A method for preparing fructose by catalytic isomerization of glucose

Abstract

The present invention relates to a method for preparing fructose by catalytic isomerization of glucose, the method comprising: placing a main catalyst-cocatalyst composite catalyst, glucose and water into a reaction vessel to form a mixed system, and performing a hydrothermal reaction in a stirring atmosphere to isomerize glucose into fructose. The composite catalyst is Pt / SiO2@Mg(OH)2. The mass ratio of the composite catalyst to glucose is (50-300):225. The temperature of the hydrothermal reaction is 110-180°C. The time of the hydrothermal reaction is 0.5-6h. Compared with the prior art, the glucose conversion rate of the present invention reaches 86.2%, and the fructose yield reaches 33%. The catalytic efficiency of glucose isomerization to fructose is high and the stability is good. Reliable technical support is provided for the industrialization of preparing high value-added fructose by glucose isomerization.

Description

Technical Field

[0001] The invention relates to the field of environmental chemical industry, and in particular to a method for preparing fructose by catalytic isomerization of glucose. Background Art

[0002] Biomass is a renewable resource that can replace traditional fossil resources and produce fuels and chemicals at the same time. Cellulose is an abundant renewable plant biomass resource in nature, and its structural unit is glucose. Glucose and fructose, as isomers, can both be converted into a series of high value-added chemicals such as propylene glycol. Compared with glucose, fructose has a higher conversion efficiency in synthesizing propylene glycol, so the isomerization of glucose to fructose is considered to be a key chemical step in converting biomass into fuels and chemicals.

[0003] The reaction of glucose isomerization to fructose can be achieved using biological enzymes, homogeneous acids or bases, and molecular sieve catalysts as catalysts. The biological enzyme catalysis process has high selectivity, but it has high processing costs and requires the use of buffer solutions to maintain the pH value; the operating temperature requirements are high; the purity of the reactants is strictly required; and the enzyme has the characteristics of irreversible inactivation, so the enzyme needs to be replaced regularly. Homogeneous acids and bases have the limitations of low selectivity, difficult separation, and low repeatability. Therefore, molecular sieve catalysts have obvious advantages in catalyzing the isomerization of glucose to fructose. Solid bases can provide higher catalytic performance, are not easy to deactivate, and can be recycled, so they become a new method for glucose isomerization. Summary of the invention

[0004] The object of the present invention is to overcome at least one of the defects of the above-mentioned prior art and to provide a method for preparing fructose by catalytic isomerization of glucose with high selectivity and high yield.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for preparing fructose by catalytic isomerization of glucose, the method comprising: placing a main catalyst-cocatalyst composite catalyst, glucose, and water into a reaction container to form a mixed system, and performing a hydrothermal reaction in a stirring atmosphere to isomerize the glucose into fructose. After the reaction is completed and cooled to room temperature, the solid and the liquid are separated by centrifugation. The liquid is analyzed by liquid chromatography and gas chromatography; the solid is washed three times with deionized water and then reused or characterized.

[0007] Furthermore, the composite catalyst is Pt / SiO2@Mg(OH)2.

[0008] Furthermore, the mass ratio of the composite catalyst to glucose is (50-300):225.

[0009] Furthermore, the mass ratio of the composite catalyst to glucose is 200:225.

[0010] Furthermore, the temperature of the hydrothermal reaction is 110-180°C.

[0011] Furthermore, the temperature of the hydrothermal reaction is 130°C.

[0012] Furthermore, the hydrothermal reaction time is 0.5-6h.

[0013] Furthermore, the hydrothermal reaction time is 4 hours.

[0014] Furthermore, the reactor is an oil bath reactor.

[0015] Furthermore, the stirring speed is 400-600r / min.

[0016] Compared with the prior art, the present invention has the characteristics of simple preparation and high product yield, and is a highly economical and environmentally friendly method for isomerizing glucose to fructose, which has potential application prospects. The glucose conversion rate reaches 86.2%, and the fructose yield reaches 33%. The catalytic efficiency of glucose isomerization to fructose is high and the stability is good. It provides reliable technical support for the industrialization of glucose isomerization to prepare high-value-added fructose. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The effect of the catalyst dosage on the glucose isomerization effect in Example 1;

[0018] Figure 2 The effect of reaction time on glucose isomerization in Example 2;

[0019] Figure 3 This is the effect of reaction temperature on glucose isomerization in Example 3. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0021] A method for preparing fructose by catalytic isomerization of glucose, the method comprising: placing a main catalyst-cocatalyst composite catalyst, glucose, and water into a reaction container to form a mixed system, and performing a hydrothermal reaction in a stirring atmosphere to isomerize the glucose into fructose. After the reaction is completed, the reaction tube is placed in ice water to quench to room temperature, the sample is centrifuged to obtain a liquid, the liquid is diluted 8 times with pure water, and then a liquid chromatography test is performed to obtain the yield of fructose.

[0022] The mass ratio of the composite catalyst to glucose is (50-300):225, preferably 200:225. The temperature of the hydrothermal reaction is 110-180° C., preferably 130° C. The time of the hydrothermal reaction is 0.5-6 hours, preferably 4 hours. The reactor is an oil bath reactor. The stirring speed is 400-600 r / min, preferably 500 r / min.

[0023] The composite catalyst is Pt / SiO2@Mg(OH)2, and the preparation method is as follows: 1g of dried SiO2 is subjected to saturated water absorption determination, and the water absorption is measured to be aml. bmg of chloroplatinic acid is dissolved in cmL of deionized water, and dmg of SiO2 is added to the above aqueous solution for immersion, aging, drying, calcination, and grinding to obtain oxidized Pt / SiO2; 10mL of deionized water, emg of MgO precursor, and fmg of oxidized Pt / SiO2 are mixed in a reactor to form a mixed system, which is hydrothermally heated for 4h under 5MPa hydrogen atmosphere and 200℃, and the obtained solution is centrifuged, dried, calcined, and ground to obtain Pt / SiO2@Mg(OH)2. The above a, b, c, d, e, and f should all satisfy c / d=a, 0.37b / d=1-5%, and 0.6e / f=2.5-100%.

[0024] Example 1

[0025] Take 225mg glucose and 10mL deionized water in a 35mL reaction tube, add 50-300mg Pt / SiO2@Mg(OH)2 to the solution, and stir and heat evenly at 130℃ at 500r / min under the action of a magnetic heating stirrer. The reaction time is 4h. After the reaction is completed, place the reaction tube in ice water to quench it to room temperature, centrifuge the sample to obtain a liquid, dilute the liquid 8 times with pure water, and perform liquid chromatography test to obtain the yield of fructose. The results are as follows Figure 1 shown.

[0026] Example 2

[0027] Take 225mg glucose and 10mL deionized water in a 35mL reaction tube, add 200mg Pt / SiO2@Mg(OH)2 to the solution, and stir and heat evenly at 130℃ at 500r / min under the action of a magnetic heating stirrer. The reaction time is 0.5h, 1h, 2h, 3h, 4h, 5h, and 6h. After the reaction is completed, place the reaction tube in ice water to quench it to room temperature, centrifuge the sample to obtain a liquid, dilute the liquid 8 times with pure water, and perform liquid chromatography test to obtain the yield of fructose. The results are as follows Figure 2 shown.

[0028] Example 3

[0029] Take 225mg glucose and 10mL deionized water in a 35mL reaction tube, add 200mg Pt / SiO2@Mg(OH)2 to the solution, and stir and heat evenly at 110-180℃ with a magnetic heating stirrer at 500r / min for 4h. After the reaction is completed, place the reaction tube in ice water to quench it to room temperature, centrifuge the sample to obtain liquid, dilute the liquid 8 times with pure water, and perform liquid chromatography test to obtain the yield of fructose. The results are as follows Figure 3 shown.

[0030] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing fructose by catalytic isomerization of glucose, characterized in that: The method comprises: placing a main catalyst-cocatalyst composite catalyst, glucose and water into a reaction container to form a mixed system, and performing a hydrothermal reaction in a stirring atmosphere to isomerize the glucose into fructose; Wherein, the composite catalyst is Pt / SiO2@Mg(OH)2; The mass ratio of the composite catalyst to glucose is 200:225; The temperature of the hydrothermal reaction is 130°C; The hydrothermal reaction time is 4 hours.

2. The method for preparing fructose by catalytic isomerization of glucose according to claim 1, characterized in that: The reactor is an oil bath reactor.

3. The method for preparing fructose by catalytic isomerization of glucose according to claim 1, characterized in that: The stirring speed is 400-600r / min.

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