PROCESS FOR MANUFACTURING HYDROXYMETHYLFURFURAL

Abstract

A process for producing 5-hydroxymethylfurfural (HMF) including a) a step of converting a carbohydrate into HMF, the converting step including providing a reaction medium including carbohydrate, catalyst, water, tetrahydrofuran (THF), and salt to form a biphasic solvent system including an aqueous phase and a THF phase and b) a step of separating the THF phase and the aqueous phase, to provide a separate THF phase and a separate aqueous phase, wherein an organic quaternary ammonium salt is present. The process results in a high conversion of carbohydrate and in the formation of HMF in high selectivity with low formation of side products, together with an efficient extraction of HMF into the THF phase.

Claims

1. A process for producing 5-hydroxymethylfurfural (HMF) comprising a) a step of converting a carbohydrate into HMF, the converting step comprising providing a reaction medium comprising carbohydrate, catalyst, water, tetrahydrofuran (THF), and salt to form a biphasic solvent system comprising an aqueous phase and a THF phase and b) a step of separating the THF phase and the aqueous phase, to provide a separate THF phase and a separate aqueous phase, wherein an organic quaternary ammonium salt is present.

2. The process according to claim 1, wherein the carbohydrate is selected from the group of lignin, sugars, starches, celluloses, and gums.

3. The process according to claim 2, wherein the carbohydrate is a sugar selected from C5 sugars such as arabinose, xylose and ribose; C6 sugars such as glucose, fructose, galactose, rhamnose and mannose; and C12 sugars such as sucrose, maltose and isomaltose.

4. The process according to claim 1, wherein the organic quaternary ammonium salt is an organic quaternary ammonium chloride.

5. The process according to claim 1, wherein the catalyst is selected from the group of halides of chromium and aluminium.

6. The process according to claim 1, wherein the organic quaternary ammonium salt is present in an amount of at least 10 wt. %, calculated on the total of carbohydrate, water, and salt.

7. The process according to claim 1, wherein the weight ratio of THF to aqueous solution containing carbohydrate and salt is in the range of 0.05:1 to 10:1.

8. The process according to claim 1, wherein the reaction is carried out at a temperature in the range of 80-180° C. for a period of 1 minute to 4 hours.

9. The process according to claim 1, wherein the step of separating the THF phase and the aqueous phase to provide a separate THF phase and a separate aqueous phase is carried out at a temperature at or below the reaction temperature.

10. The process according to claim 1, wherein the separated THF phase which contains HMF is subjected to a separation step, with THF being separated off, optionally after addition of water to the HMF-containing THF phase.

11. The process according to claim 1, wherein one or more of the following steps take place: THF resulting from the separation of HMF from the HMF-containing THF phase is recycled to the reaction step, aqueous phase comprising organic quaternary ammonium salt and, where the catalyst is homogeneous, catalyst is recycled to the reaction step, optionally after intermediate purification and/or concentration.

12. The process according to claim 1, which comprises the further step of converting the HMF to FDCA.

13. The process according to claim 12, which comprises the further step of reacting the FDCA in a polycondensation reaction with ethyleneglycol to form poly(ethylenefurandicarboxylate).

Description

EXAMPLE 1: GLUCOSE TO HMF

[0057] In an experiment according to the invention, an aqueous solution of 10 wt. % of glucose, 5 mole % of CrCl3 as catalyst (calculated on glucose) and 63 wt. % choline chloride was combined with THF in a weight/weight ratio of 1:1, forming a biphasic mixture, and brought to a reaction temperature of 130° C.

[0058] The results are presented in table 1 below:

TABLE-US-00001 TABLE 1 Results Selectivity towards HMF HMF HMF [mol HMF Glucose conversion [mol concentration - concentration- produced/mol glucose reacted/mol organic phase aqueous phase glucose converted, t [min] glucose fed, %] [wt %] [wt %] %] 10 11.0 0.02 0.01 3.8 20 44.0 0.91 0.36 40.6 30 69.2 2.00 0.81 57.0

[0059] As can be seen from Table 1, the process according to the invention makes it possible to produce HMF from glucose with good conversion and good selectivity.

EXAMPLE 2: COMPARISON OF CHOLINE CHLORIDE OR NACL IN THE AQUEOUS MEDIUM

[0060] In an experiment according to the invention, an aqueous solution of 10 wt. % of glucose, 5 mole % of CrCl3 as catalyst (calculated on glucose) and 45 wt. % choline chloride was combined with THF in a weight/weight ratio of 1:1 and brought to a reaction temperature of 130° C.

[0061] In a comparative experiment, 18.8 wt. % of NaCl was used, rather than 45 wt. % of choline chloride (equimolar amount).

[0062] The results are presented in Tables 2 and 3 below. Table 2 provides data on the sugar conversion. Table 3 provides data on the selectivity to HMF.

TABLE-US-00002 TABLE 2 Sugar conversion [mol glucose reacted/mol glucose fed %] example with 18.8 wt. % example with 45 wt. % NaCl (comparative) cholinechloride (invention) t = 40 min 52% 63% t = 60 min 59% 73%

TABLE-US-00003 TABLE 3 Selectivity towards HMF [mol HMF produced/mol glucose converted %]] example with 18.8 wt. % example with 45 wt. % NaCl (comparative) cholinechloride (invention) t = 40 min 17% 47% t = 60 min 12% 69%

[0063] From the tables it can be seen that the glucose conversion is higher when cholinechloride is used. Additionally, and even more noticeable, the selectivity for HMF is much higher for the system according to the invention which contains cholinechloride (69% versus 12%). The increased selectivity means that the process according to the invention yields more HMF per gram glucose, and less side products.

EXAMPLE 3: EXPERIMENT IN CONTINUOUS MODE WITH SUCROSE

[0064] In an experiment according to the invention, an aqueous solution of 18 wt. % of sucrose, 10 mole % of CrCl3 as catalyst (calculated on sucrose) and 63 wt. % choline chloride was continuously fed to a stirred tank reactor. At the same time, a continuous flow of THF was also fed to the stirred tank reactor. The ratio of aqueous flow to organic flows was 1:1 wt/wt.

[0065] The flows were set in order to achieve 20 minutes residence time. The reaction temperature was achieved by heating in the jacketed stirred tank reactor, and controlled via an oil bath to T=120° C.

[0066] The samples are taken after cooling down the mixed outflow to room-temperature and phase separation.

[0067] The results are presented in Tables 4 and 5 below. Table 4 provides data on the sugar conversion. Table 5 provides data on the selectivity to HMF and concentrations of HMF in both aqueous and organic phases.

TABLE-US-00004 TABLE 4 Sugar conversion [mol sucrose reacted/mol sucrose fed %] Sugar conversion [mol sucrose reacted/mol sucrose fed %] Average after steady-state 69 ± 1%

TABLE-US-00005 TABLE 5 Selectivity and HMF extraction Selectivity towards HMF [mol HMF % of HMF % of HMF produced/mol in THF in water sucrose phase (calculated phase (calculated converted %] on total HMF) on total HMF) Average after 62 ± 1% 59% 41% steady-state

[0068] From these tables it can be seen that the process according to the invention allows the conversion of sucrose into HMF through a continuous process with high conversion and high selectivity.

EXAMPLE 4: EXPERIMENT IN CONTINUOUS MODE WITH GLUCOSE AT DIFFERENT O/A RATIOS

[0069] In an experiment according to the invention, an aqueous solution of 10 wt. % of glucose, 5 mole % of CrCl3 as catalyst (calculated on glucose) and 63 wt. % choline chloride was combined with THF in a variable weight/weight ratio and brought to a reaction temperature of 130° C. in a co-current plug-flow reactor. Range of Organic/Aqueous ratio tested comprises: 0.2:1-1:1 wt/wt. The residence time inside the plug-flow reactor was 20 min.

[0070] The results are presented in Tables 6 and 7 below. Table 6 provides data on the sugar conversion. Table 7 provides data on the selectivity to HMF.

TABLE-US-00006 TABLE 6 Sugar conversion [mol glucose reacted/mol glucose fed %] Sugar conversion [mol glucose reacted/molglucose fed] example with organic-to- 75.5% aqueous ratio 0.20:1 example with organic-to- 74.2% aqueous ratio 0.49:1 example with organic-to- 63.5% aqueous ratio 0.92:1

TABLE-US-00007 TABLE 7 Selectivity towards HMF [mol HMF produced/mol glucose converted %] Selectivity towards HMF [mol HMF produced/mol glucose converted %] example with organic-to- 61.1% aqueous ratio 0.20:1 example with organic-to- 62.3% aqueous ratio 0.49:1 example with organic-to- 71.4% aqueous ratio 0.92:1

[0071] From these tables it can be seen that all ranges lead to a good conversion and selectivity. A higher organic-to-aqueous ratio leads to higher selectivity. A lower organic-to-aqueous ratio leads to higher conversion.

EXAMPLE 5: EXPERIMENT IN CONTINUOUS MODE WITH FRUCTOSE AS STARTING SUGAR

[0072] In an experiment according to the invention, an aqueous solution of 10 wt. % of fructose, 5 mole % of CrCl3 as catalyst (calculated on fructose) and 63 wt. % choline chloride was combined with THF in a 0.5 weight/weight ratio and brought to a reaction temperature of 100, 110 or 120° C. in a co-current plug-flow reactor. The residence time inside the plug-flow reactor was 20 min.

[0073] The results are presented in Tables 8 and 9 below. Table 8 provides data on the sugar conversion. Table 9 provides data on the selectivity to HMF.

TABLE-US-00008 TABLE 8 Sugar conversion [mol fructose reacted/mol fructose fed %] Sugar conversion [mol fructose reacted/molfructose fed] Temperature 100° C. 33.7% Temperature 110° C. 71.1% Temperature 120° C. 91.9%

TABLE-US-00009 TABLE 9 Selectivity towards HMF [mol HMF produced/mol sugar converted %] Selectivity towards HMF [mol HMF produced/mol fructose converted %] Temperature 100° C. 61.0% Temperature 110° C. 66.7% Temperature 120° C. 68.5%

[0074] From the tables it can be seen that higher temperatures lead to higher conversion and a benefit in terms of selectivity.