Method for producing stabilized lignin with high specific surface area

Abstract

The present invention relates to a method for producing a stabilized lignin from a lignin-containing raw material, the method comprising two process steps. The present invention also relates to the stabilized lignin thus produced.

Description

[Background technology]

[0001] Lignins derived from hardwoods, softwoods, and annual plants exhibit high solubility in many polar and alkaline media after extraction / recovery, for example, in the form of kraft lignin, lignosulfonates, or hydrolyzed lignin. Lignins exhibit a glass transition, particularly at temperatures between 80°C and 150°C. Softening, even at low temperatures, alters the microscopic structure of lignin particles. Therefore, lignin-containing materials generally cannot withstand high temperatures, which alters their properties. Furthermore, the solubility of lignin in polar solvents, such as dioxane and acetone containing 10% water, or in alkaline solvents, is typically greater than 95% (Non-Patent Document 1, Non-Patent Document 2). These and other properties mean that lignin can only be used to a limited extent in materials applications (Patent Document 1).

[0002] In the following, lignin is to be understood as meaning the collection of Klason lignin and acid-soluble lignin. The dry matter further contains other organic and inorganic components.

[0003] To overcome these disadvantages, it has been proposed to produce stabilized lignin by hydrothermal carbonization, characterized by a softening temperature (glass transition temperature) exceeding 200°C (Patent Document 2).By adjusting the pH, it is possible to obtain stabilized lignin with a defined particle size distribution (Patent Document 2).

[0004] In an improved method, lignin is used as a raw material to produce granular carbon materials that can be used, for example, as functional fillers in elastomers (Patent Document 3). An important quality parameter of the functional filler is the external surface area of the granular carbon material, determined by STSA measurements. Such methods involve hydrothermal carbonization of a lignin-containing liquid, typically at temperatures between 150°C and 250°C. Due to the high reactivity of lignin at these temperatures, achieving a high specific surface area requires a delicate balance between the pH, ionic strength, and lignin content of the lignin-containing liquid, as well as the temperature and duration of the hydrothermal carbonization. This is achieved by adjusting the pH to an alkaline range, typically above 7.

[0005] For such granular carbon materials, this opens up different applications for the material than the respective starting lignin. For example, low solubility of less than 40% and 5m 2 / g and over 200m 2 With a specific surface area of less than 1000000 / g, they can be used as reinforcing fillers in elastomers and as partial or complete replacements for carbon black.

[0006] A disadvantage of these methods is the low yield, which is generally between 40% and 60%. A further disadvantage of these methods is the high cost of adjusting the properties of the lignin-containing liquid (pH, ionic strength, lignin content) to the process parameters of hydrothermal carbonization (temperature and residence time) to achieve increasingly higher specific surface areas. 2 / g~40m 2 Although surface areas in the range of 40 m / g are easily achievable, the required sensitivity of the above balance is higher in the laboratory than in the industrial scale. 2 This means that it is easier to achieve a specific surface area above 10 ...

[0007] To produce fuel from a suspension of dried black liquor and water by hydrothermal carbonization at temperatures between 220 and 280 °C, a known method for increasing the yield of solid material and lignin conversion is the addition of formaldehyde [3]. Kang et al. propose adding 37 g of formaldehyde per 100 g of dry lignin at a 20% solids concentration (100 ml of 2.8% formaldehyde solution per 25 g of dry matter obtained by drying black liquor with a lignin content of 30% based on the dry matter). This increases the conversion of lignin present in the black liquor to solids from 60-80% to values between 90 and 100%, with the highest values being achieved at temperatures between 220 and 250 °C. According to this prior art, the increase in yield is attributed to polymerization between formaldehyde, the solids in the black liquor, and the carbonized products formed from the solids (page 716, last paragraph).

[0008] Disadvantages of this prior art High specific dosage of 37g of formaldehyde per 100g of lignin, high ash content of the dry matter used and the products produced therefrom; Polymerization between formaldehyde, the solids in the black liquor, and the carbonized products formed from the solids; and Any relevant restrictions on the use of the product for use in fuel. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] German Patent Application Publication No. 102013002574 [Patent Document 2] International Publication No. 2015 / 018944 [Patent Document 3] International Publication No. 2017 / 085278 [Non-patent literature]

[0010] [Non-Patent Document 1] Sameni et al., BioResources, 2017, Vol. 12, pp. 1548-1565 [Non-patent document 2] Podschun et al., European Polymer Journal, 2015, Vol. 67, pp. 1-11 [Non-patent document 3] Bioresource Technologie 2012, Vol. 110, pp. 715-718, Kang et al. Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention is to find a method that provides a high yield of stabilized lignin suitable for material applications.

[0012] The object of the present invention is to reducing the solubility of lignin in alkaline and / or polar media; Increase or eliminate the glass transition temperature of lignin; resulting in stabilized lignin with advantageous particle properties; and The goal is to identify a method that has a high yield. [Means for solving the problem]

[0013] Thus, in a first variant, at least 10 m from the lignin-containing raw material 2 1. A method for producing an undissolved stabilized lignin having an STSA surface area of 1000 nm / g, comprising: In a first method step, lignin dissolved in a liquid is reacted with a crosslinking agent, thereby producing a dissolved modified lignin, A method is provided in which in a second method step, the dissolved modified lignin is converted to an undissolved stabilized lignin.

[0014] Preferred lignin-containing raw materials are, in particular: Black liquor from the kraft cooking of woody biomass or solids produced therefrom (e.g., LignoBoost lignin, LignoForce lignin), solids from enzymatic hydrolysis of woody biomass, Black liquor (lignosulfonate) from sulfite cooking of woody biomass or solids produced therefrom, or liquor from solvent cooking of woody biomass or solids produced therefrom (e.g., Organosolv lignin); is.

[0015] If the lignin-containing raw material is solid, the lignin contained therein must be completely or partially dissolved in a liquid before the first method step. Methods for dissolving lignin in a liquid are prior art.

[0016] In addition to the dissolved lignin that reacts with the crosslinker in the first method step, undissolved lignin may also be present in dispersed form in the liquid. Thus, in the present method, it is not necessary for all the lignin to be dissolved in the liquid. However, it is advantageous for more than 50%, particularly preferably more than 60%, even more preferably more than 70%, particularly preferably more than 80%, and in particular more than 90% of the lignin to be dissolved in the liquid.

[0017] The dissolved modified lignin is particularly that the aromatic compounds in lignin are still primarily connected via ether bonds; the proportion of para-substituted phenol rings in the total proportion of aromatic rings is more than 95%, preferably more than 97%, particularly preferably more than 99%, and the content of free phenol is less than 200 ppm, preferably less than 100 ppm, even more preferably less than 75 ppm, particularly preferably less than 50 ppm; a Klason lignin content of at least 70%, preferably at least 75%, more preferably at least 80%, in particular at least 85%; is understood to mean

[0018] The phenolic content is determined according to DIN ISO 8974. The Klason lignin content is determined as acid-insoluble lignin according to TAPPI T222.

[0019] The term "undissolved stabilized lignin" for the purposes of the present invention should be understood to mean a solid that can be separated from the liquid after the second process step. Undissolved stabilized lignin is only sparingly soluble in alkaline liquids and has low porosity. The properties of the stabilized lignin obtained by this process are described in detail below.

[0020] Advantageously, in this first variant, there is provided an improved method for producing a non-dissolved stabilized lignin from a lignin-containing raw material, comprising the steps of: In a first method step, a lignin dissolved in a liquid, the lignin comprising phenolic aromatic compounds, aromatic and aliphatic hydroxyl and / or carboxyl groups as crosslinkable units, and a crosslinking agent comprising at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, are reacted at a first temperature T1 between a first maximum temperature T1max and a first minimum temperature T1min for a defined period of time, thereby producing a dissolved modified lignin, A method is provided in which in a second method step, the dissolved modified lignin is converted to undissolved stabilized lignin at a second temperature T2 between a second maximum temperature T2max and a second minimum temperature T2min for a defined period of time.

[0021] The present method significantly increases the yield of non-dissolved stabilized lignin compared to method modes that do not involve reaction with a crosslinking agent in the first method step.

[0022] The two-stage process format can favorably influence the conditions under which each process step is carried out.

[0023] The reaction of the crosslinker with the lignin dissolved in the liquid in the first process step ensures high selectivity in the reaction, allowing for selectively obtaining a dissolved, modified lignin, which can then be converted into an undissolved, stabilized lignin in the second process step. By carrying out the first process step in solution, the polymerization of the crosslinker with the lignin and any carbonized products formed from the lignin is reduced or completely suppressed. By converting the dissolved, modified lignin into an undissolved, stabilized lignin in the second process step, the particle properties of the undissolved, stabilized lignin can be selectively influenced, allowing for advantageous particle properties to be established.

[0024] The two-step process format of the present method surprisingly results in stabilized lignin with a yield and specific surface area that is significantly higher than stabilized lignin produced from the same starting materials according to prior art techniques that do not involve reaction with a crosslinking agent in the first process step.

[0025] Furthermore, the two-step process format of the present method surprisingly results in stabilized lignin with significantly higher yields and specific surface areas than stabilized lignin produced from the same starting materials according to the prior art in a one-step process, but involving reaction with a crosslinker.

[0026] Preferably, the yield of undissolved stabilized lignin relative to dissolved lignin is greater than 60%, preferably greater than 70%, more preferably greater than 80%, especially greater than 85%.

[0027] In one embodiment of the above process variant, the crosslinking compound is added in the first process step.

[0028] The crosslinking agent is preferably dosed so that the amount of crosslinkable units in the crosslinking agent corresponds to at most 4 mol, preferably at most 3 mol, more preferably at most 2.5 mol, particularly preferably at most 2 mol, even more preferably at most 1.75 mol, in particular at most 1.5 mol per mol of crosslinkable units in the lignin used.

[0029] Preferably, the crosslinking agent is dosed so that the amount of crosslinkable units in the crosslinking agent corresponds to at least 0.5 mol, preferably at least 0.75 mol, more preferably at least 1 mol, particularly preferably at least 1.1 mol, in particular at least 1.15 mol per mol of crosslinkable units in the lignin used.

[0030] In a second variation, there is provided a method for producing stabilized lignin from a lignin-containing feedstock, comprising the steps of: In a first method step, a lignin dissolved in a liquid, the lignin comprising phenolic aromatic compounds, aromatic and aliphatic hydroxyl and / or carboxyl groups as crosslinkable units, is reacted with a crosslinking agent comprising at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, thereby producing a dissolved modified lignin, wherein the amount of crosslinking compound is selected so that the content of crosslinkable units in the crosslinking agent is between 0.5 mol and 4 mol per 1 mol of crosslinkable units in the lignin; A method is provided in which in a second method step, the dissolved modified lignin is converted to undissolved stabilized lignin at a second temperature T2 between a second maximum temperature T2max and a second minimum temperature T2min for a defined period of time.

[0031] Thus, an alternative method is also provided in which an optimal amount of cross-linking agent is selected for the amount of lignin used, but a prescribed temperature regime is not required in the first method step. This occurred as a result of the surprising finding that the yield and specific surface area of the resulting carbonized stabilized lignin can be significantly increased if an optimal amount of cross-linking agent is selected.

[0032] In one embodiment of the second variant, the first method step can be supplemented by analogy with the first variant. In one such combination of the first and second variants, an advantageous method for producing stabilized lignin from lignin-containing raw materials is provided, which comprises: In a first method step, a lignin dissolved in a liquid, the lignin comprising phenolic aromatic compounds, aromatic and aliphatic hydroxyl and / or carboxyl groups as crosslinkable units, and a crosslinking agent comprising at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, are reacted at a first temperature T1 between a first maximum temperature T1max and a first minimum temperature T1min for a defined period of time, thereby producing a dissolved modified lignin, wherein the amount of crosslinking compound is selected so that the content of crosslinkable units in the crosslinking agent is between 0.5 mol and 4 mol per 1 mol of crosslinkable units in the lignin; A method is provided in which in a second method step, the dissolved modified lignin is converted to undissolved stabilized lignin at a second temperature T2 between a second maximum temperature T2max and a second minimum temperature T2min for a defined period of time.

[0033] The crosslinking agent can react at the free ortho- and para-positions on the phenolic ring (phenolic guaiacyl group and p-hydroxyphenyl group) in lignin. Examples of crosslinking agents suitable for reacting at the free ortho- and para-positions on the phenolic ring are aldehydes such as formaldehyde, furfural, 5-HMF, hydroxybenzaldehyde, vanillin, syringaldehyde, piperonal, glyoxal, glutaraldehyde, or sugar aldehydes. Preferred crosslinking agents for reaction at the phenolic ring are formaldehyde, furfural, and sugar aldehydes (ethanal / propanal) such as glyceraldehyde and glycolaldehyde.

[0034] Furthermore, crosslinkers can react with aromatic and aliphatic OH groups in lignin (phenolic guaiacyl groups, p-hydroxyphenyl groups, syringyl groups). For example, for this purpose, it may be preferable to use bifunctional and even polyfunctional compounds containing epoxy groups, such as glycidyl ethers, bifunctional and even polyfunctional compounds containing isocyanate groups, such as diisocyanates or oligomeric diisocyanates, or bifunctional and even polyfunctional compounds containing acid anhydrides. Preferred crosslinkers for reaction with aromatic and aliphatic OH groups are isocyanates and acid anhydrides.

[0035] The crosslinking agent may also react with carboxyl groups. For example, diols and triols can be used for this purpose. Preferred crosslinking agents for reaction with carboxyl groups are diols.

[0036] Furthermore, crosslinkers may react with phenolic rings, aromatic and aliphatic OH groups, and carboxyl groups. For example, it may be preferable to use for this purpose bifunctional and even polyfunctional compounds that contain at least two of the functional groups of the above-mentioned crosslinkers.

[0037] When using crosslinking agents that react with phenolic rings, the crosslinkable units in the lignin used are understood to mean phenolic guaiacyl groups and p-hydroxyphenyl groups. The concentration of crosslinkable units (mmol / g) can be calculated, for example, 31 It has been determined via P-NMR spectroscopy (Non-Patent Document 2), where the guaiacyl group contains one crosslinkable unit and the p-hydroxyphenyl group contains two crosslinkable units.

[0038] When using crosslinking agents which react with aromatic and aliphatic OH groups, the crosslinkable units in the lignin used are understood to mean all aromatic and aliphatic OH groups. The concentration of crosslinkable units (mmol / g) can be calculated, for example, 31 The crosslinkability of the crosslinked groups was determined via P-NMR spectroscopy, where every group contains one crosslinkable unit.

[0039] When using a crosslinking agent that reacts with carboxyl groups, it is understood that all crosslinkable units in the lignin used are carboxyl groups. The concentration of crosslinkable units (mmol / g) can be calculated, for example, 31 The crosslinkability of the crosslinked groups was determined via P-NMR spectroscopy, where every group contains one crosslinkable unit.

[0040] When a difunctional crosslinker is used, 2 moles of crosslinkable units are available per mole of difunctional crosslinker; therefore, when a trifunctional crosslinker is used, 3 moles of crosslinkable units are available per mole of trifunctional crosslinker, etc.

[0041] Preferably, the amount of cross-linking agent is at most 35 g / 100 g lignin, preferably at most 30 g / 100 g lignin, more preferably at most 25 g / 100 g lignin.

[0042] Preferably, the amount of formaldehyde is at most 25 g / 100 g (lignin), preferably at most 20 g / 100 g (lignin), more preferably at most 15 g / 100 g (lignin), in particular at most 12 g / 100 g (lignin). Thus, the amount of formaldehyde added can be in the range of 1 g / 100 g (lignin) to 20 g / 100 g (lignin), preferably 5 g / 100 g (lignin) to 15 g / 100 g (lignin), more preferably 6 g / 100 g (lignin) to 10 g / 100 g (lignin).

[0043] The temperature in the first method step is advantageously above 50°C, preferably above 60°C, particularly preferably above 70°C, and below 180°C, preferably below 150°C, further preferably below 130°C, particularly preferably below 100°C.

[0044] The average residence time in the first process step is advantageously at least 5 minutes, more preferably at least 10 minutes, more preferably at least 15 minutes, particularly preferably at least 30 minutes, in particular at least 45 minutes, but less than 300 minutes.

[0045] An advantageous combination of time and temperature window for the first process step is a minimum temperature of 50° C. and a maximum temperature of 180° C., together with a residence time of at least 15 minutes, preferably at least 20 minutes, more preferably at least 30 minutes, and particularly preferably at least 45 minutes. An alternatively advantageous combination of time and temperature window for the first process step is a minimum temperature of 50° C. and a maximum temperature of 130° C., together with a residence time of at least 10 minutes, preferably at least 15 minutes, more preferably at least 20 minutes, and particularly preferably at least 30 minutes, and in particular at least 45 minutes.

[0046] In a particularly preferred embodiment, the mixture of dissolved lignin and at least one crosslinking compound is held in a first method step at a temperature T1 between 50°C and 180°C for a residence time of at least 20 minutes, preferably at least 60 minutes.

[0047] In a further particularly preferred embodiment, the mixture of dissolved lignin and at least one crosslinking compound is held in a first method step at a temperature T1 between 70°C and 130°C for a residence time of at least 10 minutes, preferably at least 50 minutes.

[0048] Advantageously, during the first method step, the liquid containing the dissolved lignin and the crosslinking agent may be heated, preferably at a heating rate of less than 15 Kelvin per minute, more preferably less than 10 Kelvin per minute, particularly preferably less than 5 Kelvin per minute.

[0049] Advantageously, the temperature in the first method step is kept approximately constant over a period of at least 5 minutes, preferably at least 10 minutes, more preferably at least 15 minutes and particularly preferably at least 30 minutes.

[0050] A combination of heating and maintaining a constant temperature in the first method step is also advantageous.

[0051] The pressure is preferably at least 0.2 bar above the saturated vapor pressure of the lignin-containing liquid, preferably up to 20 bar above.

[0052] Advantageously, the pH of the liquid comprising the dissolved lignin is higher before the first method step than the pH of the liquid comprising the dissolved modified lignin after the first method step.

[0053] The pH of the liquid comprising dissolved lignin before the first method step is advantageously greater than 7, preferably greater than 7.5, more preferably greater than 8 and particularly preferably greater than 8.5, but less than 12.5.

[0054] The pH of the liquid containing the dissolved modified lignin after the first method step is advantageously greater than 6.5, preferably greater than 7, preferably greater than 8, but less than 12.

[0055] Preferably, the pH of the liquid comprising the dissolved modified lignin after the first method step is at least 0.2 units lower, preferably at least 0.5 units lower, more preferably at least 1 unit lower than the pH of the liquid comprising the dissolved lignin before the first method step.

[0056] The proportion of lignin relative to the total mass of the dissolved lignin-containing liquid is advantageously between 3% and 25%, preferably less than 20%, more preferably less than 18%, in the first method step.

[0057] The temperature in the second method step is advantageously below 270°C, preferably below 260°C, further preferably below 250°C, even more preferably below 240°C, additionally preferably below 230°C, additionally particularly preferably below 220°C, in particular below 215°C.

[0058] In an advantageous embodiment, the temperature in the second method step is at least 150°C, preferably at least 160°C, more preferably at least 170°C.

[0059] The temperature in the second method step may therefore range widely between 150°C and 250°C.

[0060] In a particularly preferred embodiment, the second reaction step corresponds to a hydrothermal treatment, in which the temperature T2 in the hydrothermal treatment is between 150°C and 250°C, preferably between 170°C and 240°C, more preferably between 175°C and 235°C.

[0061] The pressure is preferably at least 0.2 bar above the saturated vapor pressure of the lignin-containing liquid, preferably up to 20 bar above.

[0062] Advantageously, the average residence time in the second process step is at least 10 minutes, more preferably at least 30 minutes, particularly preferably at least 45 minutes, but less than 600 minutes, preferably less than 480 minutes, particularly preferably less than 450 minutes.

[0063] Advantageously, the pH of the liquid comprising the dissolved modified lignin is higher before the second method step than the pH of the liquid comprising the undissolved stabilized lignin after the second method step. The pH of the liquid comprising the undissolved stabilized lignin after the second method step is advantageously greater than 5, preferably greater than 6, but less than 11. The pH of the liquid comprising the undissolved stabilized lignin after the second method step is preferably at least 0.2 units lower, preferably at least 0.5 units lower, more preferably at least 1 unit lower than the pH of the liquid comprising the dissolved modified lignin before the second method step.

[0064] The proportion of lignin relative to the total mass of the liquid containing dissolved modified lignin is advantageously between 3% and 25%, preferably less than 20%, more preferably less than 18%, in the second method step.

[0065] Advantageously, the cross-linking agent is generated in situ during the first method step. The advantage of generating the cross-linking agent in the first method step is that the amount of cross-linking agent added in the first method step can be reduced or omitted entirely.

[0066] Advantageously, the cross-linking agent is prepared in situ during the first method step from a carbohydrate (preferably cellulose, hemicellulose or glucose) dispersed or dissolved in the liquid containing dissolved lignin. The carbohydrate, preferably cellulose, hemicellulose or glucose, can preferably be added to or is already present in the liquid containing dissolved lignin. In one example of such an advantageous method mode: In a first method step, a carbohydrate-based cross-linking agent, preferably an aldehyde, preferably glyceraldehyde or glycolaldehyde, obtained from a carbohydrate dissolved or dispersed in a liquid containing dissolved lignin; reacting the lignin dissolved in the liquid with a carbohydrate-based crosslinker, thereby producing a dissolved modified lignin; In a second process step, the dissolved modified lignin is converted into undissolved stabilized lignin.

[0067] Advantageously, the cross-linking agent is prepared in situ from lignin dispersed or dissolved in the liquid containing dissolved lignin during the first method step. In one example of such an advantageous method mode: In a first method step, A lignin-based cross-linking agent, preferably an aldehyde, preferably methanediol or glycolaldehyde, dissolved or dispersed in a liquid containing dissolved lignin. Lignin Obtained from reacting the remaining dissolved lignin in the liquid with a lignin-based crosslinking agent, thereby producing a dissolved modified lignin; In a second process step, the dissolved modified lignin is converted into undissolved stabilized lignin.

[0068] Preferably, the non-dissolved stabilized lignin has advantageous particle properties that allow it to be used in materials applications. Preferably, the non-dissolved stabilized lignin has a D50 in the particle size distribution of less than 500 μm, preferably less than 300 μm, more preferably less than 200 μm, particularly less than 100 μm, and particularly preferably less than 50 μm. Preferably, the non-dissolved stabilized lignin has a D50 in the particle size distribution of more than 0.5 μm, preferably more than 1 μm, and more preferably more than 2 μm.

[0069] The particle size distribution of stabilized lignin is measured in a suspension containing distilled water by laser diffraction according to ISO 13320. Before and / or during the measurement of the particle size distribution, the sample to be measured is dispersed ultrasonically until a stable particle size distribution is obtained over a number of measurements.

[0070] Preferably, the non-dissolved stabilized lignin is at least 10 ml 2 / g, more preferably at least 20m 2 / g. Preferably, the STSA is 200m 2 / g. STSA (Statistical Thickness Surface Area) is here a measure of the external surface area of the stabilized lignin particles.

[0071] In one variation of the stabilized lignin or granular carbon material, the STSA surface area is greater than 10 m 2 / g to 180m 2 / g, preferably 20m 2 / g to 180m 2 / g, more preferably 35m 2 / g to 180m 2 / g, particularly preferably 40m 2 / g to 180m 2 / g.

[0072] Advantageously, the BET surface area of the stabilized lignin deviates from the STSA surface area by no more than 20%, preferably no more than 15%, more preferably no more than 10%. The BET surface area is determined as the total surface area of the external and internal surfaces via the nitrogen surface area according to Brunauer, Emmett, and Teller.

[0073] Preferably, the undissolved stabilised lignin is present dispersed in water at the end of the second process step.

[0074] Preferably, the non-dissolved stabilized lignin has low porosity. Advantageously, the pore volume of the stabilized lignin is less than 0.1 cm 3 / g, more preferably less than 0.01 cm 3 / g, particularly preferably less than 0.005 cm 3 / g, which is typically less than 500m 2 / g, plus a BET surface area of up to 10m 2 This is a distinctive feature of the present stabilized lignin compared to finely divided porous materials such as crushed biogenic powdered activated carbon, which may also have an STSA surface area of 1 / g.

[0075] A distinctive feature of the non-dissolved stabilized lignin is the desirable advantageous particle properties, e.g., the D50 or 10m particle size distribution of the lignin-based resin produced by reaction with formaldehyde and converted from solution to a gel state into a thermosetting resin, less than 500 μm. 2 / g, preferably more than 20m 2 / g or more STSA.

[0076] The BET surface area and STSA surface area are determined according to the ASTM D6556-14 standard, whereas in the present invention, sample preparation / degassing for STSA and BET measurements is carried out at 150°C.

[0077] Insoluble stabilized lignin is understood to mean a solid that can be separated from the liquid after the second process step by solid-liquid separation. Examples of such solid-liquid separation are centrifugation or filtration.

[0078] Preferably, the non-dissolved stabilized lignin has limited solubility in the alkaline liquid, preferably less than 30%, preferably less than 25%, more preferably less than 20%.

[0079] The alkaline solubility of the undissolved stabilized lignin is determined as follows: 1. The undissolved stabilized lignin is separated from the liquid by centrifugation and washed twice with distilled water, decanting the supernatant each time. 2. Dry the product from 1 at 105°C for 24 hours. 3. A suspension of the product from 2 with a concentration of 6.6% by weight and 0.1 M NaOH is prepared, thus creating an alkaline suspension. If the pH is below 10 after adding the sodium hydroxide solution, additional sodium hydroxide solution is metered in. 4. The alkaline suspension is stirred for 2 hours at 25°C. 5. The alkaline suspension is then centrifuged at 6000 g. 6. Filter the supernatant from the centrifugation through a porosity 4 frit. 7. After centrifugation, wash the solid twice with distilled water by repeating steps 4 to 6. 8. The solid after centrifugation and the residue on the frit of porosity 4 are dried at 105°C and measured. 9. Determine the alkaline solubility of the lignin-rich solid as follows: Alkali solubility of lignin-rich solid [%] = mass of undissolved fraction from centrifugation, filtration, and drying [g] / mass of product obtained in step 2 [g] × 100.

[0080] Preferably, the non-dissolved stabilized lignin has a glass transition temperature above 160° C., more preferably above 180° C., especially preferably above 200° C., and especially above 250° C. Preferably, the non-dissolved stabilized lignin does not have a measurable glass transition temperature.

[0081] After solid-liquid separation, washing and drying, the glass transition temperature is determined according to DIN 53765 on the dried, undissolved, stabilized lignin.

[0082] The insoluble stabilized lignin also according to the invention is At least 10m 2 / g, more preferably at least 20m 2 / g of STSA (preferably, the STSA is 200m 2 / g), A solid having an intensity of 1% to 80%, preferably 5% to 60%, particularly preferably 5% to 50% of the signal of the methoxy group at 54 ppm to 58 ppm. 13 In C-NMR, signals at 0 ppm to 50 ppm, preferably 10 ppm to 40 ppm, more preferably 25 ppm to 35 ppm, and signals at 125 ppm to 135 ppm, preferably 127 ppm to 133 ppm, which are higher than the lignin used, are 13 C-NMR signal, Corresponding to the content of renewable raw materials, preferably more than 0.20 Bq / g(carbon), particularly preferably more than 0.23 Bq / g(carbon), but preferably in all cases less than 0.45 Bq / g(carbon) 14 C content, a carbon content, based on ash-free dry matter, of between 60% and 80% by weight, preferably between 65% and 75% by weight; a glass transition temperature of greater than 160°C, more preferably greater than 180°C, particularly preferably greater than 200°C, especially greater than 250°C (preferably, the undissolved stabilized lignin does not have a measurable glass transition temperature); 0.1cm 3 / g, more preferably less than 0.01 cm 3 / g, particularly preferably less than 0.005 cm 3 / g of pore volume in the stabilized lignin, It has the following characteristics.

[0083] The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawings. [Brief explanation of the drawings]

[0084] [Figure 1] 10 shows a diagram of results for the first embodiment according to exemplary embodiment 1. [Figure 2] 1 shows a C-NMR spectrum of stabilized lignin obtained according to exemplary embodiment 1. [Figure 3] 10 shows a diagram of results for the second embodiment according to exemplary embodiment 2. [Figure 4] 10 shows a plot of temperature profiles from Exemplary Embodiment 1 and Exemplary Embodiment 2. [Figure 5] 10 shows a chart depicting the effect of the amount of crosslinker used on the yield and BET value of stabilized lignin produced according to exemplary embodiment 3. [Figure 6] 1 shows a C-NMR spectrum of stabilized lignin obtained according to exemplary embodiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0085] In the examples below, BET is shown instead of STSA, however, for the non-dissolved stabilized lignin produced here, BET and STSA do not differ from each other by more than 10%. [Example]

[0086] Example 1 The raw material for this example is solids from the enzymatic hydrolysis of woody biomass (hardwood). By adding water and sodium hydroxide solution, the solids were converted into a liquid containing dissolved lignin.

[0087] To each 30 g of a liquid containing dissolved lignin and having a dry matter content of 15% and a pH of 10.9, a 23.5% formaldehyde solution was added in the amount specified in Table 1 in the first process step of the reaction of the crosslinker with formaldehyde. The liquid containing dissolved lignin and the formaldehyde solution were homogenized and treated for the time and temperature specified in Table 1 in the first process step to produce a dissolved modified lignin, which was then treated in the second process step to produce an undissolved stabilized lignin. The undissolved stabilized lignin was obtained by centrifugation. After washing twice with demineralized water and drying in an air-circulating drying oven, the yields shown in Table 1 and Figure 1 were obtained. The specific surface areas (BET) in Table 1 and Figure 1 were determined after heating at 150 °C under reduced pressure.

[0088] The dry substance used has a lignin content of 88%. The lignin content of the dry substance used has 1.3 mmol / g of phenolic guaiacyl groups and 0.1 mmol / g of p-hydroxyphenyl groups, and therefore 1.5 mmol / g of crosslinkable units.

[0089] The formaldehyde used has 66.6 mmol of crosslinkable units per gram of dry formaldehyde.

[0090] [Table 1]

[0091] As can be seen from Table 1 above, the yield and BET of the lignin material produced depends on the amount of cross-linking agent used and the use of an upstream first reaction step.

[0092] Thus, Examples D, E, and F show that using the first process step without changing the amount of crosslinker leads to an increase in the BET of the resulting material. Carrying out the first reaction step for a time of 71 or 85 minutes doubles the BET value compared to the shortened first reaction step (Example E).

[0093] The BET also initially increases with increasing amounts of crosslinker (Examples B-F), but then decreases with further increases in the amount of crosslinker (Example G).

[0094] A similar effect can be seen in Exemplary Embodiment 2 (see Table 2 below), where doubling the amount of crosslinker reduces the BET and yield of stabilized lignin (Examples I and L).

[0095] Thus, an optimum for the amount of cross-linking agent used becomes apparent.

[0096] In Example E2, 13 C-formaldehyde was used for solid-state NMR spectroscopy. The spectra of the lignin used and stabilized lignin are shown in Figure 2. This shows the preferred formation of methylene groups at 11 ppm to 36 ppm, as well as the central signals for two guaiacyl units in the stabilized lignin structure at 24 ppm to 32 ppm.

[0097] Example 2 The raw material for this example was LignoBoost lignin obtained from black liquor from kraft cooking. The solid was converted into a liquid containing dissolved lignin by adding water and sodium hydroxide solution. To each 30 g of the liquid containing dissolved lignin and having a dry matter content of 15% and a pH of 9.2, a 23.5% formaldehyde solution was added in the amount specified in Table 2 in the first process step of the reaction of the crosslinker with formaldehyde. The liquid containing dissolved lignin and the formaldehyde solution were homogenized and treated for the time and temperature specified in Table 2 in the first process step to produce a dissolved modified lignin, which was then treated in the second process step to produce an undissolved stabilized lignin. The undissolved stabilized lignin was obtained by centrifugation. After washing twice with demineralized water and drying in an air-circulating drying oven, the yields shown in Table 2 and FIG. 3 were obtained. The specific surface area (BET) of the undissolved stabilized lignin in Table 2 and Figure 3 was determined after heating at 150°C under reduced pressure.

[0098] The lignin used has 1.9 mmol / g of phenolic guaiacyl groups and 0.3 mmol / g of p-hydroxyphenyl groups, thus 2.5 mmol / g of crosslinkable units.

[0099] The formaldehyde used has 66.6 mmol of crosslinkable units per gram of dry formaldehyde.

[0100] [Table 2]

[0101] The temperature curves from Examples 1 and 2 are summarized in the graph of FIG.

[0102] Example 3 The raw material for this example is LignoBoost lignin obtained from black liquor from kraft cooking. The solid was converted to a liquid containing dissolved lignin by adding water and sodium hydroxide solution.

[0103] To each 30 g of a liquid containing dissolved lignin and having a dry matter content of 15% and a pH of 8.7, a 23.5% formaldehyde solution was added in the amount specified in Table 3 in the first process step of the reaction of the crosslinker with formaldehyde. The liquid containing dissolved lignin and the formaldehyde solution were homogenized and treated for the time and temperature specified in Table 3 in the first process step to produce a dissolved modified lignin, which was then treated in the second process step to produce an undissolved stabilized lignin. The undissolved stabilized lignin was obtained by filtration. After washing with twice the amount of demineralized water as the filtrate and drying in an air-circulating drying oven, the yields shown in Table 3 and Figure 5 were obtained. The specific surface area (BET) of the undissolved stabilized lignin in Table 3 and Figure 5 was determined after heating at 150 °C under reduced pressure.

[0104] The lignin used has 1.9 mmol / g of phenolic guaiacyl groups and 0.3 mmol / g of p-hydroxyphenyl groups, thus 2.5 mmol / g of crosslinkable units.

[0105] The formaldehyde used has 66.6 mmol of crosslinkable units per gram of dry formaldehyde.

[0106] [Table 3]

[0107] As can be seen from Table 3 above and Figure 5, the yield and BET of the lignin material produced depend on the amount of cross-linking agent used.

[0108] Thus, Examples M through Q show that the BET initially increases with increasing amounts of crosslinker (Examples M through P), but further increases in the amount of crosslinker do not result in a further increase in BET (Example Q).

[0109] Thus, an optimum for the amount of cross-linking agent used becomes apparent.

[0110] In example P2, 13 C-formaldehyde was used for solid-state NMR spectroscopy. The spectra of the lignin used and stabilized lignin are shown in Figure 6. This shows the preferred formation of methylene groups at 11 ppm to 35 ppm, as well as the central signals for two guaiacyl units in the stabilized lignin structure at 24 ppm to 32 ppm.

[0111] Example 4 The raw material for this example is LignoBoost lignin obtained from black liquor from kraft cooking. The solid was converted to a liquid containing dissolved lignin by adding water and sodium hydroxide solution.

[0112] To each 30 g of a liquid containing dissolved lignin and having a dry matter content of 15% and a pH of 9.0, a 40% glyoxal solution was added in the amount specified in Table 4 in the first process step of the reaction of the crosslinker with glyoxal. The liquid containing dissolved lignin and the glyoxal solution were homogenized and treated for the time and temperature specified in Table 4 in the first process step to produce a dissolved modified lignin, which was then treated in the second process step to produce an undissolved stabilized lignin. The undissolved stabilized lignin was obtained by centrifugation. After washing twice with demineralized water and drying in an air-circulating drying oven, the yields shown in Table 4 were obtained. The specific surface area (BET) of the undissolved stabilized lignin in Table 4 was determined after heating at 150°C under reduced pressure.

[0113] The lignin used has 1.9 mmol / g of phenolic guaiacyl groups and 0.3 mmol / g of p-hydroxyphenyl groups, thus 2.5 mmol / g of crosslinkable units.

[0114] The glyoxal used has 68.9 mmol of crosslinkable units per gram.

[0115] [Table 4]

[0116] Example 5 The raw material for this example is LignoBoost lignin obtained from black liquor from kraft cooking. The solid was converted to a liquid containing dissolved lignin by adding water and sodium hydroxide solution.

[0117] To each 30 g of a liquid containing dissolved lignin and having a dry matter content of 15% and a pH of 9.0, the crosslinker specified in Table 5 was added in the first process step of reaction with glyceraldehyde. The liquid containing dissolved lignin and the glyceraldehyde solution were homogenized and treated for the time and temperature specified in Table 5 in the first process step to produce a dissolved modified lignin, which was then treated in the second process step to produce an undissolved stabilized lignin. The undissolved stabilized lignin was obtained by centrifugation. After washing twice with demineralized water and drying in an air-circulating drying oven, the yields shown in Table 5 were obtained. The specific surface area (BET) of the undissolved stabilized lignin in Table 5 was determined after heating at 150°C under reduced pressure.

[0118] The lignin used has 1.9 mmol / g of phenolic guaiacyl groups and 0.3 mmol / g of p-hydroxyphenyl groups, thus 2.5 mmol / g of crosslinkable units.

[0119] The glyceraldehyde used has 22.2 mmol of crosslinkable units per gram.

[0120] [Table 5]

[0121] Example 6 The raw material for this example was lignosulfonate in the form of black liquor from sulfite cooking. By adding water and sodium hydroxide solution, the starting material was converted into a liquid containing dissolved lignin. To each 30 g of the liquid containing dissolved lignin and having a dry matter content of 12.4% and a pH of 10.4, a 23.5% formaldehyde solution was added in the amount specified in Table 6 in the first process step of the reaction of the crosslinker with formaldehyde. The liquid containing dissolved lignin and the formaldehyde solution were homogenized and treated for the time and temperature specified in Table 6 in the first process step to produce dissolved modified lignin, which was then treated in the second process step to produce undissolved stabilized lignin. The undissolved stabilized lignin was obtained by centrifugation. After washing twice with demineralized water and drying in an air-circulating drying oven, the yields shown in Table 6 were obtained. The specific surface area (BET) of the undissolved stabilized lignin in Table 6 was determined after heating at 150° C. under reduced pressure.

[0122] The dry matter of the black liquor used has a lignin content of 70%. The lignin content of the dry matter used has 0.6 mmol / g of phenolic guaiacyl groups and therefore crosslinkable units.

[0123] The formaldehyde used has 66.6 mmol of crosslinkable units per gram of dry formaldehyde.

[0124] [Table 6]

Claims

1. At least 10 m from lignin-containing raw materials ２ 1. A method for producing a non-dissolved stabilized lignin having an STSA surface area of 1000 nm / g, comprising: In a first method step, a lignin dissolved in a liquid, the lignin containing phenolic aromatic compounds, aromatic and aliphatic hydroxyl groups, and / or carboxyl groups as crosslinkable units, is reacted with a crosslinking agent containing at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, thereby producing a dissolved modified lignin, In a second method step, converting the dissolved modified lignin into an undissolved stabilized lignin at a temperature of at least 150°C but less than 270°C; the pH of the liquid containing the dissolved modified lignin before the second method step is higher than the pH of the liquid containing the undissolved stabilized lignin after the second method step. A method for producing a non-dissolvable stabilized lignin.

2. in a first method step, reacting lignin dissolved in a liquid, the lignin comprising phenolic aromatic compounds, aromatic and aliphatic hydroxyl and / or carboxyl groups as crosslinkable units, with a crosslinking agent comprising at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, at a first temperature T1 lying between a first maximum temperature T1max and a first minimum temperature T1min, the first temperature T1 being greater than 50°C and less than 180°C, and the average residence time in the first method step being at least 5 minutes and less than 300 minutes, thereby producing a dissolved modified lignin, 2. The method of claim 1, wherein in a second method step, the reaction is carried out at a second temperature T2 between a second maximum temperature T2max and a second minimum temperature T2min, the second temperature T2 being greater than 150°C and less than 270°C, and the average residence time in the second method step is at least 10 minutes and less than 600 minutes, thereby converting the dissolved modified lignin into undissolved stabilized lignin.

3. 3. The method according to claim 1, wherein the addition of the crosslinking agent is carried out in the first method step, and the amount of crosslinkable units in the crosslinking agent corresponds to a maximum of 4 mol per mol of crosslinkable units in the lignin used.

4. 4. The method according to claim 3, characterized in that the amount of crosslinking agent is such that the amount of crosslinkable units in the crosslinking agent corresponds to at least 0.5 mol per 1 mol of crosslinkable units in the lignin used.

5. At least 10 m from lignin-containing raw materials ２ 1. A method for producing a stabilized lignin having an STSA surface area of 1000 nm / g, comprising: In a first method step, a lignin dissolved in a liquid, the lignin containing phenolic aromatic compounds, aromatic and aliphatic hydroxyl groups, and / or carboxyl groups as crosslinkable units, is reacted with a crosslinking agent containing at least one functional group as a crosslinkable unit capable of reacting with the crosslinkable units in the lignin, thereby producing a dissolved modified lignin, wherein the amount of crosslinking compound is selected so that the content of crosslinkable units in the crosslinking agent is between 0.5 mol and 4 mol per 1 mol of crosslinkable units in the lignin; In a second method step, the reaction is carried out at a second temperature T2 between a second maximum temperature T2max and a second minimum temperature T2min, the second temperature T2 being greater than 150°C and less than 270°C, and the average residence time in the second method step being at least 10 minutes and less than 600 minutes, characterised in that the pH of the liquid comprising the dissolved modified lignin before the second method step is higher than the pH of the liquid comprising the undissolved stabilized lignin after the second method step, and the pH of the liquid comprising the undissolved stabilized lignin after the second method step is greater than 5 but less than 11. converting the dissolved modified lignin into an undissolved stabilized lignin.

6. 6. The method according to any one of claims 1 to 5, characterized in that the amount of cross-linking agent is at most 35 g / 100 g lignin.

7. 7. The method according to claim 1, wherein an aldehyde or a bifunctional compound is added as the crosslinking agent.

8. 8. The method according to any one of claims 1 to 7, characterized in that the pH of the liquid comprising the dissolved lignin is at least 7.5 before the first method step and is higher than the pH of the liquid comprising the dissolved modified lignin after the first method step.

9. 9. The method according to any one of claims 1 to 8, characterized in that the pH of the liquid comprising the dissolved modified lignin is at least 7 before the second method step and is higher than the pH of the liquid comprising the undissolved stabilized lignin after the second method step.

10. In a first method step, obtaining a carbohydrate-based cross-linking agent from a carbohydrate dissolved or dispersed in the liquid containing the dissolved lignin; reacting the lignin dissolved in the liquid with the carbohydrate-based crosslinker, thereby producing a dissolved modified lignin; 10. The method according to any one of claims 1 to 9, characterized in that in a second method step, the dissolved modified lignin is converted into an undissolved stabilized lignin.

11. In a first method step, obtaining a lignin-based cross-linking agent from lignin dissolved or dispersed in said dissolved lignin-containing liquid; reacting the remaining dissolved lignin in the liquid with a lignin-based crosslinker, thereby producing a dissolved modified lignin; 11. The method according to any one of claims 1 to 10, characterized in that in a second method step, the dissolved modified lignin is converted into an undissolved stabilized lignin.

12. At least 10 meters ２ 12. A non-dissolved stabilized lignin obtainable in the process according to any one of claims 1 to 11, characterized by an STSA surface area of 1 / g.

13. 0.1 cm ３ 13. The non-dissolved stabilized lignin of claim 12, characterized by a pore volume of less than 1000 / g.

14. 14. The non-dissolved stabilized lignin of any one of claims 12 and 13, characterized by a solubility in alkaline liquid of less than 30%.

15. 15. The non-dissolved stabilized lignin according to any one of claims 12 to 14, characterized by a glass transition temperature above 160°C.

16. At least 10 meters ２ / g of STSA, Solid having an intensity of 1% to 80% of the signal of the methoxy group at 54 ppm to 58 ppm １３ In C-NMR, signals at 0 ppm to 50 ppm and at 125 ppm to 135 ppm, which are higher than the lignin used. １３ C-NMR signal, More than 0.20 Bq / g carbon, but in all cases less than 0.45 Bq / g carbon, corresponding to the content of renewable raw materials １４ C content, a carbon content on ash-free dry matter between 60% and 80% by mass; The insoluble stabilized lignin according to any one of claims 12 to 15, characterized in that

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