EP3802505A1

EP3802505A1 - Preparation of hmf catalyzed by a mixture of salt and acid

Info

Publication number: EP3802505A1
Application number: EP19730696.2A
Authority: EP
Inventors: Alireza Haji Begli; Christine KRÖNER; Kay MANTYK; Ralf RIEMENSCHNITTER
Original assignee: Suedzucker AG
Current assignee: Suedzucker AG
Priority date: 2018-05-29
Filing date: 2019-05-28
Publication date: 2021-04-14
Also published as: CA3101904A1; EA202092881A1; AU2019276050B2; WO2019229080A4; US11548863B2; WO2019229080A1; MX2020012880A; DE102018208510A1; AU2019276050A1; CN112236419A; BR112020024326A2; JP2021525732A; JP7410058B2; US20210214326A1

Abstract

The present invention relates to a process for preparing 5-hydroxymethylfurfural (HMF) which converts a fructose-containing component, using a catalyst system that comprises a mixture of salt and acid at a temperature of 90 to 200°C and results in an HMF-containing product mixture, advantageously obtaining a high HMF selectivity and simultaneously considerably reducing the buildup of byproducts.

Description

DESCRIPTION

Salt and acid mixture catalyzed HMF production

The present invention relates to a process for the preparation of 5-hydroxymcthylfurfural (HMF), which converts a fructose-containing component using a catalyst system comprising a solution of a salt and acid mixture at a temperature of 90 to 200 ° C and to obtain a HMF containing product mixture, wherein advantageously a high HMF selectivity is achieved at the same time significantly lower by-product formation.

5-Hydroxymethylfurfural (HMF) is a multifunctional molecule with an aromatic 5-ring system, an aldehyde and an alcohol group. The many functionalities make the molecule a versatile platform chemical that can serve as the basis for a wide variety of other compounds. The compounds which can be produced on the basis of HMF include, on the one hand, chemicals which are already produced on a mass scale by petrochemical means, for example caprolactam or adipic acid, but also compounds with a large application potential, for which hitherto no technical manufacturing process has been used Available, such as 2,5-furandicarboxylic acid (FDCA).

Despite the great potential of HMF and FDCA, there is still a lack of economical, technically established production processes for these compounds. The multifunctionality of HMF as one of the major advantages of the molecule has also proven to be a major drawback in terms of the resulting potential subsequent chemistry. Especially in aqueous systems, HMF is not stable under the reaction conditions required for the synthesis (acidic pH, elevated temperature) and, on the one hand, reacts with itself and / or the educts and intermediates to form so-called humins, which are soluble depending on the chain length or insoluble and lead to a brown to black coloration of the reaction solution. Another undesirable consequence reaction is the acid-catalyzed rehydration of HMF to levulinic and formic acid, in particular levulinic acid with HMF can react to other undesirable by-products. For the most economical production of HMF, it is therefore essential that these occur To avoid side reaction as well as the subsequent reaction of HMF and levulinic acid as much as possible.

Basically, in the many different synthetic routes described in the prior art for the preparation of HMF, a distinction can be made between single-phase and two-phase reaction systems. In both approaches, both homogeneous and heterogeneous catalysts can be used. In the case of single-phase systems, the HMF synthesis can be carried out not only purely aqueous systems but also in organic solvents, such as DMSO, DMF and sulfolane, or in ionic liquids. Although the avoidance of aqueous systems leads to better selectivities for HMF based purely on the chemical reaction, high temperatures are often necessary for the removal of the solvents, under which the thermal decomposition of HMF can occur, which in turn increases the purity and yield of the HMF is significantly deteriorated. In addition, when using anhydrous systems, the cost of solvents and safety and environmental considerations play a major role. It also proves disadvantageous that the hexoses used for HMF synthesis, in particular fructose and / or glucose, have poor solubility in many common organic solvents.

In the biphasic reaction systems, the reaction of the hexose to HMF is carried out in the aqueous phase and the resulting HMF is extracted continuously using an organic solvent. In this case, the solvent must not be miscible with water and must have a sufficiently high partition coefficient for HMF between aqueous and organic phase in order to ensure efficient extraction of the HMF. In particular, since the distribution coefficients are not very high for most solvents, very large amounts of solvent often have to be used in such systems. The most commonly used in two-phase reaction systems organic solvent is methyl isobutyl ketone (MIBK), which is optionally used in combination with Phasenmodifizierem such as 2-butanol. However, as already shown for the one-phase anhydrous reaction systems, the final removal of the solvent (s) or solvents used in this case proves to be problematic because of the high boiling points of suitable solvents.

EP 0 230 250 B1 discloses processes for the preparation of 5-hydroxymethylfurfural including a crystalline product using water alone as the solvent. In the described batch process, saccharides are dissolved in aqueous solution decomposed at a temperature of above 100 ° C with an acidic catalyst to a mixture of hexoses and HMF and then separated the HMF formed on ion exchange columns at a temperature of 35 to 85 ° C by-products so that in addition to a HMF fraction a saccharide Fraction can be obtained, which is available for a new HMF synthesis according to the described method. The batchwise reaction disclosed in this document is accompanied by a high fructose conversion and an immediately following high concentration of HMF in the reaction solution which, under the prevailing conditions, leads to an increased formation of by-products and degradation products, as a result of the amount of fructose reacted to a reduced HMF yield comes.

WO 2013/106136 A1 relates to a process for the preparation of HMF and HMF derivatives from sugars comprising the recovery of unreacted sugars suitable for direct use in ethanol fermentation. In this case, hexose-containing solutions are reacted in the aqueous phase by acid-catalyzed dehydration to HMF, then the unreacted sugars contained in the product mixture are separated by adsorption and / or solvent extraction from the product mixture and this finally used in aerobic or anaerobic Permentationsverfahren for ethanol production. It is taught to carry out the acid catalyzed dehydration reaction at a temperature of 175 to 205 ° C.

WO 2015/113060 A2 discloses the conversion of fructose-containing starting materials to HMF-containing products. By means of the described process, fructose, water, an acid catalyst and at least one other solvent are mixed in a reaction zone and brought to reaction by choosing suitable reaction parameters for a period of about 1 to 60 minutes, so that an HMF yield of 80% is not exceeded , Upon reaching the specified conversion, the reaction components are immediately cooled to minimize the formation of undesirable by-products.

WO 2014/158554 discloses processes for preparing HMF or derivatives thereof from glucose and / or fructose-containing solutions, wherein the acid-catalyzed dehydration reaction is carried out under oxygen-reduced conditions. This is intended to increase the stability of HMF and prevent possible degradation reactions, thus reducing the formation of undesirable by-products. Optionally, antioxidants are added to prevent an auto-oxidation reaction of HMF. Li et al. (RSC Adv., 2017, 7, 14330-14336) describe the conversion of glucose to HMF without isomerization to fructose with the aid of a mixture of hydrochloric acid and sodium chloride in a W ascr / g-Va 1 c ro 1 ac to n -S ystcm at a temperature of 140 ° C and a reaction time of 60 minutes. However, as already mentioned above, the final removal of the solvent is problematic because of the high boiling point of 205 ° C, since the decomposition of HMF already takes place from a temperature of 170 ° C.

To ensure a cost effective and effective HMF production process, it is crucial that during the reaction of a fructose-containing starting solution to HMF, the formation of undesirable by-products and the decomposition of the HMF formed by the dehydration reaction be avoided as much as possible by the choice of suitable reaction conditions and process steps. Furthermore, it makes economic sense if the unreacted fructose is separated from the interfering byproducts formed during the dehydration reaction and is thus optionally provided in the purest possible form for the return to the continuous production process.

A corresponding method for the cost-effective and effective production of HMF, preferably in a continuous process, is hitherto unknown from the prior art.

It is therefore the object of the present invention to overcome the disadvantages and limitations of the known from the prior art, in particular to provide a method of highly selective fructose, especially with maximum avoidance of by-product formation and in a cost effective and effective way to implement HMF.

The object of the present invention is achieved by the technical teaching of the claims. In particular, the present invention relates to a process for the preparation of

Hydroxymethylfenuric (HMF) comprising the steps of: a) providing a fructose-containing component and a catalyst system comprising a solution of a salt and acid mixture, b) mixing the fructose-containing component with the catalyst system to obtain a reaction solution, c) reacting the fructose present in the reaction solution to HMF at a temperature of 90 ° C to 200 ° C to obtain a liquid HMF-containing product mixture and d) a liquid HMF-containing product mixture.

According to the invention, a process is thus provided which produces 5-hydroxymethylfurfural (HMF) by selective, preferably highly selective, reaction of the fructose of a fructose-containing component. For the reaction of the fructose, a catalyst system comprising a solution, in particular an aqueous solution, a salt and acid mixture is used according to the invention. The present invention thus advantageously provides for mixing a fructose-containing component with a solution, in particular an aqueous solution, a salt and acid mixture, and then carrying out a reaction of the fructose present in the reaction solution to form HMF. The use of a salt and acid mixture for reacting the fructose present in the fructose-containing component to form HMF is advantageous in that a compared to conventional HMF production processes, which use for example sulfuric acid alone as a catalyst, a significantly higher HMF selectivity at at the same time significantly reduced by-product formation and comparable Fructoseumsätzen is provided. Thus, in an advantageous preferred embodiment, fructose conversions> 30% are possible with an acceptable selectivity of more than 80%. In addition, the use of the salt and acid mixture also allows a higher carbohydrate concentration in the reaction solution, namely in an advantageous preferred embodiment up to 40% dry matter carbohydrate. According to the invention, the use of the catalyst system comprising a solution of a salt and acid mixture leads to very high HMF selectivities, without the use of other catalysts in homogeneous or heterogeneous form being necessary in an advantageous preferred embodiment. In addition, the use of the catalyst system according to the invention leads to a significantly lower humic substance formation, in particular of insoluble humin, which leads to technical problems in the conventional process by caking and encrustations. The use according to the invention of the salt and acid mixture, ie of the catalyst system, accordingly leads, in particular, to significantly higher fructose conversions with economically meaningful HMF selectivity. In a particularly preferred embodiment, the procedure according to the invention, in particular the implementation of process steps a) to d), allows significantly higher HMF selectivity to be achieved, with comparable fructose conversions compared to the prior art reduced by-product formation, in particular a reduced rehydration of HMF to levulinic acid and formic acid occurs.

In a particularly preferred embodiment, the selectivity for levulinic acid in the process according to the invention, in particular the process steps a) to d), <6%, preferably <5%, preferably <4%, particularly preferably <3% (based on the reacted fructose). The catalyst system according to the invention comprises a solution of a salt and acid mixture, wherein the acid is preferably a mineral acid and / or an organic acid and the salt is preferably a salt of a mineral acid and / or an organic acid.

In a particularly preferred embodiment, the inventive

Catalyst system, a solution of a salt and acid mixture, wherein the acid is preferably a mineral acid, an organic acid or a mixture of a mineral acid and an organic acid.

In a particularly preferred embodiment, the inventive

Catalyst system is a solution of a salt and acid mixture, wherein the salt is preferably a salt of a mineral acid, a salt of an organic acid or a mixture of salts of a mineral acid and an organic acid.

The mineral acid is particularly preferably selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; and the organic acid selected from the group consisting of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid and gluconic acid. Especially preferred is the salt of a mineral acid selected from the group consisting of alkali halides, alkaline earth halides, alkali nitrates, alkaline earth nitrates, alkali metal sulphates, alkaline earth sulphates, alkali phosphates, alkaline earth phosphates and mixtures thereof; and the salt of an organic acid selected from the group consisting of acetates, citrates, tartrates, oxalates, glycolates, gluconates and mixtures thereof. In a preferred embodiment, the acid present in the catalyst system according to the invention is a mineral acid. The mineral acid is particularly preferably selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. Particularly preferred is the mineral acid hydrochloric acid or nitric acid. In a further preferred embodiment, the acid contained in the catalyst system is an organic acid. The organic acid is particularly preferably selected from the group consisting of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid and gluconic acid.

In a preferred embodiment, the salt contained in the catalyst system according to the invention is a salt of a mineral acid. More preferably, the salt is selected from the group consisting of alkali halides, alkaline earth halides, alkali nitrates, alkaline earth nitrates, alkali metal sulfates, alkaline earth sulfates, alkali phosphates, alkaline earth phosphates, and mixtures thereof. Most preferably, the salt is sodium chloride, sodium nitrate, calcium chloride, magnesium chloride or mixtures thereof. In a further preferred embodiment, the salt contained in the catalyst system is a salt of an organic acid. The salt is particularly preferably selected from the group consisting of acetates, citrates, tartrates, oxalates, glycolates, gluconates and mixtures thereof.

In a particularly preferred embodiment, the solution of a salt and acid mixture is an aqueous solution. According to the invention, a single-phase process is preferably provided leadership. Preferably, a two-phase process is excluded leadership. Preferably, no phase separation, in particular no induced phase separation, is provided. The catalyst system according to the invention comprises, in particular consists of, an aqueous solution of a salt and acid mixture, wherein the acid is a mineral acid, preferably selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid and the salt is a salt of a mineral acid, preferably selected from the group consisting of sodium chloride, sodium nitrate, calcium chloride and magnesium chloride.

In a particularly preferred embodiment, the catalyst system according to the invention comprises sodium chloride as salt and hydrochloric acid as mineral acid.

In a further preferred embodiment, the catalyst system according to the invention comprises sodium nitrate as salt and nitric acid as mineral acid. In a further preferred embodiment of the present invention, the catalyst system according to the invention comprises hydrochloric acid as mineral acid and calcium chloride as salt.

In a further preferred embodiment of the present invention, the catalyst system according to the invention comprises hydrochloric acid as mineral acid and magnesium chloride as salt.

In a further preferred embodiment, the salt is an alkali metal or alkaline earth metal salt, in particular an alkali metal salt, in particular an alkaline earth metal salt.

Surprisingly, HMF selectivity was achieved with a mixture of nitric acid and sodium nitrate catalyst system in the process of the present invention, although nitrates have heretofore been considered an unsuitable catalyst for the formation of HMF (see Examples 4 and 6; Tao et al., Journal of Molecular Catalysis A: Chemical, 357, 2012, 11-18, Tyrlik et al., Starch / Stärke, 47 (5), 1995, 171-174).

In a further embodiment, the catalyst system comprises, in particular, an aqueous solution of a salt and acid mixture, the acid being an organic acid, preferably selected from the group consisting of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid and gluconic acid and the salt is an organic acid salt, preferably selected from the group consisting of acetates, citrates, tartrates, oxalates, glycolates and gluconates.

The concentration of the salt and acid mixture, ie of the catalyst system, in the process according to the invention is preferably 0.01 to 2.00% by weight, preferably 0.05 to 1.75% by weight, preferably 0.1 to 1, 5 wt .-%, preferably 0.2 to 1.4 wt .-%, preferably 0.3 to 1.3 wt .-%, preferably 0.4 to 1.2 wt .-%, preferably 0.5 to 1.1 wt .-%, preferably 0.6 to 1.0 wt .-%, preferably 0.75 to 0.9 wt .-%, (in each case based on the total weight of the reaction solution obtained in step b)). The catalyst system is preferably used in a concentration of at most 2.0% by weight, preferably at most 1.75% by weight, preferably at most 1.5% by weight, preferably at most 1.3% by weight, preferably at most 1 , 0 wt .-%, preferably at most 0.75 wt .-%, preferably at most 0.5 wt .-% (in each case based on the total weight of the obtained in step b) reaction solution). These concentrations are well below the concentrations used in the prior art. Surprisingly, however, arises precisely for these low concentrations of salt and Acid mixture a particularly high HMF selectivity in combination with a low formation of by-products.

In a preferred embodiment, the salt concentration of the reaction solution in process step b) of the process according to the invention is 1 × 10 ⁵ to 0.45 mol / l, preferably 5 × 10 ⁵ to 0.4 mol / l, preferably 1 × 10 ⁴ to 0.35 mol / l, preferably 1 x 10 ³ to 0.3 mol / l, particularly preferably 0.01 to 0.25 mol / l.

In a preferred embodiment, the acid concentration of the reaction solution in process step b) of the process according to the invention is 1 × 10 ⁶ to 0.35 mol / l, preferably 8 × 10 ⁶ to 0.3 mol / l, preferably 1 × 10 ⁵ to 0.25 mol / l, preferably 1 x 10 ⁴ to 0.2 mol / l, particularly preferably 1 x 10 ³ to 0.15 mol / l.

Within the catalyst system according to the invention, the ratio of salt to free acid in the reaction solution obtained in process step b) is 0.8 to 10, preferably 1 to 9, preferably 1.2 to 8, preferably 1.5 to 7, preferably 2 to 6, preferably from 2.3 to 5, preferably 2.5 to 4 (in each case mol / mol). In this case, the ratio of anions of the salt and acid mixture to cations of the salt of the salt and acid mixture in the reaction solution obtained in process step b) is particularly preferably 0.55 to 4, preferably 1.0 to 3.5, preferably 1.1 to 2.0, preferably 1.5 to 3, preferably 1.75 to 2.75, preferably 2 to 2.5 (in each case mol / mol).

According to the invention, the concentration of anions of the catalyst system in the reaction solution obtained in process step b) is preferably 1 × 10 ⁵ to 0.6 mol / l, preferably 8 × 10 ⁵ to 0.55 mol / l, preferably 1 × 10 ⁴ to 0, 53 mol / l, preferably 1 x 10 ³ to 0.45 mol / l, preferably 0.01 to 0.35 mol / l, preferably 0.05 to 0.5 mol / l, preferably 0.1 to 0.4 mol / l, preferably 0.2 to 0.3 mol / l.

According to the invention, the concentration of cations of the catalyst system in the reaction solution obtained in process step b) is preferably 1 × 10 ⁵ to 0.45 mol / l, preferably 5 × 10 ⁵ to 0.4 mol / l, preferably 1 × 10 ⁴ to 0, 35 mol / l, preferably 1 x 10 ³ to 0.3 mol / l, particularly preferably 0.01 to 0.25 mol / l.

The use of the catalyst system according to the invention in the abovementioned preferred concentrations preferably leads to a pH value which is in process step b). reaction solution of 1.2 to 4.5, preferably 1.3 to 4, preferably 1.4 to 3.5, preferably 1.5 to 3, preferably 1.7 to 2.5, preferably 2 to 2.2. The pH of the reaction solution obtained in step b) is thus usually higher by the use of the salt in the catalyst system according to the invention than in purely acid-catalyzed process, but surprisingly by a higher HMF selectivity can be achieved (see examples).

Preferably, in the process according to the invention, in particular in process steps a) to d), in particular a) to c), apart from the salt and acid mixture, no further catalytically active component is used.

In a particularly preferred embodiment, it is provided that no organic solvent is used in the process according to the invention, in particular in process steps a) to d), in particular a) to c). In particular, in process steps a) to d), in particular a) to c), no organic solvent is used which is miscible with water or immiscible with water.

In particular, process steps a) to d) take place in aqueous solution.

In addition to the salt and acid mixture, a fructose-containing component is provided in step a) of the process according to the invention. This is preferably a solid fructose-containing component, in particular fructose, or a liquid fructose-containing component, in particular a fructose syrup, a fructose / glucose syrup or a fructose solution, in particular an aqueous fructose solution. The fructose-containing component is therefore also referred to herein as fructose-containing starting solution. According to the invention, the fructose-containing component can also be obtained from sucrose or starch or glucose obtained from biomass can be isomerized to fructose. The fructose-containing component preferably has a dry matter content (TS) of 40 to 100% by weight, preferably 50 to 90% by weight, preferably 60 to 85% by weight, of fructose.

In a preferred embodiment of the present invention, the components provided in step a) are obtained in step b) to obtain a reaction solution having a carbohydrate content of from 5% by weight to 50% by weight (dry matter, hereinafter also TS, carbohydrate Total weight of reaction solution) and reacted according to process step c). The carbohydrate content of the reaction solution in step b) is particularly preferably 10% by weight to 45% by weight, preferably 15% by weight to 40% by weight, preferably 25% by weight to 35% by weight, preferably 20% by weight, 30% by weight or 40% by weight (in each case TS carbohydrate with respect to total weight of reaction solution).

In a preferred embodiment of the present process, the fructose content of the reaction solution obtained in process step b) is 40% by weight to 100% by weight, preferably 70% by weight to 100% by weight, preferably 80% by weight to 100% by weight .%, Preferably 90 wt .-% to 100 wt.%, Preferably 95 wt .-% to 100 wt.%, Preferably 40 wt .-% to 99 wt .-%, preferably 45 wt .-% to 99 wt. -%, preferably 50 wt .-% to 95 wt .-%, preferably 45 wt .-% to 90 wt .-%, preferably 55 wt .-% to 85 wt .-% (each TS fructose in terms of dry matter the carbohydrate portion, that is all carbohydrates present in the reaction solution).

In a particularly preferred embodiment of the present invention, the components provided in step a) in step b) for obtaining a reaction solution having a carbohydrate content of 5 wt .-% to 50 wt .-%, preferably 10 wt .-% to 45 wt. -%, preferably 15 wt .-% to 40 wt .-%, preferably 25 wt .-% to 35 wt .-%, preferably 20 wt .-%, 30 wt .-% or 40 wt .-%, (each TS carbohydrate with respect to total weight of reaction solution) and a fructose content of 40 wt.% To 100 wt.%, Preferably 70 wt.% To 100 wt.%, Preferably 80 wt.% To 100 wt.%, Preferably 90 Wt .-% to 100 wt.%, Preferably 95 wt .-% to 100 wt.%, Preferably 40 wt .-% to 99 wt .-%, preferably 45 wt .-% to 99 wt .-%, preferably 50 Wt .-% to 95 wt .-%, preferably 45 wt .-% to 90 wt .-%, preferably 55 wt .-% to 85 wt .-% (each TS fructose with respect to the dry matter of the carbohydrate content, ie all carbohydrates present in the reaction solution) and mixed according to Verfa Step c) implemented.

In a particularly preferred embodiment, mixing, ie step b) of the process according to the invention, of the components used for the preparation of the reaction solution, that is to say in particular the fructose-containing component and the catalyst system, takes place in a mixing device and / or a line. The mixing device or the conduit and the reactor system in which the reaction, that is, step c), of the present method takes place, may be spatially separated units, which are connected by at least one Feitung, they may also separate but integral parts of a device represent. The reaction solution is preferably introduced into the reactor system by means of a pump, in particular a high-pressure pump. In a preferred embodiment of the present invention, the fructose-containing component, the catalyst system or both provided in step a) is adjusted to a temperature of from 90 ° C. to 200 ° C. before step b). Preferably, therefore, before step b), at least one, preferably all, of the components provided in step a), ie the fructose-containing component and the catalyst system, are separated from one another at a temperature of 90 ° C. to 200 ° C., preferably 100 ° C. to 175 ° C, preferably preheated 150 ° C to 175 ° C. In a preferred embodiment of the present invention, before step b), at least one, preferably all, of the components provided in step a) are heated to a temperature of 120 ° C to 180 ° C, preferably 130 ° C to 180 ° C, preferably 140 ° C preheated to 180 ° C. In particular, at least one, preferably all, of the components provided in step a) are preheated separately from one another to a temperature of 160 ° C., 165 ° C., 170 ° C. or 175 ° C. before step b).

In an alternative preferred embodiment of the present invention, the reaction solution obtained in step b) is adjusted to a temperature of 90 ° C to 200 ° C. Preferably, therefore, the reaction solution obtained in step b) by mixing the components provided in step a), preferably after step b) and before step c), to a temperature of 90 ° C to 200 ° C, preferably 100 ° C to 175 ° C, preferably 150 ° C to 175 ° C heated. Preferably, the reaction solution obtained in step b), preferably after step b) and before step c), to a temperature of 120 ° C to 180 ° C, preferably 130 ° C to 180 ° C, preferably 140 ° C to 180 ° C. heated. In particular, the reaction solution obtained in step b) is heated to a temperature of 160 ° C, 165 ° C, l70 ° C or 175 ° C.

In a particularly preferred embodiment, the subsequent step c) of the present process, ie the reaction of the fructose present in the reaction solution to form HMF, at a temperature of 90 to 200 ° C, in particular 120 to 195 ° C, in particular 140 to 190 ° C, in particular 150 to 180 ° C, in particular 160 to 175 ° C, in particular 165 to 170 ° C, in particular 165 to 175 ° C, in particular 170 to 175 ° C, in particular 160 to 165 ° C, in particular 165 ° C, in particular 170 ° C, in particular 175 ° C performed.

According to the invention, the temperature used to carry out the process according to the invention in a preferred embodiment at any time at most 200 ° C, preferably at most 175 ° C, in particular at most 165 ° C. In a preferred embodiment of the present invention, the reaction of the fructose contained in the reaction solution to HMF in step c) in a period of 0.1 to 20 min, in particular 0.1 to 15 min, especially 8 to 13 min, in particular 4 to 10 min, in particular 8 to 10 min, preferably 0.1 to 8 min, preferably 0.2 to 7 min, preferably 0.5 to 5 min, preferably 1 to 4 min, preferably 5 to 6 min. The reaction of the fructose into HMF in step c) preferably takes place in a period of at most 10 min, preferably at most 9 min, preferably at most 8 min, preferably at most 7 min, preferably at most 6 min, preferably at most 5 min, preferably at most 4 min.

In a preferred embodiment, the invention provides that in step c) a fructose conversion of 1 mol% to 50 mol% is achieved. In a preferred embodiment, the conversion of the fructose into HMF in step c) takes place with adjustment of a fructose conversion of from 1 mol% to 50 mol%, preferably from 5 mol% to 40 mol%, preferably from 10 mol% to 30 mol%, preferably 15 mol% to 25 mol%, preferably 20 mol% to 25 mol%. The conversion of the fructose into HMF in step c) preferably takes place with adjustment of a fructose conversion of at most 50 mol%, preferably at most 40 mol%, preferably at most 30 mol%, preferably at most 25 mol%, preferably at most 20 mol -%. This is done according to the invention at a temperature of 90 ° C to 200 ° C.

In connection with the present invention, "adjustment of a fructose conversion" means that the reaction parameters used for the conversion of fructose into HMF, in particular the reaction temperature and the reaction time in the reactor, are chosen such that there is only a limited conversion of the fructose of a maximum of 50 mol%, whereby a high HMF selectivity and thus a low by-product formation can be achieved.

Thus, it is preferably possible to provide specifically defined fructose conversions within the scope of the given parameters, in particular by using the inventively preferred reaction temperature, optionally in a preferred embodiment also the reaction time, for step c). On the basis of these parameters, it is also possible to set a preferred HMF selectivity according to the invention. In accordance with the invention, preference may be given to adjusting the desired fructose conversion, and optionally HMF selectivity, by sampling during the process, analysis of the sample, and subsequent calculation of the parameters to be maintained or adjusted to achieve the desired fructose conversion values and optionally desired HMF selectivity , In a particularly preferred embodiment, the reaction of the fructose contained in the fructose-containing component in step c) at a temperature of 90 to 200 ° C, preferably 150 to 190 ° C, in particular 160 ° C, 165 ° C, 170 ° C. or 175 ° C for a period of 4 to 7 minutes, preferably 5 to 6 minutes, especially 5.6 minutes. This preferably leads to a fructose conversion of 1 to 50 mol%.

In a preferred embodiment of the present invention, the process is adjusted so that in step c) an HMF selectivity of 60 mol% to 100 mol%, preferably 65 mol% to 100 mol%, preferably 70 mol% to 100 mol%, preferably 75 mol% to 100 mol%, preferably 80 mol% to 100 mol%, preferably 85 mol% to 100 mol%, preferably 90 mol% to 100 mol% is obtained , The HMF selectivity in step c) is preferably at least 60 mol%, preferably at least 65 mol%, preferably at least 70 mol%, preferably at least 75 mol%, preferably at least 80 mol%, preferably at least 85 mol% , preferably at least 90 mol%, preferably at least 95 mol%.

In a preferred embodiment of the present invention, the process is adjusted so that in step c) an HMF selectivity of 60 mol% to 100 mol%, preferably 65 mol% to 100 mol%, preferably 70 mol% to 100 mol%, preferably 75 mol% to 100 mol%, preferably 80 mol% to 100 mol%, preferably 85 mol% to 100 mol%, preferably 90 mol% to 100 mol%, preferably at least 60 mol%, preferably at least 65 mol%, preferably at least 70 mol%, preferably at least 75 mol%, preferably at least 80 mol%, preferably at least 85 mol%, preferably at least 90 mol%, preferably at least 95 mol% and a fructose conversion of 1 mol% to 50 mol%, preferably 5 mol% to 40 mol%, preferably 10 mol% to 30 mol%, preferably 15 mol% to 25 mol% , preferably 20 mol% to 25 mol%, preferably at most 50 mol%, preferably at most 40 mol%, preferably at most 30 mol%, preferably at most 25 mol%, preferably at most 20 mol% is obtained.

In a particularly preferred embodiment of the present invention, the process is adjusted such that in step c) an HMF selectivity of 60 mol% to 100 mol%, preferably 65 mol% to 100 mol%, preferably 70 mol% to 100 mol%, preferably 75 mol% to 100 mol%, preferably 80 mol% to 100 mol%, preferably 85 mol% to 100 mol%, preferably 90 mol% to 100 mol%, preferably at least 60 mol%, preferably at least 65 mol%, preferably at least 70 mol%, preferably at least 75 mol%, preferably at least 80 mol%, preferably at least 85 mol%, preferably at least 90 mol%, preferably at least 95 mol% and a fructose conversion of 1 mol% to 50 mol%, preferably 5 mol% to 40 mol%, preferably 10 mol% to 30 mol%, preferably 15 mol% to 25 mol%, preferably 20 mol% to 25 mol%, preferably at most 50 mol%, preferably at most 40 mol -%, preferably at most 30 mol%, preferably at most 25 mol%, preferably at most 20 mol% is obtained, this by means of a temperature of 90 to 200 ° C, in particular 140 to 190 ° C, in particular 150 to 180 ° C, in particular 160 to 175 ° C, in particular 165 to 170 ° C, in particular 165 to 175 ° C, in particular 170 to 175 ° C, in particular 160 to 165 ° C, in particular 165 ° C, in particular 170 ° C, in particular 175 ° C and within a period of 0.1 to 20 minutes, in particular 0.1 to 15 minutes, in particular 8 to 13 minutes, in particular 4 to 10 minutes, in particular 8 to 10 minutes, preferably 0.1 to 8 minutes, preferably 0, 2 to 7 minutes, preferably 0.5 to 5 minutes, preferably 1 to 4 minutes, preferably 5 to 6 minutes.

In the context of the present invention, the HMF selectivity is based on the amount of fructose that has been converted, whereby proportions of other carbohydrates, in particular glucose, are disregarded.

In a preferred embodiment of the present invention, the HMF yield is 3 to 50 mol%, preferably 5 to 45 mol%, preferably 10 to 40 mol%, preferably 15 to 35 mol%, particularly preferably 20 to 30 mol%.

In a preferred embodiment of the present invention, in step c), the pressure for reacting the fructose present in the reaction solution to HMF is adjusted so that boiling of the reaction solution and thus the occurrence of vapor bubbles is avoided. The pressure for reacting the fructose present in the reaction solution to form HMF in the reactor system is preferably 0.1 to 2 MPa, preferably 0.2 to 1.5 MPa, particularly preferably 1 MPa.

According to the invention, it is provided that the fructose present in the reaction solution is converted to HMF in step c) by adjusting various parameters such as temperature, reaction time, pH, catalyst concentration, acid / salt ratio and / or pressure and in step d) a liquid HMF-containing product mixture is obtained. The process is thus preferably carried out in such a way that, by adjusting the temperature, and preferably also the reaction time, a limited reaction of the fructose of 1 mol% to 50 mol% occurs, as a result of which a surprisingly high HMF selectivity, preferably of 60 mol% to 100 mol%, can be achieved. In a particularly preferred embodiment, the reaction of the fructose present in the reaction solution to HMF and the obtaining of HMF according to process steps c) and d) provide for a one-step process. In particular, the procedure according to the invention according to process steps c) and d) is preferably not a two-step procedure.

In a preferred embodiment, the present process further comprises the step of: e) cooling the liquid HMF product mixture obtained in step d) to a temperature of 20 ° C to 80 ° C, preferably 25 ° C to 70 ° C, preferably 30 ° C to 60 ° C, preferably 30 ° C to 55 ° C, preferably 30 ° C to 50 ° C, preferably 30 ° C to 45 ° C, preferably 30 ° C to 40 ° C, preferably 80 ° C, preferably 70 ° C, preferably 60 ° C, preferably 55 ° C, preferably 50 ° C, preferably 45 ° C, preferably 40 ° C, preferably 35 ° C, preferably 30 ° C. The liquid HMF product mixture is preferably heated in step e) to a temperature of at most 75 ° C., preferably at most 70 ° C., preferably at most 60 ° C., preferably at most 55 ° C., preferably at most 50 ° C., preferably at most 45 ° C. preferably at most 40 ° C, preferably at most 35 ° C cooled. This can be done according to the invention in one or two stages.

In a preferred embodiment of the present invention, the temperature of the liquid HMF product mixture in step e) in a period of 0.1 to 10 minutes, preferably 0.1 to 9 minutes, preferably 0.1 to 8 minutes, preferably 0.2 to 7 min, preferably 0.2 to 6 min, preferably 0.5 to 5 min, preferably 0.5 to 4 min, preferably 0.5 to 3 min set, or cooled. The temperature of the product mixture in step e) is preferably not more than 10 min, preferably not more than 9 min, preferably not more than 8 min, preferably not more than 7 min, preferably not more than 6 min, preferably not more than 5 min, preferably not more than 4 min, preferably not more than 3 min. preferably at most 2 minutes, preferably at most 1 minute, preferably set at most 0.5 minutes, or cooled. Thus, the HMF-containing product mixture obtained in step d) is cooled to a temperature of 20 ° C to 80 ° C after reaching the limited fructose conversion of not more than 50 mol% in step e). This advantageously prevents as far as possible the formation of undesirable by-products and the decomposition of the HMF formed. The process according to the invention for producing HMF is preferably carried out in a suitable reactor system. According to the invention, this is preferably a continuous reactor system.

In a particularly preferred embodiment, the continuous reactor system used is designed as a tubular reactor system. Such a continuous reactor system is a reactor system known to those skilled in the art. In a particularly preferred embodiment, it is also possible to use a continuous reactor system, in particular a continuous system, with little backmixing. In a particularly preferred embodiment, a plug-flow reactor (PFR) can be used as the continuous reactor system. In a preferred embodiment, the continuous reactor system can also be designed as a flow tube, stirred tank or stirred tank cascade. In the context of the present invention, a plug-flow reactor (PFR) is understood to be a so-called ideal flow tube (IR), that is to say a tubular reactor in which there is a plug flow. In particular, such a reactor is also distinguished by the fact that no mixing, backflow or turbulence of the reaction solution carried out takes place, but rather a uniform flow takes place under mass transfer taking place in parallel. In particular, the plug-flow reactor ensures that each substance fed into the plug-flow reactor, in particular each component fed in, is continuously reacted under the same conditions, ie all components are exposed to the conversion process for the same period of time.

In a preferred embodiment, the present process optionally further comprises the step of: f) filtering, decolorizing and / or purifying the liquid HMF product mixture.

That is, in a further preferred embodiment, there is a filtration of the HMF product mixture, preferably via a suitable filter or a suitable filter system, and a decolorization and / or purification of the product mixture, preferably a decolorization and / or purification over activated carbon instead. Filtration of the product mixture preferably takes place via a suitable filter or a suitable filter system and decolorization and / or purification of the product mixture, for example via activated carbon after step e). Preferably, a filtration of the product mixture via a suitable filter or a suitable filter system and a decolorization and / or purification of the product mixture, for example via activated carbon before Step g) or h). In a particularly preferred embodiment, after process step e) and / or process step g) in any order a filtration through a suitable filter or a suitable filter system, a decolorization and / or purification of the product mixture, in particular over activated carbon and optionally after step g) a repeated filtration be carried out via a suitable filter or a suitable filter system. In a particularly preferred embodiment, after step e) and / or process step g), first a filtration through a suitable filter or a suitable filter system, then a decolorization and / or purification, in particular via activated carbon and optionally after step g) a repeated filtration over a suitable Filter or a suitable filter system performed in this order. According to the invention, a metal sintered filter is preferably used for the filtration.

Preference is given to removing unwanted by-products, in particular soluble and insoluble humic substances, from the product mixture by filtering the product mixture through a suitable filter or a suitable filter system and decolorizing and / or purifying via, for example, activated carbon.

In a preferred embodiment of the present invention, the product mixture obtained in step e) or optionally step f) has a dry matter content of 5 to 50 wt .-%, preferably 10 to 40 wt .-%, preferably at least 5 wt .-%, preferably at least 10 wt .-%, preferably at most 40 wt .-%, preferably at most 60 wt .-% on.

If the dry matter content of the product mixture obtained in step e) or optionally f) is too low, it may be provided according to the invention that the present process optionally further comprises the step of: g) adjusting the liquid HMF product mixture to a dry matter content of 20 to 70 Wt .-%, preferably 25 to 50 wt .-%, preferably 25 to 45 wt .-%, preferably 30 to 45 wt .-%, preferably 30 to 40 wt .-%.

In a further preferred embodiment, the product mixture obtained in step e) or optionally f) to a dry matter content of 20 to 70 wt .-%, preferably at least 20 wt .-%, preferably at least 30 wt .-%, preferably at least 40 wt. -%, preferably at least 50 wt .-%, preferably at most 70 wt .-%, preferably at most 60 wt .-%, preferably at most 50 wt .-% set. In a preferred embodiment, the present method further comprises the steps of: h) purifying the liquid HMF product mixture by means of chromatography, ultrafiltration and / or nanofiltration, extraction with a suitable extractant, adsorption to a suitable material and subsequent targeted desorption and / or electrodialysis Separating at least one HMF fraction, and i) obtaining at least one HMF fraction.

That is, preferably by the application of at least one of said purification processes, at least one HMF fraction is separated from the liquid HMF-containing product mixture so that only other components contained in the product mixture, such as unreacted fructose, glucose or by-products such as organic acids and humins, remain , It may also be provided according to the invention to use a combination of at least two or more of said purification processes for the separation of at least one HMF fraction and / or optionally other fractions containing one or more other components of the product mixture.

In an alternative preferred embodiment, the present method further comprises the steps of: h) purifying the liquid HMF product mixture by means of chromatography, ultra- and / or nanofiltration, extraction with a suitable extractant, adsorption to a suitable material and subsequent targeted desorption and / or electrodialysis for separating at least one fraction selected from the group consisting of an HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction, and i) obtaining at least one fraction selected from the group consisting of an HMF fraction, a glucose fraction, a fructose fraction and an organic acid

Fraction.

It may further be provided, at least one of the fractions obtained in step i) by means of a purification process selected from the group consisting of chromatography, ultra and / or nanofiltration, extraction with a suitable Extracting agent to further treat adsorption to a suitable material and subsequent targeted desorption and / or electrodialysis.

One of the purification processes envisaged in the process according to the invention is ultra-filtration and / or nanofiltration. This can be done via suitable membranes on the one hand, a concentration of the liquid HMF-containing product mixture, on the other hand, but also a removal of soluble and / or insoluble humins or in the case of nanofiltration, a separation of HMF and / or organic acids from the product mixture. Therefore, a concentrated product mixture, a product mixture freed from soluble and / or insoluble humic substances, an HMF fraction and a product mixture freed of HMF, an HMF fraction and / or an organic acid fraction and a product mixture freed from HMF and / or organic acids, or a glucose and / or fructose fraction and a product mixture freed from humins and / or glucose and / or fructose.

Another purification process provided in the process according to the invention is the extraction with a suitable extraction agent. For the extraction of HMF from the HMF-containing product mixture it is preferred to use a solvent which is immiscible or hardly miscible with water and which has a sufficiently high affinity for HMF. Ideally, the boiling point of the organic solvent is preferably relatively low and the density difference between water and the solvent sufficiently high so that phase separation can be achieved. Suitable solvents are preferably methyl isobutyl ketone, ethyl acetate, methyl ethyl ketone, butanol, diethyl ether, methyl butyl ether, isoamyl alcohol, methyl tetrahydrofuran or the like. After the extraction step, an aqueous product mixture containing unreacted fructose and glucose remains and an organic phase containing HMF and optionally organic acids is obtained.

Another purification process provided in the process according to the invention is the adsorption on a suitable material and the subsequent desorption. The adsorption of HMF can in principle be carried out on any material which preferably adsorbs HMF from hexose-containing solutions. Preferred materials are Polymcr-basicrtc resins such as divinylbenzene-styrene copolymers, adsorbent resins, activated carbons, zeolites, aluminas, non-functionalized resins or cation exchange resins. The product mixture obtained in step e), f) or g) is preferably continuously mixed with the HMF adsorbing material in Contact, but not more than exhaustion of the material. Subsequently, the adsorbed HMF is desorbed with a suitable desorbent such as water or polar organic solvents such as alcohols, ethyl acetate, THF or the like. From the organic solvent HMF can then be recovered by suitable methods.

Another purification process provided in the process according to the invention is electrodialysis. This is an electrochemically driven membrane process that utilizes ion exchange membranes in combination with an electrical potential difference to separate ionic species from uncharged species or contaminants in the solution. In the case of the present process, the electrodialysis can be used to rid the product mixture of inorganic and / or organic cations and anions, such as salts of the salt and acid mixture, lavulinic and formic acids as by-products.

Another purification process provided in the process according to the invention is chromatography. This will be explained in more detail below.

All the aforementioned purification processes can be used individually or in combination with each other.

In step h), the HMF contained in the product mixture is particularly preferably separated off from the further components of the product mixture using a chromatographic method, in particular by means of chromatography on ion exchange resins, in particular cation exchange resins, in particular by means of single or multistage chromatography on ion exchange resins, in particular cation exchange resins.

In a particularly preferred embodiment of the present invention, the chromatography, in particular chromatography on ion exchange resins, in particular chromatography on cation exchange resins, is an ion exchange chromatography, in particular a cation exchange chromatography.

In a preferred embodiment of the present invention, the liquid HMF product mixture in step h) is chromatographed in at least four fractions comprising an HMF fraction, a glucose fraction, a fructose fraction and a separated organic acids fraction and in step i) at least one HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction.

Particularly preferably, the purification of the product mixture obtained in step e), if appropriate f) or optionally g) in step h) is carried out continuously by chromatography. Continuous chromatography is also preferably understood to mean simulated countercurrent chromatography, such as Simulated Moving Bed Chromatography (SMB).

Continuous chromatography methods are well known to those skilled in the art. For example, US 2011/0137084 Al shows the operation of the SMB method. Other suitable chromatography methods are described in A. Rajendran et al .; J. Chromatogr. A 1216 (2009), pages 709-738.

Simulated Moving Bed (SMB) systems or enhancements of the SMB system, such as Sequential SMB (SSMB), Intermittent / Improved SMB (ISMB) or New MCI (NMCI) advantageously allow the separation and recovery of the four described fractions in continuous operation.

In a preferred embodiment of the present invention, chromatography, in particular chromatography on ion exchange resins, in step h) is a Simulated Moving Bed (SMB) method, a Sequentially Simulated Moving Bed (SSMB) method or an Improved Simulated Moving Bed method or intermittent Simulated moving bed method (ISMB). Preference is given to chromatography, in particular chromatography on ion exchange resins, in step h) a simulated moving bed method (SMB), a sequential simulated moving bed method (SSMB), an improved simulated moving bed method (ISMB) or a new MCI Procedure (NMCI). By using a Simulated Moving Bedding (SMB) method, a Sequentially Simulated Moving Bedding (SSMB) method, an Improved Simulated Moving Bed (ISMB) method, or a New MCI (NMCI) method in step h), it is advantageous possible to carry out the purification of the product mixture obtained in step e), f) or g) for the separation of an HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction in a continuous procedure. In a preferred embodiment of the present invention, the chromatography, in particular chromatography on ion exchange resins, in particular on cation exchange resins, in step h) is a one-step process. Chromatography, in particular chromatography on ion exchange resins, in particular on cation exchange resins, in step h) is preferably a multi-stage process, preferably a two-stage process.

The chromatography, in particular chromatography on ion exchange resins, in particular on cation exchange resins, in step h) preferably comprises a plurality of stages, preferably at least two stages, preferably at least three stages, preferably two stages, preferably three stages.

In a preferred embodiment of the present invention, in step h) in a first stage of the chromatography for the separation of at least one fraction, preferably exactly one fraction, in particular an HMF fraction or a glucose fraction, preferably at least two fractions, preferably exactly two fractions, preferably exactly three fractions.

In a further preferred embodiment of the present invention, in step h) in a second stage of the chromatography to separate at least one fraction, preferably exactly one fraction, preferably at least two fractions, preferably exactly two fractions, preferably exactly three fractions, especially one Glucose fraction, a fructose fraction and an organic acid fraction or an HMF fraction, a fructose fraction and an organic acid fraction.

In a preferred embodiment of the present invention, the first step of the chromatography in step h) is a chromatography method selected from the group consisting of Simulated Moving Bed (SMB), Sequentially Simulated Moving Bed (SSMB), Improved Simulated Moving Bed Method (ISMB) and New MCI Method (NMCI).

Preferably, the first step of the chromatography in step h) is an Improved Simulated Moving Bed (ISMB) method. Preference is given in step h) in a first stage for the separation of at least one fraction, preferably exactly one fraction, in particular an HMF fraction or an organic acid fraction, by means of a Chromatography method selected from the group consisting of Simulated Moving Bed (SMB), Sequentially Simulated Moving Bed (SSMB), Improved Simulated Moving Bed (ISMB), and New MCI (NMCI), preferably using an Improved Simulated Moving Bed Method (ISMB).

In a preferred embodiment of the present invention, the second step of chromatography in step h) is a chromatography method selected from the group consisting of Simulated Moving Bed (SMB), Sequentially Simulated Moving Bed (SSMB), Improved Simulated Moving Bed Method (ISMB) and New MCI Method (NMCI).

Preferably, the first step of the chromatography in step h) is a New MCI method (NMCI). Preference is given in step h) in a second stage for the separation of at least one fraction, preferably exactly one fraction, preferably at least two fractions, preferably exactly two fractions, preferably at least three fractions, preferably exactly three fractions, in particular a glucose fraction, a Fructose fraction and an organic acid fraction or an HMF fraction, a fructose fraction and an organic acid fraction, by means of a chromatography method selected from the group consisting of simulated moving bed (SMB) method, sequentially simulated moving bed method ( SSMB), Improved Simulated Moving Bed (ISMB) and New MCI (NMCI), preferably using a New MCI (NMCI) method.

In particular, an at least two-stage chromatography separation is preferred, in which the HMF fraction is separated off in the first stage. Alternatively, in the first stage, the glucose fraction can be separated. The first stage of the at least two-stage chromatography separation is preferably a moving bed method (ISMB). Preferably, the second stage of at least two-step chromatography separation is a New MCI method (NMCI).

In particular, a two-stage chromatography separation is preferred in which the HMF fraction is separated in the first stage. Alternatively, in the first stage, the glucose fraction can be separated. Preferably, the first stage of the two-stage chromatography separation is a moving bed process (ISMB). Preferably, the second stage of the two-stage chromatography separation is a New MCI method (NMCI). Prefers In the second stage of the two-stage chromatography separation, the organic acid fraction, the fructose fraction and the glucose fraction are separated from one another. Alternatively, in the second stage of the two-step chromatography separation, the organic acid fraction, the fructose fraction and the HMF fraction are separated from each other.

In a preferred embodiment of the present invention, the chromatography, in particular chromatography on ion exchange resins in step h) is a chromatography on cation exchange resins.

In a preferred embodiment of the present invention, the chromatography, in particular chromatography on ion exchange resins in step h) is carried out using a cation exchange resin in H ⁺ form.

In a preferred embodiment, the chromatography, in particular chromatography on ion exchange resins, in step h) at a temperature of 40 ° C to 80 ° C, preferably 40 ° C to 70 ° C, preferably 40 ° C to 60 ° C, preferably 50 ° C to 80 ° C, preferably 50 ° C to 70 ° C, preferably 50 ° C to 60 ° C, preferably 60 ° C to 80 ° C, preferably 60 ° C to 70 ° C, carried out.

The fructose fraction optionally obtained in step i) is preferably recycled continuously to process step a). The optionally obtained in step i) fructose fraction is advantageously largely, preferably completely, freed from formed Fävulinsäure. In a further preferred embodiment, the fructose fraction obtained in step i) is advantageously as far as possible, preferably completely, freed of educated favulinic and formic acid.

In a particularly preferred embodiment, the fructose fraction optionally obtained in step i), if appropriate after concentration, is continuously preferably completely recycled to step a). In a further preferred embodiment, the fructose fraction obtained in step i) is continuously, optionally after concentration, at least partially, in particular at least 70%, preferably at least 80%, preferably at least 90%, preferably at least 95%, preferably at least 98%, preferably at least 99%, in step a) (in each case% by weight of the recycled fructose fraction relative to the fructose fraction obtained in step i). According to the invention, a "recycled fructose fraction" is understood to mean a purified fraction of unreacted fructose which has been obtained by the process according to the invention and which is largely, preferably completely, made up of by-products formed during the fructose conversion, especially fecal and formic acid and humic substances. In this case, the resulting aqueous fraction of unreacted fructose to such a high purity that in a preferred embodiment directly, optionally after concentration, that is, without further purification, in the process step a) is recycled and after mixing with the fructose-containing component and the catalyst system, that is, step b), for further conversion to HMF in step c) is available. It is therefore particularly preferable for step a) of the process according to the invention to provide a fructose-containing component, a salt and acid mixture and a recycled fructose fraction which are mixed in step b) to obtain a reaction solution. Since in this preferred embodiment initially no recirculated fructose fraction is available in the initiation of the process according to the invention, in this case preferably a correspondingly larger amount of the fructose-containing component is used.

In step i) of the process according to the invention, ie after carrying out the purification, in addition to the HMF fraction optionally a glucose fraction, a fructose fraction and an organic acid fraction are obtained, in particular isolated. Advantageously, the individual fractions obtained via the purification processes used have such high purities that they can be used directly, optionally after concentration, ie without further purification, in different subsequent processes.

According to the invention, the optionally obtained fructose fraction is largely free, in particular completely free, of educated faevulinic acid. According to the invention, the fructose fraction obtained is preferably substantially free, in particular completely free from formed organic acids, in particular favulinic and formic acids.

Fävulinsäure disadvantageously favors the humic substance formation during the HMF synthesis. Thus, an increased content of faevulinic acid in the reaction solution caused by the fructose fraction recycled according to a preferred embodiment would lead to an increased formation of humic substances from HMF and carbohydrates and thus significantly reduce the economic efficiency of the process. However, the fructose fraction optionally obtained in step i) in the process according to the invention advantageously has one such high purity, in particular free of educated levulinic acid, particularly preferably free from levulinic and formic acid, that in a preferred embodiment, directly, optionally after concentration, in particular without purification steps, for further implementation in the process, in particular step a), returned can be. In particular, it comes by the provided by the novel limited reaction of fructose and the associated reduced formation of by-products and degradation products, especially lavulinic and formic acid and humic substances, as well as in a preferred embodiment by recycling a fraction separated from the product fraction unreacted fructose to high HMF selectivity and high HMF yield.

In a particularly preferred embodiment, the process according to the invention consists of the process steps a), b), c) and d), in particular between these

Process steps performed no further process steps.

In a particularly preferred embodiment of the present invention, the method according to the invention comprises the method steps a), b), c) and d), wherein no further method steps are carried out between the method steps a), b), c) and d), but optionally after execution of process step d) further process steps are carried out.

According to the invention, the present process comprises the steps a) to d), preferably a) to e), preferably a) to f), preferably a) to g), preferably a) to h), in particular a) to i). According to the invention, the present process comprises the steps a), b), c), d), e), f), g), h) and i). However, it can also be provided that the present process comprises the steps a), b), c), d), e), h) and i) or a), b), c), d), e), f ), h) and i) or a), b), c), d), e), g) h) and i). In a particularly preferred embodiment, the present process consists of process steps a) to d), preferably a) to e), preferably a) to f), preferably a) to g), preferably a) to h), in particular a) to i). In a particularly preferred embodiment, the present process consists of the process steps a), b), c), d), e), h) and i) or a), b), c), d), e), f), h) and i) or a), b), c), d), e), g) h) and i). In a preferred embodiment, the process is carried out in the sequence of process steps a), b), c), d), e), f), g), h) and i). However, it can also be provided that the present process can be carried out in the sequence of process steps a), b), c), d), e), h) and i) or a), b), c), d), e ), f), h) and i) or a), b), c), d), e), g) h) and i). According to the invention, in the process for the preparation of 5-hydroxymethylfurfüral according to steps a) to i), the reaction of the present in the reaction mixture fructose to HMF in a continuous reactor system and the subsequent purification of the resulting product mixture for the separation of at least four fractions continuously, that is under constant supply of educts and removal of products.

A continuous process according to the invention is preferably understood as meaning a process in which not only the reactor system is continuous, but also the purification of the product mixture.

The present invention makes it possible to provide processes for the preparation of HMF and / or formic acid and / or levulinic acid, in particular for the simultaneous preparation from a starting material, namely a fructose-containing component and optionally a recycled fructose fraction.

The process according to the invention for the production of HMF in a preferred embodiment is therefore also a process for the preparation of HMF and formic acid and levulinic acid, which comprises the steps a) to i) and serves for the targeted preparation of three products of interest.

The process according to the invention for the production of HMF in a preferred embodiment is therefore also a process for the preparation of HMF and formic acid which comprises the steps a) to i) and which serves for the production of two valuable substances of interest. The process according to the invention for the production of HMF in a preferred embodiment is therefore also a process for the preparation of HMF and levulinic acid which comprises the steps a) to i) and which serves for the preparation of two valuable substances of interest.

According to the invention, the glucose fraction obtained in step i) comprises at least 20% by weight of the glucose present in the product mixture (in each case based on the product mixture). In a further preferred embodiment of the present invention, if appropriate, the glucose fraction obtained in step i) has a sufficiently high purity, is in particular free of fermentation inhibitors, directly, optionally after concentration, both as feed (feed material) in fermentative processes, in particular for ethanol production, in particular glucose fermentation to ethanol, as well as educt in chemical processes, in particular the oxidation of glucose to gluconic acid, can be used.

In a further preferred embodiment, the glucose fraction optionally obtained in step i) is used for the production of ethanol, in particular glucose fermentation to ethanol, in particular for the bioethanol recovery, and / or for gluconic acid recovery.

The present invention therefore also provides a process for the production of a feed for fermentative processes, in particular for ethanol production, in particular glucose fermentation to ethanol, or for the preparation of a starting material, that is educts, in chemical processes, in particular for the production of gluconic acid A process of the present invention is carried out with the process steps a) to i) to obtain a glucose fraction, which can be used as feed or starting material.

In a particularly preferred embodiment, a process is provided for the production of ethanol, in particular glucose fermentation to ethanol, in which the process according to the invention, in particular the process steps a) to i), are carried out, in particular to obtain a glucose fraction, the glucose obtained -Fraction for ethanol production, in particular glucose fermentation to ethanol, in particular for the bio-ethanol extraction, is used.

In a further preferred embodiment, the glucose fraction optionally obtained in step i) is used for gluconic acid recovery, optionally after concentration.

In a particularly preferred embodiment there is provided a process for the production of gluconic acid comprising the process according to the invention, in particular the process steps a) to i), in particular for obtaining a glucose fraction which is suitable for obtaining glucose and for subsequent oxidation of the glucose to gluconic acid is used.

In a preferred embodiment of the present invention, the organic acid fraction optionally obtained in step i) is used for the isolation of levulinic and formic acid. In a further preferred embodiment, the organic acid fraction obtained in step i) is used for the isolation of levulinic acid. In another In the preferred embodiment, the organic acid fraction obtained in step i) is used for the isolation of formic acid.

The present invention therefore also relates to a process for the preparation of levulinic acid, formic acid or levulinic acid and formic acid, wherein a process comprising steps a) to i) of the present invention is carried out and in step i) levulinic acid, formic acid or levulinic acid and formic acid is obtained.

In a further preferred embodiment of the present invention, the HML fraction obtained in step i) is oxidized directly in an additional step to 2,5-lurandicarboxylic acid (LDCA), optionally after concentration, that is to say without the need for further purification.

The present invention therefore also relates to a process for the preparation of LDCA comprising steps a) to i) of the present invention, wherein the HML-lraction obtained in step i), preferably directly, optionally after concentration, and without the need for elaborate further purification , is oxidized to LDCA. According to the invention, the optionally obtained glucose lraction contains 0.8% by weight to 100% by weight of glucose, 0% by weight to 99.2% by weight of lructose, at most 2% by weight, preferably at most 1% by weight. %, preferably at most 0.5 wt.%, preferably at most 0.1 wt.%, levulinic and formic acid and at most 10 wt.%, preferably at most 5 wt.%, preferably at most 2 wt. , more preferably at most 1 wt .-%, preferably at most 0.5 wt .-%, preferably at most 0.1 wt .-%, HML (each TS, based on the sum of the analyzed components (glucose, lructose, levulinic acid, formic acid, HML, Difructose Anhydride (DLA)) According to the invention, the glucose-lraction preferably contains at most 10% by weight, more preferably at most 5% by weight, of HML.

The lructose fraction optionally obtained in step i) contains at least 70% by weight, preferably at least 80% by weight, of the lructose contained in the product mixture

(each TS based on product mixture).

According to the invention, the optionally obtained lructose lraction contains 0% by weight to 60% by weight of glucose, 40% by weight to 100% by weight of lructose, at most 2% by weight, preferably at most 1% by weight, preferably not more than 0.5% by weight, preferably not more than 0.1% by weight of levulinic acid, at most 2 wt .-%, preferably at most 1.5 wt .-%, preferably at most 1 wt .-%, preferably at most 0.5 wt .-%, preferably at most 0.25 wt .-%, preferably at most 0.1 Wt .-%, formic acid and at most 2 wt .-%, preferably at most 1.5 wt .-%, preferably at most 1 wt .-%, preferably at most 0.8 wt .-%, preferably at most 0.6 wt. %, preferably at most 0.4 wt .-%, preferably at most 0.2 wt .-%, preferably at most 0.1 wt .-%, HMF (in each case TS, based on the sum of the analyzed components (glucose, fructose, levulinic acid According to the invention, the fructose fraction preferably contains at most 2% by weight of HMF. According to the invention, the fructose fraction preferably contains at most 2% by weight of levulinic acid In a particularly preferred embodiment the ratio is from fructose to glucose in the fructose fraction not smaller than in the fructose-containing component provided in step a).

According to the invention, the organic acid fraction optionally obtained in step i) contains at least 60% by weight, preferably at least 65% by weight, preferably at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight. %, preferably at least 95 wt .-%, preferably at least 98 wt .-%, preferably at least 99 wt .-%, preferably at least 99.5 wt .-%, preferably at least 99.8 wt .-%, preferably 100 wt. -% of lavulinic and formic acid contained in the product mixture (in each case TS, based on product mixture).

According to the invention, the optionally obtained organic acid fraction contains 50 wt.% To 100 wt.%, Preferably 60 wt.% To 100 wt.%, Preferably, more preferably 65 wt.% To 100 wt. preferably from 70% by weight to 100% by weight, preferably from 80% by weight to 100% by weight, preferably from 90% by weight to 100% by weight, preferably from 95% by weight to 100% by weight %, preferably 98% to 100%, preferably 99% to 100%, preferably 99.5% to 100%, preferably 99.7% by weight % to 100% by weight of levulinic and formic acid (in each case TS, based on the sum of the analyzed components (glucose, fructose, levulinic acid, formic acid, HMF, diffusanhydrides (DFA)) According to the invention, the organic acid fraction preferably contains at least 50% by weight. % Levulinic acid, more preferably at least 60% by weight levulinic acid, more preferably at least 70% by weight levulinic acid.

The HMF fraction obtained in step i) contains at least 70% by weight, preferably at least 80% by weight, more preferably at least 90% by weight, preferably at least 98% by weight, preferably at least 99% by weight, according to the invention. , preferably at least 99.5% by weight, preferably at least 99.8 wt .-%, preferably 100 wt .-% of the HMF contained in the product mixture (in each case TS, based on product mixture).

According to the invention, the HMF fraction contains 80% by weight to 100% by weight, preferably 85% by weight to 100% by weight, preferably 90% by weight to 100% by weight, preferably 95% by weight to 100 wt.%, preferably 98 wt.% to 100 wt.%, preferably 99 wt.% to 100 wt.%, preferably 99.5 wt.% to 100 wt.%, preferably 99 , 7 wt .-% to 100 wt .-% HMF and at most 16 wt .-%, preferably at most 14 wt .-%, preferably at most 12 wt .-%, preferably at most 10 wt .-%, preferably at most 8 wt. -%, preferably at most 6 wt .-%, preferably at most 4 wt .-%, preferably at most 2 wt .-%, preferably at most 1 wt .-%, favulinic and formic acid, at most 2 wt .-%, preferably at most 1 % By weight, preferably at most 0.8% by weight, preferably at most 0.6% by weight, preferably at most 0.4% by weight, preferably at most 0.2% by weight, preferably at most 0.1 Wt .-%, glucose and at most 2 wt .-%, preferably at most 1 wt .-%, preferably at most 0.8 wt .-%, preferably at most 0.6 wt .-%, preferably highest ns 0.4 wt .-%, preferably at most 0.2 wt .-%, preferably at most 0.1 wt .-% fructose (in each case TS, based on the sum of the analyzed components (glucose, fructose, faevulinic acid, formic acid, HMF, Diffusion Anhydride (DFA)).

In a preferred embodiment, in the process according to the invention, in particular during steps a) to g), if appropriate a) to i), no organic solvents, in particular no ionic liquids, are used.

In a preferred embodiment, the process according to the invention, in particular during steps a) to i), is not carried out under oxygen-reduced conditions.

The term "and / or" in the context of the present invention is understood to mean that all members of a group, which are connected by the term "and / or" are disclosed both alternatively to each other and in each case cumulatively in any combination. This means for the expression "A, B and / or C" that the following disclosure content is to be understood: A or B or C or (A and B) or (A and C) or (B and C) or (A and B and C).

In the context of the present invention, the term "comprising" is understood to mean that, in addition to the elements explicitly covered by the term, further elements not explicitly mentioned may also be added. In connection with the present The invention also means by these terms that only the explicitly mentioned elements are detected and no further elements are present. In this particular embodiment, the meaning of the term "comprising" is synonymous with the term "consisting of". In addition, the term "encompassing" also encompasses entities which, in addition to the explicitly mentioned elements, also contain other elements which are not mentioned, but which are of a functional and qualitatively subordinate nature. In this embodiment, the term "comprising" is synonymous with the term "consisting essentially of".

Further preferred embodiments emerge from the subclaims.

The invention will be explained in more detail with reference to the following embodiments and the accompanying figures.

The figures show:

FIG. 1 shows a schematic representation of the reactor system used according to the invention.

Figure 2 shows a schematic representation of the method according to the invention, wherein the provided in step a) components are first mixed in step b) and the resulting reaction solution is heated and after the purification step h) an HMF fraction is obtained (step i)).

Figure 3 shows a schematic representation of the method according to the invention analogous to Figure 2, wherein in step h) a column chromatographic separation is carried out and an HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction is obtained (step i )).

Figure 4 shows a schematic representation of the method according to the invention, wherein the provided in step a) components are heated separately and then mixed in step b) to obtain a reaction solution and after the purification step h) an HMF fraction is obtained (step i )). Figure 5 shows a schematic representation of the inventive method analogous to Figure 4, wherein in step h) a column chromatographic separation is performed and an HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction is obtained (step i )). FIG. 6 shows results of the HMF synthesis with 20% TS KH (85% fructose unit) and 0.08% by weight HCl without added salt at temperatures of 145-152 ° C. Presentation of fructose conversion, HMF, faevulinic acid and formic acid selectivity as well as the balance.

Figure 7 shows results of HMF synthesis with 20% TS KH (85% fructose unit) and 0.18 wt .-% HNO ₃ without addition of salt at temperatures of 145 - 152 ° C. Presentation of fructose conversion, HMF, faevulinic acid and formic acid selectivity as well as the balance.

Figure 8 shows the reaction temperatures necessary for a fructose conversion of -18% depending on the sodium content at constant chloride content and HMF, faevulinic and formic acid selectivities and the balance at this point. Figure 9 shows the reaction temperatures necessary for a fructose conversion of -20% depending on the sodium content at constant nitrate content and HMF, faevulinic and formic acid selectivities and the balance at this point.

Figure 10 shows the reaction temperatures necessary for a fructose conversion of -20%, depending on the concentration of the salt and acid mixture at constant chloride / sodium ratio and HMF, faevulinic and formic acid selectivities and the balance at this point.

Figure 11 shows the reaction temperatures necessary for fructose conversion of -27%, depending on the concentration of the salt and acid mixture at constant nitrate / sodium ratio, and HMF, faevulinic and formic acid selectivities, and the balance at this point.

Figure 12 shows the HMF synthesis with 20% TS KH (85% fructose unit) and 0.12 wt .-% HCl / CaCl ₂ at temperatures of 165-169 ° C. Presentation of fructose conversion, HMF, faevulinic acid and formic acid selectivity as well as the balance.

Figure 13 shows the HMF synthesis with 20% TS KH (85% fructose unit) and 0.12 wt .-% HCl / MgCl ₂ at temperatures of 162-169 ° C. Presentation of fructose conversion, HMF, faevulinic acid and formic acid selectivity as well as the balance. EXAMPLES

In the process according to the invention are used as starting materials, a fructose-containing component having a variable ratio of fructose to glucose and an aqueous solution of a salt and acid mixture. The fructose-containing component is mixed with the aqueous solution of a salt and acid mixture, so that a reaction solution with a dry matter content of> 20% TS is obtained. The reaction solution thus obtained was pumped by means of an HPLC pump into the heated tubular reactor (outer diameter 8 mm, inner diameter 6 mm, length 630 mm). The tube reactor is constructed as a double tube heat exchanger in countercurrent, the temperature is controlled by means of a thermal oil in the outer jacket of the heat exchanger, the temperature of the thermal oil is controlled by means of a thermostat. After this so-called heating zone of the tubular reactor, the transition into the cooling zone takes place directly. This is also designed as a double-tube heat exchanger in countercurrent (dimensions of the product-carrying inner tube outer diameter 8 mm, inner diameter 6 mm, length 125 mm). Within the cooling zone, the reaction solution is cooled to room temperature and the reaction is stopped. Subsequently, the product mixture is filtered through a metal sintered filter (pore size 7 mhi) and freed of any resulting insoluble humic substances. The pressure in the reactor system is adjusted by means of a pressure holding valve so that a boiling of the reaction solution and thus the occurrence of vapor bubbles is avoided (about 1 MPa at 180 ° C). The following examples show the implementation of the method according to the invention with different salts and acids, different acid or salt concentrations, and different temperatures. Furthermore, comparative experiments were performed without added salt.

For all experiments, samples were taken during the experiment and analyzed by HPLC (BIORAD Aminex 87-H, 5 mmol / L sulfuric acid, 50 ° C). From the

Analysis results were then fructose, HMF selectivity and balance (balance = (sum of unreacted sugars, HMF and formic acid (in mol) * 100 / used sugar (in mol)) .Lävulinsäure is not included in the balance, as ever Molecular formic acid and levulinic acid arise from one molecule of HMF. Example 1: HMF synthesis with 0.08% by weight hydrochloric acid (comparative experiment without addition of salt)

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with DI water and hydrochloric acid added so that the resulting solution had a dry matter content of 20% TS and a hydrochloric acid content of 0.08 wt% based on the total solution (corresponding to 0.025 mol / L). The pH of the reaction solution was 1.52. This reaction solution was then reacted with a residence time of 5.6 minutes in the heating zone at a temperature of 145 ° C - 152 ° C (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady-state. The results for fructose conversion, HMF, faevulinic and formic acid selectivity and balance are shown in FIG. 6 and Table 1.

Table 1: Fructose conversion, HMF, levulinic acid and formic acid selectivity and balance as a function of the reaction temperature using 0.08 wt .-% HCl.

Example 2: HMF synthesis with 0.18% by weight of nitric acid (comparative experiment without salt addition)

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with demineralized water and nitric acid added so that the resulting solution had a dry matter content of 20% TS and a nitric acid content of 0.18% by weight based on the total solution (corresponding to 0.03 mol / l). The pH of the reaction solution was 1.44. This reaction solution was then reacted with a residence time of 5.6 minutes in the heating zone at a temperature of 145 ° C - 150 ° C (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady-state. The results for fructose sales, HMF-, Faevulinic and formic acid selectivity and balance are shown in Figure 7 and Table 2.

Table 2: Fructose conversion, HMF, levulinic and formic acid selectivity and balance as a function of the reaction temperature using 0.18 wt .-% HNO ₃ .

Example 3: HMF synthesis with sodium chloride / hydrochloric acid mixtures - Influence of the sodium chloride / hydrochloric acid ratio

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with deionized water and admixed with hydrochloric acid and sodium chloride in the desired ratio, so that the resulting solution had a dry matter content of 20% TS and a chloride content of 0.09% by weight based on total solution (corresponding to 0.03 mol / l) had. Chloride / sodium ratios, salt / acid ratio and resulting pH are shown in Table 3.

Table 3: Chloride contents, chloride / sodium ratio, salt / acid ratio and pH values and used reaction temperatures of the reaction solutions used in Example 3.

These reaction solutions were then reacted with a residence time of 5.6 minutes in the heating zone at the reaction temperatures indicated in Table 3 (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady state. In Figure 8 and Table 4, the necessary reaction temperatures and the resulting HMF, Fävulinsäure- and formic acid selectivities and balances are each shown at a fructose conversion of -18%.

Table 4: HMF, levulinic acid and formic acid selectivity and balance at the reaction temperature required for 18% fructose conversion, depending on the sodium content (at constant chloride concentration).

It turns out that with increasing sodium content and thus increasing pH value, although a higher temperature is necessary to achieve the same conversion (see FIG. 6), at the same time the achieved selectivity for HMF increases from 85% without sodium up to 94% at 500 mg / L sodium.

Example 4: HMF synthesis with sodium nitrate / nitric acid mixtures - Influence of the sodium nitrate / nitric acid ratio

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with DI water and with nitric acid and Sodium nitrate added in the desired ratio, so that the resulting solution had a dry matter content of 20% TS and a nitrate content of 0.19 wt .-% based on total solution (corresponding to 0.03 mol / l) had. The nitrate / sodium ratios, salt / acid ratio and resulting pH are shown in Table 5.

Table 5: Nitrate contents, nitrate / sodium ratio, salt / acid ratio and pH values and reaction temperatures used of the reaction solutions used in Example 4.

These reaction solutions were then reacted with a residence time of 5.6 minutes in the heating zone at the reaction temperatures indicated in Table 5 (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady state.

In Figure 9 and Table 6, the necessary reaction temperatures and the resulting HMF, levulinic and formic acid selectivities and the balances are each shown at a Fructoseumsatz of ~ 20%. Again, it can be seen that with increasing sodium content and thus increasing pH, a higher temperature is necessary to achieve the same sales, but at the same time the selectivity to HMF increases significantly from 86.3% (at 19.7% conversion) without sodium to 93.1% (at 17.6% conversion) at 600 mg / l sodium. The selectivities to the by-products levulinic and formic acid are also lower in the presence of sodium, when the same sales are compared.

Table 6: HMF, levulinic acid and formic acid selectivity and C balance at the reaction temperature required for 18% fructose conversion as a function of the sodium content (at constant nitrate concentration).

Example 5: HMF synthesis with hydrochloric acid / sodium chloride mixtures - influence of the concentration of the acid / salt mixture

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with deionized water and treated with a mixture of hydrochloric acid and sodium chloride, which had a chloride / sodium ratio of 1.3. Thus, various reaction solutions were prepared, all having a dry matter content of 20% TS and a variable acid / salt mix concentration between 0.01 and 0.75 wt% based on the total solution. These reaction solutions were then reacted with a residence time of 5.6 minutes in the heating zone at the reaction temperatures indicated in Table 7 (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady state.

Table 7: Concentration of the hydrochloric acid / sodium chloride mixture, pH values and reaction temperatures of the reaction solutions used in Example 5.

In Figure 10 and Table 8, the necessary reaction temperatures and the resulting HMF, levulinic and formic acid selectivities and the balances are each shown at a Fructoseumsatz of ~ 20%.

Table 8: HMF, levulinic acid and formic acid selectivity and balance at different reaction temperatures as a function of the concentration of the acid / salt mixture at a constant chloride / sodium ratio. With increasing salt concentration significantly lower temperatures are necessary to achieve the same conversion. It can also be seen that the high HMF selectivities of ~ 90% are still achieved even at high fructose conversions of> 30%.

Example 6: HMF synthesis with nitric acid / sodium nitrate mixtures - influence of the concentration of the acid / salt mixture

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with deionized water and treated with a mixture of nitric acid and sodium nitrate, which had a nitrate / sodium ratio of 1.2. Thus, various reaction solutions were prepared, all of which had a dry matter content of 20% TS and a variable acid / salt mix concentration of between 0.01 and 1.5% by weight, based on total solution. These reaction solutions were then reacted with a residence time of 5.6 minutes in the heating zone at the reaction temperatures indicated in Table 9 (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady-state.

Table 9: Concentration of the nitric acid / sodium nitrate mixture, pH values and reaction temperatures of the reaction solutions used in Example 5.

In Figure 11 and Table 10, the necessary reaction temperatures and the resulting HMF, Fävulinsäure- and formic acid selectivities and the balances are each shown at a Fructoseumsatz of ~ 27%.

Table 10: HMF, levulinic acid and formic acid selectivity and balance at different reaction temperatures as a function of the concentration of the acid / salt mixture at a constant nitrate / sodium ratio.

With increasing salt concentration significantly lower temperatures are necessary to achieve the same conversion. It can also be seen that the high HMF selectivity of ~ 90% is still achieved even with high fructose conversions of> 37%. Even with a fructose conversion of ~ 47%, an HMF selectivity of ~ 89% is achieved.

Example 7: HMF synthesis with 0.11% by weight hydrochloric acid / calcium chloride mixture The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with demineralized water and treated with a mixture of hydrochloric acid and calcium chloride, which resulted in the same amount of free acid as in Example 5 with 0.12 wt% HCl / NaCl, Table 7 Experiment 2. The pH Value of the reaction solution was 2.08. This reaction solution was then reacted with a residence time of 5.6 minutes in the heating zone at a temperature of 165 ° C - 169 ° C (temperature of the thermal oil). After each temperature increase, the system was given 2 hours in the steady-state reach. The results for fructose conversion, HMF, faevulinic and formic acid selectivity and balance are shown in FIG. 12 and Table 11.

Table 11: Fructose conversion, HMF, levulinic acid and formic acid selectivity and C balance as a function of the reaction temperature when using 0.12% by weight of HCl / CaCl ₂ .

Example 8: HMF synthesis with 0.12% by weight hydrochloric acid / magnesium chloride mixture

The educt used was a fructose syrup with 85% fructose unit and a TS content of 75%. The fructose syrup was diluted with deionised water and treated with a mixture of hydrochloric acid and magnesium chloride, which resulted in the same amount of free acid as in Example 5 with 0.12 wt% HCl / NaCl, Table 7 Experiment 2. The pH Value of the reaction solution was 2.09. This reaction solution was then reacted with a residence time of 5.6 minutes in the heating zone at a temperature of 162 ° C - 169 ° C (temperature of the thermal oil). After each temperature increase, the system was given 2 hours to reach the steady state. The results for fructose conversion, HMF, faevulinic and formic acid selectivity and balance are shown in FIG. 13 and Table 12.

Table 12: Fructose conversion, HMF, levulinic acid and formic acid selectivity and the balance as a function of the reaction temperature using 0.12 wt .-% HCl / MgCl ₂ . Examples 7 and 8 show that the positive effects with regard to the high HMF selectivities are achieved even when other cations (here calcium and magnesium) are used.

Claims

A process for preparing 5-hydroxymethylfurfural (HMF) comprising the steps of: a) providing a fructose-containing component and a catalyst system comprising a solution of a salt and acid mixture, b) mixing the fructose-containing component with the catalyst system to obtain a Reaction solution, c) reacting the fructose present in the reaction solution to HMF at a temperature of 90 ° C to 200 ° C to obtain a liquid HMF-containing product mixture and d) obtaining a liquid HMF-containing product mixture.

2. The method of claim 1, wherein the acid is a mineral acid and / or an organic acid and the salt is a salt of a mineral acid and / or an organic acid.

3. The method according to claim 1 or 2, wherein the mineral acid is in particular selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; and the organic acid is in particular selected from the group consisting of acetic acid, citric acid, tartaric acid, oxalic acid, glycolic acid and gluconic acid.

A process according to any one of the preceding claims wherein the salt of a mineral acid is especially selected from the group consisting of alkali halides, alkaline earth halides, alkali nitrates, alkaline earth nitrates, alkali sulphates, alkaline earth sulphates, alkali phosphates, alkaline earth phosphates and mixtures thereof; and the salt of an organic acid, in particular, is selected from the group consisting of acetates, citrates, tartrates, oxalates, glycolates, gluconates and mixtures thereof.

5. The method according to any one of the preceding claims, wherein the concentration of the salt and acid mixture 0.01 to 2.00 wt .-% (based on total weight of the reaction solution obtained in step b)).

6. The method according to any one of the preceding claims, wherein the pH of the reaction solution obtained in step b) 1.2 to 4.5, preferably 1.5 to 3, is.

7. The method according to any one of the preceding claims, wherein in step b) a reaction solution having a carbohydrate content of 5 to 50% by weight (dry matter Carbohydrate with respect to total weight of reaction solution) and used in process step c).

8. The method according to any one of the preceding claims, wherein in step b), a reaction solution having a fructose content of 40 to 100 wt .-% (dry matter fructose with respect to dry matter carbohydrate) and in step c) is used.

9. The method according to any one of the preceding claims, wherein the fructose-containing component is a solid fructose-containing component, in particular fructose, or a liquid fructose-containing component, in particular a fructose syrup or a fructose solution.

10. The method according to any one of the preceding claims, wherein the ratio of salt to free acid in the reaction solution obtained in step b) is 0.8 to 10 (mol / mol).

11. The method according to any one of the preceding claims, wherein the ratio of anions of the salt and acid mixture to cations of the salt of the salt and acid mixture in the reaction solution obtained in step b) 0.5 to 4 (mol / mol).

12. The method according to any one of the preceding claims, wherein the concentration of anions of the catalyst system in the reaction solution obtained in step b) 1 xlO ⁵ to 0.6 mol / 1.

13. The method according to any one of the preceding claims, wherein the provided in step a) fructose-containing component, the catalyst system or both before step b) are set to a temperature of 90 ° C to 200 ° C or wherein the obtained in step b) Reaction solution is adjusted to a temperature of 90 ° C to 200 ° C.

14. The method according to any one of the preceding claims, wherein the method is performed so that in process step c) a fructose conversion of 1 to 50 mol% is achieved.

15. The method according to any one of the preceding claims, wherein the method is adjusted so that in step c) an HMF selectivity of 60 to 100 mol% is obtained.

16. The method according to any one of the preceding claims, wherein no further catalytically active component is used in the method apart from the catalyst system.

17. V experienced according to any one of the preceding claims, comprising the step: e) cooling the liquid HMF product mixture to a temperature of 20 ° to 80 ° C.

18. The method according to any one of the preceding claims, comprising the step: f) filtration, decolorization and / or purification of the liquid HMF product mixture.

A method according to any one of the preceding claims, comprising the step of: g) adjusting the liquid HMF product mixture to a dry matter content of from 20 to 70% by weight.

20. The method according to any one of the preceding claims, comprising the steps: h) Purification of the liquid HMF product mixture by chromatography, ultra- and / or nanofiltration, extraction with a suitable extraction agent, adsorption to a suitable material and subsequent targeted desorption and / or electrodialysis for separating at least one HMF fraction, and i) obtaining at least one HMF fraction.

21. The method of claim 20, wherein the liquid HMF product mixture in step h) is separated by chromatography into at least four fractions comprising an HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction and in step i ) at least one HMF fraction, a glucose fraction, a fructose fraction and an organic acid fraction is obtained.

22. The method according to claim 21, wherein the fructose fraction obtained in process step i) is recycled to step a).

23. The method according to any one of the preceding claims 21 to 22, wherein the obtained in step i) glucose fraction is used for the production of ethanol.

24. The method according to any one of the preceding claims 21 to 23, wherein the organic acid fraction obtained in step i) is used for the isolation of levulinic and formic acid.

25. The method according to any one of the preceding claims 20 to 24, wherein the obtained in step i) HMF fraction is oxidized directly and without the need for further purification in a further step to 2,5-furandicarboxylic acid (FDCA).