Process for preparing 5-(chloromethyl)furfural from plant biomass

Abstract

A process for preparing 5-(chloromethyl)furfural from particulate plant biomass. More in particular, said process comprises the steps of hydrolyzing the plant biomass with aqueous hydrochloric acid, mixing and heating with a halogenated aromatic extraction solvent which solvent also serves to extract the formed 5-(chloromethyl)furfural.

Description

[0001] PROCESS FOR PREPARING 5-(CHLOROMETHYL)FURFURAL FROM PLANT BIOMASS

[0002] Introduction

[0003] The present invention relates to a process for preparing 5-(chloromethyl)furfural from particulate plant biomass. More in particular, said process comprises the steps of hydrolyzing the plant biomass with aqueous hydrochloric acid, mixing and heating with a halogenated aromatic extraction solvent which solvent also serves to extract the formed 5-(chloromethyl)furfural.

[0004] Background of the invention

[0005] The chemical compound 5-(chloromethyl)furfural (hereinafter: CMF) is a promising compound, for two reasons: it can be formed from treating carbohydrate-containing biomass (and as such it is a compound from a renewable source), and it can be converted in several other compounds such as HMF (hydroxymethylfurfural) and MMF (methoxymethylfurfural). These furanic compounds are versatile building blocks used for the production of bio-based materials, shown for instance in the synthesis of furan-2,5-dicarboxylic acid (FDCA) during the obtention of PEF (polyethylene 2,5-furandicarboxylate), a renewable alternative to PET (polyethylene terephthalate) that presents better physical properties in the food and beverage industry.

[0006] Patent application WO2019 / 149853 discloses a process in which pine wood chips are treated with strong hydrochloric acid. Such wood chip material contains as main fractions hemicellulose, cellulose and lignin. The process of the referred patent application subjects the substantially dried lignocellulosic material first to hydrochloric acid in a concentration of 42% at room temperature. The aqueous product is separated from the residue. The aqueous product, which contained mainly glucose and mannose carbohydrates was mixed with toluene as extraction solvent and heated to 80 or 100°C for 1 to 2 hours. This gave yields of furfural of between 0.06 and 0.24 mol%, and yields of CMF of between 13 and 41 mol %.

[0007] M. Mascal et al (Angew Chem. Int. Ed. 2008. 47, 7924-7926) disclose that microcrystalline cellulose can be converted into CMF with isolated yields of furanic products of 80%. CMF was the main product (71%) with other products being present in substantial amounts as well. Extraction requires the presence of LiCI. D.R. Lane et al (Renewable Energy, 85 (2016), 994-1001) disclose production of CM F from glucose. The reaction involves contacting the carbohydrate with concentrated (about 20%) hydrochloric acid at 79°C, removing humic matter by filtration, and extracting the aqueous phase with a solvent at room temperature. The various solvents tested were: chlororalkanes (dichloromethane, 1,1,2-trichloroethane, 1,2-dichlororethane, 1,1, 2, 2, -tetrachloroethane, toluene, perchloroethane). It reports on solvent effects, in that all chloroalkanes gave similar yields of CMF, and that toluene and perchloroethane gave lower yields.

[0008] H.H. Szmant et al (J. Chem. Tech. Biotechnol., 1981, 31, 205-212) disclose that fructose and high fructose corn syrup (HFCS) could be converted to CMF in a yield of 90-95%. For glucose the yields were lower (30- 45%), and for corn starch even less (14-20%). The process involved subjecting the carbohydrate to concentrated (39%) hydrochloric acid at room temperature, adding heated (75°C) chlorobenzene and with yields determined after 2 or 24 hours.

[0009] The last two references above study monosaccharides and starch as source for CMF. Although such can be considered renewable sources for CMF, as such sources compete with use for food and / or feed, the use of such fructose, glucose, HFCS, and starch as a source to produce CMF on an industrial scale is undesired. The first reported reference (WO2019 / 149853) requires a renewable material which does not suffer such disadvantage, but yield in useful products is moderate. Also, the presence of mannose leads to a more or less degree to the formation of humins. Formation of humins is undesired, as such are end products that form black deposits which can block lines etcetera. Additionally, mannose degradation lowers total CMF yields, it decompose to HMF and polycondensation derivatives that can react with glucose. The reference by Mascal et al requires the presence of LiCI, and thus an additional component (in the form of lithium chloride) that needs to be recovered and purified for reuse.

[0010] Hence, there is a desire for a process that can yield CMF in an economically attractive way, from a source that is not simple mono- or disaccharides, as such are generally preferred for use in food or feed, and which does not require the presence of auxiliary components like LiCI.

[0011] Summary of the invention

[0012] It has now been found objective that the above may be achieved, at least in part, by a process for preparing 5-(chloromethyl)furfural from particulate plant biomass, the particulate plant biomass comprising cellulose and hemicellulose, said hemicellulose having a mannose content of below 20 wt% on hemicellulose, and a xylose content of above 50 wt % on hemicellulose, said process comprising the steps of: a. hydrolyzing at least part of said particulate plant biomass at a temperature of less than 40°C and for a duration of between 10 and 30 hours with aqueous hydrochloric acid in a concentration of between 36 wt% to 51 wt%, in a weight ratio plant biomass to hydrochloric acid of between 1 : 5 to 1 : 20, b. separating the product resulting from step a. in a solid fraction and an aqueous liquid fraction, c. mixing the aqueous liquid fraction of b. with a halogenated aromatic extraction solvent and heating the mixture to a temperature of between 60 and 120°C and reacting said mixture for a duration of between 20 and 400 minutes, d. separating the mixture of step c. into an aqueous fraction comprising hydrochloric acid and an organic fraction, said organic fraction comprising halogenated aromatic extraction solvent, 5- chloromethylfurfural.

[0013] Detailed description of the invention

[0014] Although the process of hydrolyzing hemicellulose and cellulose by concentrated hydrochloric acid, and converting the glucose monosaccharides so-formed into CMF, and extracting such with an organic solvent which is not water-miscible is known from the prior art, most of such prior art focusses on research, and not on providing an economically viable process. It is presently claimed process, which firstly aims for a specific carbohydrate source, secondly uses an organic extraction solvent which provides improved extraction.

[0015] On the particulate plant biomass comprising cellulose and hemicellulose in the present invention said hemicellulose preferably has a mannose content of below 10 wt% on hemicellulose, more preferably below 8 wt%. Likewise, said hemicellulose preferably has a xylose content of above 60 wt % on hemicellulose. Next to hemicellulose and cellulose other plant material may be present, such as lignin. Hence, in the present invention the particulate plant biomass comprises, next to cellulose and hemicellulose, lignin. Suitable sources of such material is hardwood. Hence, preferably the particulate plant biomass comprises hardwood. Preferably the particulate plant material is hardwood of Fagaceae, Betulaceae, Aceraceae, Salicaceae, Ulmaceae. The particulate plant biomass in the present invention is preferably particulate such that the material has a particle size of at least P16A and at most P100, preferably P45A or P45B, conforming European Standard EN 14961-1 on solid biofuels. This is in particular preferred when performing the hydrolysis and extraction along the lines of WO 2019 / 149853.

[0016] In the process of the invention, it is preferred that the aqueous composition comprising hydrochloric acid in step a. has a concentration HCI of 39-48 wt%, preferably 42-45 wt%. The temperature during hydrolysis in step a. in the process according to the invention is preferably between 15 and 35°C, preferably between 20 and 30°C. Typical ly, the temperature will be the temperature of the environment when the process is operated in temperate climate. As no heating or cooling is necessary, this is advantageous. The duration of the hydrolysis in step a. in the process of the present invention is preferably between 15 and 25 hours. The now claimed process does not need LiCI to be present during hydrolysis, and hence to the mixture in step a. preferably no LiCI is added.

[0017] In step c. the aqueous liquid fraction of b. is mixed with a halogenated aromatic extraction solvent. The aim is that the desired components CMF that were formed in the previous stages of the process, are extracted by the halogenated aromatic solvent. The aqueous phase can then be recycled for further use and / or recovery of the HCI. For the extraction step c. it is preferred that the volume ratio of the halogenated aromatic extraction solvent : aqueous liquid fraction is between 1 : 1 and 10 : 1, preferably between 2 : 1 and 6 : 1. It is preferred that the temperature of the reaction in step c. of said mixture is between 70 and 110°C, preferably between 75 and 100°C. As to the time required for extracting the CMF, the duration of step c. is between 50 and 250 minutes, preferably between 50 and 150 minutes.

[0018] Although processes for hydrolyzing (hemi-)cellulose with concentrated hydrochloric acid, and subsequent extraction are known from the prior art, the extraction solvent used for such were usually toluene or chlorinated aliphatic hydrocarbons, such as dichloromethane, dichloroethane, and the like. It was found by present inventors that using a halogenated aromatic solvent as extraction solvent in the process concerned gives substantially higher yields than these components. Preferred halogenated aromatic extraction solvent for this purpose are: mono-chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p- dichlorobenzene, 1,2,4-trichlorobenzene, mono-fluorobenzene, o-difluorobenzene, m-difluorobenzene, p- diflurorobenzene, 1,2,4-trifluorobenzene, l,3-dichloro-2-fluorobenzene, fluorotoluene, chlorotoluene, with fluorobenzene being most preferred. The CMF can after the process of the present invention be isolated from the halogenated aromatic extraction solvent, or processed further in other components.

[0019] EXAMPLES Pine wood (soft wood) chips were hydrolysed in two stages, according to the process of example 1 of WO2019 / 149843, using hydrochloric acid of 40 wt%. The hydrolysate obtained from the cellulose fraction (the second fraction), obtained after hydrolysis had the carbohydrate composition as in table 1.

[0020] Table 1: hydrolysate composition (sugar content in total weight %) This hydrolysate further contained HCI (40 wt%). This hydrolysate was used in the following experiment.

[0021] Materials

[0022] Ace glass high pressure tubes (able to withstand 10.3 bar at 120°C). Procedure

[0023] 1 ml of hydrolysate was put in a reaction tube, together with 3 ml of extraction solvent, and the tubes were closed. Multiple reaction tubes were placed in a heated heating block (80°), and reaction timing was started after insertion in the heating block. Pressure in each reaction tube was about 7.5-8 bar. Each tube had a magnetic stirrer. After an initial reaction - extraction for a duration of 3 hours, the tube was taken out of the reaction block, and the organic layer was separated from the aqueous phase. To the remaining aqueous phase was added 3 ml of toluene and mixed for 1 hour at room temperature, the organic phase separated, and this procedure was repeated once more. The organic phase obtained after 3 hours and of both room temperature extraction operations were combined. From this organic phase 1 ml is taken, and added to this is 0.1 ml dioxane as internal standard, and the resulting composition was subjected to analysis on CMF.

[0024] For toluene as extractant the total yield of CMF, expressed as molar yield on total carbohydrates, obtained by three extractions was: 59.34 %. For fluorobenzene as extractant instead of toluene the same experiment was carried out four times, using an amount of hydrolysate of: 1.193 g, 1.175 g. 1.168 g, 1.18 g (all equaling about 1 ml).

[0025] The total amount of CMF obtained by these extractions for each of these four experiments, expressed as molar yield on total carbohydrates were: 76.3%, 75.0%, 79.1 %, 74.2 % (average: 76.15 %).

[0026] This example shows that fluorobenzene as extraction solvent yields substantially higher yields in CMF than toluene does.

Claims

CLAIMS1. Process for preparing 5-(chloromethyl)furfural from particulate plant biomass, the particulate plant biomass comprising cellulose and hemicellulose, said hemicellulose having a mannose content of below 20 wt% on hemicellulose, and a xylose content of above 50 wt % on hemicellulose, said process comprising the steps of: a. hydrolyzing at least part of said particulate plant biomass at a temperature of less than 40°C and for a duration of between 10 and 30 hours with aqueous hydrochloric acid in a concentration of between 36 wt% to 51 wt%, in a weight ratio plant biomass to hydrochloric acid of between 1 : 5 to 1 : 20, b. separating the product resulting from step a. in a solid fraction and an aqueous liquid fraction, c. mixing the aqueous liquid fraction of b. with a halogenated aromatic extraction solvent and heating the mixture to a temperature of between 60 and 120°C and reacting said mixture for a duration of between 20 and 400 minutes, d. separating the mixture of step c. into an aqueous fraction comprising hydrochloric acid and an organic fraction, said organic fraction comprising halogenated aromatic extraction solvent, 5-chloromethylfurfural.

2. Process according to claim 1, wherein the aqueous composition comprising hydrochloric acid in step a. has a concentration HCI of 39-48 wt%, preferably 42-45 wt%.

3. Process according to claim 1 or 2, wherein the temperature during hydrolysis in step a. is between 15 and 35°C, preferably between 20 and 30°C.

4. Process according to any of the preceding claims, wherein the duration of the hydrolysis in step a. is between 15 and 25 hours.

5. Process according to any of the preceding claims, wherein in step c. the volume ratio of the halogenated aromatic extraction solvent : aqueous liquid fraction is between 1 : 1 and 10 : 1, preferably between 2 : 1 and 6 : 1.

6. Process according to any of the preceding claims, wherein the temperature of the reaction in step c. of said mixture is between 70 and 110°C, preferably between 75 and 100°C.

7. Process according to any of the preceding claims, wherein the duration of step c. is between 50 and 250 minutes, preferably between 50 and 150 minutes.

8. Process according to any of the preceding claims, wherein the halogenated aromatic extraction solvent is selected from the group consisting of: mono-chlorobenzene, o- dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, 1,2,4-trichlorobenzene, monofluorobenzene, o-difluorobenzene, m-difluorobenzene, p-diflurorobenzene, 1,2,4- trifluorobenzene, l,3-dichloro-2-fluorobenzene, fluorotoluene, chlorotoluene, and mixtures thereof.

9. Process according to claim 8, wherein the halogenated aromatic extraction solvent comprises mono-fluorobenzene.

10. Process according to any of the preceding claims, wherein the particulate plant biomass comprises, next to cellulose and hemicellulose, lignin.

11. Process according to any of the preceding claims, wherein the particulate plant biomass comprises hardwood, preferably hardwood of Fagaceae, Betulaceae, Aceraceae, Salicaceae, Ulmaceae.

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