added, e.g. as a gas, to water to give sulfurous acid, which may be further diluted for its use as "pulping liquor".
  • the lignocellulosic material may be brought into contact with the pulping reactive agents for more than three hours, preferably 4 to 14 hours.
  • the temperature is typically above 120°C, preferably ranging from 1 30 to 1 60°C, depending on the reactive agents and their concentrations used.
  • lignosulfonate The modified lignin-derived components resulting from the sulfite process are generally designated as "lignosulfonate". Due to the nature of the sulfite process, "lignosulfonate” typically contains significant amounts of sulfur-based moieties (typically in the form of sulfonate groups), for example, in the aliphatic side chains of the modified lignin-derived components.
  • Lignosulfonate is a complex (heterogeneous) mixture of modified lignin-derived components, i.e. water-soluble anionic lignin-derived polyelectrolytes, which carry -SO 3 H functional groups. Lignosulfonate typically exhibits by its heterogeneous components a broad molecular weight range (broader than observed for Kraft lignin). Lignosulfonate is polydisperse with a polydispersity being typically higher than that of the Kraft process (about 4 to 9). As the sulfite process is less destructive than Kraft pulping, it does not degrade lignin to the same extent as the Kraft process.
  • sulfite process-derived lignosulfonate typically has a higher average molecular weight than Kraft lignin as described herein.
  • a maximum molecular weight of 140.000 Da is reported for softwood lignosulfonates, while maximum values for hardwoods are usually lower, e.g. lower than 50.000 Da.
  • the typical range of the molecular weight for lignosulfonate polymers is about 5.000 to 50.000 Da, preferably about 5.000 to 20.000 Da ⁇ Brogdon, B.N., Dimmel, D.R. J. Wood Chem. Technol. 1996, 16, 297).
  • it comprises about 1 0 to 300 building blocks, preferably 20 to 200, most preferably 25 to 1 50 building blocks, and thus, may have a "polymerization degree" of 1 0 to 300, preferably 20 to 200, most preferably of 25 to 1 50. It typically exhibits a higher sulfur content (about 3% to 8% w/w) than (unsulfonated) Kraft lignin (having a sulfur content of typically less than 1 % w/w).
  • Lignosulfonates are used in the art as low-value chemicals in tanning leather, making concrete, drilling mud and drywall, such as binders or additives for building material.
  • Sulfite process-derived lignosulfonates are typically soluble in water over essentially the entire pH range. Sulfite process-derived lignosulfonate may also be soluble in highly polar organic and amine solvents. Its approximate "molecular formulas" are described as C9H 8 .502.5(OCH3)o.85(S0 3 H)o.4 for softwood or as C9H7.5O2.5 (OCH 3 )i.39(SO3H) 0 .6 for hardwood, respectively, as starting material for sulfite process-derived lignosulfonate.
  • Sulfite process- derived lignosulfonate may comprise biphenylic moieties for some of the components of the larger number of components representing the "lignosulfonate" fraction. That holds specifically for lignocellulosic material of spruce origin. Hence, spruce may be the preferred starting material for the inventive method, if biphenylic target products are desired.
  • modified lignin-derived components such as (sulfonated) "Kraft lignin” and/or “lignosulfonate”, are typically dissolved or dispersed in the consumed pulping liquor, once processed according to step (B).
  • Said liquor (process stream leaving step (B)) usually also comprises most of the hemicellulose and/or its hydrolysis products (poly-, oligo and/or monosaccharides) in dissolved form.
  • the pH of the aqueous alkaline solution in sub-step (b) of step (B.1 ) is > 1 0. More preferably, the pH in sub-step (b) of step (B.1 ) is > 12.
  • the temperature of the aqueous alkaline solution in sub-step (b) of step (B.1 ) is typically less than 1 00°C, e.g. in the range from 70°C to 90°C.
  • the pH of the aqueous preferably acidic solution is preferably 1 to 5 and more preferably 1 .5 to 4.
  • the temperature of the aqueous (preferably acidic) solution in sub-step (b) of step (B.2) is also typically less than 100°C, e.g. from 70°C to 90°C.
  • either of the sulfide and/or sulfate salt comprised in the alkaline solution used in step (B.1 ) or the sulfite or bisulfite salt comprised in the aqueous preferably acidic solution in step (B.2) is a salt with a cationic counter ion preferably selected from the group consisting of sodium, calcium, magnesium and ammonium.
  • the sulfhydryl and/or polysulfide agent employed by step (B.1 ) is preferably an organic, non-salt agent.
  • step (B.1 ) is carried out in a pressurized vessel ("digester") for at least 2 hours at a temperature of at least 1 50°C Cooking in sub-step (c) of step (B.2) is carried out in a pressurized vessel for at least 3 hours at a temperature of at least 1 20°C. Under such conditions, pulp and modified l igni n-derived components may be separated from each other.
  • Sub-step (c) of either of step (B.1 ) or (B.2) may more preferably be carried out at a pressure of at least 4 bar in the pressurized vessel, preferably at 5 to 1 0 bar.
  • a pressurized vessel is typical ly a digester as it is commonly used in the art of chemical pulping.
  • Kraft process sub-step (c) of step (B.1 ) is carried out at a temperature of 1 50 to 1 90°C, preferably 1 70 to 1 80°C.
  • the sulfite process sub-step (c) of step (B.2) is preferably carried out at a temperature of 1 20 to 1 70°C, more preferably at a temperature of 1 30 to 1 60°C.
  • Such temperatures typically provide higher yields (by improved separation of the l ignin and the cel lulosic fraction) and process efficiency.
  • i n particular in combination with the appl ied overpressure may lead to undesired excessive degradation of the ligni n and/or the cel lulosic fraction and is unfavorable in terms of the energy consumption i nvolved.
  • Sub-step (c) of the Kraft process (B.1 ) is preferably carried out for 2 to 24 hours, preferably 3 to 5 hours.
  • Sub-step (c) of the sulfite process (B.2) is preferably carried out for 4 to 24 hours, preferably 4 to 6 hours.
  • Such conditions typically enable satisfying yields, whi le stil l ensuring overall process efficiency.
  • lignin polymers and hemicellulose are sufficiently degraded, such that their lower molecular weight (lower than the starti ng material's natural lignin and hemicel lulose) degradation products are released from the cel lulose scaffold as a result of the cooking step.
  • Such lower molecular weight degradation products are typically more soluble in (strongly) basic solution than the polymers of the l ignocellulosic starti ng material.
  • sub-step (c) of either step (B.1 ) or (B.2) is carried out either in a batch mode or i n a continuous mode.
  • the conti nuous mode the lignocellulosic starti ng material is fed into a digester at a rate, which allows the pulping reaction to be complete by the time the materials exit the reactor.
  • the continuous mode is preferred to ensure higher throughput and improved efficiency.
  • Digesters producing 1 .000 tons or more of pulp per day are common and may be used according to the i nventive method.
  • the I ign in-derived fraction of any pulping process may be forwarded to separation step (C) for its further processing towards the low molecular weight target compound.
  • “Kraft lignin” upon application of sub-steps (a) to (c) of the Kraft process in step (B.1 ), or “lignosulfonate” upon application of the sulfite process in step (B.2) or “sulfonated Kraft lignin” upon application of sub-steps (a) to (d) of the Kraft process in step (B.1 ) may be employed for further processing by step (C).
  • the method of the present invention employs the steps of separating pulp in step (C) from the process stream and, subsequently, isolating the fraction of modified lignin- derived components in step (D) from other components being present in the process stream.
  • Step (C) may be carried out by any suitable separation method preferably selected from the group consisting of blowing, sieving, countercurrent flow, centrifugation, filtration, washing, stripping, ion-exchange, or any combination thereof. Separation of the pulp from the process stream is more preferably carried out by blowing, sieving and/or washing.
  • Step (D) i.e. isolation of the fraction of modified lignin-derived components from other (e.g. hemicellulosic) components in the process stream, may preferably be carried out by fi ltration including ultra- and/or nanofiltration, extraction, countercurrent flow, stripping, ion- exchange, precipitation by di- or multivalent cations, such as calcium cations (which may e.g. be provided as calcium hydroxide), precipitation by C0 2 in acidic solution, or any combination of thereof.
  • isolation is carried out by any type of extraction or filtration, preferably ultrafiltration and/or nanofiltration.
  • Ultrafiltration and/or (depending on the size of the lignin-derived components to be isolated) nanofiltration may be preferably employed in step (D).
  • Ultrafiltration typically employs a pore size of 2-100 nm and a molecular weight cut-off value of about 5 kDa.
  • Nanofiltration typically refers to a filtration mode based on a pore size of 1 -2 nm and a molecular weight cut-off value of 0.1 -5 kDa. Accordingly, ultrafiltration is typically employed to separate or isolate larger lignin-derived components (e.g. larger than 5.000 Da, larger than 8.000 Da or larger than 10.000 Da) from the process stream (containing components of whatever e.g.
  • That isolated larger molecular weight fraction may be subject to further separation in order to separate larger isolated components of distinct fractions, e.g. to isolate the lignin-derived components from residual cellulosic degradation products or hemicellulosic components.
  • the isolated lignin-derived fraction of the molecular weight retained by the chosen cut-off value of the ultrafiltration device may then be further proceed in step (D). Also, the remaining components of the lignin-derived fraction in the process stream having a molecular weight lower than the cut-off level chosen for initial ultrafiltration may be isolated from other components in the process stream.
  • the process stream may be subjected to another filtration step with a lower cut-off level than chosen for the initial ultrafiltration step, e.g. by additional lower cut-off level ultrafiltration and/or nanofi ltration.
  • the lignin- derived components of a molecular weight lower than the cut-off- level of the first filtration step and larger than the cut-off level of the second filtration step may be isolated.
  • That retained lignin-derived fraction may be subject to further isolation to separate the lignin-derived component fraction from components of similar size of other fractions (e.g. from hemicellulosic degradation products of similar size).
  • the inventive method may be set up such that components of the lignin-derived fraction are isolated, which fall within the individually desired smaller molecular weight range of e.g. between 3.000, 4.000, 5.000 or 6.000 Da (cut-off level of the second filtration step) and 5.000, 6.000, 8.000 or 10.000 Da (cut-off level of the first filtration step).
  • a more homogeneous lignin-derived fraction may be forwarded to decomposition step (E).
  • two ultrafiltration steps or ultrafiltration and nanofiltration, repectively may e.g.
  • a modified lignin-derived fraction of a defined molecular weight range e.g. 5.000 to 10.000 or 1 .000 to 5.000 Da, repectively for Kraft lignin.
  • isolation may preferably be performed by employing suitable isolation methods, e.g. as described by Lebo et al. ⁇ Lebo, Stuart E. Jr.; Gargulak, Jerry D.; McNally, Timothy J. (2001). "Lignin”. Kirk-Othmer Encyclopedia of Chemical Technology. Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc.), which is incorporated herein by reference.
  • “Lignosulfonate” (due to the larger molecular weight of its components) will preferably be based on two ultrafiltration steps resulting e.g. in a molecular weight range of the isolated lignin-derived components of between 6.000Da and 15.000 Da or 8.000 Da and 12.000 Da.
  • Ultra- and/or nanofiltration typically employ membranes, which are preferably tubular membranes exposing solvent resistance, i.e. which are preferably resistant at high and low pH values. Ultra- and/or nanofiltration is typically performed at elevated pressure, preferably above 5 bar, more preferably above 10 bar, most preferably at a pressure of 10-1 5 bar. Further, the applied temperature for the filtration step is typically higher than room temperature (25°C) to facilitate isolation of the fraction of modified lignin-derived components. Usually, the temperature is chosen such that degradation of the components to be isolated is essentially avoided. The temperature may be at least 40°C, preferably at least 50°C, most preferably about 60-65°C.
  • the preferred membrane's cut-off size of the employed ultra- or nanofiltration in step (D) may depend on the expected molecular weight of the target modified lignin-derived components.
  • Kraft lignin being of a relatively small molecular weight may require a membrane cut-off of about 2 to kDa or from 2 to 8 kDa
  • larger lignosulfonate may require a membrane cut-off of about 5 to 50 kDa or even up to 100 kDa.
  • the cut-off size for membranes to isolate lignosulfonate may be about 5 to 20 kDa. If ultra- and/or nanofiltration is applied, it is preferably preceded by a pre-filtration step to separate larger debris, e.g.
  • the pre-filter typically has a larger pore size and/or molecular weight cut-off than the ultra- and/or nanofiltration membrane.
  • step (E.1 ) comprises oxidizing the modified lignin derived-components, preferably in the presence of a heterogeneous or homogeneous catalyst or a combination of catalysts.
  • a heterogeneous or homogeneous catalyst or a combination of catalysts Preferably cracking and oxidizing the modified lignin-derived components is performed. Cracking and oxidizing is preferably carried out in a single reaction vessel, preferably simultaneously. "Cracking" is a catalytic reaction to break or dissociate larger molecules into their smaller fragments by dissociation of covalent bonds of the larger molecule. In general, cracking makes use of a reactor and a regenerator for regenerating the catalytic material. More specifically, isolated modified lignin- derived components as starting material e.g.
  • step (E.1 ) may be injected onto preferably hot, fluidized catalysts.
  • the resulting vapor-phase products may be separated from the catalytic materials and fractionated into various product or product fragment fractions by condensation.
  • the catalyst is typically introduced into a regenerator, wherein air or oxygen is preferably used to separate any residual components by an oxidation reaction, such that the surface of the catalyst is freed from any by-products, which are formed as a result of the cracking process.
  • the hot regenerated catalyst may then be recycled to the reactor to complete its cycle.
  • cracking was developed for petrochemistry to disrupt larger e.g. gasoil molecules into smaller gasoline molecules and olefins.
  • analogous cracking reactions may be applied to modified lignin-derived material of step (D) obtainable from renewable sources, according to the present invention.
  • Step (E.1 ) is typically carried out in the presence of an oxidizing agent such as air, O2 or H2O2, preferably air, and preferably a catalyst or a mixture of catalysts, which is/are preferably of heterogeneous nature, e.g. with regard to a cracking reaction, but may also be of homogeneous nature.
  • the catalyst may comprise a metal ion, preferably selected from Co(ll), Cu(ll) and Fe(lll), more preferably Cu(ll).
  • the catalyst may comprise a metalloid element.
  • the "metalloid element" and/or the metal ion is/are preferably provided as coordination complex or, alternatively, as a salt.
  • a metalloid element or metal ion forms the coordination center.
  • a "metalloid” is a chemical element with metallic and non-metallic properties.
  • Metalloid may be any element selected from boron, silicon, germanium, arsenic, antimony, tellurium, aluminum, and selenium.
  • a metalloid may have a metallic appearance, it is typically brittle and only a fair conductor of electricity. Chemically, it may behave mostly like a non-metal.
  • Metalloid comprising agents are particularly useful as catalysts.
  • the metalloid catalyst comprises the metalloids B(lll), Si(IV) and/or Al(lll).
  • the metalloid catalyst may preferably be a boron catalyst, comprising preferably B(lll).
  • step (E.I ) may be a hydroboration-oxidation reaction, which is preferably a two-step organic reaction. It converts, e.g., an alkene into a neutral alcohol by the net addition of water to the double bond.
  • the hydrogen and hydroxyl group are preferably added in syn addition providing an alcohol in cis stereochemistry.
  • Hydroboration-oxidation typically reflects an anti-Markovnikov reaction, with the hydroxyl group being attached to the less-substituted carbon.
  • the homogeneous catalyst in step (E.1 ) is selected from the group consisting of a salt, a coordination complex, a zeolite, a polyoxometalate, and a combination of any of them.
  • Any such catalysts preferably comprises a metal ion selected from Co(ll), Cu(ll) and Fe(lll), most preferably Cu(ll).
  • zeolites are typically microporous, aluminosilicate minerals, which are known as adsorbents and catalysts. Zeolites are widely used as catalysts in the petrochemical industry, for instance in fluid catalytic cracking and hydrocracking. Zeolites may also be used as active catalytic solid-state acids in applications other than in petrochemistry. Hence, zeolites may facilitate numerous acid-catalyzed reactions, as they may be foreseen for the present invention. They may be employed as catalysts for the cracking and oxidizing reaction e.g. of step (E.I ) of the present inventive method.
  • E.I step
  • Catalysts reflecting polyoxometalate(s) are polyatomic ions, usually anions that may be composed of three or more transition metal oxyanions, which are linked together by shared oxygen atoms to form a closed 3-dimensional framework. POMs may advantageously be employed for oxidation of organic compounds, in particular for oxidation of the fraction of modified lignin-derived components isolated in step (D).
  • cracking and oxidizing according to step (E.1 ) may be performed in the presence of a metal catalyst, in particular a Cu(ll) or Fe(lll) containing catalyst.
  • a Co(ll) comprising catalyst may be employed.
  • the catalyst is preferably a heterogeneous catalyst, but may also be a homogeneous catalyst.
  • the metal catalyst, in particular the Cu(ll) or Fe (III) containing catalyst, is preferably a salt or, more preferably, a coordination complex.
  • the cracking and oxidizing reaction is preferably carried out under elevated temperature and/or pressure conditions.
  • the reaction of step (E.1 ) may be carried out at a temperature of 30 to 400°C, preferably 100 to 350°C.
  • the temperature chosen for that reaction is selected such that it is significantly lower than pyrolytic temperatures, e.g. lower than 1 000°C or 800°C or lower than 500°C.
  • pyrolytic temperatures e.g. lower than 1 000°C or 800°C or lower than 500°C.
  • the reaction products are typically less diverse than by a purely pyrolytic reaction (or pyrolytic decomposition).
  • the solution comprising the fraction of modified lignin-derived components of step (D), e.g. lignosulfonate is made alkaline, preferably by adjusting the pH value to at least 9.
  • the medium may be acidic.
  • the metal and/or metalloid catalyst, in particular the Cu(ll) containing catalyst, may be added thereafter to that solution.
  • Said catalyst comprising solution may be heated to a temperature of at least 150°C, preferable to a temperature of 1 50 to 300°C, more preferably 1 60-1 70°C.
  • the pressure may be set to an overpressure of at least 5 atm, preferably from 10 to 12 atm.
  • step (E.1 ) employing a metal and/or metalloid catalyst, in particular the Cu(ll) contai ning catalyst may be conducted in an oxygen enriched environment, more preferably under increased pressure, in particular increased oxygen partial pressure.
  • Said pressure may - preferably under alkaline conditions - be at least 3 bar ⁇ ( ⁇ 2), more preferably 4 to 5 bar p(0 2 ).
  • the p(0 2 ) may advantageously be at least 1 0 bar, sometimes at least 20 bar.
  • an alcohol preferably methanol
  • the alcoholic ingredient may be added in an amount of at least 5%, preferably at least 1 0%, more preferably at least 20% with respect to the total reaction volume.
  • the temperature is preferable at least 1 50°C, more preferably at least 1 70°C.
  • the reaction may be carried out in solution under constant stirri ng, e.g. above 1 .000 rpm. Said oxidation in the presence of an oxygen environment may be performed i n a fluidized bed reactor, particularly a reactor comprising a sand bed.
  • the temperature may be set to at least 250°C, preferably to at least 300°C.
  • the oxidation rate may advantageously be increased.
  • decomposition in step (E) may be carried out by cracking and reduci ng the fraction of modified l ignin-derived components isolated in step (D), which is carried out in the presence of a reducing agent (alternative E.2).
  • the reducing agent is preferably hydrogen or an alcohol as H-donor.
  • Such a reaction under reduci ng conditions typical ly also requires a heterogeneous catalyst comprising, e.g., a metal selected from nickel, platinum, palladium, ruthenium, rhenium and gold.
  • the catalyst is preferably provided on the surface of a support material preferably selected from the group consisti ng of active carbon, si lica, titaniumoxide and/or aluminumoxide.
  • the lignin-derived components may be subject to e.g. hydrogen based "lysis" by cleavage of carbon-carbon or carbon-heteroatom single bonds (hydrogenolysis).
  • hydrolysis e.g. hydrogen based "lysis" by cleavage of carbon-carbon or carbon-heteroatom single bonds
  • cracki ng and reduci ng the fraction of modified ligni n-derived components isolated i n step (D) may be carried out by means of a catalyst comprising nickel, e.g. supported on activated carbon (Ni/C).
  • Ni/C activated carbon
  • a fragmentation-hydrogenolysis process of the modified lignin into lower molecular weight l ignin-derived target compounds, e.g. di- or monomeric phenolic target compounds, i n alcoholic solvents over nickel-based catalysts may be performed.
  • This reaction involves hydrogenolysis of modified lignin components into di- or monomeric phenolic compounds over nickel catalysts, wherein alcohol is preferably the source of active hydrogen as the reducing agent.
  • the fraction of modified lignin-derived components from step (D) may be preferably cracked and reduced in the presence of Ruthenium deposited on a carbon catalyst (Ru/C) in preferably an organic solvent, such as methanol, under a reducing atmosphere, such as an H 2 atmosphere, preferably at elevated temperatures.
  • Ru/C Ruthenium deposited on a carbon catalyst
  • organic solvent such as methanol
  • the resulting phenol- rich lignin oi l typically consist more than 50% (w/w) of phenolic monomers as target compounds of the present invention(mainly) and 10% to 25%, preferably less than 20% (w/w) of phenolic dimers.
  • the obtainable target compounds by that reaction (or alternative reactions) are one or more of syringol, in particular 4-n-propylsyringol, 4-ethylphenol, and guaiacol, in particular 4-ethylguaiacol and 4-n-propylguaiacol.
  • steps (B) (degradation) and (E) (decomposition) may be combined, which does preferably not require steps (C) and (D).
  • the combined degradation/decomposition reaction (steps (B) and (E) combined) mode of the inventive method may preferably, but not necessarily be carried out by employing step (E.2) according to the inventive method.
  • the natural lignocellulosic material provided in step (A) may be delignified through simultaneous solvolysis and catalytic hydrogenolysis of the lignin material in one single step.
  • Combined solvolysis and catalytic hydrogenolysis may preferably be carried out in the presence of Ruthenium preferably deposited on a carbon catalyst (Ru/C), preferably in an organic solvent, such as methanol, under a reducing atmosphere, such as an H 2 atmosphere.
  • the reaction is preferably carried out at elevated temperatures.
  • the resulting product of combined solvolysis and catalytic hydrogenolysis may be further processed as described herein to obtain a purified fraction of low molecular weight aromatic lignin-derived (mono- or dimeric) compounds.
  • decomposition in step (E) may be carried out by electro-oxidation (alternative E.3).
  • Electro-oxidation is defined as an electrochemical process, wherein the oxidation reaction occurs by applying an electric field between two electrodes, e.g. a working electrode and a counter electrode, for the oxidation reaction to take place.
  • the "working electrode” (electrode in an electrochemical system, on which the reaction of interest takes place) is cathodic or anodic, respectively, depending on whether the reaction on the electrode is reduction or oxidation.
  • Common working electrodes may comprise inert metals, such as gold, si lver or platinum, or inert carbon, such as glassy carbon or pyrolytic carbon, or mercury drop and fi lm electrodes.
  • the worki ng electrode employed by the present invention may alternatively also be a nickel electrode.
  • the counter electrode may be a platinum electrode, in particular whenever the working electrode is a nickel electrode.
  • the electrodes may be, for example, sintered electrodes, which preferably benefit from extended life time and show a higher oxidation capacity than other technologies. Electro-oxidation may be advantageous, as it provides i nstant operation on demand ("on/off"). Further, no aggressive chemicals are required, and reaction temperatures may be kept low. As the large diversity of by-products is avoided, it al lows to efficiently produce lower molecular weight aromatic ligni n-derived target compounds. As compared to thermal decomposition methods, energy consumption is reduced.
  • the electro-oxidation reaction may preferably performed in strong alkaline solution of at least pH 1 0, and preferably, constant current is applied. Preferred is electro-oxidation carried out galvanostatically at pH 1 0 to 1 4.
  • the solution comprising the modified lignin- derived components, e.g. lignosulfonate acts as anolyte and, typical ly, NaOH solution as catholyte.
  • an anolyte is the part of the electrolyte, which is under direct influence of the anode upon electrolysis.
  • a catholyte is the part of the electrolyte, which is under direct influence of the cathode upon electrolysis.
  • electro- oxidation may preferably also be carried out under acidic conditions.
  • the modified lignin-derived components in solution may serve as anolyte and catholyte at the same time.
  • no (semi-permeable) membrane is required for the i nventive method.
  • the electrolyte no specific electrolyte is required, if the reaction is carried out in acidic or alkal i ne medium.
  • a salt or distinct salts, preferably an alkali salt may be added to the electrolyte, e.g. a sodium salt, preferably sodium sulfate.
  • decomposition may alternatively be accomplished by biotechnological means, e.g. by enzymatic degradation of l ignin.
  • biotechnological means e.g. by enzymatic degradation of l ignin.
  • typical ly cel lulose and hemicellulose are degraded, and low molecular weight l igni n-derived components may advantageously be obtained by chemical decomposition. They may be isolated from the cellulosic and hemicellulosic fraction by the means disclosed herein.
  • isolation step (F) of the inventive method is another purification and isolation step, which may preferably comprise fi ltration and/or extraction, preferably fi ltration.
  • Fi ltration may be selected from ultrafiltration and nanofiltration, which may be carried out by an ultrafiltration and/or nanofiltration cell, preferably having a pre-filtration section for increasing the efficiency of the filtration step (e.g. avoidance of membrane blockade, e.g. by higher molecular weight lignin-derived components).
  • Stirred ultrafiltration cells as described by Duval et al. (Holzaba 2015, 69, 127-134) may be applied as well.
  • the ultrafi ltration and/or nanofiltration cell comprises at least one molecular weight cut-off unit, preferably at least two molecular weight cut-off units allowing to isolate target compounds within a molecular weight range, which reflects the molecular weight of monomeric and dimeric target compounds , e.g. from 1 50 Da to 1 .000 Da or from 150 to 500 Da.
  • a cascade of cut-off units e.g. strating with one or more ultrafiltration cell(s) and one or more subsequent nanofiltration cell(s) with preferably decreasing cut-off values may be employed to fractionate the resulting lignin-derived decomposition products obtained in step (E).
  • the decomposition products obtained in step (E) may usually be fractionated in solution or may be isolated as dried matter and be re-dissolved thereafter, if required.
  • the ultra- and/or nanofiltration may be followed by further purification steps to increase purity of the lower molecular weight aromatic lignin-derived target compound according to the present invention.
  • diafiltration against water may be used to remove residual sugars and reactive agents from the low molecular weight target compound fraction.
  • the present invention refers to low molecular weight lignin-derived compounds, which are obtainable by a method according to the first aspect.
  • the target compound obtained by step (F) of the inventive method comprises one or two aromatic (carbocyclic) ring(s), separated by a linker or directly l inked by a bond (biphenylic compound).
  • a target compound comprising one aromatic ring is typically derived from a monomer of the modified lignin precursor component as the intermediate of the inventive method.
  • a target compound comprising two aromatic rings is typically derived from two covalently linked monomers (dimer) of the modified lignin precursor component as the intermediate of the inventive method.
  • Target compounds containing two aromatic rings, which form a biphenylic system are obtainable by choosing the appropriate lignocellulosic starting material, which encompasses such moieties, e.g. from spruce.
  • a biphenylic system typically comprises phenylbenzene or 1 ,1 '-biphenyl as essential chemical structure.
  • Biphenylic moieties are typically formed by 5-5-linkage of natural lignin monomers. Such a bond occurs more frequently in softwood than in hardwood.
  • spruce may comprise more than 1 5%, preferably more than 20%, even more preferred more than 25% biphenylic moieties among its phenyl-propane units making up its natural lignin.
  • biphenylic target compounds it may be preferred to use spruce wood as a lignocellulosic starting material in step (A) of the inventive method.
  • Biphenylic low molecular weight compounds may be further processed by chemical reactions, e.g. in further oxidizing reactions, in order to provide e.g. redox active compounds for multiple beneficial uses.
  • the aromatic ring(s) of the low molecular weight aromatic lignin-derived compound is/are substituted in at least one, preferably in at least two positions by a functional group, wherein the at least one functional group is preferably alkoxy or hydroxyl.
  • a monocyclic compound is typically substituted in at least two positions by a functional group, wherein the functional group is preferably alkoxy or hydroxyl.
  • a compound having two ring systems, in particular a biphenylic compound, is typically substituted in at least one position per aromatic ring by a functional group.
  • each ring system exhibits its individual substitution pattern being different from the other substitution pattern of the other ring system.
  • the at least one functional group is alkoxy or hydroxyl.
  • the at least one low molecular weight aromatic lignin-derived compound of the inevtion is characterized by general Formula (la):
  • each of R ⁇ R 5 is independently selected from H, optionally substituted G-ealkyl, optionally substituted G-6 al kenyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, phosphoryl, and phosphonyl; wherein at least one of R 1 , R 3 or R 5 is hydroxy or optionally substituted G-6 alkoxy; and R 6 is selected from the group consisting of hydrogen, hydroxy, linear or branched G- 6 carboxyl, linear or branched G-6 aldehyde, and linear or branched G-6 alcohol.
  • At least one low molecular weight aromatic lignin-derived compound is characterized by general Formula (lb):
  • each of R ⁇ R 9 is independently selected from H, optionally substituted G- 6 alkyl, optionally substituted G- 6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, phosphoryl, and phosphonyl; wherein R 5 is hydroxy or optionally substituted G-6 alkoxy; and
  • R 10 is selected from the group consisting of hydrogen, hydroxy, linear or branched G. 6 carboxyl, linear or branched G-e aldehyde, and linear or branched G-6 alcohol.
  • Alkoxy in the context of the present invention is preferably a group of formula -OR, wherein R is preferably an alkyl group, as defined.
  • Halogen is fluoro, chloro, bromo, or iodo.
  • Hydroxy or "Hydroxyl” is -OH.
  • Amino is -NH 2 .
  • An exemplary ion of amino is -NH 3 + .
  • Niro is preferably NO 2 .
  • Carboxyl is preferably -COOH.
  • An exemplary ion of carboxyl is -COO-.
  • Sulfonyl is -SO 3 H.
  • An exemplary ion of sulfonyl is -SO 3 -.
  • Phosphoryl is preferably -PO 3 H 2 .
  • Exemplary ions of phosphoryl are -PO 3 H " and -PO 3 2" .
  • Phosphonyl is preferably - PO 3 R 2 , wherein each R is independent H or alkyl, as defined herein.
  • An exemplary ion of phosphoryl is -PO 3 K.
  • the at least one low molecular weight aromatic lignin-derived compound is selected from the group consisting of phenolic derivatives of biphenyl, benzylalcohol, benzalde-hydes and benzoic acid, preferably derivatives of p-hydroxy benzylalcohol, p- hydroxy benzaldehydes and p-hydroxy benzoic acid, or more preferably vanillin, guaiacol, eugenol, syringol, phenol, syringaldehyde, and/or a derivative of any of the above, and/or a combination of the above.
  • a monocyclic compound provided by step (F) is further reacted in a step (G) to an aromatic bi- or tricyclic compound, to a tetracyclic or pentacyclic compound.
  • Annulated bicyclic or pentacyclic compounds may be preferred. They may be purified and further processed according to the present invention.
  • Such an aromatic annulated compound comprising more than one ring is of particular value as a precursor for further oxidation.
  • Said reaction type is typically known as annulation, which serves in organic chemistry as a chemical reaction, which allows to anneal two aromatic (mono-, di- or n-aromatic) ring systems.
  • the two or more precursor molecules of the annulation reaction are both or all e.g. monomeric or dimeric target compounds.
  • the annulation is, for example, achieved by a Diels-Alder reaction or a Friedel-Crafts acylation.
  • the at least one low molecular weight aromatic lignin-derived compound provided by step (F) comprises one aromatic ring and is further processed in a step (G), wherein said low molecular weight aromatic lignin-derived compound comprising one aromatic ring is subjected to an annulation reaction, preferably a Diels-Alder reaction or a Friedel-Crafts acylation, wherein the annulation reaction product is a low molecular weight aromatic bi- or tricyclic annulated aromatic lignin-derived compound, wherein said compound is characterized by general Formula (II), (III) or (IV)
  • each of R 2 -R 7 of Formula (II) is independently selected from H, optionally substituted Ci-6 alkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, phosphoryl, phosphonyl, wherein at least one of R 2 , R 4 , R 5 , and R 7 is hydroxy or G-3 alkoxy, and
  • Ri and/or R 8 of Formula (II) is/are selected from the group consisting of hydrogen, hydroxy, linear or branched G-6 carboxyl, linear or branched G-6 aldehyde, and linear or branched G-6 alcohol,
  • each of R 2 -R 8 of Formula (III) is independently selected from H, optionally substituted G-6 alkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, phosphoryl, phosphonyl, wherein at least one of R 2 , R 4 , R 5 , R 6 and R 8 is hydroxy or G-3 alkoxy, and
  • R 1 , R 9 and/or R 10 of Formula (III) is/are selected from the group consisting of hydrogen, hydroxy, linear or branched G-6 carboxyl, linear or branched G-6 aldehyde, and linear or branched G-6 alcohol,
  • each of R 2 -R 9 of Formula (IV) is independently selected from H, optionally substituted
  • G-6 alkyl optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, phosphoryl, phosphonyl, wherein at least one of R 2 , R 4 , R 7 , and R 9 is hydroxy or
  • G-3 alkoxy, and R 1 and/or R 10 of Formula (IV) is selected from the group consisting of hydrogen, hydroxy, linear or branched G-6 carboxyl, linear or branched G-6 aldehyde, and linear or branched G-6 alcohol.
  • the annulation reaction is a Friedel-Crafts acylation. This is particularly surprising as such acylation reactions were previously known preferably in the petrochemical field with regard to annulation reactions. Transferri ng said annulation reaction to compounds according to the present invention from renewable sources opens new synthesis options.
  • Friedel-Crafts acylation is the acylation of aromatic ri ngs with an acyl chloride using a strong Lewis acid catalyst.
  • a Diels-Alder reaction is understood as an organic chemical reaction, typical ly a [4+2] cycloaddition, between a conjugated diene and a substituted alkene, commonly termed the dienophi le, to form a substituted cyclohexene system. Said formed cyclohexene system is preferably aromatic.
  • the Diels-Alder reaction is particularly useful i n synthetic organic chemistry as a reliable method for formi ng 6-membered systems with good control over regio- and stereochemical properties.
  • monocycl ic compounds comprisi ng only one aromatic ring may be subjected to reactions, which increase the number of aromatic ri ng. Hence, the respective compound undergoes annulation.
  • an "annulation" in organic chemistry is a chemical reaction, in which a new ring is constructed on another molecule, typical ly another ring.
  • a monocyclic compound provided by step (F) of the present invention may be extended to a bicycl ic, tricyclic, tetracyclic or even higher n-cycl ic compound.
  • anthracene derivatives which may be precursors for anthraqui none-derivatives, are preferred i n the context of the present invention as they show that redox potentials decrease with increased annulation and, thus, the more annulated derivatives are more stable.
  • the Diels-alder reaction may be catalysed by any suitable catalyst known in the art, preferably by one or more metal lic chlorides and/or zeol ites.
  • the subsequent oxidation step may or may not be necessary. If a reduced catalyst is sti ll present from earl ier reaction steps, the newly annulated ring may be instantly oxidized and aromatized, yielding in a multi-ring quinone.
  • aeration in alkali ne solution may be used, e.g., to obtai n an anthraquinone derivative.
  • the condensation is preferably carried out prior to the optional downstream oxidation to obtai n a redox active compound, or prior to derivatization i n order to avoid, e.g. steric hindrance, and, in consequence, lower yields in condensed and derivatized product.
  • Derivatization as used herein with regard to the compounds obtainable from step (F) or (G) aims to improve solubil ity and electrochemical properties
  • the at least one low molecular weight aromatic ligni n-derived compound obtained from step (F) (or (G)) is further modified in a step (H) by oxidizing the at least one low molecular weight aromatic l igni n-derived compound in the presence of (i.) an oxidizi ng agent selected from the group consisting of O2 and air and (ii .) a heterogeneous catalyst comprising a metal ion or a metalloid, or performing homogeneous catalysis in the presence of NaOH .
  • an oxidizi ng agent selected from the group consisting of O2 and air
  • a heterogeneous catalyst comprising a metal ion or a metalloid
  • usual ly no catalyst comprisi ng a metal ion or a metal loid is requi red.
  • Co(ll) complexes are employed because they have a high selectivity towards qui nones.
  • (pyr)Co(l l)salen may be employed in the presence of O 2 at overpressure, e.g. at least 3 bar.
  • Such a reaction may preferably be conducted at roomtemperature in an organic solvent such as MeOH.
  • organic solvent such as MeOH.
  • Other preferred catalysts are Co(3-methoxysalen) and CO(N-N-Me salpr). In the latter case, the preferred organic solvent may be CH2CI2.
  • Said oxidation provides an oxidized low molecular weight aromatic lignin-derived compound, which is generally understood herein as hydroquinone compound according to the present invention and/or, upon further oxidation, as a quinone compound according to the present invention.
  • step (H) provides at least one hydroquinone compound (step H.I), characterized by general Formula (Va):
  • each of R'-R 5 is independently selected from optionally substituted Ci-e aikyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, carboxyl, nitro, phosphoryl, and phosphonyl, and wherein one of R 1 , R 3 and R 5 is hydroxy; or by general formula (Vb),
  • each of R ⁇ R 9 is independently selected from optionally substituted G ealkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, carboxyl, nitro, phosphoryl, and phosphonyl; and wherein R 5 is hydroxy.
  • step (H) provides at least one quinone compound (step H.2) under harsher oxidation conditions than in step (H.l ), characterized by any of general Formulae (Via) to (Vlb):
  • each of R'-R 2 and R -R 5 is independently selected from optionally substituted Ci-6 alkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, carboxyl, nitro, phosphoryl, and phosphonyl; or
  • each of R 2 -R 5 is independently selected from optionally substituted Ci -6 alkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, carboxyl, nitro, phosphoryl, and phosphonyl; or
  • each of R 1 -R 4 is independently selected from optionally substituted G. 6 alkyl, optionally substituted G-6 alkenyl, halogen, optionally substituted G-6 alkoxy, amino, carboxyl, nitro, phosphoryl, and phosphonyl; or
  • each of R'-R 4 and R 6 -R 9 is independently selected from H, optionally substituted G-6 alkyl, halogen, optionally substituted G-6 alkoxy, amino, nitro, carboxyl, phosphoryl, and phosphonyl.
  • the at least one hydroquinone compound provided by step (H.1 ) is further oxidized, preferably in the cell stack of a battery or by an oxidant, optionally in the presence of a heterogeneous catalyst, in a step (I) to obtain a quinone compound characterized by any of Formulas (VI a) to (VI d) as defined herein.
  • a hydroquinone compound according to the present invention which compound already is redox active and may be oxidized or a part of the total amount of employed molecules of said hydroquinone compound may get oxidized.
  • step (H) and optionally step (I) provide a compound represented by one or both of the following structures:
  • steps (E) and (H) of the inventive method may be combined together in one step.
  • a modified lignin- derived component typically alternative (E.1 ) or (E.3)
  • the component is oxidized to a hydroquinone and/or quinone compound according to the present invention.
  • said combination may save time and resources in terms of reactants, reactive agents and/or process equipment and apparatus means. Accordingly, such a combination lead to significant more economic and simple method for producing redox active compounds of renewable origin such as the hydroquinone and/or quinone compounds according to the present invention.
  • Such a combined method step is preferably faci litated by applying electrooxidation of step (E.3), but catalyst-facilitated oxidation under (E.1 ) may also be applied.
  • electrooxidation wherein direct oxidation from a modified lignin such as lignosulfonate to a hydroquinone and/or quinone compound is controlled by the respective set electrochemical conditions.
  • the modified lignin is diluted to a concentration below 20% (w/w), preferably below 10% (w/w), more preferably below 5% (w/w), even more preferably below 2% (w/w).
  • the solution may have a pH of 1 to 14.
  • Preferred is electrooxidation under acidic conditions.
  • the preferred pH is at least 1 1 , more preferably at least 1 3.
  • the electrooxidation is preferably conducted in a flow cell, wherein the flow is at least corresponding to 1 ml/min, preferably 1 0 ml/min or 50 ml/min, more preferably at least 200 ml/min, but may be up-scaled to significantly higher flows.
  • Electrolysis may typically be conducted galvanostatically, preferably for at least 10 min, preferably at least 30 min, alternatively for at least 1 hour, preferably for at least 4 hours. Most preferred is a time period for conducting electrolysis of at least 30 min, e.g. to save time and resources.
  • electrolysis is carried out by applying a current of preferably at least 0.5 mA/cm 2 , more preferably 1 mA/cm 2 , even more preferably at least 5, 10 or 1 00 mA/cm 2 .
  • the low molecular weight aromatic bi- or tricyclic annulated compound obtained from step (G) is further modified in a step (H) by oxidizing the at least one low molecular weight aromatic bi- or tricyclic annulated compound in the presence of (i.) an oxidizing agent selected from the group consisting of H 2 O 2 , O2 and air, and (ii.) a heterogeneous catalyst comprising a metal ion or a metalloid, or performing homogeneous catalysis in the presence of NaOH (in which case, usually no catalyst comprising a metal ion or a metalloid is required), to obtain at least one quinone and/or hydroquinone compound, wherein said compound is characterized by any of general Formula (VII), (VIII) and/or (IX):
  • each of R 1 -R 8 with regard to Formula (VII) and/or each of Ri-R 10 with regard to Formula (VII) and (IX) is independently selected from H, optional ly substituted Ci_ & alkyl, halogen, optional ly substituted G-ealkoxy, ami no, nitro, carboxyl, phosphoryl, phosphonyl; wherein at least one of R 8 and R 5 or R 1 and R 4 of Formula (VII) are hydroxy or oxo, or at least one of R 9 and R 6 , R 10 and R 5 , or R 1 and R 4 of Formula (VI II) are hydroxy or oxo, or at least one of R 10 and R 7 or R 1 and R 4 of Formula (IX) are hydroxy or oxo.
  • step (H) may provide a compound characterized by the following structure:
  • the at least one quinone and/or hydroquinone compound, provided by step (H), (H.1 ), (H.2) or (H.1 ) and (I) is subjected to a purification step (J) to separate the at least one quinone and/or hydroqui none compound from residual compounds by an extraction method, preferably by solid phase extraction or fluid-fluid phase extraction as generally known i n the art.
  • Said at least one filtered quinone and/or hydroquinone typically is a redox active compound.
  • a redox active compound is understood in the context of the present invention as a chemical compound, which may form a pair of an oxidizing and reducing agent, i.e. a redox pair, which are involved in a particular reaction. Thus, said compound is preferably suitable for any electrochemical application.
  • the at least one quinone and/or hydroquinone compound is further modified by being subjected to a derivatization step (K), wherein one or more SO 3 H-, NH 2 -, OH-, PO 3 -, alkoxy and/or CH 3 - groups are introduced into a compound according to any of Formulae (I) to (IX) at a position of the aryl structure other than those characterized by an oxo or hydroxyl group, wherein said group(s) is/are directly bound to the aryl structure or bound via an alkyl linker to the aryl structure, preferably via a methyl linker.
  • NO2- may also be introduced but is less preferred for stability reasons of the resulting compound.
  • a monomeric aromatic lignin-derived compound substituted with one or more SO 3 H-, OH- and/or CH 3 -groups may be provided as a material for a low potential electrolyte. Additionally, or alternatively, a monomeric aromatic lignin- derived substituted with one or more NC>2-groups may provide a material for a high potential electrolyte.
  • sulfonation may be carried out in the presence of concentrated aqueous sulfuric acid.
  • sulfur trioxide may be mixed with inert gas, such as air, N2 and/or CO2, or complexed with a complexing agent such as pyridine, dioxane, (CH 3 ) 3 N or DMF.
  • a complexing agent such as pyridine, dioxane, (CH 3 ) 3 N or DMF.
  • sulfonation is preferably performed at higher temperatures due to increased yields. Therein, an increased temperature is understood to be at least 50°C, preferably 100°C. However, the temperature is not so high that the modified compound is prone to pyrolysis. Separation of the sulfonated compound bay may subsequently be carried out, for example, by filtration or salting out as described herein.
  • Oxidized annulated compounds preferably are superb redox active compounds for versati le use. It is especially preferred that they may be produced from renewable sources and, at the same time, contribute to the valorization of otherwise by products from the pulping industry.
  • step (K) of the method according to a second aspect of the present invention may preferably provide a compound characterized by the following structure:
  • a low molecular weight aromatic lignin-derived compound is provided, which is obtainable by a method according to the present invention.
  • said compound is of a structure as defined herein.
  • the compound may be a low molecular weight aromatic lignin compound obtainable by step (F).
  • Said compound may serve as a precursor for any of steps (G) to (K).
  • the final compound is preferably a valuable, e.g. redox active compound resulting from a renewable lignocellulosic source.
  • an assembly for conducting steps (C) to (F), which are not part of a conventional pulp and/or paper manufacturing plant.
  • pulp separation from the process stream originating from the pulping process (step (B)) is conducted as a core activity to obtain the target product of a conventional pulp and/or paper manufacturing plant.
  • the separation of the process stream into at least two partial process streams as optionally devised in step (C) is not part of a known pulp and/or paper manufacturing plant.
  • the assembly according to the present invention comprises (i) optionally a stream separator, (ii) an isolation unit, (iii) a decomposition unit, and (iv) a separation unit.
  • the provision of the process stream in step (D) to provide partial process streams in step (D.2) is preferably conducted in a stream separation unit, comprising mechanical and/or pneumatic means known in the art.
  • the isolation of the modified lignin may be conducted in an isolation unit, comprising, for example, means for conducting (ultrafiltration, extraction and countercurrent flow.
  • the (i) stream separator of the assembly facilitates that the substantially pulp-free process stream of step (C) is divided into at least two partial process streams.
  • the ratio of the at least two partial process streams may be controlled, which streams may be supplied to different further processing.
  • the fraction of modified lignin-derived components of one of the partial process streams is not isolated. Instead the stream comprising the original content of modified lignin is forwarded to a combustion and recovery unit. Using some of the fraction of modified lignin-derived components as an internal energy fuel for the energy supply for the pulp and/or paper manufacturing plant. Additionally, residual reactive agents are regained, e.g. from the black or brown liquor or from organic solvents.
  • These reactive agents are typically salts, which withstand temperatures of, for example, at least 500°C, or even at least 750°C, or even at least 1000°C.
  • sodium sulfate may be reduced to sodium sulfide by the organic carbon in the mixture, which may be reused in the pulping process.
  • the organic material, which serves as internal fuel such as the modified lignin, hemicellulose, residual cellulose and/or fragments thereof, are burned at temperatures of, for example, at least 500°C, or even at least 750°C, or even at least 1000°C.
  • excess black liquor typically contains about 1 5% (w/w) solids and may be concentrated in a multiple effect evaporator. After said concentration, the black liquor is typically enriched to about 20 - 30% (w/w) solids. At such a concentration of solids, a naturally comprised soap called rosin soap rises to the surface and is skimmed off. The collected soap is further processed to tall oil. Removal of the soap improves the combustion operation. Soap-depleted black liquor with about 20 - 30% (w/w) solids is be called weak black liquor.
  • the fraction of modified lignin-derived components of the process stream coming from step (B) of the inventive method is typically an important fuel for paper and pulp manufacturing plant as it contributes heavily to a pulp and/or paper production plant's energy self-sufficiency.
  • the pulp and paper industry traditionally has a highly efficient infrastructure for growth, harvesting, transport, and processing of forest materials.
  • Kraft operations are highly integrated and depend on the (modified) lignin fraction from wood as a fuel to operate the incredibly expensive chemical recovery boi lers that are the heart of their operation. In the past, diverting this fuel source to other uses would have required the pulping operation to supplement its energy needs by purchasing natural gas or coal, potentially upsetting the plant's economics. Therefore, the Kraft process in contrast to the sulfite process essentially did not provide a source of lignin-derived raw material.
  • the inventive assembly provides means to balance the needs for energy supply to the Kraft process on the one hand and the diverting of lignin and derivatives thereof on the other hand.
  • the flexible control of the diverting means allows to direct exactly the share of the process stream to the generation of electricity and/or steam, which is actually needed to run the pulp and/or paper manufacturing plant.
  • modified lignin-derived components not required in combustion may entirely be directed to other uses such as the further processing of modified lignin according to the present invention. Therefore, less or even no modified lignin is wasted anymore as fuel in excess generation of electricity and/or steam.
  • any modified lignin or lignin-derived compound or fragment thereof, which does not yield the target low molecular weight aromatic lignin-derived compound may be recycled back to the process stream feeding the energy supply of the pulp and/or paper manufacturing plant.
  • pulp and/or paper manufacturing plants become more and more energy efficient, thus the required modified lignin supply for energy providing purposes is about to shrink.
  • energy losses could be mediated by using forest residues and/or by transferring to black liquor gasification. In that scenario, the industry could continue to generate the power they need, but because of the higher efficiency of gas turbines, could also produce a separate syngas stream for the production of higher-value products.
  • the assembly comprises a decomposition unit, providing means to sustain elevated temperature and/or pressure, and to provide the required reactants in solid, liquid and/or gaseous form, preferably in one reaction vessel only.
  • the decomposition unit of the assembly provides a suitable electrochemical cell such as a flow cell.
  • the assembly comprises an isolation unit providing means for isolating low molecular weight aromatic lignin-derived compounds, such as monomers and dimers are used herein, from higher molecular weight lignin-derived components and/or other material involved in the inventive method.
  • said means is an ultra- and/or nanofiltration unit or an extraction. All ducts and/or product and/or process stream contacting parts are preferably made from inert materials.
  • valves and/or pumps or gravity assisting means may typically be employed to facilitate the required flow of the stream downwards to the next step of the inventive method.
  • said assembly for conducting the steps (C) to (K) further comprises (v) optionally an annulation unit, (vi) an oxidizing unit, (vii) optionally a derivatization unit and (viii) optionally a purification unit.
  • step (G) is conducted in an annulation unit, step (H) and optionally (I), in an oxidizing unit, step (J) in a derivatizing unit and step (K) in a purification unit.
  • the preferred requirements for such assembly units may be derived from the conditions and characteristics of the method steps described herein, which are performed in said assembly units.
  • said assembly is directly connected to a conventional pulp and/or paper production plant.
  • the apparatus is not directly associated or attached with the conventional pulp and/or paper manufacturing plant. Instead.
  • the process stream originating from step (B), e.g. of a conventional pulp and/or paper manufacturing plant, is collected and then transferred to a distinct apparatus suitable to conduct the steps (C) to (F) and optionally (G) to (K).
  • a direct integration of the apparatus suitable to conduct the steps (C) to (F) and optionally (G) to (K) is preferred, as such direct integration provides for a flexible separation of the lignin-derived compounds in the process stream depending on the energy needs and further parameters of the pulp and/or paper manufacturing plant.
  • a method for applying a pulp and/or paper manufacturing process using the pulping process by a plant, wherein the plant is equipped with an assembly according to the present invention. Accordingly, said method refers to modifying an existing pulp and/or paper manufacturing plant, working e.g. under the Kraft or sulfite process, wherein the plant is provided with the assembly according to the present invention.
  • composition encompasses the term “consist of”.
  • comprising thus encompasses “including” as well as “consisting” e.g., a composition “comprising” X may consist exclusively of X or may include something additional e.g., X + Y.
  • Example 1 Preparation of low molecular weight aromatic lignin-derived compounds by cracking and reduction by a nickel catalyst
  • Cracking and reducing of a modified lignin-derived component according to step (E.2) of the inventive method may for example be carried out by means of a catalyst comprising nickel, e.g. supported on activated carbon (Ni/C).
  • the catalysts are typically prepared by an incipient- wetness impregnation method and further treated by a carbothermal reduction method known in the art.
  • nickel nitrate(ll) hexahydrate [Ni(N0 3 ) 2 6H20] is used and optionally added into water in a beaker known in the art.
  • the solution is then stirred, e.g. for at least 30 min, to prepare an impregnation stock solution.
  • Activated carbon having a water absorption capacity of typically above 1 .8 mL g 1 is added into the solution and the beaker may then covered by a culture dish to keep the sample wet for a prescribed time, preferably more than 12 h, more preferably 24 h.
  • the sample is then dried at a temperature above 80°C, e.g. 120 °C overnight.
  • the actual reduction is carried out in a container such as a preferably horizontal furnace in a flow of inert gas such as N 2 .
  • the flow is, e.g., 10 mL min 1 or more, preferably 30 mL min 1 or more.
  • the reduction temperature preferably reaches at least 400°C, preferably 450°C, e.g. over set time period such as at least 30 min, preferably at least 60 min.
  • the temperature for conducting the reduction is maintained at 450°C for at least 1 h, more preferably for at least 2 h.
  • the Ni/ SBA-15 catalysts are reduced at 550°C for 2 h.
  • the Ni/Al 2 0 3 catalyst is reduced at 700°C for 2 h.
  • the metal loading for each nickel- and copper-based catalyst is 1 0 % (w/w) relative to the support.
  • birch sawdust serves as lignocellulosic material and is treated with the ethanol-benzene mixture (v/v ratio 1 : 2) for 1 2 h.
  • the treated birch sawdust, solvent (m/v 1 :20), and catalyst (w/w 20: 1 ) are placed in an autoclave reactor.
  • the reactor is sealed and purged with Ar 4 to 6 times to expel air.
  • the reduci ng reaction is conducted at 200 °C at a stirring speed of at least 300 rpm, preferably 500 rpm.
  • the desired reaction time (usual ly 2 to 1 0 h) is reached, the reactor is cooled to ambient temperature before sampl ing.
  • reaction generates 4-propylguaiacol and 4-propylsyringol as major products, together with minor alkene-substituted 4-propylguaiacol and 4-propylsyringol, as determined by standard gas chromatography.
  • the compounds are isolated according to step (F), preferably by extraction.
  • Example 2 Preparation of monomeric aromatic lignin-derived molecules from lignosulfonate of a sulfite process by electrooxidation
  • Lignosulfonate is provided by step (D) accordi ng to the present invention.
  • a 1 M aqueous NaOH solution is prepared, comprisi ng 1 % ⁇ W/W) lignosulfonate.
  • Said solution is subjected to an electrooxidation according to step (E.3).
  • the solution is employed as anolyte.
  • a 1 M aqueous solution is employed as katalyte.
  • a flow cel l with a flow rate of 250 ml /min is used.
  • Electrolysis is allowed to take place galvanostatically for 8 h applying current of 1 mA/cm 2 .
  • a typical resulting voltage is 1 ,4 V.
  • the voltage curve typical ly is asymptotic and the solution changes preferably color from brown to dark brown. Samples of the solution are taken every hour over a time span of 8 h and subsequently examined photometrical ly. Thereof, an absorption profi le typical for ortho- benzoquinone is determined. Hence, a lower molecular weight aromatic l ignin-derived compound, quinone compound, is prepared by said method. Said compound is then isolated accordi ng to step (F) of the present invention. Therefore, said compound is extracted by dichloromethane and subsequently subjected to cycles of chargi ng and discharging processes in a flow cel l. The voltage curve shows that the compound is redox active, which may be reversibly electrolyzed.
  • Example 3 Preparation of an annulated quinone compound by a Friedel-Crafts acylation
  • Vanillin as a low molecular weight aromatic lignin-derived compound is provided by step (F) according to the present invention.
  • Said compound is further annulated according to step (G) and oxidized according to step (H) according to the present invention in five steps as follows:
  • Vanillin (1 ) (1 .0 eq.) and benzyl chloride (1 .2 eq.) are dissolved in Y/V-dimethylformamide and potassium iodine (0.5 mol%) is added. Afterwards potassium carbonate is added and the reaction is stirred above 60°C, preferably between 60 to 120 °C for at least 1 h, preferably 1 to 8 h. After completion of the reaction, the solution is diluted with distilled water and extracted with an appropriate solvent. The organic phase is washed with brine and the product is then isolated from the organic phase.
  • Isolated product 3 (1 .0 eq.) is dissolved in thionyl chloride (5-20 eq.) and the mixture is stirred at 60 to 120 °C for 1 to 8 h. After completion of the reaction excess thionyl chloride is evaporated to yield desired acyl chloride 4.
  • Aluminiumtrichloride (0.1 eq.) is added to the crude acyl chloride 4 and the mixture is stirred for 30 to 300 min at -20 to 60 °C. After completion of the reaction the mixture is carefully quenched with bicarb solution. The product is extracted with an appropriate solvent and the organic layer is washed with brine. The product is then isolated from the organic phase.
  • Anthraquinone 5 or 6 are dissolved in ethyl acetate, methanol or ethanol and palladium on charcoal (1 to 30 weight%) is added. The mixture is stirred at room temperature under hydrogen atmosphere (1 -10 bar). The catalyst is filtered off and the product (9) is isolated from the mixture.
  • the product is then characterized by spectrograph ic means, and provided as redox active compound according to the present invention.

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Abstract

La présente invention concerne un procédé de production d'un ou plusieurs composés aromatiques de bas poids moléculaire dérivés de la lignine. Le procédé comprend de préférence la préparation d'un matériau lignocellulosique, la soumission du matériau lignocellulosique à un procédé de réduction en pâte, la séparation de la pâte pour fournir un écoulement de procédé sensiblement sans pâte comprenant un composant modifié dérivé de lignine, l'isolement du composant modifié dérivé de lignine, la soumission du composant isolé modifié dérivé de lignine à une étape de décomposition comprenant la fissuration et l'oxydation ou la réduction sous l'influence d'un catalyseur ou l'électro-oxydation, et la soumission des produits résultants à une étape d'isolement, pour produire un composé aromatique de bas poids moléculaire dérivé de lignine. Ledit composé peut en outre être modifié, par exemple par annulation. Le procédé inventif comprend préférablement en outre l'oxydation dudit composé en composé actif rédox. De manière additionnelle, la présente invention concerne des composés pouvant être obtenus par le procédé inventif et un ensemble de conduite du procédé inventif. En outre, la présente invention désigne un procédé consistant à fournir une usine de fabrication de pâte et/ou de papier grâce audit ensemble.
PCT/EP2016/000575 2016-04-07 2016-04-07 Procédé de production de composés aromatiques de bas poids moléculaire dérivés de la lignine WO2017174098A1 (fr)

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PCT/EP2016/000575 WO2017174098A1 (fr) 2016-04-07 2016-04-07 Procédé de production de composés aromatiques de bas poids moléculaire dérivés de la lignine
BR112018069518A BR112018069518A8 (pt) 2016-04-07 2017-04-07 Compostos aromáticos sulfonados
EP22203539.6A EP4180503A1 (fr) 2016-04-07 2017-04-07 Procédé de production de composés aromatiques dérivés de lignine de faible poids moléculaire
CA3017991A CA3017991A1 (fr) 2016-04-07 2017-04-07 Procede de production de composes derives de lignine aromatique de bas poids moleculaire
JP2019503619A JP2019516781A (ja) 2016-04-07 2017-04-07 スルホン化芳香族化合物
KR1020187032231A KR20180134369A (ko) 2016-04-07 2017-04-07 설폰화된 방향족 화합물
CN201780022496.4A CN109072089B (zh) 2016-04-07 2017-04-07 经磺化的芳香族化合物
JP2019503620A JP7050747B2 (ja) 2016-04-07 2017-04-07 低分子量芳香族リグニン由来化合物を製造するための方法
MYPI2018703302A MY191139A (en) 2016-04-07 2017-04-07 Method for producing low molecular weight aromatic lignin-derived compounds
CN201780022306.9A CN109072088B (zh) 2016-04-07 2017-04-07 制备低分子量的芳香族木质素衍生化合物的方法
AU2017246493A AU2017246493A1 (en) 2016-04-07 2017-04-07 Sulfonated aromatic compounds
CA3017989A CA3017989A1 (fr) 2016-04-07 2017-04-07 Composes aromatiques sulfones
BR112018069113-5A BR112018069113B1 (pt) 2016-04-07 2017-04-07 Método para a produção de compostos derivados de lignina aromática de baixo peso molecular
US16/091,436 US11008284B2 (en) 2016-04-07 2017-04-07 Sulfonated aromatic compounds
EP17716793.9A EP3440158A1 (fr) 2016-04-07 2017-04-07 Procédé de production de composés dérivés de lignine aromatique de bas poids moléculaire
EP22203648.5A EP4180504A3 (fr) 2016-04-07 2017-04-07 Composés aromatiques sulfonés
PCT/EP2017/000461 WO2017174206A1 (fr) 2016-04-07 2017-04-07 Composés aromatiques sulfonés
US16/091,437 US11225756B2 (en) 2016-04-07 2017-04-07 Method for producing low molecular weight aromatic lignin-derived compounds
KR1020187032226A KR20180133888A (ko) 2016-04-07 2017-04-07 저분자량 방향족 리그닌-유래 화합물의 제조 방법
PCT/EP2017/000462 WO2017174207A1 (fr) 2016-04-07 2017-04-07 Procédé de production de composés dérivés de lignine aromatique de bas poids moléculaire
AU2017246494A AU2017246494B2 (en) 2016-04-07 2017-04-07 Method for producing low molecular weight aromatic lignin-derived compounds
EP17716792.1A EP3440157A1 (fr) 2016-04-07 2017-04-07 Composés aromatiques sulfonés
ZA2018/06214A ZA201806214B (en) 2016-04-07 2018-09-14 Method for producing low molecular weight aromatic lignin-derived compounds
ZA2018/06216A ZA201806216B (en) 2016-04-07 2018-09-14 Sulfonated aromatic compounds
US17/177,567 US11773537B2 (en) 2016-04-07 2021-02-17 Sulfonated lignin-derived compounds and uses thereof
JP2021142062A JP2022000431A (ja) 2016-04-07 2021-09-01 スルホン化芳香族化合物
AU2023202814A AU2023202814A1 (en) 2016-04-07 2023-05-05 Sulfonated aromatic compounds
US18/197,415 US20230304221A1 (en) 2016-04-07 2023-05-15 Sulfonated Lignin-Derived Compounds And Uses Thereof

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US11891349B2 (en) 2018-02-13 2024-02-06 Cmblu Energy Ag Aminated lignin-derived compounds and uses thereof
CN112495424A (zh) * 2020-11-16 2021-03-16 华南理工大学 一种改性分子筛负载钌催化剂及其制备与在木质素制烃类物质中的应用
CN113387766B (zh) * 2021-07-16 2022-04-12 中国科学院化学研究所 一种金属负载型催化剂催化转化木质素制备纯苯的方法
CN113387766A (zh) * 2021-07-16 2021-09-14 中国科学院化学研究所 一种金属负载型催化剂催化转化木质素制备纯苯的方法

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