PRODUCTION OF FURANS

Abstract

The invention relates to obtaining furans from biomass. In particular, the invention relates to obtaining furans from polyols, such as tetrahydroxybutane. In accordance with the invention tetrahydroxybutane is converted to furan in the presence of a catalyst. The tetrahydroxybutane may be dissolved in a solvent such as water.

Claims

1. Method for obtaining furan comprising providing tetrahydroxybutane and converting said tetrahydroxybutane to furan in the presence of a catalyst, wherein the tetrahydroxybutane is heated in the presence of the catalyst to a temperature of at least 130° C.

2. Method according to claim 1, wherein the tetrahydroxybutane is dissolved in a solvent, preferably a polar solvent, more preferably a polar protic solvent, most preferably water.

3. Method according to claim 1, wherein the tetrahydroxybutane is heated in the presence of the catalyst to a temperature of at least 150° C., preferably between 150 and 300° C., more preferably between 150 and 250° C., even more preferably between 175 and 225° C., most preferably about 220° C.

4. Method according to claim 1, wherein the tetrahydroxybutane is heated in the presence of the catalyst for a period of 1 to 60 minutes, preferably 5 to 30 minutes, more preferably between 10 and 20 minutes, most preferably about 16 minutes.

5. Method according to claim 1, wherein the catalyst is an acid, base or an anhydride, preferably a Brønsted acid having a pK.sub.a of less than 4, preferably less than 2, and is optionally immobilized on a solid support.

6. Method according to claim 1, wherein the catalyst is selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, acetic acid, formic acid, propylphosphonic anhydride and combinations thereof.

7. Method according to claim 1, wherein the tetrahydroxybutane is dissolved in the solvent in an concentration of 1 to 1450 g/L, preferably, 2 to 500 g/L, more preferably 4 to 200 g/L, most preferably about 10 g/L.

8. Method according to claim 1, wherein the tetrahydroxybutane is heated by microwave irradiation.

9. Method according to claim 1, wherein the tetrahydroxybutane is converted to furan at a pressure of 0 to 200 bar, preferably 5 to 50 bar, more preferably 10 to 30 bar, most preferably about 20 bar.

10. Method according to claim 1, wherein furan is selectively evaporated from the reaction mixture.

11. Method according to claim 1, wherein the tetrahydroxybutane is converted to furan in a conversion of at least 5 mol %, preferably at least 15 mol %, more preferably at least 30%.

Description

EXAMPLE 1

Preparation

[0033] Reaction mixtures were prepared according to the following procedure.

[0034] Solutions of sulfuric acid (H.sub.2SO.sub.4) in water were prepared to obtain 1 wt. %, 3 wt. % and 15 wt. % aqueous H.sub.2SO.sub.4 solutions.

[0035] 500 mL duran bottles were charged with either 5, 50 or 725 gram of erythritol and a 1 wt. %, 3 wt. % or 15 wt. % H.sub.2SO.sub.4 solution such that a total volume of 500 mL was obtained. The bottle was placed in an ultrasonic bath, connected to a vacuum pump and evacuated during 15 min while the ultrasonic batch was turned on. Next, the headspace of the bottle was flushed with nitrogen and the cap of the bottle was replaced by a septum.

Reaction

[0036] In an anaerobic glovebox, a reaction vessel was charged with 10 mL of the prepared reaction mixture and sealed with a septum. The reaction vessel was loaded in a microwave (Monowave 300 from Anton Paar GmbH, Austria). The desired temperature and reaction time were programmed in the microwave according to Table 1 and the reaction was started.

Sample Preparation and Analysis

[0037] After completion of the programmed reaction time, the reaction vessel was removed from the microwave, cooled and the gas in the headspace of the reaction vessel was transferred to a headspace vial for analysis. The furan concentration in both the liquid and the gas resulting from the reaction was determined by a gas chromatography/mass spectroscopy apparatus (GC-MS) using standard techniques.

[0038] Gas chromatography was performed on a HP6890 with a Factorfour VF-1301 column of 30 m*0.25 mm, df. 1 μm, with helium as the carrier gas using an optimized temperature program.

[0039] Mass spectroscopy was performed on a Agilent 5973N MSD, with an EI ionization modus and mass detection range of 25-550 m/z.

[0040] The liquid resulting from the reaction was prepared for GS-MS analysis by extracting 1 mL reaction mixture with 1 mL dichloromethane or ethyl acetate and injecting the organic layer in the GS-MS.

Results

[0041] Results of the experiments are shown in Table 1.

TABLE-US-00001 TABLE 1 Concentration Concentration furan in furan in erythritol H.sub.2SO.sub.4 Temp Time Headspace Liquid Conversion. Sample (g/L) (wt. %) (° C.) (min) (mg/L) (mg/L) (%) 1 10 1 220 16 2 201 3.6 2 10 1 180 16 0.1 14 0.25 3 10 1 220 4 1.1 106 1.9 4 1450 1 180 4 0.04 4 0 5 1450 1 220 16 5.2 515 0.06 6 10 3 180 16 0.6 57 1.0 7 10 3 220 4 2.2 223 4.0 8 10 3 180 4 0.2 22 0.39 9 10 15 220 16 9.5 951 17 10 10 15 180 16 1.7 169 3.0 11 10 15 220 4 5 498 8.9 12 10 15 180 4 1.2 116 2.1 13 100 3 220 16 16.3 1630 2.9 14 100 3 220 4 11.8 1184 2.1 15 100 3 180 16 2.7 274 0.49 16 100 3 180 4 1.1 115 0.21

EXAMPLE 2

[0042] Example 1 was repeated using different acids than H.sub.2SO.sub.4. The use of hydroiodic acid (HI), phosphoric acid (H.sub.3PO.sub.4) and hydrochloric acid produced similar results as in Example 1.

[0043] From the results of Examples 1 and 2 it may be derived that furan may be obtained using different concentrations of erythritol, different acids and acid concentrations at various temperatures for various reaction times.