Catalyst for catalytic oxidation of furfural for preparation of maleic acid, preparation method and use thereof

Abstract

A catalyst for catalytic oxidation of furfural to prepare maleic acid is composed of a carbon nitride doped with a potassium salt. A method for preparing the catalyst includes mixing the potassium salt, a precursor of the carbon nitride and a solvent to obtain a mixture, and drying and calcining the mixture to obtain the catalyst. A use of the catalyst in catalytic oxidation of furfural to prepare maleic acid, wherein the maleic acid is prepared by the step of oxidizing furfural in a solvent in the presence of the catalyst. The invention has the advantages that by using the method provided by the invention to prepare maleic acid, the conversion rate of furfural can be 99% or more and the yield of maleic acid can be up to 70.40%.

Claims

1. A method of preparing maleic acid, comprising: performing a catalytic oxidation reaction on furfural using a catalyst in a solvent; wherein the catalyst consists of a carbon nitride doped with a potassium salt.

2. The method according to claim 1, wherein an oxidant used in the catalytic oxidation reaction is one or more compounds selected from the group consisting of hydrogen peroxide, potassium permanganate, potassium chlorate and oxygen.

3. The method according to claim 1, wherein the catalytic oxidation reaction on the furfural is carried out at a temperature of 60-120° C.

4. The method according to claim 1, wherein a mass ratio of the furfural to the catalyst is 1-200:1.

5. The method according to claim 1, wherein a ratio of a volume of the solvent to a mass of the furfural is 1 mL-50 mL:1 mg.

6. The method according to claim 1, wherein the potassium salt is one selected from the group consisting of potassium bromide, potassium chloride and potassium nitrate, and a precursor of the carbon nitride is one selected from the group consisting of urea, dicyandiamide and melamine.

7. The method according to claim 1, wherein a mass ratio of the potassium salt added to a precursor of the carbon nitride added is 0.01-0.2:1.

8. The method according to claim 6, wherein an oxidant used in the catalytic oxidation reaction is one or more compounds selected from the group consisting of hydrogen peroxide, potassium permanganate, potassium chlorate and oxygen.

9. The method according to claim 7, wherein an oxidant used in the catalytic oxidation reaction is one or more compounds selected from the group consisting of hydrogen peroxide, potassium permanganate, potassium chlorate and oxygen.

10. The method according to claim 6, wherein the catalytic oxidation reaction on the furfural is carried out at a temperature of 60-120° C.

11. The method according to claim 7, wherein the catalytic oxidation reaction on the furfural is carried out at a temperature of 60-120° C.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present invention will be further described in detail below with reference to the drawings and examples of the specification.

(2) The test materials, reagents and the like, used in the following examples, are commercially available, unless otherwise specified.

Example 1

(3) A catalyst composed of carbon nitride doped with potassium bromide was prepared by the following steps: (1) 10 g of urea and 0.5 g of potassium bromide were added to 30 g of water to obtain a mixed solution, the mixed solution was then stirred at room temperature until homogeneous; (2) The stirred solution in step (1) was dried at 80° C. and then ground into a powder, before placing the powder into a crucible with a lid; (3) The powder from step (2) was placed in a muffle furnace and calcined at 550° C. for 2 hours, to obtain the catalyst composed of carbon nitride doped with potassium bromide.

(4) The alkalinity of the surface of the carbon nitride doped with potassium bromide prepared in this example was 1.61 mmol/g.

Example 2

(5) A catalyst composed of carbon nitride doped with potassium chloride was prepared by the following steps: (1) 10 g of urea and 0.5 g of potassium chloride were added to 30 g of water to obtain a mixed solution, the mixed solution was then stirred at room temperature until homogeneous; (2) The stirred solution in step (1) was dried at 80° C. and then ground into a powder, before placing the powder into a crucible with a lid; (3) The powder from step (2) was placed in a muffle furnace and calcined at 550° C. for 2 hours, to obtain the catalyst composed of carbon nitride doped with potassium chloride.

Example 3

(6) A catalyst composed of carbon nitride doped with potassium nitrate was prepared by the following steps: (1) 10 g of urea and 0.5 g of potassium nitrate were added to 30 g of water to obtain a mixed solution, the mixed solution was then stirred at room temperature until homogeneous; (2) The stirred solution in step (1) was dried at 80° C. and then ground into a powder, before placing the powder into a crucible with a lid; (3) The powder from step (2) was placed in a muffle furnace and calcined at 550° C. for 2 hours, to obtain the catalyst composed of carbon nitride doped with potassium nitrate.

Example 4

(7) A catalyst composed of carbon nitride was prepared by the following steps: (1) 10 g of urea was added to 30 g of water to obtain a mixed solution, the mixed solution was then stirred at room temperature until homogeneous; (2) The stirred solution in step (1) was dried at 80° C. and then ground into a powder, before placing the powder into a crucible with a lid; (3) The powder from step (2) was placed in a muffle furnace and calcined at 550° C. for 2 hours, to obtain the catalyst composed of carbon nitride.

Example 5

(8) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 1. The preparation method includes the following steps:

(9) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium bromide prepared in Example 1 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube, and then 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 3 hours. Immediately after completion of this process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain the filter residue (carbon nitride doped with potassium bromide), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(10) The components in the above filtrate were detected. The results showed that the main component of the filtrate was maleic acid with a yield of 70.40%.

(11) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was 99% or more.

Example 6

(12) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst prepared in Example 2. The preparation method includes the following steps:

(13) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium chloride prepared in Example 2 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube and 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and the above solution was placed in an oil bath at the rotation speed of 500 rpm, while raising the temperature to 100° C. for 3 hours. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain the filter residue, which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(14) The components in the above filtrate were detected. The results showed that the components of the filtrate were maleic acid, furanone and succinic acid whose yields were 21.12%, 26.19% and 22.41%, respectively.

(15) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was 99% or more.

Example 7

(16) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 3. The preparation method includes the following steps:

(17) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium nitrate prepared in Example 3 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube, and 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at the rotation speed of 500 rpm, while raising the temperature to 100° C. for 3 hours. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride doped with potassium nitrate), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(18) The components in the above filtrate were detected. The results showed that the main components of the filtrate were maleic acid, furanone and succinic acid whose yields were 13.32%, 27.48% and 32.58%, respectively.

(19) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was 99% or more.

Example 8

(20) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 4. The preparation method includes the following steps:

(21) 1 mmol of furfural and 50 mg of carbon nitride prepared in Example 4 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube, and 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 3 hours. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(22) The components in the above filtrate were detected. The results showed that the main components of the filtrate were maleic acid, furanone and succinic acid whose yields were 16.82%, 27.01% and 24.72%, respectively.

(23) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was 99% or more.

Example 9

(24) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 4. The preparation method includes the following steps:

(25) 1 mmol of furfural, 25 mg of carbon nitride prepared in Example 4 and 25 mg of potassium bromide were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube, and 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 3 hours. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(26) The components in the above filtrate were detected. The results showed that the main component of the filtrate was maleic acid with a yield of 47.31%.

(27) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was 99% or more.

Example 10

(28) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 1. The preparation method includes the following steps:

(29) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium bromide prepared in Example 1 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was placed in a thick-walled pressure-resistant tube, and then 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 30 minutes. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the process was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride doped with potassium bromide), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(30) The components in the above filtrate were detected. The results showed that the main component of the filtrate was maleic acid with a yield of 27.32%.

(31) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was about 40%.

Example 11

(32) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 1. The preparation method includes the following steps:

(33) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium bromide prepared in Example 1 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was placed in a thick-walled pressure-resistant tube, and then 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 60 minutes. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the chemical reaction was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride doped with potassium bromide), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(34) The components in the above filtrate were detected. The results showed that the main component of the filtrate was maleic acid with a yield of 45.36%.

(35) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was about 63%.

Example 12

(36) Maleic acid was prepared by catalytic oxidation of furfural with the catalyst of Example 1. The preparation method includes the following steps:

(37) 1 mmol of furfural and 50 mg of carbon nitride doped with potassium bromide prepared in Example 1 were added to 4 mL of deionized water to obtain a mixed solution. The mixed solution was then placed in a thick-walled pressure-resistant tube, and 1 mL of 30% hydrogen peroxide solution was added. After that, a magnetic stirrer was placed in the thick-walled pressure-resistant tube, and then the above solution was placed in an oil bath at a rotation speed of 500 rpm, while raising the temperature to 100° C. for 120 minutes. Immediately after completion of the process, the thick-walled pressure-resistant tube was taken out and air cooled to room temperature. Subsequently, the compound created from the chemical reaction was transferred from the reaction vessel and filtered to obtain filter residue (carbon nitride doped with potassium bromide), which was dried for further use. A portion of the filtrate obtained by the filtration was used to detect the components therein, and another portion was evaporated and recrystallized to give a white solid which was a maleic acid product.

Experimental Results

(38) The components in the above filtrate were detected. The results showed that the main component of the filtrate was maleic acid with a yield of 50.32%.

(39) After diluting 20 times, the filtrate was measured and analyzed using Waters 515 HPLC (high performance liquid chromatography). The results showed that the conversion rate of furfural in this example was about 75%.

Example 13

(40) The recycling performance of carbon nitride doped with potassium bromide was tested.

(41) (1) Primary Recycling Test

(42) Maleic acid was prepared in accordance with the preparation method of Example 2, except that the above filter residue was used instead of the carbon nitride doped with potassium bromide used in Example 2 as the catalyst.

Experimental Results

(43) After drying, the filter residue obtained by filtration during the preparation of maleic acid was characterized. As a result, the alkalinity of the surface of the filter residue was 1.52 mmol/g.

(44) The yield of the obtained maleic acid product was detected. As a result, the yield was 60.32% (in the case of primary recycling of the catalyst).

(45) (2) Secondary Recycling Test

(46) Maleic acid was prepared under the preparation conditions of the primary recycling test, except that the filter residue obtained in the primary recycling test was used instead of the catalyst used in the primary recycling test.

Experimental Results

(47) The yield of the obtained maleic acid product was detected. As a result, the yield was 55.82% (in the case of secondary recycling of the catalyst).

(48) After diluting 20 times, the filtrate obtained by filtration during the preparation of maleic acid was measured and analyzed using Waters 515 HPLC (high performance liquid chromatograph). The results showed that the conversion rate of furfural in this example was 85%.

(49) The results of the primary and secondary recycling tests show that the catalyst prepared in Example 1 of the present invention has good recycling performance.

(50) The foregoing descriptions are merely preferred embodiments of the present invention. However, the protective scope of the present invention is not limited to the above examples. Various process solutions without substantial difference from the concepts of the present invention should fall within the protective scope of the present invention.