Method for catalyzing isomerization of glucose into mannose by using supported metal catalyst

Abstract

The invention belongs to the technical field of biomass high-valued treatment, and particularly relates to a supported Mo resin catalyst and a preparation method thereof, and further relates to catalysis of glucose isomerization by the supported Mo resin catalyst at low temperature. Anion exchange resin and molybdate are used as raw materials, anion resin is used as a metal carrier, and the catalyst is obtained through an impregnation method. The Mo-loaded resin catalyst prepared by the invention is simple in preparation method, and the cost of the catalyst is remarkably reduced by taking anion exchange resin as a carrier. The Mo-loaded resin catalyst prepared by the invention realizes high-efficiency low-temperature thermal catalysis of glucose isomerization for synthesis of mannose, the yield of mannose reaches 29%, the selectivity of mannose reaches 95%, when xylose is used as a substrate, the yield of lyxose reaches 31.48%, the selectivity of lyxose reaches 94.01%, and the yield of lyxose reaches 31.48%. A new synthesis path is provided for efficient catalytic synthesis of high-value monosaccharide by taking glucose and xylose as raw materials.

Description

Technical Field

[0001] The present invention relates to the technical field of glucose isomerization, and specifically to a method for low-temperature catalytic glucose isomerization using a Mo-loaded resin catalyst and its application in the preparation of mannose. Background Art

[0002] Glucose, as the main component of lignocellulose, has great potential as a platform chemical for various applications. The isomerization of biomass-derived glucose can synthesize a variety of high-value monosaccharides, such as fructose, mannose, and allulose, which are precursors of various drugs and high-value-added chemicals. Mannose, as an isomer of glucose, is also valuable in industries such as food and pharmaceuticals and plays a crucial role in the valorization of lignocellulose. Mannose plays an important role in the synthesis of antiviral drugs and the preparation of low-calorie sweeteners. In addition, mannose can enhance the body's immunity, regulate the immune system, and has anti-inflammatory properties, effectively inhibiting inflammatory reactions. Traditional glucose isomerization methods mostly use enzymatic catalysis or acid catalysis, but there are problems such as harsh reaction conditions, poor catalyst activity and stability, and high costs. Developing an efficient and sustainable catalytic system for isomerizing lignocellulose-derived glucose into mannose is of great significance.

[0003] Heterogeneous catalysts have less corrosion and are easily recoverable from the reaction system. Resins, metal oxides, hydrotalcites, and modified zeolites have been used as heterogeneous catalysts for glucose isomerization. Molybdenum, as a transition metal, has excellent catalytic performance and can effectively promote the glucose isomerization reaction to convert it into high-value-added isomers, such as fructose and mannose. Elemental Mo is usually loaded on macroscopic support materials, such as activated carbon (AC) and alumina (Al2O3). CN115094465B introduces a carbon cloth-supported Mo-doped Co-9S-8 nanoarray composite material, where the carbon cloth used is beneficial to improving the conductivity and stability of the material. CN115672346B introduces a Ni-Mo bimetal-loaded catalyst, which uses alumina-titania as the carrier to increase the mechanical strength of the catalyst, provide a large specific surface area, and promote the high dispersion of the metal on the surface of the carrier. In the present invention, Mo is loaded into the anion exchange resin by an impregnation method, and by regulating the concentration of the loading solution and the pH of the loading solution, a Mo-loaded resin catalyst is successfully prepared and applied in the low-temperature catalytic glucose isomerization. The resin material (such as styrene-divinylbenzene copolymer) provides a stable carrier, endowing the catalyst with good mechanical strength and chemical stability, enabling it to maintain high efficiency under harsh reaction conditions.

[0004] Ion exchange resins are an important class of solid catalysts with a wide range of applications, second only to molecular sieves and

[0005] Oxide catalysts. Due to their unique polymer structure and functional groups, these materials play an important role in the fields of chemical industry,

[0006] environmental protection, water treatment, food processing, and medicine. CN115624971A prepared an amino resin-supported palladium nanocatalytic material, effectively improving the environmental adaptability and selectivity of the material for selenate removal, and making the selenium concentration in the effluent stable and meeting the discharge standards. CN119425789A introduced an amine-functionalized resin-supported nano-zero-valent ruthenium composite material and its preparation method. Based on the fact that the propylenediamine functional group itself has certain adsorption and reduction capabilities for bromate, the reduction ability and selectivity of the reaction were enhanced by zero-valent ruthenium. CN113980364B introduced a thermoplastic starch resin, which is easy to degrade and has high strength, and can be applied to food packaging materials.

[0007] Resin is a functional material with a polymer backbone. Common types include phenolic resin, epoxy resin, and styrene-based resin, etc. In the preparation process of this invention, styrene-based resin was mainly selected and different groups were loaded, including quaternary ammonium groups (IRA402 resin, IRA900 resin) and tertiary amine groups (D301 resin). Macroporous styrene-based resin has become a research and application hotspot due to its high stability, excellent efficiency, and strong versatility. This type of resin usually realizes its adsorption function through chelation and ion exchange principles, and can effectively separate and purify target substances. There are many types of macroporous styrene-based resins, and their adsorption effects vary due to factors such as the pore size, specific surface area, type and distribution of functional groups of the resin. For example, some resins have a high selective adsorption ability for heavy metal ions, while others are more suitable for the separation and purification of organic substances. In this invention, the mainly used resin is macroporous styrene-based resin, whose matrix is copolymerized from styrene and divinylbenzene. This copolymer structure endows the resin with excellent mechanical strength and chemical stability, enabling it to maintain stable performance under harsh conditions such as high temperature, strong acid, or strong base. In addition, the styrene-divinylbenzene copolymer backbone also provides the basis for the formation of macroporous structure, making the resin have a high specific surface area and adsorption capacity. The functional groups of macroporous styrene-based resin include quaternary ammonium groups (-N + (CH3)3), which can efficiently adsorb anions in the solution through ion exchange. The presence of quaternary ammonium groups makes the resin have a high affinity for anions, especially suitable for treating wastewater containing chloride ions, sulfate ions, nitrate ions, etc. Another significant advantage of this resin is its regenerability. Through simple pickling or alkali washing treatment, the resin can restore its adsorption and catalytic capabilities, thus realizing multiple cycles of use. This characteristic not only reduces the use cost but also reduces environmental pollution, meeting the concepts of green chemistry and sustainable development.

[0008] The unique structure of the Mo-loaded resin catalyst enables it to exhibit high activity and high selectivity under low-temperature conditions. Low-temperature catalysis not only reduces energy consumption but also decreases the occurrence of side reactions and improves the purity of the target product (such as mannose). In addition, as a heterogeneous catalyst, the Mo-loaded resin catalyst is easy to recover and can be reused. Due to its heterogeneous nature, the catalyst can be recovered by simple filtration separation after the reaction and still maintain high activity and selectivity after multiple cycles of use. The stability of this catalyst makes it have broad application prospects in industrial production, effectively reducing production costs and improving efficiency. Summary of the Invention

[0009] The object of the present invention is to provide an application of a Mo-loaded resin catalyst in the low-temperature catalytic isomerization of glucose to mannose. In the present invention, the active component of the supported metal catalyst is metal Mo (the active ingredient is anionic M O O4 2- ), and the carrier is a polystyrene-divinylbenzene resin with quaternary amino groups. The active component M O O4 2- is loaded on the carrier polystyrene-divinylbenzene resin by forming an ionic bond with the quaternary amino group. This supported metal catalyst can not only maintain a certain mechanical strength but also ensure the effective dispersion of catalyst particles in the system to participate in the catalytic reaction, and can efficiently thermally catalyze the isomerization of glucose to synthesize mannose.

[0010] The technical solution adopted by the present invention to achieve the object is: to provide a Mo-loaded resin catalyst for low-temperature catalytic isomerization of glucose to mannose, including the following steps:

[0011] (1) Dissolve molybdate in deionized water to obtain a molybdate solution;

[0012] (2) Immerse the anion exchange resin in the molybdate solution, and after adsorption equilibrium, filter to obtain a saturated resin;

[0013] (3) Filter, wash and dry the saturated resin to obtain the product.

[0014] (4) Glucose isomerization reaction: Place the Mo-loaded resin catalyst in a glucose solution, and carry out the glucose isomerization reaction at a certain temperature, pH value and reaction time to generate mannose.

[0015] (5) Product separation and catalyst recovery: Separate the reaction product from the catalyst by methods such as filtration and centrifugation, and then recover the catalyst through steps such as washing and drying for reuse.

[0016] Furthermore, the mass fraction of the molybdate solution in step (1) is 10wt% - 20wt%.

[0017] Further, the temperature of the adsorption equilibrium in step (2) is 25 - 30°C, the time of the adsorption equilibrium is 24 - 48 h, and the adsorption equilibrium is carried out in a manner assisted by stirring.

[0018] Further, the molybdate salt in step (2) is anhydrous sodium molybdate.

[0019] Further, for the washing of the saturated resin in step (3), 600 ml - 800 ml of deionized water is used; the drying temperature is 60°C.

[0020] A Mo-loaded resin catalyst is prepared by using the above-mentioned preparation method of the Mo-loaded resin catalyst.

[0021] An application of a Mo-loaded resin catalyst, wherein the Mo-loaded resin catalyst is added to an aqueous solution of glucose, and glucose is heated and catalyzed to isomerize into mannose.

[0022] Further, the concentration of the aqueous solution of glucose is 100 - 300 g / L; for each mL of the aqueous solution of glucose, the added mass of the resin catalyst is 50 mg; the temperature of the heating and catalysis is 80 - 90°C.

[0023] Beneficial effects

[0024] The present invention uses an anion resin as the loading matrix. The matrix of this resin is a styrene-divinylbenzene copolymer, and this structure endows the resin with good mechanical strength and chemical stability. Its functional group is a quaternary ammonium group (-N + (CH3)3), which can effectively adsorb and exchange anions in the solution. The resin can restore its activity through simple regeneration treatments such as pickling, alkali washing, or organic solvent washing, and can be reused multiple times. This not only reduces the use cost but also reduces the generation of waste, having environmental protection significance. The resin substrate has a wide source, low price, and the catalyst preparation process is simple and easy for industrial production.

[0025] By utilizing the structural stability and excellent adsorption capacity of this ion exchange resin and the obvious effect of metal Mo on glucose isomerization, a Mo-loaded resin catalyst is successfully prepared, and efficient thermal catalysis for glucose isomerization to synthesize mannose is realized, providing a new synthetic route for the efficient catalytic synthesis of high-value monosaccharides including fructose and mannose from glucose as a raw material.

[0026] The present invention prepares a supported Mo resin catalyst by an impregnation method and applies it to the synthesis of high-value monosaccharides. This catalyst exhibits excellent performance in the reaction of catalytic isomerization of glucose to mannose and fructose. During the reaction process, only water is used as a green reaction medium, avoiding the use of traditional organic solvents, which fully embodies the concept of green chemistry. Using water as a solvent does not introduce additional impurities, facilitating the purification and subsequent treatment of the products; in addition, the use of water also avoids the potential safety hazards and environmental pollution problems caused by organic solvents. This green reaction system with water as the medium not only meets the requirements of sustainable development but also provides an environmentally friendly and efficient technical route for the industrial production of high-value monosaccharides. Through the combination of the supported Mo resin catalyst and the green reaction medium, the present invention maximizes the reduction of environmental impact while achieving efficient catalytic reactions, and has important application prospects and promotion value.

[0027] Traditional high-temperature catalytic reactions have high energy consumption and many by-products, which not only increase production costs but also impose a burden on the environment. In contrast, the present invention can efficiently carry out reactions at lower temperatures, significantly reducing energy consumption and waste of energy. At the same time, the low-temperature conditions inhibit the occurrence of side reactions, improve the selectivity and product purity of the reaction, and reduce the generation of waste. This green and efficient catalytic method conforms to the development trend of green chemistry, helps to achieve sustainable industrial production, and promotes the development of the chemical industry towards a more environmentally friendly and economical direction.

[0028] For the supported Mo resin catalyst of the present invention, under the optimal conditions of 90 °C and 120 min, the yield of mannose obtained by glucose isomerization reaches 29.61%, and the selectivity of mannose is 95.31%. After the catalyst is reused 7 times, the yield still remains at 22.35%, and the selectivity drops to 46.26%. Using xylose as the substrate, the yield of lyxose reaches 31.48%, and the selectivity of lyxose is 94.01%. Description of the Drawings

[0029] Figure 1 It is a catalytic efficiency diagram of the supported Mo resin catalyst for catalytic glucose at 90 °C with different reaction times in Example 1.

[0030] Figure 2 It is a catalytic efficiency diagram of the supported Mo resin catalyst for catalytic glucose at 90 °C for 120 min (repeated seven times) in Example 1.

[0031] Figure 3 It is a catalytic efficiency diagram of the supported Mo resin catalyst for catalytic xylose at 90 °C with different reaction times in Example 1.

[0032] Figure 4 It is an FTIR spectrum diagram of the supported Mo resin catalyst under different pH conditions in Examples 1 and 2. Detailed implementation manners

[0033] The present invention will be specifically described below in conjunction with specific embodiments.

[0034] Example 1

[0035] The preparation method of the supported Mo resin catalyst in this example includes the following steps:

[0036] 1. Dissolve 12.5 g of anhydrous sodium molybdate in 50 ml of deionized water to obtain a 20 wt% molybdate solution, and adjust the pH = 1 with sulfuric acid;

[0037] 2. Immerse 10 g of anion exchange resin in the molybdate solution, and let it stand for adsorption for 48 h to obtain the supported Mo anion resin;

[0038] 3. Filter the resin catalyst, wash it with 800 ml of deionized water, and dry it in a vacuum drying oven at 40 °C to obtain the supported Mo resin catalyst.

[0039] Put 20 mL of a glucose aqueous solution with a concentration of 100 g / L into a screw-cap glass sample bottle with a volume of 40 mL, add 1 g of the resin catalyst to the glucose aqueous solution, and place the glass sample bottle in a water bath at 90 °C, stir and heat to catalyze the isomerization of glucose to obtain mannose.

[0040] Using glucose as the substrate, the Mo-supported resin catalyst prepared in this example was used to catalyze the isomerization synthesis of mannose at 90 °C under the conditions of different catalytic reaction times. The catalytic results are shown in Table 1.

[0041] Table 1 Catalytic selectivity of the supported Mo resin catalyst using glucose as the substrate

[0042]

[0043] From 0.5 h to 2 h, the glucose conversion rate gradually increased from 18.15% to 31.52%, indicating that the reaction continued and glucose was continuously consumed. The selectivity was 84.31% at 0.5 h, exceeded 95% after 1 h, reached a peak of 97.10% at 1.5 h, and then decreased slightly to 95.31%, remaining at a relatively high level overall, indicating that the reaction mainly produced mannose. The mannose selectivity was always higher than 84% and reached a peak at 1.5 h, indicating that the reaction had a high specificity for the production of mannose.

[0044] The repeatability diagram of the supported Mo resin catalyst prepared in this example for catalyzing glucose under optimal conditions is as Figure 2 shown. Figure 2The results after reusing the Mo-loaded resin catalyst prepared in this example seven times under the conditions of a catalytic reaction temperature of 90 °C, a catalytic reaction time of 120 min, a glucose aqueous solution concentration of 100 g / L, a volume of 20 ml, and a catalyst dosage of 1 g. After repeating seven times, the yield of mannose still remains 79% of the first yield, indicating that the Mo-loaded resin catalyst can be reused after repeated washing and drying. The catalyst of this example is filtered, washed with deionized water, and then dried.

[0045] Using the Mo-loaded resin catalyst prepared in this example with xylose as the substrate, under the conditions of 90 °C and different catalytic reaction times, xylose is catalytically isomerized to produce lyxose, and the catalytic results are shown in Table 2.

[0046] Table 2 Catalytic selectivity of the Mo-loaded resin catalyst with xylose as the substrate

[0047]

[0048] According to Table 2, in the reaction of catalytically isomerizing xylose to produce lyxose with the Mo-loaded resin catalyst at 90 °C, as the reaction time increases, both the xylose conversion rate and the lyxose yield show a trend of first increasing and then stabilizing. The conversion rate reaches a relatively high level at about 1.5 hours of reaction time, and the selectivity of lyxose remains at a relatively high level (>94%) in the initial and later stages of the reaction, indicating that the catalyst can efficiently catalyze the conversion of xylose to lyxose in a short time and has a high selectivity.

[0049] The FT-IR diagram of the Mo-loaded resin catalyst prepared in this example is as Figure 4 shown. Obvious peaks appear at 3000 - 3500 cm -1 and 1600 - 1450 cm-1 for the original resin and the resin catalyst prepared under the condition of pH = 1, corresponding to the vibration peaks of the styrene skeleton of the resin. The absorption peaks in the range of 1400 - 1500 cm-1 are related to the stretching vibration of the C-N bond, and the vibration peaks of the O-H bond are located in the range of 3200 - 3600 cm-1. The peaks appearing in the region of 800 - 1000 cm-1 are related to the stretching vibration of the Mo-O bond, and the presence of this peak indicates that Mo has been successfully loaded onto the resin. In the Mo-O bond region (1050 - 1150 cm-1), the spectra of the resin catalysts prepared under different pH conditions show different peak intensities and shapes, and the absorption peak intensity of the Mo-O bond changes with the change of the pH factor, indicating that the pH condition affects the loading of Mo on the resin.

[0050] Example 2

[0051] The preparation method of the Mo-loaded resin catalyst in this example includes the following steps:

[0052] 1. Dissolve 12.5 g of anhydrous sodium molybdate in 50 ml of deionized water to obtain a 20 wt% molybdate solution, and adjust the pH = 4 with sulfuric acid;

[0053] 2. Immerse 10 g of anion exchange resin in the molybdate solution, and after standing and adsorbing for 48 h, obtain the anion resin loaded with Mo;

[0054] 3. Filter the resin catalyst, wash it with 800 ml of deionized water, and dry it in a vacuum drying oven at 60 °C to obtain the resin catalyst loaded with Mo.

[0055] Put 20 mL of a glucose aqueous solution with a concentration of 100 g / L into a screw-cap glass sample bottle with a volume of 40 mL. Add 1 g of the resin catalyst to the glucose aqueous solution, and put the glass sample bottle into a water bath at 90 °C, stir and heat to catalyze the isomerization of glucose to obtain mannose.

[0056] Example 3

[0057] The preparation method of the resin catalyst loaded with Mo in this example includes the following steps:

[0058] 1. Dissolve 12.5 g of anhydrous sodium molybdate in 50 ml of deionized water to obtain a 20 wt% molybdate solution, and adjust the pH = 7 with sulfuric acid;

[0059] 2. Immerse 10 g of anion exchange resin in the molybdate solution, and after standing and adsorbing for 48 h, obtain the anion resin loaded with Mo;

[0060] 3. Filter the resin catalyst, wash it with 800 ml of deionized water, and dry it in a vacuum drying oven at 40 °C to obtain the resin catalyst loaded with Mo.

[0061] Put 20 mL of a glucose aqueous solution with a concentration of 100 g / L into a screw-cap glass sample bottle with a volume of 40 mL. Add 1 g of the resin catalyst to the glucose aqueous solution, and put the glass sample bottle into a water bath at 90 °C, stir and heat to catalyze the isomerization of glucose to obtain mannose.

[0062] Example 4

[0063] The preparation method of the resin catalyst loaded with Mo in this example includes the following steps:

[0064] 1. Dissolve 5 g of anhydrous sodium molybdate in 45 ml of deionized water to obtain a 10 wt% molybdate solution, and adjust the pH = 1 with sulfuric acid;

[0065] 2. Immerse 10 g of anion exchange resin in the molybdate solution, and after standing and adsorbing for 48 h, obtain the anion resin loaded with Mo;

[0066] 3. Filter the resin catalyst, wash it with 800 ml of deionized water, and dry it in a vacuum drying oven at 60 °C to obtain the Mo-loaded resin catalyst.

[0067] Put 20 mL of a 100 g / L glucose aqueous solution into a screw-cap glass sample bottle with a volume of 40 mL. Add 1 g of the above resin catalyst to the glucose aqueous solution. Place the glass sample bottle in a water bath at 90 °C and stir and heat to catalyze the isomerization of glucose to obtain mannose.

[0068] Example 5

[0069] The preparation method of the Mo-loaded resin catalyst in this example includes the following steps:

[0070] 1. Dissolve 7.5 g of anhydrous sodium molybdate in 42.5 ml of deionized water to obtain a 15 wt% molybdate solution, and adjust the pH = 1 with sulfuric acid;

[0071] 2. Immerse 10 g of anion exchange resin in the molybdate solution, and let it stand and adsorb for 48 h to obtain the Mo-loaded anion resin;

[0072] 3. Filter the resin catalyst, wash it with 800 ml of deionized water, and dry it in a vacuum drying oven at 60 °C to obtain the Mo-loaded resin catalyst.

[0073] Put 20 mL of a 100 g / L glucose aqueous solution into a screw-cap glass sample bottle with a volume of 40 mL. Add 1 g of the resin catalyst to the glucose aqueous solution. Place the glass sample bottle in a water bath at 90 °C and stir and heat to catalyze the isomerization of glucose to obtain mannose.

Claims

1. A preparation method of a Mo-loaded resin catalyst, characterized in that, It includes the following steps: (1) Dissolve molybdate in deionized water to obtain a molybdate solution; (2) Immerse an anion exchange resin in the molybdate solution, and after adsorption equilibrium, filter to obtain a saturated resin; (3) Filter, wash and dry the saturated resin to obtain a Mo-loaded resin catalyst.

2. The preparation method of the supported Mo resin catalyst according to claim 1, characterized in that, The concentration of the molybdate solution is 10wt% - 20wt%, and the mass of the resin is 10 g.

3. The preparation method of the supported Mo resin catalyst according to claim 1, characterized in that, In step (2), the temperature of the adsorption equilibrium is 25 - 30 °C, the time of the adsorption equilibrium is 24 - 48 h, and the adsorption equilibrium is carried out in a stirring-assisted manner.

4. The preparation method of the supported Mo resin catalyst according to claim 1 or 2, characterized in that, The molybdate is anhydrous sodium molybdate.

5. The preparation method of the supported Mo resin catalyst according to claim 1, characterized in that, In step (3), the saturated resin is washed with 600 - 800 ml of deionized water; the drying temperature is 60 °C.

6. A Mo-loaded resin catalyst, characterized in that, It is prepared by the preparation method as described in claim 1.

7. Use of a supported Mo resin catalyst as described in claim 6, characterized in that, The resin catalyst is added to an aqueous solution of glucose, and heated to catalyze the isomerization of glucose to obtain mannose.

8. The application of the supported Mo resin catalyst according to claim 6, characterized in that, The concentration of the aqueous solution of glucose is 100 - 300 g / L; in each mL of the aqueous solution of glucose, the added mass of the resin catalyst is 50 mg; the temperature of the heating catalysis is 90 °C.

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