Aqueous-phase stable cadmium-based catalysts for aldose isomerization and their applications

Abstract

This invention belongs to the field of solid acid catalyst preparation, and specifically discloses an aqueous-phase stable cadmium-based catalyst for aldose isomerization reactions and its applications. The catalyst preparation method includes obtaining a supported cadmium-based catalyst using a precursor calcination method, precipitation method, or supported method. The obtained catalyst powder is applied to the isomerization reaction of sugars (especially xylose) in an aqueous phase, with a catalyst-to-sugar mass ratio of 1:1 to 1:50, and the reaction is carried out at 80℃ to 150℃ for 10 to 240 minutes. After the reaction, the catalyst can be recovered by centrifugation, and the reaction solution can be purified by ion exchange resin to remove cadmium and concentrated by evaporation to obtain a high content of isomerized products. The catalyst of this invention exhibits good stability, high efficiency, and reusability in aqueous phase reactions, and can be applied to the isomerization of other sugars such as glucose, mannose, and ribose.

Description

Technical Field

[0001] This invention belongs to the field of solid acid catalyst preparation, and specifically relates to an aqueous-phase stable cadmium-based catalyst for aldose isomerization reaction and its application. Background Technology

[0002] As an inexpensive and renewable resource, the high-value utilization of carbohydrate biomass is currently a research hotspot in academia and industry. Converting common and inexpensive aldoses into rare ketoses via isomerization is an important pathway to achieving this high-value utilization. While research on the conversion of glucose to fructose via isomerization (ketogenesis) is relatively mature, research on the isomerization of xylose, the second most abundant natural sugar after glucose, into xylulose is relatively limited. Current catalysts for xylose isomerization still suffer from problems such as numerous side reactions, poor reaction kinetics, and poor catalyst stability. Therefore, designing catalysts that can efficiently catalyze the isomerization of xylose to xylulose remains a significant challenge.

[0003] Currently, the isomerization of xylose to xylulose is mainly achieved through enzymatic and chemical catalysis. Immobilized xylose isomerase can yield 28% xylulose by reacting for 6 hours at 70°C and pH 6.0. However, enzymatic catalysis has stringent requirements regarding the purity of raw materials, the presence of impurities, and reaction conditions. Even slight deviations from optimal conditions such as pH and temperature can significantly reduce or even deactivate enzyme activity, leading to unstable production processes and increased costs. Chemical catalysis, on the other hand, offers advantages such as a wide operating temperature range and ease of catalyst preparation and storage. Therefore, researchers are currently focusing on developing chemical catalysts to provide new solutions for the xylose isomerization process. In the research and application of homogeneous catalysts, researchers have explored the catalytic effects of various homogeneous catalysts, including AlCl3, CaCl2, CrCl3, KOH, NaOH, and Na2HPO4-NaH2PO4, on the xylose isomerization reaction, achieving a maximum yield of xylulose of up to 30%. However, homogeneous catalysis generates numerous byproducts, resulting in low reaction selectivity, difficulty in catalyst separation and recovery, and these inorganic acids and bases can cause equipment corrosion, environmental pollution, and production safety issues. Unlike homogeneous catalysis, solid-phase catalysts exist in different phases from reactants and products in the reaction system. This gives them significant advantages that homogeneous catalysts lack, such as ease of separation and reusability, and holds promise for opening up a new, efficient, and green pathway for xylose isomerization.

[0004] Solid-phase catalysts for xylose isomerization can be broadly classified into solid bases and solid acids. Solid bases mainly include hydrotalcite, basic anion exchange resins, and some alkali metal oxides. Ventura et al. synthesized Ca-Al hydrotalcite, which yielded 11% xylulose after reacting at 90°C for 180 min. Tawil-Lucas et al. tested the activity of commercially available macroporous and gel-type resins in the isomerization process; the macroporous resin IRA-900, based on a styrene-divinylbenzene copolymer, yielded 15% xylulose after reacting at 60°C for 120 min. Although both methods achieved xylulose preparation, their catalytic efficiencies were relatively low. Antunes et al. synthesized Na / K / Mg / Ca modified AM-4 material; Ca-AM-4 showed the best catalytic effect, achieving 39% xylulose after reacting at 100°C for 120 min. However, this type of catalyst suffers from significant ion loss in the aqueous phase, altering the catalyst composition and structure, leading to a sharp decline in both catalyst activity and stability. Li Wenxuan et al. reported a core-shell structured catalyst, Pt / SiO2@Mg(OH)2, which yielded 23% xylulose after reacting at 130℃ for 60 min, and 31.74% xylulose after reacting with water:methanol (8:2) solvent. However, the use of the precious metal Pt in the synthesis process increased the research and development and production costs; the Mg(OH)2 contained in the catalyst has poor stability in the aqueous phase, and Mg ions are easily lost, resulting in poor reusability of the catalyst. Furthermore, a large amount of carbon deposits appear on the catalyst surface during continuous use, further leading to catalyst deactivation and a continuous decrease in xylulose yield.

[0005] Common solid acids that can be used for xylose isomerization include zeolites, metal oxides, and organic-inorganic hybrid materials. Tin-containing zeolites, formed by isomorphously replacing some silicon (Si) atoms in the zeolite framework with tin (Sn) atoms, can catalyze the isomerization of aldoses to ketoses. Gunther et al. obtained 13% xylose using Sn-β zeolite at 85 °C for 15 min. Lew et al. synthesized Sn-MFI and Sn-β zeolites, reacting at 90 °C for 210 min, achieving xylose yields of 19% and 24%, respectively. Choudhary et al. prepared Sn-β zeolite, reacting at 100 °C for 15 min to obtain 27% xylose. Although tin-containing zeolites can achieve certain yields in the reaction, the synthesis methods of Sn-MFI and Sn-β zeolites are complex and have long preparation cycles, currently only at the laboratory level and unable to meet the requirements for industrial-scale preparation. Furthermore, tin atoms in the framework may be lost during the catalytic process, leading to catalyst deactivation and reduced catalyst stability. Paniagua et al. employed a two-step methanol etherification-hydrolysis method to prepare xylulose from xylose. Xylose first reacts with methanol to form methylxylglycoside, which is then hydrolyzed to obtain xylulose. Using HY, H-USY, and H-β zeolites as catalysts, 23%, 39%, and 31% xylulose were obtained after 60 min at 100 °C, respectively. However, the catalyst activity decreased significantly after three uses. Although this reaction system could achieve a high theoretical yield, a large proportion of xylulose remained in the form of methylxylglycoside, requiring a lengthy hydrolysis process to obtain the free form of xylulose. This method also suffers from solvent effects; the aforementioned zeolites, such as H-USY, cannot catalyze the xylose isomerization reaction in pure aqueous solution. The first step of the reaction must use anhydrous alcohols (such as methanol or ethanol) as solvents. Furthermore, when ethanol is used as a solvent, steric hindrance makes xylulose etherification more difficult, producing more byproducts and resulting in lower reaction selectivity. Thatiane et al. investigated the catalytic effects of tin oxide (Sn100), molybdenum oxide (Mo100), and a mixed tin-molybdenum oxide (SnMo25) in xylose conversion. SnMo25, as a catalyst, yielded 17.2% xylulose at 150 °C for 180 min. However, severe carbon deposition on the catalyst surface during the reaction continuously reduced its activity. Fraga et al. prepared Pt / SBA-15-SO3H and Pt / Nb2O5. In both two-phase systems and water-organic solvent mixtures, the highest xylulose formation rate was approximately 7.5-10%, with a selectivity of 26-55%. After three uses, the catalytic activity decreased by nearly 45%, meaning the xylulose formation rate dropped below 5%. Furthermore, a substrate concentration of approximately 1.0 wt.% was required to maintain a high reaction efficiency.

[0006] In summary, solid-phase catalysis has made significant progress in the isomerization conversion of xylose to xylulose. However, several challenges remain for large-scale production and industrialization. These include catalyst ion loss and surface carbon accumulation leading to decreased stability and activity, resulting in unstable production processes; low catalytic efficiency causing poor productivity (the amount of xylulose produced per unit weight of catalyst per unit time); and unsatisfactory reaction kinetics. Therefore, a stable and efficient catalyst in an aqueous phase is needed to achieve the conversion of xylose to xylulose. Summary of the Invention

[0007] The purpose of this invention is to provide an aqueous-phase stable cadmium-based catalyst for aldose isomerization reactions and its applications, overcoming the shortcomings of existing technologies. The method of this invention involves obtaining cadmium-based catalysts with different structures using precursor calcination, precipitation, and supported methods. The synthesized catalysts exhibit high surface structural stability, minimal ion leakage during aqueous-phase reactions, and high selectivity in catalyzing the conversion of high-concentration xylose to xylulose; they also maintain high catalytic efficiency during multiple catalytic cycles. Thus, an aqueous-phase stable cadmium-based catalyst is prepared using a simple process, and a product with high xylulose content is efficiently obtained under relatively mild conditions. This catalyst can be applied to the isomerization of other sugars such as glucose, mannose, and ribose.

[0008] To achieve the objectives of this invention, the specific technical solution adopted is as follows:

[0009] A water-phase stable cadmium-based catalyst for aldose isomerization reaction, wherein the cadmium-based catalyst is specifically cadmium oxide or a supported cadmium oxide catalyst; the support for the supported cadmium oxide catalyst is one or more of TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, and SiO2.

[0010] Aqueous-phase stable, highly efficient, and reusable catalysts for xylose isomerization reactions are obtained by methods including precursor calcination, precipitation, and impregnation.

[0011] Cadmium oxide can be prepared by precursor calcination or precipitation.

[0012] Precursor calcination method: A certain amount of Cd(NO3)2·4H2O solid is placed in a muffle furnace and calcined at 400-900℃ for 4-10 hours. After cooling, the resulting gray-black solid powder is CdO. The obtained CdO powder is ground and used as a catalyst.

[0013] Precipitation method: Cd(NO3)2·4H2O solid is dissolved in deionized water to prepare a solution of a certain concentration. 25wt% concentrated ammonia (the solution pH is neutral) is slowly added dropwise to the above solution. A white flocculent precipitate appears in the solution. The mixture is stirred at room temperature for about 3 hours to allow the precursor to react fully. After filtration and washing, a white flocculent precipitate is obtained. The precipitate is dried in an oven, ground into powder, and calcined in a muffle furnace at 400-900℃ for 4-10 hours. The obtained solid powder is further ground and used as a catalyst.

[0014] The preparation method of the supported cadmium oxide catalyst is the supported method.

[0015] Specific loading method: Cd(NO3)2·4H2O solid is dissolved in deionized water to prepare a solution of a certain concentration. The catalyst support (TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, SiO2) is then dispersed in the solution. After stirring for 6 hours, the solution is dried in an oven. The dried solid is ground into powder and calcined at 400–900℃ for 4–10 hours. The resulting solid powder is the supported cadmium-based catalyst. Further grinding of the powder allows it to be used as a catalyst. Preferably, cadmium oxide catalyst supported on silica exhibits the best effect. Furthermore, cadmium oxide accounts for 10–50% of the support mass in the supported cadmium oxide catalyst.

[0016] The cadmium-based catalyst obtained above is applied to the isomerization reaction of sugars, mainly through the following steps: the catalyst powder and the reactant sugar are dissolved in deionized water at a mass ratio of 1:1 to 1:50, the reaction temperature is 80℃ to 150℃, the reaction time is 10 minutes to 240 minutes, the reaction liquid is collected and separated by centrifugation, the cadmium-based catalyst is separated, the filtrate (reaction liquid) is used to remove the residual cadmium ions in the reaction liquid with ion exchange resin, and then concentrated by evaporation to obtain a high content of isomerization product.

[0017] This invention can catalyze the isomerization of aldoses, including sugars such as xylose, glucose, ribose, or mannose.

[0018] Effects of the invention: The optimizations that can be achieved by using the technical solution of this invention include:

[0019] 1. The cadmium-based catalyst of this invention belongs to the category of solid acid catalysts, characterized by high surface stability and catalytic activity during aqueous phase reactions. After being supported on a carrier such as high-surface-area silica, the atom utilization rate of cadmium oxide is significantly improved. When used for aqueous phase catalytic xylose isomerization, it exhibits high product yield, high selectivity, low ion loss, and minimal deactivation, achieving green and efficient catalytic conversion of sugars. The selectivity of some reactions can reach over 85%.

[0020] 2. The xylose-to-xylulose catalytic isomerization of the present invention is a solid-liquid two-phase catalytic system. After the reaction, the catalyst can be easily separated by filtration or centrifugation. The catalyst can be used in the next reaction after water washing and alcohol washing. After being reused ten times, the catalytic activity does not decrease significantly. That is, the catalyst recovery process does not require calcination activation, which can shorten the process flow and reduce production costs such as energy consumption. The production process is more operable and can reduce the cost of catalytic conversion of sugars. Attached Figure Description

[0021] Figure 1 The chromatograms are for (A) xylitol; (B) xylulose; (C) xylose standards and (D) xylulose prepared by the reaction of xylose with 20% CdO-SiO2-Cal-400 catalyst. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the embodiments:

[0023] Comparative Example 1, compared with the zeolite catalyst in US10246477B2: Different commercially available acidic zeolite catalysts were tested in the comparative example. Although the reaction system could achieve a high theoretical yield, a large proportion of xylulose still existed in the form of methyl xylulosin, requiring a long hydrolysis process to obtain the free form of xylulose. The method also suffers from solvent effect, that is, the above-mentioned zeolites such as H-USY cannot catalyze the xylose isomerization reaction in pure aqueous solution, and the first step of the reaction must use anhydrous alcohols (such as methanol, ethanol) as solvents.

[0024] Comparative Example 2, compared with MgO catalyst: 1g xylose was dissolved in 100ml deionized water, 0.2g MgO was added, and the mixture was stirred at 120℃ for 60min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The same reaction conditions as in Example 80 were used, but the results showed a xylose reaction rate of 51.23%, a xylulose formation rate of 15.52%, and a selectivity of 30.29%.

[0025] Comparative Example 3, compared with Bi₂O₃ catalyst: 1g xylose was dissolved in 100ml deionized water, 0.2g Bi₂O₃ was added, and the mixture was stirred at 120℃ for 60min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The same reaction conditions as in Example 80 were used, but the results showed a xylose reaction rate of 16.09%, a xylulose formation rate of 3.61%, and a selectivity of 22.45%.

[0026] Example 1, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 400°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-400.

[0027] Example 2, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 500°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-500.

[0028] Example 3, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 600°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-600.

[0029] Example 4, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 700°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-700.

[0030] Example 5, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 800°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-800.

[0031] Example 6, Synthesis of CdO catalyst by precursor calcination: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and placed in a muffle furnace and calcined at 900°C for 5 h. After the sample was cooled to room temperature, a gray-black solid was obtained and ground to obtain CdO powder, which can be used as a catalyst and is denoted as CdO-Cal-900.

[0032] Example 7, Precipitation method for synthesizing CdO catalyst: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 400°C for 5 hours to obtain a yellow-brown CdO solid powder. The powder was further ground and used as a catalyst, denoted as CdO-Pre-400.

[0033] Example 8, Precipitation method for synthesizing CdO catalyst: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 500°C for 5 hours to obtain a yellow-brown CdO solid powder. The powder was further ground and used as a catalyst, denoted as CdO-Pre-500.

[0034] Example 9, Precipitation method for synthesizing CdO catalyst: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 600°C for 5 hours to obtain a yellow-brown CdO solid powder. The powder was further ground and used as a catalyst, denoted as CdO-Pre-600.

[0035] Example 10, Precipitation method for synthesizing CdO catalyst: 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 700°C for 5 hours to obtain a yellow-brown CdO solid powder. The powder was further ground and used as a catalyst, denoted as CdO-Pre-700.

[0036] Example 11: Synthesis of CdO catalyst by precipitation method

[0037] 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 800°C for 5 hours to obtain a yellowish-brown CdO solid powder. The powder can be further ground and used as a catalyst, denoted as CdO-Pre-800.

[0038] Example 12: Synthesis of CdO catalyst by precipitation method

[0039] 0.01 mol of Cd(NO3)2·4H2O solid was weighed and dissolved in a beaker containing 10 ml of deionized water. The mixture was stirred until the solid was completely dissolved. 10 ml of concentrated ammonia (25 wt%) was slowly added dropwise to the solution. A white flocculent precipitate appeared in the solution. The mixture was stirred at room temperature for about 3 hours, and then filtered. The filter cake was washed three times with water until the pH of the filtrate became neutral. The filter cake was then dried in an oven at 80°C for 3 hours. The collected Cd(OH)2 was a white flaky solid. The collected Cd(OH)2 was spread evenly in a crucible and calcined in a muffle furnace at 900°C for 5 hours to obtain a yellowish-brown CdO solid powder. The powder can be further ground and used as a catalyst, denoted as CdO-Pre-900.

[0040] Example 13 Synthesis of TiO2-supported CdO catalyst

[0041] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-TiO2-Cal-400).

[0042] Example 14 Synthesis of TiO2-supported CdO catalyst

[0043] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-TiO2-Cal-400).

[0044] Example 15 Synthesis of TiO2-supported CdO catalyst

[0045] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-TiO2-Cal-400).

[0046] Example 16 Synthesis of TiO2-supported CdO catalyst

[0047] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-400).

[0048] Example 17 Synthesis of TiO2-supported CdO catalyst

[0049] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-TiO2-Cal-400).

[0050] Example 18 Synthesis of TiO2-supported CdO catalyst

[0051] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-TiO2-Cal-400).

[0052] Example 19 Synthesis of TiO2-supported CdO catalyst

[0053] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h. The resulting white powder is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-500).

[0054] Example 20 Synthesis of TiO2-supported CdO catalyst

[0055] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-600).

[0056] Example 21 Synthesis of TiO2-supported CdO catalyst

[0057] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-700).

[0058] Example 22 Synthesis of TiO2-supported CdO catalyst

[0059] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-800).

[0060] Example 23 Synthesis of TiO2-supported CdO catalyst

[0061] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of TiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h. The resulting white powder is the 30% supported cadmium oxide (30%CdO-TiO2-Cal-900).

[0062] Example 24 Synthesis of ZrO2-supported CdO catalyst

[0063] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-ZrO2-Cal-400).

[0064] Example 25 Synthesis of ZrO2-supported CdO catalyst

[0065] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-ZrO2-Cal-400).

[0066] Example 26 Synthesis of ZrO2-supported CdO catalyst

[0067] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-ZrO2-Cal-400).

[0068] Example 27 Synthesis of ZrO2-supported CdO catalyst

[0069] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-ZrO2-Cal-400).

[0070] Example 28 Synthesis of ZrO2-supported CdO catalyst

[0071] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-ZrO2-Cal-400).

[0072] Example 29 Synthesis of ZrO2-supported CdO catalyst

[0073] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-ZrO2-Cal-400).

[0074] Example 30 Synthesis of ZrO2-supported CdO catalyst

[0075] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-ZrO2-Cal-500).

[0076] Example 31 Synthesis of ZrO2-supported CdO catalyst

[0077] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-ZrO2-Cal-600).

[0078] Example 32 Synthesis of ZrO2-supported CdO catalyst

[0079] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-ZrO2-Cal-700).

[0080] Example 33 Synthesis of ZrO2-supported CdO catalyst

[0081] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-ZrO2-Cal-800).

[0082] Example 34 Synthesis of ZrO2-supported CdO catalyst

[0083] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of ZrO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25%CdO-ZrO2-Cal-900).

[0084] Example 35 Synthesis of Al2O3-supported CdO catalyst

[0085] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-Al2O3-Cal-400).

[0086] Example 36 Synthesis of Al2O3-supported CdO catalyst

[0087] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Al2O3-Cal-400).

[0088] Example 37 Synthesis of Al2O3-supported CdO catalyst

[0089] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-Al2O3-Cal-400).

[0090] Example 38 Synthesis of Al2O3-supported CdO catalyst

[0091] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-Al2O3-Cal-400).

[0092] Example 39 Synthesis of Al2O3-supported CdO catalyst

[0093] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-Al2O3-Cal-400).

[0094] Example 40 Synthesis of Al2O3-supported CdO catalyst

[0095] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-Al2O3-Cal-400).

[0096] Example 41 Synthesis of Al2O3-supported CdO catalyst

[0097] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25%CdO-Al2O3-Cal-500).

[0098] Example 42 Synthesis of Al2O3-supported CdO catalyst

[0099] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25%CdO-Al2O3-Cal-600).

[0100] Example 43 Synthesis of Al2O3-supported CdO catalyst

[0101] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25%CdO-Al2O3-Cal-700).

[0102] Example 44 Synthesis of Al2O3-supported CdO catalyst

[0103] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the supported cadmium oxide (25%CdO-Al2O3-Cal-800) with a loading of 25%.

[0104] Example 45 Synthesis of Al2O3-supported CdO catalyst

[0105] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Al2O3 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25%CdO-Al2O3-Cal-900).

[0106] Example 46 Synthesis of Nb₂O₅-supported CdO catalyst

[0107] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-Nb2O5-Cal-400).

[0108] Example 47 Synthesis of Nb₂O₅-supported CdO catalyst

[0109] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-Nb2O5-Cal-400).

[0110] Example 48 Synthesis of Nb₂O₅-supported CdO catalyst

[0111] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-Nb2O5-Cal-400).

[0112] Example 49 Synthesis of Nb₂O₅-supported CdO catalyst

[0113] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-Nb2O5-Cal-400).

[0114] Example 50 Synthesis of Nb₂O₅-supported CdO catalyst

[0115] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-Nb2O5-Cal-400).

[0116] Example 51 Synthesis of Nb2O5-supported CdO catalyst

[0117] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-Nb2O5-Cal-400).

[0118] Example 52 Synthesis of Nb₂O₅-supported CdO catalyst

[0119] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Nb2O5-Cal-500).

[0120] Example 53 Synthesis of Nb2O5-supported CdO catalyst

[0121] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Nb2O5-Cal-600).

[0122] Example 54 Synthesis of Nb₂O₅-supported CdO catalyst

[0123] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Nb2O5-Cal-700).

[0124] Example 55 Synthesis of Nb₂O₅-supported CdO catalyst

[0125] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Nb2O5-Cal-800).

[0126] Example 56 Synthesis of Nb2O5-supported CdO catalyst

[0127] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Nb2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Nb2O5-Cal-900).

[0128] Example 57 Synthesis of Ta2O5-supported CdO catalyst

[0129] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-Ta2O5-Cal-400).

[0130] Example 58 Synthesis of Ta2O5-supported CdO catalyst

[0131] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-400).

[0132] Example 59 Synthesis of Ta2O5-supported CdO catalyst

[0133] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-Ta2O5-Cal-400).

[0134] Example 60 Synthesis of Ta2O5-supported CdO catalyst

[0135] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-Ta2O5-Cal-400).

[0136] Example 61 Synthesis of Ta2O5-supported CdO catalyst

[0137] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-Ta2O5-Cal-400).

[0138] Example 62 Synthesis of Ta2O5-supported CdO catalyst

[0139] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-Ta2O5-Cal-400).

[0140] Example 63 Synthesis of Ta2O5-supported CdO catalyst

[0141] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-500).

[0142] Example 64 Synthesis of Ta2O5-supported CdO catalyst

[0143] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-600).

[0144] Example 65 Synthesis of Ta2O5-supported CdO catalyst

[0145] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-700).

[0146] Example 66 Synthesis of Ta2O5-supported CdO catalyst

[0147] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-800).

[0148] Example 67 Synthesis of Ta2O5-supported CdO catalyst

[0149] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of Ta2O5 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-Ta2O5-Cal-900).

[0150] Example 68 Synthesis of SiO2-supported CdO catalyst

[0151] Weigh 0.3g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 10% supported cadmium oxide (10% CdO-SiO2-Cal-400).

[0152] Example 69 Synthesis of SiO2-supported CdO catalyst

[0153] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-SiO2-Cal-400).

[0154] Example 70 Synthesis of SiO2-supported CdO catalyst

[0155] Weigh 0.75g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 25% supported cadmium oxide (25% CdO-SiO2-Cal-400).

[0156] Example 71 Synthesis of SiO2-supported CdO catalyst

[0157] Weigh 0.9g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 30% supported cadmium oxide (30%CdO-SiO2-Cal-400).

[0158] Example 72 Synthesis of SiO2-supported CdO catalyst.

[0159] Weigh 1.2g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 40% supported cadmium oxide (40%CdO-SiO2-Cal-400).

[0160] Example 73 Synthesis of SiO2-supported CdO catalyst

[0161] Weigh 1.5g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and place it in an oven to dry at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 400℃ for 5h to obtain a white powder, which is the 50% supported cadmium oxide (50%CdO-SiO2-Cal-400).

[0162] Example 74 Synthesis of SiO2-supported CdO catalyst

[0163] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 500℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-SiO2-Cal-500).

[0164] Example 75 Synthesis of SiO2-supported CdO catalyst

[0165] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 600℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-SiO2-Cal-600).

[0166] Example 76 Synthesis of SiO2-supported CdO catalyst

[0167] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 700℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-SiO2-Cal-700).

[0168] Example 77 Synthesis of SiO2-supported CdO catalyst

[0169] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 800℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20% CdO-SiO2-Cal-800).

[0170] Example 78 Synthesis of SiO2-supported CdO catalyst

[0171] Weigh 0.6g of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 5ml of deionized water. Stir until the solid is completely dissolved. Add 1g of SiO2 powder, which has been dried at 80℃ for 1h, to the above solution and place it in an ultrasonic cleaner for 5min to sonicate the carrier evenly in the solution. Stir the resulting mixture for 7h, then transfer it to an evaporating dish and dry it in an oven at 80℃ until completely dry. Grind the resulting white solid into powder and calcine it in a muffle furnace at 900℃ for 5h to obtain a white powder, which is the 20% supported cadmium oxide (20%CdO-SiO2-Cal-900).

[0172] Example 79 Synthesis of xylulose

[0173] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of CdO-Pre-600 and stir at 120℃ for 60min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 53.17%, the xylulose formation rate was 20.73%, and the selectivity was 38.98%.

[0174] Example 80: Synthesis of xylulose

[0175] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of CdO-Cal-700 and stir at 120℃ for 60min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 42.67%, the xylulose formation rate was 23.04%, and the selectivity was 54.00%.

[0176] Example 81 Synthesis of fructose

[0177] Weigh 1g of glucose and dissolve it in 100ml of deionized water. Add 0.2g of CdO-Cal-700 and stir at 120℃ for 60min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity fructose product. The glucose reaction rate was 31.72%, the fructose formation rate was 20.53%, and the selectivity was 64.73%.

[0178] Example 82 Synthesis of Fructose

[0179] Weigh 1g of mannose and dissolve it in 100ml of deionized water. Add 0.2g of CdO-Cal-700 and stir the mixture at 120℃ for 60min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity fructose product. The mannose reaction rate was 35.32%, the fructose formation rate was 20.93%, and the selectivity was 59.26%.

[0180] Example 83: Synthesis of L-xylitol

[0181] Weigh 1 g of L-xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Cal-700 and stir the mixture at 120 °C for 60 min, then cool to room temperature. Centrifuge the reaction solution at 10000 r / min, filter to remove the solid catalyst, and add 30 g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity L-xylulose product. The L-xylose reaction rate was 30.74%, the L-xylulose formation rate was 21.73%, and the selectivity was 70.68%.

[0182] Example 84: Synthesis of L-fructose

[0183] Weigh 1 g of L-glucose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Cal-700 and stir the mixture at 120 °C for 60 min, then cool to room temperature. Centrifuge the reaction solution at 10000 r / min, filter to remove the solid catalyst, and add 30 g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity L-fructose product. The L-glucose reaction rate was 26.02%, the L-fructose formation rate was 18.34%, and the selectivity was 70.52%.

[0184] Example 85 Effect of xylose concentration on xylulose synthesis efficiency

[0185] Weigh 5g of xylose and dissolve it in 100ml of deionized water. Add 1g of CdO-Cal-700 and stir at 120℃ for 50min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 51.69%, the xylulose formation rate was 20.96%, and the selectivity was 40.54%.

[0186] Example 86 Effect of xylose concentration on xylulose synthesis efficiency

[0187] Weigh 10g of xylose and dissolve it in 100ml of deionized water. Add 2g of CdO-Cal-700 and stir at 120℃ for 50min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 71.95%, the xylulose formation rate was 19.87%, and the selectivity was 27.62%.

[0188] Example 87 Effect of xylose concentration on xylulose synthesis efficiency

[0189] Weigh 15g of xylose and dissolve it in 100ml of deionized water. Add 3g of CdO-Cal-700 and stir at 120℃ for 50min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 67.22%, the xylulose formation rate was 19.40%, and the selectivity was 28.86%.

[0190] Example 88 Effect of xylose concentration on xylulose synthesis efficiency

[0191] Weigh 20g of xylose and dissolve it in 100ml of deionized water. Add 4g of CdO-Cal-700 and stir at 120℃ for 50min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 77.89%, the xylulose formation rate was 12.57%, and the selectivity was 16.14%.

[0192] Example 89 Effect of xylose concentration on xylulose synthesis efficiency

[0193] Weigh 30g of xylose and dissolve it in 100ml of deionized water. Add 6g of CdO-Cal-700 and stir at 120℃ for 50min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 81.75%, the xylulose formation rate was 8.07%, and the selectivity was 9.87%.

[0194] Example 90: Optimization of xylulose synthesis through solvent effect

[0195] A solution was prepared by thoroughly mixing water and methanol at a mass ratio of 6:4. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 35.33%, the xylulose formation rate was 24.21%, and the selectivity was 68.53%.

[0196] Example 91: Optimization of xylulose synthesis through solvent effect

[0197] A solution was prepared by thoroughly mixing water and ethanol at a mass ratio of 6:4. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 45.90%, the xylulose formation rate was 27.86%, and the selectivity was 60.69%.

[0198] Example 92: Optimization of xylulose synthesis through solvent effect

[0199] A solution was prepared by thoroughly mixing water and n-propanol at a mass ratio of 6:4. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 36.68%, the xylulose formation rate was 19.73%, and the selectivity was 53.79%.

[0200] Example 93: Optimization of xylulose synthesis through solvent effect

[0201] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 47.27%, the xylulose formation rate was 28.71%, and the selectivity was 60.73%.

[0202] Example 94 Effect of isopropanol dosage on xylulose synthesis efficiency

[0203] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 9:1. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 48.05%, the xylulose formation rate was 27.22%, and the selectivity was 56.65%.

[0204] Example 95 Effect of isopropanol dosage on xylulose synthesis efficiency

[0205] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 46.67%, the xylulose formation rate was 28.41%, and the selectivity was 60.87%.

[0206] Example 96 Effect of isopropanol dosage on xylulose synthesis efficiency

[0207] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 4:6. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 29.82%, the xylulose formation rate was 23.48%, and the selectivity was 78.74%.

[0208] Example 97 Effect of isopropanol dosage on xylulose synthesis efficiency

[0209] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 2:8. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 17.40%, the xylulose formation rate was 13.64%, and the selectivity was 78.44%.

[0210] Example 98 Effect of isopropanol dosage on xylulose synthesis efficiency

[0211] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 1:9. 1 g of xylose was dissolved in 100 ml of this solution, and 0.2 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 40 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 14.32%, the xylulose formation rate was 11.25%, and the selectivity was 78.56%.

[0212] Example 99 Effect of isopropanol dosage on xylulose synthesis efficiency

[0213] Weigh 1g of xylose and dissolve it in 100ml of isopropanol. Add 0.2g of CdO-Cal-700 and stir at 130℃ for 40min, then cool to room temperature. Centrifuge the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 12.54%, the xylulose formation rate was 10.02%, and the selectivity was 79.90%.

[0214] Example 100: Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0215] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 5g of xylose was dissolved in 100ml of this solution, and 1g of CdO-Cal-700 was added. The mixture was stirred at 130℃ for 20min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 39.45%, the xylulose formation rate was 26.03%, and the selectivity was 65.98%.

[0216] Example 101 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0217] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 10g of xylose was dissolved in 100ml of this solution, and 2g of CdO-Cal-700 was added. The mixture was stirred at 130℃ for 20min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 39.12%, the xylulose formation rate was 25.74%, and the selectivity was 65.80%.

[0218] Example 102 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0219] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 15g of xylose was dissolved in 100ml of this solution, and 3g of CdO-Cal-700 was added. The mixture was stirred at 130℃ for 20min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 41.00%, the xylulose formation rate was 23.75%, and the selectivity was 57.92%.

[0220] Example 103 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0221] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 20g of xylose was dissolved in 100ml of this solution, and 4g of CdO-Cal-700 was added. The mixture was stirred at 130℃ for 20min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 42.41%, the xylulose formation rate was 21.30%, and the selectivity was 50.22%.

[0222] Example 104 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0223] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 30 g of xylose was dissolved in 100 ml of this solution, and 6 g of CdO-Cal-700 was added. The mixture was stirred at 130 °C for 20 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form of the catalyst was then added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 44.85%, the xylulose formation rate was 18.70%, and the selectivity was 41.69%.

[0224] Example 105 Synthesis of xylulose

[0225] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 30% CdO-TiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 19.18%, the xylulose formation rate was 10.65%, and the selectivity was 55.50%.

[0226] Example 106 Synthesis of xylulose

[0227] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 25% CdO-ZrO2-Cal-600 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 35.26%, the xylulose formation rate was 20.33%, and the selectivity was 57.66%.

[0228] Example 107 Synthesis of xylulose

[0229] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 25% CdO-Al2O3-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 39.50%, the xylulose formation rate was 20.98%, and the selectivity was 53.10%.

[0230] Example 108 Synthesis of xylulose

[0231] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 20% CdO-Nb2O5-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 37.65%, the xylulose formation rate was 19.33%, and the selectivity was 51.34%.

[0232] Example 109 Synthesis of xylulose

[0233] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 20% CdO-Ta2O5-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 38.41%, the xylulose formation rate was 19.56%, and the selectivity was 50.92%.

[0234] Example 110 Synthesis of xylulose

[0235] Weigh 1g of xylose and dissolve it in 100ml of deionized water. Add 0.2g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 32.64%, the xylulose formation rate was 23.07%, and the selectivity was 70.68%.

[0236] Example 111 Effect of xylose concentration on xylulose synthesis efficiency

[0237] Weigh 5g of xylose and dissolve it in 100ml of deionized water. Add 1g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 40min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 44.90%, the xylulose formation rate was 24.78%, and the selectivity was 55.19%.

[0238] Example 112 Effect of xylose concentration on xylulose synthesis efficiency

[0239] Weigh 10g of xylose and dissolve it in 100ml of deionized water. Add 2g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 40min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 46.05%, the xylulose formation rate was 23.63%, and the selectivity was 51.31%.

[0240] Example 113 Effect of xylose concentration on xylulose synthesis efficiency

[0241] Weigh 15g of xylose and dissolve it in 100ml of deionized water. Add 3g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 40min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 51.70%, the xylulose formation rate was 22.59%, and the selectivity was 43.68%.

[0242] Example 114 Effect of xylose concentration on xylulose synthesis efficiency

[0243] Weigh 20g of xylose and dissolve it in 100ml of deionized water. Add 4g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 40min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 54.20%, the xylulose formation rate was 21.83%, and the selectivity was 40.28%.

[0244] Example 115 Effect of xylose concentration on xylulose synthesis efficiency

[0245] Weigh 30g of xylose and dissolve it in 100ml of deionized water. Add 6g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 40min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 57.64%, the xylulose formation rate was 19.68%, and the selectivity was 34.14%.

[0246] Example 116 Optimization of xylulose synthesis through solvent effect

[0247] A solution was prepared by thoroughly mixing water and methanol at a mass ratio of 8:2. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 44.65%, the xylulose formation rate was 27.33%, and the selectivity was 61.20%.

[0248] Example 117 Optimization of xylulose synthesis through solvent effect

[0249] A solution was prepared by thoroughly mixing water and ethanol at a mass ratio of 8:2. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 43.71%, the xylulose formation rate was 28.69%, and the selectivity was 65.64%.

[0250] Example 118: Optimization of xylulose synthesis through solvent effect

[0251] A solution was prepared by thoroughly mixing water and n-propanol at a mass ratio of 8:2. 1 g of xylose was weighed and dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 35.62%, the xylulose formation rate was 22.08%, and the selectivity was 61.99%.

[0252] Example 119 Effect of isopropanol dosage on xylulose synthesis efficiency

[0253] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 9:1. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 42.76%, the xylulose formation rate was 27.29%, and the selectivity was 63.82%.

[0254] Example 120 Effect of isopropanol dosage on xylulose synthesis efficiency

[0255] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 41.13%, the xylulose formation rate was 29.74%, and the selectivity was 72.32%.

[0256] Example 121 Effect of isopropanol dosage on xylulose synthesis efficiency

[0257] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 6:4. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 34.70%, the xylulose formation rate was 27.19%, and the selectivity was 78.35%.

[0258] Example 122 Effect of isopropanol dosage on xylulose synthesis efficiency

[0259] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 4:6. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 25.28%, the xylulose formation rate was 21.33%, and the selectivity was 84.40%.

[0260] Example 123 Effect of isopropanol dosage on xylulose synthesis efficiency

[0261] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 2:8. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 22.37%, the xylulose formation rate was 17.15%, and the selectivity was 76.68%.

[0262] Example 124 Effect of isopropanol dosage on xylulose synthesis efficiency

[0263] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 1:9. 1 g of xylose was dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 19.66%, the xylulose formation rate was 13.51%, and the selectivity was 68.72%.

[0264] Example 125 Effect of isopropanol dosage on xylulose synthesis efficiency

[0265] Weigh 1g of xylose and dissolve it in 100ml of isopropanol. Add 0.2g of 20% CdO-SiO2-Cal-400 and stir at 150℃ for 10min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 16.13%, the xylulose formation rate was 11.06%, and the selectivity was 68.57%.

[0266] Example 126 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0267] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 5g of xylose was dissolved in 100ml of this solution, and 1g of 20% CdO-SiO2-Cal-400 was added. The mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 40.58%, the xylulose formation rate was 28.78%, and the selectivity was 70.94%.

[0268] Example 127 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0269] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 10g of xylose was dissolved in 100ml of this solution. 2g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 40.82%, the xylulose formation rate was 28.27%, and the selectivity was 69.27%.

[0270] Example 128 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0271] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 15g of xylose was dissolved in 100ml of this solution. 3g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 43.33%, the xylulose formation rate was 27.40%, and the selectivity was 63.23%.

[0272] Example 129 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0273] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 20g of xylose was dissolved in 100ml of this solution. 4g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 51.36%, the xylulose formation rate was 27.09%, and the selectivity was 52.75%.

[0274] Example 130 Effect of xylose concentration on xylulose synthesis efficiency in a water-isopropanol system

[0275] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 30g of xylose was dissolved in 100ml of this solution. 6g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity xylulose product. The xylose reaction rate was 55.24%, the xylulose formation rate was 26.11%, and the selectivity was 47.27%.

[0276] Example 131 Synthesis of Ribulose

[0277] Weigh 1g of ribose and dissolve it in 100ml of deionized water. Add 0.2g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 42.65%, the ribulose formation rate was 29.98%, and the selectivity was 70.30%.

[0278] Example 132 Effect of ribose concentration on ribulose synthesis efficiency

[0279] Weigh 5g of ribose and dissolve it in 100ml of deionized water. Add 1g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 48.31%, the ribulose formation rate was 32.94%, and the selectivity was 68.20%.

[0280] Example 133 Effect of ribose concentration on ribulose synthesis efficiency

[0281] Weigh 10g of ribose and dissolve it in 100ml of deionized water. Add 2g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 53.34%, the ribulose formation rate was 35.17%, and the selectivity was 65.94%.

[0282] Example 134 Effect of ribose concentration on ribulose synthesis efficiency

[0283] Weigh 15g of ribose and dissolve it in 100ml of deionized water. Add 3g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 56.40%, the ribulose formation rate was 36.47%, and the selectivity was 64.66%.

[0284] Example 135 Effect of ribose concentration on ribulose synthesis efficiency

[0285] Weigh 20g of ribose and dissolve it in 100ml of deionized water. Add 4g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst, and add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 62.44%, the ribulose formation rate was 31.42%, and the selectivity was 50.32%.

[0286] Example 136 Effect of ribose concentration on ribulose synthesis efficiency

[0287] Weigh 30g of ribose and dissolve it in 100ml of deionized water. Add 6g of 20% CdO-SiO2-Cal-400 and stir at 130℃ for 60min, then cool to room temperature. After centrifuging the reaction solution at 10000r / min, filter to remove the solid catalyst. Add 30g of hydrogen form to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 68.82%, the ribulose formation rate was 28.56%, and the selectivity was 41.51%.

[0288] Example 137 Optimization of Ribulose Synthesis through Solvent Effect

[0289] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 1 g of ribose was weighed and dissolved in 100 ml of this solution. 0.2 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 35.17%, the ribulose formation rate was 33.58%, and the selectivity was 95.48%.

[0290] Example 138 Effect of ribose concentration on ribulose synthesis efficiency in a water-isopropanol system

[0291] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 5g of ribose was dissolved in 100ml of this solution, and 1g of 20% CdO-SiO2-Cal-400 was added. The mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 40.77%, the ribulose formation rate was 37.67%, and the selectivity was 92.40%.

[0292] Example 139 Effect of ribose concentration on ribulose synthesis efficiency in a water-isopropanol system

[0293] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 10g of ribose was dissolved in 100ml of this solution, and 2g of 20% CdO-SiO2-Cal-400 was added. The mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 43.45%, the ribulose formation rate was 39.58%, and the selectivity was 91.08%.

[0294] Example 140 Effect of ribose concentration on ribulose synthesis efficiency in a water-isopropanol system

[0295] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 15g of ribose was dissolved in 100ml of this solution, and 3g of 20% CdO-SiO2-Cal-400 was added. The mixture was stirred at 150℃ for 10min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 50.73%, the ribulose formation rate was 39.70%, and the selectivity was 78.26%.

[0296] Example 141 Effect of ribose concentration on ribulose synthesis efficiency in a water-isopropanol system

[0297] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 20 g of ribose was weighed and dissolved in 100 ml of this solution. 4 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 56.80%, the ribulose formation rate was 33.70%, and the selectivity was 59.34%.

[0298] Example 142 Effect of ribose concentration on ribulose synthesis efficiency in a water-isopropanol system

[0299] A solution was prepared by thoroughly mixing water and isopropanol at a mass ratio of 8:2. 30 g of ribose was weighed and dissolved in 100 ml of this solution. 6 g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 150 °C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen form was added to the resulting solution. Residual cadmium ions in the solution were removed using an ion exchange resin of type 120, followed by concentration and purification to obtain a high-purity ribulose product. The ribose reaction rate was 62.07%, the ribulose formation rate was 29.33%, and the selectivity was 47.26%.

[0300] Example 143 Catalyst reuse for xylulose synthesis

[0301] The performance stability of the catalyst during multiple recycling processes was tested (Table 1) to evaluate its reusability. 5g of xylose was dissolved in 100ml of deionized water to prepare a solution. 1g of CdO-Cal-700 was added, and the mixture was stirred at 120℃ for 50min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form was added to the resulting solution. 120 ion exchange resin removes residual cadmium ions from the solution, and then the solution is concentrated and refined to obtain a high-purity xylulose product.

[0302] The catalyst was reused continuously under the above reaction conditions for a series of catalytic reactions. After each catalytic reaction, the catalyst was recovered by filtration, washed three times with ethanol and water, dried at 80°C, and then used in the next round of reaction. In ten consecutive catalytic tests, the xylulose yield remained constant at approximately 20%, as shown in Table 1. The results clearly demonstrate that the catalytic performance of CdO-Cal-700 is maintained in continuous catalytic reactions, exhibiting good reusability.

[0303] Table 1

[0304]

[0305]

[0306] Example 144 Catalyst Reuse for Xylitol Synthesis

[0307] The performance stability of the catalyst during multiple recycling processes was tested (Table 2) to evaluate its reusability. 5g of xylose was dissolved in 100ml of deionized water to prepare a solution. 1g of 20% CdO-SiO2-Cal-400 was added, and the mixture was stirred at 130℃ for 40min, then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen form catalyst was added to the resulting solution. 120 ion exchange resin removes residual cadmium ions from the solution, and then the solution is concentrated and refined to obtain a high-purity xylulose product.

[0308] The catalyst was reused continuously under the above reaction conditions for a series of catalytic reactions. After each catalytic reaction, the catalyst was recovered by filtration, washed three times with ethanol and water, dried at 80°C, and then used in the next round of reaction. In ten consecutive catalytic tests, the xylulose yield remained constant at approximately 24%, as shown in Table 2. The results clearly demonstrate that the catalytic performance of 20% CdO-SiO2-Cal-400 is maintained in continuous catalytic reactions, exhibiting good reusability.

[0309] Table 2

[0310]

[0311] Figure 1 The chromatograms are for (A) xylitol; (B) xylulose; (C) xylose standards; and (D) the chromatogram of xylose prepared by the reaction of xylose with 20% CdO-SiO2-Cal-400 catalyzed reaction. It can be seen that the xylulose synthesized by this invention exists in a free form in solution and has a high formation rate.

[0312] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for isomerization of a saccharide, characterized by, A cadmium-based catalyst and an aldose reactant are mixed in deionized water at a mass ratio of 1:1 to 1:50; the reaction is carried out at a reaction temperature of 80℃ to 150℃ for 10 minutes to 240 minutes; after the reaction is completed, the cadmium-based catalyst is separated and recovered, and the treated reaction solution is evaporated and concentrated to obtain the isomerized product; the aldose includes xylose, glucose, ribose or mannose. The cadmium-based catalyst is cadmium oxide or a supported cadmium oxide catalyst; the support for the supported cadmium oxide catalyst is one or more of TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, and SiO2.

2. The method of saccharide isomerization reaction according to claim 1, wherein Cadmium oxide can be prepared by precursor calcination or precipitation.

3. The method of isomerization of saccharides according to claim 2, characterized in that, The preparation method of the precursor by calcination is as follows: Cd(NO3)2·4H2O solid is placed in a muffle furnace and calcined at 400~900℃ for 4~10 hours. After cooling, CdO is obtained, ground, and used as a catalyst.

4. The method of isomerization of saccharides according to claim 2, characterized in that, The preparation method of precipitation is as follows: Cd(NO3)2·4H2O solid is dissolved in deionized water to prepare a solution. Concentrated ammonia is added dropwise to the above solution until the pH of the solution is neutral. A white flocculent precipitate appears in the solution. The mixture is stirred at room temperature to allow the precursor to react fully. After filtration and washing, a white flocculent precipitate is obtained, dried, ground, and calcined in a muffle furnace at 400~900℃ for 4~10 hours. The obtained solid powder is further ground and used as a catalyst.

5. The method of isomerization of saccharides according to claim 1, characterized in that, The preparation method of the supported cadmium oxide catalyst is as follows: cadmium nitrate is dissolved in deionized water to make a solution, the support is dispersed in the above solution, the mixture is stirred and dried, and the dried solid is calcined at 400℃~900℃ for 4~10 hours to obtain the supported cadmium-based catalyst powder.

6. The method of isomerization of saccharides according to claim 1, characterized in that, In supported cadmium oxide catalysts, cadmium oxide accounts for 10-50% of the support mass.

7. The method of isomerization of saccharides according to claim 1, characterized in that, The support for the supported cadmium oxide catalyst is SiO2.

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