METHOD FOR PREPARING 2,5-DIMETHYLFURAN BY DIRECTLY CATALYZING CARBOHYDRATE USING MODIFIED PD/C

Abstract

A preparation method of an acidic and hydrophobic Pd/C catalytic material comprises performing a simple treatment with chlorosulfonic acid and trimethylchlorosilane, washing and drying a treatment product to obtain a modified Pd/C catalytic material. A method for preparing 2,5-methylfuran by catalyzing a carbohydrate with modified Pd/C comprises: dissolving the carbohydrate in alcohol, allowing a reaction to proceed with modified Pd/C as a catalyst and polymethylhydrosiloxane as a hydrogen donor at a temperature of 80140 C. for 1-5 hours, and performing centrifugation to separate the catalyst from the product. The content of the modified Pd/C content is 1-3 mol % relative to the carbohydrate; the polymethylhydrosiloxane amount is equivalent to 4-10 times the carbohydrate amount, and the carbohydrate concentration in the alcohol is 2-6 wt %. The method overcomes the defect of being difficult to prepare the 2,5-methylfuran by directly catalyzing the carbohydrate, and features moderate reaction conditions and high activity.

Claims

1-6. (canceled)

7. A method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C, comprising: heating a mixture solution comprising the carbohydrates, the modified Pd/C as a catalyst, and a hydrogen donor to obtain the 2,5-methylfuran; wherein the modified Pd/C is obtained by treating Pd/C with chlorosulfonic acid to obtain an acidic Pd/C catalytic material, and then reacting the acidic Pd/C catalytic material with trimethylchlorosilane.

8. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein the modified Pd/C comprises a Pd content within a range of 0.515 wt %.

9. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein the hydrogen donor is polymethylhydrosiloxane.

10. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 9, wherein an amount of the polymethylhydrosiloxane is equivalent to 4-10 times by weight an amount of the carbohydrates used.

11. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein the mixture solution further comprises an alcohol as a solvent, and an concentration of the carbohydrates relative to the alcohol is about 2-6 wt %.

12. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein the carbohydrates are hexose, including fructose, glucose, maltose, saccharose, cellose, starch, synanthrin or cellulose.

13. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 11, wherein the alcohol is methanol, ethanol, n-propanol, n-butanol or n-hexanol.

14. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein heating the mixture solution is performed at a temperature in a range of about 80140 C. for a time in a range of about 1-5 hours.

15. The method of preparing 2,5-methylfuran by directly catalyzing carbohydrates with modified Pd/C according to claim 7, wherein treating Pd/C with chlorosulfonic acid to obtain the acidic Pd/C catalytic material comprises: dispersing Pd/C in methylene dichloride to obtain a Pd/C dispersion, and reacting the Pd/C solution with chlorosulfonic acid at room temperature to obtain the acidic Pd/C catalytic material.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0033] FIG. 1 shows the distribution of modified 5 wt % Pd/C in water and in butanol (left) and the contact angle of surface water drops (right);

[0034] FIG. 2 shows the distribution of 5 wt % Pd/C in water and in butanol (left) and the contact angle of surface water drops (right);

[0035] FIG. 3 is an XRD spectrogram obtained after the modified Pd/C is used for six times repeatedly (upper) and an XRD spectrogram of the modified Pd/C that is newly manufactured (lower).

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1

(1) Preparation of Modified 5 Wt % Pd/C

[0036] The preparation mainly involves the following two processes: (A) 0.5 g of 5 wt % Pd/C was weighed and added into 15 mL of methylene dichloride, and the mixed materials were stirred until they were homogeneously distributed. Next, 0.2 mL of chlorosulfonic acid was slowly dropped (about 2 min) to obtain a mixture; the mixture was stirred for 12 hours at room temperature, and then was filtered and repeatedly washed with methylene dichloride and water in turn until filtrate was neutral; a product obtained after the filtration was dried in vacuum at a temperature of 90 C. for 6 hours to obtain an acidic Pd/C catalytic material. (B) 0.25 g of the obtained acidic Pd/C catalytic material was weighed and placed in 7.5 mL of cyclohexane to obtain a mixed system; then, 1.5 mL of trimethylchlorosilane was slowly added into the mixed system drop by drop; after dropping, the obtained mixture was heated to a temperature of 60 C. and continuously stirred for 12 hours at the temperature of 60 C. to make sure that a reaction proceeded; after the reaction ends, the obtained reaction product was washed with n-hexane for 5 times, dried in vacuum at a temperature of 90 C. for 6 hours, and then ground to obtain the acidic and hydrophobic Pd/C catalytic material, namely the modified 5 wt % Pd/C.

[0037] From FIG. 1 it can be seen that the modified 5 wt % Pd/C was homogeneously dispersed in the n-butanol, but was basically separated from water (left figure); at the same time, a relatively large water drop contact angle (134) also verified that the modified 5 wt % Pd/C had high hydrophobicity (right figure). Besides, an acid-base titration also verifies that the catalytic material has a relatively high acid content (1.1 mmol/g). Thus, it can be judged that the modified 5 wt % Pd/C has relatively ideal hydrophobicity and acidity at the same time.

(2) Preparation of the 2,5-methylfuran by Directly Catalyzing Fructose

[0038] 6 wt % fructose, 1.5 mL of n-butanol, 2 mol % modified 5 wt % Pd/C and 9 equivalent times (relative to the fructose) of polymethylhydrosiloxane were added into a 15 mL pressure-resistant glass reactor; the mixed materials were heated to a temperature of 80 C. and then stirred for 4 hours at the temperature of 80 C., or heated to a temperature of 120 C. and stirred for 1 hour at the temperature of 120 C. to make sure that a reaction proceeded. After the reaction ended, centrifugation was carried out to separate the solid catalyst, and the conversion rate of the fructose and the yield of the 2,5-methylfuran in the reaction liquid were respectively determined using HPLC (High Performance Liquid Chromatography) and GC (Gas Chromatography). Standard curves of corresponding standard solutions were prepared, and peak areas of samples to be measured were brought into the curves to obtain the conversion rate of the fructose and the yield of the 2,5-methylfuran, which were 96% and 88%, respectively.

[0039] (3) The solid catalyst obtained after filtration and separation was washed for 4-6 times respectively using ethanol and n-hexane, then dried at a temperature of 90 C. for 5-12 hours, and ground to obtain a regenerative catalyst; the regenerative modified 5 wt % Pd/C was used to directly catalyze the fructose to prepare the 2,5-methylfuran, wherein the amounts of the raw materials and the reaction conditions were respectively identical with those in Embodiment 1(2); liquid chromatography and gas chromatography were carried out to obtain the conversion rate of the fructose and the field of the 2,5-methylfuran in the reaction mixed liquid, which were 98% and 92%, respectively. Correspondingly, the almost the same XRD spectrograms (FIG. 3) obtained before and after the use of the modified 5 wt % Pd/C also well proved that the catalytic material had a stable structure.

Comparative Example 1

[0040] 5 wt % Pd/C used was a commercially available reagent, purchased from Beijing Innochem Scientific Co., Ltd. FIG. 2 shows that the 5 wt % Pd/C had good hydrophily (left figure), and a relatively low water drop contact angle (28) also reflected that the material had an average hydrophobic ability.

[0041] The commercially available 5 wt % Pd/C obtained using such embodiment was used to catalyze fructose to prepare 2,5-methylfuran, and the amounts of all raw materials, reaction conditions, sample test methods were identical with those in Embodiment 1 (2). After the reaction ended, the conversion rate of the fructose and the yield of the 2,5-methylfuran in the mixed solution were measured through liquid and gas chromatography, which were 52% and 43%, respectively.

[0042] Correspondingly, 5 wt % Co/C, 5 wt % Ni/C, 5 wt % Ru/C and 5 wt % Pt/C were used to catalyze fructose under the same reaction conditions to prepare the 2,5-methylfuran, and the yields were 0, 0, 10% and 20%, respectively.

Embodiment 2

(1) Preparation of Modified 2 Wt % Pd/C

[0043] The preparation mainly involves the following two processes: (A) 0.5 g of 2 wt % Pd/C was weighed and added into 15 mL of methylene dichloride, and the mixed materials were stirred until they were homogeneously distributed. Next, 0.1 mL of chlorosulfonic acid was slowly dropped (about 1 min) to obtain a mixture; the mixture was stirred for 12 hours at room temperature, and then was filtered and repeatedly washed with methylene dichloride and water in turn until the filtrate was neutral; a product obtained after the filtration was dried in vacuum at a temperature of 90 C. for 6 hours to obtain an acidic Pd/C catalytic material. (B) 0.25 g of the obtained acidic Pd/C catalytic material was weighed and placed in 7.5 mL of cyclohexane to obtain a mixed system; then, 1.5 mL of trimethylchlorosilane was slowly added into the mixed system drop by drop; after dropping, the obtained mixture was heated to a temperature of 60 C. and continuously stirred for 12 hours at the temperature of 60 C. to make sure that a reaction proceeded; after the reaction ends, the obtained reaction product was washed with n-hexane for 5 times, dried in vacuum at a temperature of 90 C. for 6 hours, and then ground to obtain the acidic and hydrophobic Pd/C catalytic material, namely the modified 2 wt % Pd/C.

(2) Preparation of the 2,5-methylfuran by Directly Catalyzing Glucose

[0044] 4 wt % glucose, 1.5 mL of n-hexanol , 1.5 mol % modified 2 wt % Pd/C and 5 equivalent times (relative to the glucose) of polymethylhydrosiloxane were added into a 15 mL pressure-resistant glass reactor; the mixed materials were heated to a temperature of 120 C. and stirred for 2 hours at the temperature of 120 C. to make sure that a reaction proceeded. After the reaction ended, centrifugation was carried out to separate the solid catalyst, and the conversion rate of the glucose and the yield of the 2,5-methylfuran in the reaction liquid were respectively determined using HPLC (High Performance Liquid Chromatography) and GC (Gas Chromatography). Standard curves of corresponding standard solutions were prepared, and peak areas of samples to be measured were brought into the curves to obtain the conversion rate of the glucose and the yield of the 2,5-methylfuran, which were 87% and 65%, respectively.

Embodiment 3

(1) Preparation of Modified 0.5 Wt % Pd/C

[0045] The preparation mainly involves the following two processes: (A) 0.5 g of 0.5 wt % Pd/C was weighed and added into 15 mL of methylene dichloride, and the mixed materials were stirred until they were homogeneously distributed. Next, 0.3 mL of chlorosulfonic acid was slowly dropped (about 3 min) to obtain a mixture; the mixture was stirred for 12 hours at room temperature, and then was filtered and repeatedly washed with methylene dichloride and water in turn until the filtrate was neutral; a product obtained after the filtration was dried in vacuum at a temperature of 90 C. for 6 hours to obtain an acidic Pd/C catalytic material. (B) 0.25 g of the obtained acidic Pd/C catalytic material was weighed and placed in 7.5 mL of cyclohexane to obtain a mixed system; then, 1.5 mL of trimethylchlorosilane was slowly added into the mixed system drop by drop; after dropping, the obtained mixture was heated to a temperature of 60 C. and continuously stirred for 12 hours at the temperature of 60 C. to make sure that a reaction proceeded; after the reaction ends, the obtained reaction product was washed with n-hexane for 5 times, dried in vacuum at a temperature of 90 C. for 6 hours, and then ground to obtain the acidic and hydrophobic Pd/C catalytic material, namely the modified 0.5 wt % Pd/C.

(2) Preparation of the 2,5-methylfuran by Directly Catalyzing Saccharose

[0046] 4 wt % saccharose, 1.5 mL of ethanol , 3 mol % modified 0.5 wt % Pd/C and 10 equivalent times (relative to the saccharose) of polymethylhydrosiloxane were added into a 15 mL pressure-resistant glass reactor; the mixed materials were heated to a temperature of 100 C. and stirred for 5 hours at 100 C. to make sure a reaction proceeded. After the reaction ended, centrifugation was carried out to separate the solid catalyst, and the conversion rate of the saccharose and the yield of the 2,5-methylfuran in the reaction liquid were respectively determined using HPLC (High Performance Liquid Chromatography) and GC (Gas Chromatography). Standard curves of corresponding standard solutions were prepared, and peak areas of samples to be measured were brought into the curves to obtain the conversion rate of the saccharose and the yield of the 2,5-methylfuran, which were 95% and 83%, respectively.

Embodiment 4

(1) Preparation of Modified 15 Wt % Pd/C

[0047] The preparation mainly involves the following two processes: (A) 0.5 g of 15 wt % Pd/C was weighed and added into 15 mL of methylene dichloride, and the mixed materials were stirred until they were homogeneously distributed. Next, 0.15 mL of chlorosulfonic acid was slowly dropped (about 1.5 min) to obtain a mixture; the mixture was stirred for 12 hours at room temperature, and then was filtered and repeatedly washed with methylene dichloride and water in turn until the filtrate was neutral; a product obtained after the filtration was dried in vacuum at a temperature of 90 C. for 6 hours to obtain an acidic Pd/C catalytic material. (B) 0.25 g of the obtained acidic Pd/C catalytic material was weighed and placed in 7.5 mL of cyclohexane to obtain a mixed system; then, 1.5 mL of trimethylchlorosilane was slowly added into the mixed system drop by drop; after dropping, the obtained mixture was heated to a temperature of 60 C. and continuously stirred for 12 hours at the temperature of 60 C. to make sure that a reaction proceeded; after the reaction ends, the obtained reaction product was washed with n-hexane for 5 times, dried in vacuum at a temperature of 90 C. for 6 hours, and then ground to obtain the acidic and hydrophobic Pd/C catalytic material, namely the modified 15 wt % Pd/C.

(2) Preparation of the 2,5-methylfuran by Directly Catalyzing Synanthrin

[0048] 2 wt % synanthrin, 1.5 mL of methanol , 1 mol % modified 15 wt % Pd/C and 6 equivalent times (relative to the synanthrin) of polymethylhydrosiloxane were added into a 15 mL pressure-resistant glass reactor; the mixed materials were heated to a temperature of 140 C. and stirred for 3 hours at 140 C. to make sure a reaction proceeded. After the reaction ended, centrifugation was carried out to separate the solid catalyst, and the conversion rate of the synanthrin and the yield of the 2,5-methylfuran in the reaction liquid were respectively determined using HPLC (High Performance Liquid Chromatography) and GC (Gas Chromatography). Standard curves of corresponding standard solutions were prepared, and peak areas of samples to be measured were brought into the curves to obtain the conversion rate of the synanthrin and the yield of the 2,5-methylfuran, which were 99% and 90%, respectively.