Cadmium-based catalyst with stable aqueous phase for aldose isomerization reaction and application of cadmium-based catalyst

Abstract

The invention belongs to the field of preparation of solid acid catalysts, and particularly discloses a water-phase-stable cadmium-based catalyst for aldose isomerization reaction and application of the water-phase-stable cadmium-based catalyst. The preparation method of the catalyst comprises the step of obtaining the supported cadmium-based catalyst by using a precursor calcination method, a precipitation method or a loading method. The obtained catalyst powder is applied to an isomerization reaction of saccharides (especially xylose), and in a water phase, the mass ratio of the catalyst to the saccharides is (1: 1)-(1: 50), and the reaction is performed for 10-240 minutes at the temperature of 80-150 DEG C. After the reaction, the catalyst can be recycled through centrifugal separation, and a high-content isomerization product can be obtained by removing cadmium from reaction liquid through ion exchange resin and evaporating and concentrating. The catalyst provided by the invention shows good stability, high efficiency and reusability in a water phase reaction, and can be applied to isomerization of glucose, mannose, ribose and other saccharides.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of solid acid catalysts, and particularly relates to an aqueous-phase stable cadmium-based catalyst for aldose isomerization reaction and its application. Background Art

[0002] As a cheap and renewable resource, the high-value utilization of carbohydrate biomass is a current research hotspot in academia and industry. Converting common and cheap aldoses into rare ketoses through isomerization reaction is an important way to achieve the high-value utilization of carbohydrate biomass. At present, the research on converting glucose into fructose through isomerization (ketoalkylation) is relatively mature. However, for xylose, which ranks second only to glucose in nature, the research on its isomerization into xylulose is relatively less. Currently, the catalysts for xylose isomerization reaction still have problems such as many side reactions, poor reaction kinetic performance, and poor catalyst stability. Therefore, designing a catalyst that can efficiently catalyze the isomerization of xylose into xylulose remains a formidable challenge.

[0003] Currently, the isomerization of xylose into xylulose is mainly achieved through enzymatic catalysis and chemical catalysis. By reacting with immobilized xylose isomerase at 70 °C and pH = 6.0 for 6 hours, 28% of xylulose can be obtained. However, enzymatic catalysis has relatively strict requirements on the purity of raw materials, the presence or absence of impurity ions, and reaction conditions. For example, if the pH value, temperature, etc. deviate slightly from the optimal conditions, the activity of the enzyme may decrease significantly or even inactivate, resulting in unstable production processes and increased production costs. Chemical catalysis has the advantages of a wide operating temperature range and easy preparation and storage of catalysts. Therefore, researchers are currently committed to the development of 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 such as AlCl3, CaCl2, CrCl3, KOH, NaOH, Na2HPO4-NaH2PO4, etc. on the xylose isomerization reaction, and the highest yield of xylulose that can be obtained is 30%. However, there are many by-products generated during the homogeneous catalysis process, that is, the reaction selectivity is low, the separation and recovery of the catalyst are difficult, and these inorganic acids and bases will cause problems such as equipment corrosion, environmental pollution, and production safety. Different from homogeneous catalysis, solid-phase catalysts are in different phases from reactants and products in the reaction system, which makes them have significant advantages such as easy separation and reusable, which are not possessed by homogeneous catalysts, and are expected to open up a new efficient and green path for the xylose isomerization reaction.

[0004] Solid-phase catalysts for xylose isomerization can be divided into two categories: solid bases and solid acids. Solid bases mainly include hydrotalcite, basic anion resins, and some alkali metal oxides. The Ca-Al hydrotalcite synthesized by Ventura et al. obtained 11% xylulose after reacting at 90 °C for 180 min. Tawil-Lucas et al. tested the activities of commercially available macroporous and gel-type resins during isomerization. The macroporous resin IRA-900 based on a styrene-divinylbenzene copolymer obtained 15% xylulose after reacting at 60 °C for 120 min. Although both achieved the preparation of xylulose, their catalytic efficiencies were at a relatively low level. Antunes et al. synthesized the Na / K / Mg / Ca-modified AM-4 material, and Ca-AM-4 had the best catalytic effect, with xylulose reaching 39% after reacting at 100 °C for 120 min. However, this type of catalyst had an obvious ion leaching problem in the aqueous phase, and both the catalyst composition and structure changed, resulting in a sharp decline in both the catalyst activity and stability. Li Wenxuan et al. reported a core-shell structure catalyst Pt / SiO2@Mg(OH)2, which obtained 23% xylulose after reacting at 130 °C for 60 min, and 31.74% xylulose under a solvent ratio of water:methanol (8:2). However, this catalyst used the noble metal Pt during the synthesis process, increasing the R & D and production costs; the Mg(OH)2 contained in the catalyst had poor stability in the aqueous phase, and Mg ions were extremely easy to leach, resulting in poor reusability of the catalyst, and a large amount of carbon deposition appeared on the catalyst surface during continuous use, further leading to catalyst deactivation, thus causing the continuous decline of the xylulose yield.

[0005] Common solid acids that can be used for xylose isomerization include zeolites, metal oxides, organic-inorganic hybrid materials, etc. Tin-containing zeolites formed by isomorphously substituting some silicon (Si) atoms in the zeolite framework with tin (Sn) atoms can catalyze the isomerization of aldose to ketose. Gunther et al. obtained 13% xylulose by reacting Sn-β zeolite at 85 °C for 15 min. Lew et al. synthesized Sn-MFI and Sn-β zeolites and obtained xylulose yields of 19% and 24% respectively by reacting at 90 °C for 210 min. The Sn-β zeolite prepared by Choudhary et al. obtained 27% xylulose by reacting at 100 °C for 15 min. Although tin-containing zeolites can achieve a certain yield in the reaction, the synthesis methods of Sn-MFI and Sn-β zeolites are complex and the preparation cycle is long. Currently, they can only be at the laboratory level and cannot meet the requirements of industrial production; moreover, during the catalytic process, the tin atoms in their framework may be lost, resulting in catalyst deactivation and reducing the stability of the catalyst. Paniagua et al. prepared xylulose from xylose by a two-step method of methanol etherification-hydrolysis, that is, xylose first reacts with methanol to form methyl xyloside, and then xylulose is obtained by hydrolysis. Using H-Y, H-USY, and H-β three zeolites as catalysts, 23%, 39%, and 31% xylulose were obtained respectively after reacting at 100 °C for 60 min; however, the activity of the catalyst decreased significantly after being used three times. Although this reaction system can achieve a relatively high theoretical yield, a large proportion of xylulose still exists in the form of methyl xyluloside and requires a long hydrolysis process to obtain free xylulose. This method also has a solvent effect, that is, zeolites such as the above-mentioned H-USY cannot catalyze the xylose isomerization reaction in pure aqueous solution, and anhydrous alcohols (such as methanol, ethanol) must be used as solvents in the first step reaction; and when ethanol is used as a solvent, due to the influence of steric hindrance, the etherification of xylulose is more difficult and more by-products will be produced, resulting in a lower reaction selectivity. Thatiane et al. studied the catalytic effects of tin oxide (Sn100), molybdenum oxide (Mo100), and tin-molybdenum mixed oxide (SnMo25) in the conversion of xylose. SnMo25 as a catalyst obtained 17.2% xylulose by reacting at 150 °C for 180 min, but serious carbon deposition formed on the catalyst surface during the reaction, continuously reducing the catalyst activity. Fraga et al. prepared Pt / SBA-15-SO3H and Pt / Nb2O5. In a biphasic system or a water-organic solvent mixed solvent system, the highest xylulose formation rate was about 7.5-10%, and the selectivity was 26-55%; the catalytic activity decreased by nearly 45% after being used three times, that is, the xylulose formation rate decreased to less than 5%; and the substrate concentration had to be about 1.0 wt.% to maintain a relatively high reaction effect.

[0006] In summary, solid-phase catalysis has made great progress in the isomerization of xylose to xylulose so far. However, there are still problems that need to be solved urgently in large-scale preparation or actual industrialization. For example, ion loss of the catalyst and surface carbon deposition lead to a decrease in stability and activity, resulting in an unstable production process; poor productivity due to low catalytic efficiency (the amount of xylulose that can be prepared by a unit weight of the catalyst per unit time); a series of problems such as poor reaction kinetic performance. Therefore, it is necessary to design a stable and efficient catalyst in aqueous phase to realize the conversion of xylose to xylulose. Summary of the Invention

[0007] The object of the present invention is to provide an aqueous-phase stable cadmium-based catalyst for aldose isomerization reaction and its application to overcome the defects in the prior art. The method of the invention is: using the precursor calcination method, precipitation method and loading method to obtain cadmium-based catalysts with different structures. The synthesized catalyst has high surface structure stability, less ion leakage during the aqueous-phase reaction process, can selectively catalyze the conversion of high-concentration xylose to xylulose; maintains a high catalytic efficiency during multiple catalytic cycles. Thus, an aqueous-phase stable cadmium-based catalyst is prepared by a simple process, and a product with a high xylulose content is efficiently obtained under relatively mild conditions, and can be applied to the isomerization of other sugars such as glucose, mannose and ribose.

[0008] To achieve the object of the present invention, the specific technical solutions adopted are as follows:

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

[0010] An aqueous-phase stable, highly efficient and reusable catalyst for xylose isomerization reaction, the obtaining method includes: precursor calcination method, precipitation method and impregnation method.

[0011] The preparation method of cadmium oxide is the precursor calcination method or the precipitation method.

[0012] Precursor calcination method: Place a certain amount of Cd(NO3)2·4H2O solid in a muffle furnace and calcine it at 400-900 °C for 4-10 hours. After cooling, the obtained grayish-black solid powder is CdO. Grind the obtained CdO powder and use it as a catalyst.

[0013] Precipitation method: Dissolve Cd(NO3)2·4H2O solid in deionized water to prepare a solution with a certain concentration. Slowly add 25wt% concentrated ammonia water drop by drop to the above solution (the pH of the solution is neutral). White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 hours to allow the precursor to react fully. Then, filter and wash to obtain white flocculent precipitates. Place the obtained precipitates in an oven to dry, grind them into powder, and calcine them in a muffle furnace at 400 - 900 °C for 4 - 10 hours. Further grind the obtained solid powder and use it as a catalyst.

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

[0015] Specific impregnation method: Dissolve Cd(NO3)2·4H2O solid in deionized water to prepare a solution with a certain concentration. Then disperse the catalyst carriers (TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, SiO2) in the above solution. After stirring for 6 hours, place it in an oven to dry. Grind the obtained solid into powder. Calcinate the powder at 400 - 900 °C for 4 - 10 hours. The obtained solid powder is the supported cadmium-based catalyst. Further grind the powder and it can be used as a catalyst. Preferably, the cadmium oxide catalyst supported on silica has the best effect. Further, the cadmium oxide in the supported cadmium oxide catalyst accounts for 10 - 50% of the mass of the carrier.

[0016] The obtained cadmium-based catalyst is applied to the isomerization reaction of saccharides, mainly through the following steps: Dissolve the catalyst powder and the reactant sugar in a mass ratio of 1:1 - 1:50 in deionized water. The reaction temperature is 80 °C - 150 °C, and the reaction time is 10 minutes - 240 minutes. Collect the reaction solution and separate the cadmium-based catalyst by centrifugation. The obtained filtrate (reaction solution) is passed through an ion exchange resin to remove the residual cadmium ions in the reaction solution, and then high-content isomerization products can be obtained through evaporation and concentration.

[0017] The present invention can realize the isomerization of aldoses including saccharides such as xylose, glucose, ribose, or mannose.

[0018] Effects of the invention: Using the technical solution of the present invention, the optimizations that can be brought include:

[0019] 1. The cadmium-based catalyst of the present invention belongs to a solid acid catalyst, with the characteristics of high surface stability and catalytic activity during the aqueous-phase reaction process. After being supported on carriers such as high-surface-area silica, the atomic utilization rate of cadmium oxide has been greatly improved. When used for the aqueous-phase catalytic isomerization of xylose, the product yield is high, the selectivity is high, the ion loss is less, and the deactivation is light, realizing the green and efficient catalytic conversion of saccharides. The selectivity of some reactions can be as high as over 85%.

[0020] 2. The catalytic isomerization of xylose to xylulose in the present invention is a solid-liquid two-phase catalytic system. After the reaction, the catalyst can be conveniently separated by filtration or centrifugation. After being washed with water and then with alcohol, the catalyst can be put into the next reaction. After being reused ten times, the catalytic activity does not decrease significantly. That is, in the catalyst recovery process, roasting activation is not required, 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 sugar substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 They are the standard chromatograms of (A) xylitol; (B) xylulose; (C) xylose and (D) the chromatogram of xylulose prepared by the catalytic reaction of xylose with 20% CdO-SiO2-Cal-400. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention is further described in detail below in conjunction with embodiments:

[0023] Comparative Example 1, comparison with the zeolite catalyst in US10246477B2: Different commercially available acidic zeolite catalysts were tested in the comparative example. Although the reaction system can achieve a relatively high theoretical yield, a large proportion of xylulose still exists in the form of methyl xyluloside and requires a long hydrolysis process to obtain free xylulose. There is also a solvent effect in this method, that is, zeolites such as H-USY cannot catalyze the xylose isomerization reaction in pure aqueous solution, and anhydrous alcohols (such as methanol, ethanol) must be used as solvents in the first step of the reaction.

[0024] Comparative Example 2, comparison with the MgO catalyst: Weigh 1 g of xylose and dissolve it in 100 ml of deionized water, add 0.2 g of MgO, and stir and react at 120 °C for 60 min, then cool to room temperature. After the reaction solution is centrifuged at 10,000 r / min and then filtered to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. Using the same reaction conditions as in Example 80, but the results show that the xylose reaction rate is 51.23%, the xylulose formation rate is 15.52%, and the selectivity is 30.29%.

[0025] Comparative Example 3, comparison with the Bi2O3 catalyst: Weigh 1 g of xylose and dissolve it in 100 ml of deionized water, add 0.2 g of Bi2O3, and stir and react at 120 °C for 60 min, then cool to room temperature. After the reaction solution is centrifuged at 10,000 r / min and then filtered to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then a high-purity xylulose product is obtained through concentration and refinement. The same reaction conditions as in Example 80 are adopted, but the results show that the xylose reaction rate is 16.09%, the xylulose formation rate is 3.61%, and the selectivity is 22.45%.

[0026] Example 1, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 400 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-400.

[0027] Example 2, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 500 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-500.

[0028] Example 3, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 600 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-600.

[0029] Example 4, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 700 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-700.

[0030] Example 5, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 800 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-800.

[0031] Example 6, synthesis of CdO catalyst by precursor calcination method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and place it in a muffle furnace, calcine it at 900 °C for 5 h. After the sample is cooled to room temperature, a grayish-black solid is obtained and ground to obtain CdO powder that can be used as a catalyst, denoted as CdO-Cal-900.

[0032] Example 7, Synthesis of CdO Catalyst by Precipitation Method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly add 10 ml of concentrated ammonia water (25 wt%) drop by drop to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, then filter it. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 evenly in a crucible and place it in a muffle furnace to calcine at 400 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-400.

[0033] Example 8, Synthesis of CdO Catalyst by Precipitation Method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly add 10 ml of concentrated ammonia water (25 wt%) drop by drop to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, and then filter it. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 evenly in a crucible and place it in a muffle furnace to calcine at 500 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-500.

[0034] Example 9, Synthesis of CdO Catalyst by Precipitation Method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly add 10 ml of concentrated ammonia water (25 wt%) drop by drop to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, and then filter it. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 evenly in a crucible and place it in a muffle furnace to calcine at 600 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-600.

[0035] Example 10. Synthesis of CdO catalyst by precipitation method: Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly dropwise add 10 ml of concentrated ammonia water (25 wt%) to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, then filter. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 flat in a crucible and put it into a muffle furnace and calcine it at 700 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-700.

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

[0037] Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly dropwise add 10 ml of concentrated ammonia water (25 wt%) to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, then filter. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 flat in a crucible and put it into a muffle furnace and calcine it at 800 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-800.

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

[0039] Weigh 0.01 mol of Cd(NO3)2·4H2O solid and dissolve it in a beaker containing 10 ml of deionized water. Stir to completely dissolve the solid. Slowly dropwise add 10 ml of concentrated ammonia water (25 wt%) to the above solution. White flocculent precipitates appear in the solution. Stir the mixture solution at room temperature for about 3 h, then filter. During this process, wash the filter cake three times with water until the pH of the filtrate becomes neutral. Then place the filter cake in an oven at 80 °C and dry it for 3 h. The collected Cd(OH)2 is a white flaky solid. Spread the collected Cd(OH)2 flat in a crucible and put it into a muffle furnace and calcine it at 900 °C for 5 h to obtain a yellowish-brown CdO solid powder. After further grinding the powder, it can be used as a catalyst, denoted as CdO-Pre-900.

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

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

[0042] Example 14 Synthesis of TiO2-Supported CdO Catalyst

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

[0044] Example 15 Synthesis of TiO2-Supported CdO Catalyst

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

[0046] Example 16 Synthesis of TiO2-Supported CdO Catalyst

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

[0048] Example 17 Synthesis of TiO2-Supported CdO Catalyst

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

[0050] Example 18 Synthesis of TiO2-Supported CdO Catalyst

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

[0052] Example 19 Synthesis of TiO2-Supported CdO Catalyst

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

[0054] Example 20 Synthesis of TiO2-Supported CdO Catalyst

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

[0056] Example 21 Synthesis of TiO2-Supported CdO Catalyst

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

[0058] Example 22 Synthesis of TiO2-Supported CdO Catalyst[[ID=I6]]

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

[0060] Example 23 Synthesis of TiO2-Supported CdO Catalyst

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

[0062] Example 24 Synthesis of ZrO2-Supported CdO Catalyst

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

[0064] Example 25 Synthesis of ZrO2-Supported CdO Catalyst

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

[0066] Example 26 Synthesis of ZrO2-Supported CdO Catalyst

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

[0068] Example 27 Synthesis of ZrO2-Supported CdO Catalyst

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

[0070] Example 28 Synthesis of ZrO2-Supported CdO Catalyst

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

[0072] Example 29 Synthesis of ZrO2-Supported CdO Catalyst

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

[0074] Example 30 Synthesis of ZrO2-Supported CdO Catalyst

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

[0076] Example 31 Synthesis of ZrO2-Supported CdO Catalyst

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

[0078] Example 32 Synthesis of ZrO2-Supported CdO Catalyst

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

[0080] Example 33 Synthesis of ZrO2-Supported CdO Catalyst

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

[0082] Example 34 Synthesis of ZrO2-Supported CdO Catalyst

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

[0084] Example 35 Synthesis of Al2O3-Supported CdO Catalyst

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

[0086] Example 36 Synthesis of Al2O3-Supported CdO Catalyst

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

[0088] Example 37 Synthesis of Al2O3-Supported CdO Catalyst

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

[0090] Example 38 Synthesis of Al2O3-Supported CdO Catalyst

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

[0092] Example 39 Synthesis of Al2O3-Supported CdO Catalyst

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

[0094] Example 40 Synthesis of Al2O3-Supported CdO Catalyst

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

[0096] Example 41 Synthesis of Al2O3-Supported CdO Catalyst

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

[0098] Example 42 Synthesis of Al2O3-Supported CdO Catalyst

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

[0100] Example 43 Synthesis of Al2O3-Supported CdO Catalyst

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

[0102] Example 44 Synthesis of Al2O3-Supported CdO Catalyst

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

[0104] Example 45 Synthesis of Al2O3-Supported CdO Catalyst

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

[0106] Example 46 Synthesis of Nb2O5-Supported CdO Catalyst

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

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

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

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

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

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

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

[0114] Example 50 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0116] Example 51 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0118] Example 52 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0120] Example 53 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0122] Example 54 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0124] Example 55 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0126] Example 56 Synthesis of Nb2O5-Supported CdO Catalyst

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

[0128] Example 57 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0130] Example 58 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0132] Example 59 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0134] Example 60 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0136] Example 61 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0138] Example 62 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0140] Example 63 Synthesis of Ta2O5-Supported CdO Catalyst

[0141] Weigh 0.6 g of Cd(NO3)2·4H, dissolve it in a beaker containing 5 ml of deionized water. Stir to completely dissolve the solid. After drying 1 g of Ta2O5 powder at 80 °C for 1 h, add it to the above solution, and place it in an ultrasonic cleaner and ultrasonicate for 5 min to disperse the carrier evenly in the solution. Stir the resulting mixture solution for 7 h, then transfer it to an evaporating dish, place it in an oven and dry at 80 °C until completely dry. Grind the obtained white solid into powder, place it in a muffle furnace and calcine at 500 °C for 5 h to obtain a white powder, which is the supported cadmium oxide with a loading amount of 20% (20% CdO-Ta2O5-Cal-500).

[0142] Example 64 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0144] Example 65 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0146] Example 66 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0148] Example 67 Synthesis of Ta2O5-Supported CdO Catalyst

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

[0150] Example 68 Synthesis of SiO2-Supported CdO Catalyst

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

[0152] Example 69 Synthesis of SiO2-Supported CdO Catalyst

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

[0154] Example 70 Synthesis of SiO2-Supported CdO Catalyst

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

[0156] Example 71 Synthesis of SiO2-Supported CdO Catalyst

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

[0158] Example 72 Synthesis of SiO2-Supported CdO Catalyst.

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

[0160] Example 73 Synthesis of SiO2-Supported CdO Catalyst

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

[0162] Example 74 Synthesis of SiO2-Supported CdO Catalyst

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

[0164] Example 75 Synthesis of SiO2-Supported CdO Catalyst

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

[0166] Example 76 Synthesis of SiO2-Supported CdO Catalyst

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

[0168] Example 77 Synthesis of SiO2-Supported CdO Catalyst

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

[0170] Example 78 Synthesis of SiO2-Supported CdO Catalyst

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

[0172] Example 79 Synthesis of Xylulose

[0173] Weigh 1 g of xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Pre-600 and stir and react at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen form 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then through concentration and purification, a high-purity xylulose product is obtained. The reaction rate of xylose is 53.17%, the formation rate of xylulose is 20.73%, and the selectivity is 38.98%.

[0174] Example 80 Synthesis of Xylulose

[0175] Weigh 1 g of xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Cal-700 and stir at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then through concentration and purification, a high-purity xylulose product is obtained. The reaction rate of xylose is 42.67%, the formation rate of xylulose is 23.04%, and the selectivity is 54.00%.

[0176] Example 81 Synthesis of Fructose

[0177] Weigh 1 g of glucose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Cal-700 and stir at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then through concentration and purification, a high-purity fructose product is obtained. The reaction rate of glucose is 31.72%, the formation rate of fructose is 20.53%, and the selectivity is 64.73%.

[0178] Example 82 Synthesis of Fructose

[0179] Weigh 1 g of mannose and dissolve it in 100 ml of deionized water. Add 0.2 g of CdO-Cal-700 and stir at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then through concentration and purification, a high-purity fructose product is obtained. The reaction rate of mannose is 35.32%, the formation rate of fructose is 20.93%, and the selectivity is 59.26%.

[0180] Example 83 Synthesis of L-Xylulose

[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 reaction at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity L-xylulose product through concentration and purification. The reaction rate of L-xylose is 30.74%, the formation rate of L-xylulose is 21.73%, and the selectivity is 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 reaction at 120 °C for 60 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity L-fructose product through concentration and purification. The reaction rate of L-glucose is 26.02%, the formation rate of L-fructose is 18.34%, and the selectivity is 70.52%.

[0184] Example 85 Effect of Xylose Concentration on the Synthesis Efficiency of Xylulose

[0185] Weigh 5 g of xylose and dissolve it in 100 ml of deionized water. Add 1 g of CdO-Cal-700 and stir the reaction at 120 °C for 50 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 51.69%, the formation rate of xylulose is 20.96%, and the selectivity is 40.54%.

[0186] Example 86 Effect of Xylose Concentration on the Synthesis Efficiency of Xylulose

[0187] Weigh 10 g of xylose and dissolve it in 100 ml of deionized water. Add 2 g of CdO-Cal-700 and stir the reaction at 120 °C for 50 min, then cool to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering to remove the solid catalyst, add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 71.95%, the formation rate of xylulose is 19.87%, and the selectivity is 27.62%.

[0188] Example 87: Influence of Xylose Concentration on the Synthesis Efficiency of Xylulose

[0189] Weigh 15 g of xylose and dissolve it in 100 ml of deionized water. Add 3 g of CdO-Cal-700 and stir the reaction at 120 °C for 50 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 67.22%, the formation rate of xylulose is 19.40%, and the selectivity is 28.86%.

[0190] Example 88: Influence of Xylose Concentration on the Synthesis Efficiency of Xylulose

[0191] Weigh 20 g of xylose and dissolve it in 100 ml of deionized water. Add 4 g of CdO-Cal-700 and stir the reaction at 120 °C for 50 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 77.89%, the formation rate of xylulose is 12.57%, and the selectivity is 16.14%.

[0192] Example 89: Influence of Xylose Concentration on the Synthesis Efficiency of Xylulose

[0193] Weigh 30 g of xylose and dissolve it in 100 ml of deionized water. Add 6 g of CdO-Cal-700 and stir the reaction at 120 °C for 50 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 81.75%, the formation rate of xylulose is 8.07%, and the selectivity is 9.87%.

[0194] Example 90: Optimization of Xylulose Synthesis through Solvent Effect

[0195] Fully mix water and methanol in a mass ratio of 6:4 to prepare a solution. Weigh 1 g of xylose and dissolve it in 100 ml of the above solution. Add 0.2 g of CdO-Cal-700 and stir the reaction at 130 °C for [40 min], then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin was used to remove the residual cadmium ions in the solution, and then a high-purity xylulose product was obtained through concentration and refinement. 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] Water and ethanol were fully mixed in a mass ratio of 6:4 to prepare a solution. 1 g of xylose was weighed and dissolved in 100 ml of the above solution. 0.2 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 40 min, and then cooled to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form 120 ion exchange resin was used to remove the residual cadmium ions in the solution, and then a high-purity xylulose product was obtained through concentration and refinement. 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] Water and n-propanol were fully mixed in a mass ratio of 6:4 to prepare a solution. 1 g of xylose was weighed and dissolved in 100 ml of the above solution. 0.2 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 40 min, and then cooled to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form 120 ion exchange resin was used to remove the residual cadmium ions in the solution, and then a high-purity xylulose product was obtained through concentration and refinement. The xylose reaction rate was 36.68%, the xylulose formation rate was 19.73%, and the selectivity was 53.79%.

[0200] [[ID=I9]]Example 93 Optimization of Xylulose Synthesis through Solvent Effect

[0201] Water and isopropanol were fully mixed in a mass ratio of 6:4 to prepare a solution. 1 g of xylose was weighed and dissolved in 100 ml of the above solution. 0.2 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 40 min, and then cooled to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form 120 ion exchange resin was used to remove the residual cadmium ions in the solution, and then a high-purity xylulose product was obtained through concentration and refinement. 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 the Synthesis Efficiency of Xylulose

[0203] Water and isopropanol were thoroughly mixed in a mass ratio of 9:1 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of CdO-Cal-700 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 48.05%, the xylulose production rate was 27.22%, and the selectivity was 56.65%.

[0204] Example 95 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0205] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of CdO-Cal-700 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 46.67%, the xylulose production rate was 28.41%, and the selectivity was 60.87%.

[0206] Example 96 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0207] Water and isopropanol were thoroughly mixed in a mass ratio of 4:6 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of CdO-Cal-700 was added and stirred at 130°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 29.82%, the xylulose production rate was 23.48%, and the selectivity was 78.74%.

[0208] Example 97 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0209] Water and isopropanol were thoroughly mixed in a mass ratio of 2:8 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of CdO-Cal-700 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 17.40%, the xylulose production rate was 13.64%, and the selectivity was 78.44%.

[0210] Example 98 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0211] Water and isopropanol were thoroughly mixed in a mass ratio of 1:9 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of CdO-Cal-700 was added and stirred at 130°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 14.32%, the xylulose production rate was 11.25%, and the selectivity was 78.56%.

[0212] Example 99 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0213] 1g xylose was weighed and dissolved in 100ml isopropanol, 0.2g CdO-Cal-700 was added, and the mixture was stirred at 130℃ for 40min, and then cooled to room temperature. The reaction solution was centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 12.54%, the xylulose production rate was 10.02%, and the selectivity was 79.90%.

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

[0215] Water and isopropanol were thoroughly mixed in a mass ratio of 6:4 to prepare a solution. 5 g of xylose was weighed and dissolved in 100 ml of the above solution. 1 g of CdO-Cal-700 was added and 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-type The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then high-purity xylulose product was obtained through concentration and refinement. The reaction rate of xylose was 39.45%, the formation rate of xylulose was 26.03%, and the selectivity was 65.98%.

[0216] Example 101 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0217] Water and isopropanol were fully mixed according to a mass ratio of 6:4 to prepare a solution. 10 g of xylose was weighed and dissolved in 100 ml of the above solution. 2 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 20 min, and then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and then filtered to remove the solid catalyst. 30 g of hydrogen-form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then high-purity xylulose product was obtained through concentration and refinement. The reaction rate of xylose was 39.12%, the formation rate of xylulose was 25.74%, and the selectivity was 65.80%.

[0218] Example 102 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0219] Water and isopropanol were fully mixed according to a mass ratio of 6:4 to prepare a solution. 15 g of xylose was weighed and dissolved in 100 ml of the above solution. 3 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 20 min, and then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and then filtered to remove the solid catalyst. 30 g of hydrogen-form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then high-purity xylulose product was obtained through concentration and refinement. The reaction rate of xylose was 41.00%, the formation rate of xylulose was 23.75%, and the selectivity was 57.92%.

[0220] Example 103 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0221] Water and isopropanol were fully mixed according to a mass ratio of 6:4 to prepare a solution. 20 g of xylose was weighed and dissolved in 100 ml of the above solution. 4 g of CdO-Cal-700 was added, and the mixture was stirred and reacted at 130 °C for 20 min, and then cooled to room temperature. The reaction solution was centrifuged at 10000 r / min and then filtered to remove the solid catalyst. 30 g of hydrogen-form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then high-purity xylulose product was obtained through concentration and refinement. The reaction rate of xylose was 42.41%, the formation rate of xylulose was 21.30%, and the selectivity was 50.22%.

[0222] Example 104 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0223] Water and isopropanol were thoroughly mixed in a mass ratio of 6:4 to prepare a solution. 30 g of xylose was weighed and dissolved in 100 ml of the above solution. 6 g of CdO-Cal-700 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 44.85%, the xylulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 19.18%, the xylulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 35.26%, the xylulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then a high-purity xylulose product was obtained through concentration and purification. 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 1 g of xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of 20% CdO-Nb2O5-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then a high-purity xylulose product was obtained through concentration and purification. 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 1 g of xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of 20% CdO-Ta2O5-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then a high-purity xylulose product was obtained through concentration and purification. 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 1 g of xylose and dissolve it in 100 ml of deionized water. Add 0.2 g of 20% CdO-SiO2-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen form The residual cadmium ions in the solution were removed by 120 ion exchange resin, and then a high-purity xylulose product was obtained through concentration and purification. 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 the Synthesis Efficiency of Xylulose

[0237] Weigh 5 g of xylose and dissolve it in 100 ml of deionized water. Add 1 g of 20% CdO-SiO2-Cal-400 and stir the reaction at 130 °C for 40 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 44.90%, the formation rate of xylulose is 24.78%, and the selectivity is 55.19%.

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

[0239] Weigh 10 g of xylose and dissolve it in 100 ml of deionized water. Add 2 g of 20% CdO-SiO2-Cal-400 and stir the reaction at 130 °C for 40 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 46.05%, the formation rate of xylulose is 23.63%, and the selectivity is 51.31%.

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

[0241] Weigh 15 g of xylose and dissolve it in 100 ml of deionized water. Add 3 g of 20% CdO-SiO2-Cal-400 and stir the reaction at 130 °C for 40 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin to remove the residual cadmium ions in the solution, and then obtain a high-purity xylulose product through concentration and purification. The reaction rate of xylose is 51.70%, the formation rate of xylulose is 22.59%, and the selectivity is 43.68%.

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

[0243] Weigh 20 g of xylose and dissolve it in 100 ml of deionized water. Add 4 g of 20% CdO-SiO2-Cal-400 and stir the reaction at 130 °C for 40 min, then cool it to room temperature. After centrifuging the reaction solution at 10,000 r / min and filtering, remove the solid catalyst. Add 30 g of hydrogen-form 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 54.20%, the xylulose production rate was 21.83%, and the selectivity was 40.28%.

[0244] Example 115 Effect of Xylose Concentration on Xylulose Synthesis Efficiency

[0245] 30g of xylose was weighed and dissolved in 100ml of deionized water. 6g of 20% CdO-SiO2-Cal-400 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 57.64%, the xylulose production rate was 19.68%, and the selectivity was 34.14%.

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

[0247] Water and methanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 44.65%, the xylulose production rate was 27.33%, and the selectivity was 61.20%.

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

[0249] Water and ethanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 43.71%, the xylulose production rate was 28.69%, and the selectivity was 65.64%.

[0250] Example 118 Optimization of xylulose synthesis by solvent effect

[0251] Water and n-propanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 35.62%, the xylulose production rate was 22.08%, and the selectivity was 61.99%.

[0252] Example 119 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0253] Water and isopropanol were thoroughly mixed in a mass ratio of 9:1 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 42.76%, the xylulose production rate was 27.29%, and the selectivity was 63.82%.

[0254] Example 120 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0255] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 41.13%, the xylulose production rate was 29.74%, and the selectivity was 72.32%.

[0256] Example 121 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0257] Water and isopropanol were thoroughly mixed in a mass ratio of 6:4 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 34.70%, the xylulose production rate was 27.19%, and the selectivity was 78.35%.

[0258] Example 122 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0259] Water and isopropanol were thoroughly mixed in a mass ratio of 4:6 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 25.28%, the xylulose production rate was 21.33%, and the selectivity was 84.40%.

[0260] Example 123 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0261] Water and isopropanol were thoroughly mixed in a mass ratio of 2:8 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 22.37%, the xylulose production rate was 17.15%, and the selectivity was 76.68%.

[0262] Example 124 Effect of Isopropanol Amount on Xylulose Synthesis Efficiency

[0263] Water and isopropanol were thoroughly mixed in a mass ratio of 1:9 to prepare a solution. 1g of xylose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 19.66%, the xylulose production rate was 13.51%, and the selectivity was 68.72%.

[0264] Example 125 Effect of Isopropanol Amount 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 16.13%, the xylulose production rate was 11.06%, and the selectivity was 68.57%.

[0266] Example 126 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0267] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 5g of xylose was weighed and dissolved in 100ml of the above solution. 1g of 20% CdO-SiO2-Cal-400 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 40.58%, the xylulose production rate was 28.78%, and the selectivity was 70.94%.

[0268] Example 127 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0269] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 10g of xylose was weighed and dissolved in 100ml of the above solution. 2g of 20% CdO-SiO2-Cal-400 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 40.82%, the xylulose production rate was 28.27%, and the selectivity was 69.27%.

[0270] Example 128 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0271] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 15g of xylose was weighed and dissolved in 100ml of the above solution. 3g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 43.33%, the xylulose production rate was 27.40%, and the selectivity was 63.23%.

[0272] Example 129 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0273] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 20 g of xylose was weighed and dissolved in 100 ml of the above solution. 4 g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 51.36%, the xylulose production rate was 27.09%, and the selectivity was 52.75%.

[0274] Example 130 Effect of Xylose Concentration on Xylulose Synthesis Efficiency in Water-Isopropanol System

[0275] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 30 g of xylose was weighed and dissolved in 100 ml of the above solution. 6 g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C for 10 min, then cooled to room temperature. The reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst. 30 g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then high-purity xylulose was obtained through concentration and purification. The xylulose reaction rate was 55.24%, the xylulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 42.65%, the ribulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 48.31%, the ribulose production 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. The reaction solution is centrifuged at 10000r / min and filtered to remove the solid catalyst. 30g of hydrogen-type The 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then a high-purity ribulose product is obtained through concentration and refinement. The ribose reaction rate is 53.34%, the ribulose formation rate is 35.17%, and the selectivity is 65.94%.

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

[0283] Weigh 15 g of ribose and dissolve it in 100 ml of deionized water. Add 3 g of 20% CdO-SiO2-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution is centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form The 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then a high-purity ribulose product is obtained through concentration and refinement. The ribose reaction rate is 56.40%, the ribulose formation rate is 36.47%, and the selectivity is 64.66%.

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

[0285] Weigh 20 g of ribose and dissolve it in 100 ml of deionized water. Add 4 g of 20% CdO-SiO2-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution is centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form The 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then a high-purity ribulose product is obtained through concentration and refinement. The ribose reaction rate is 62.44%, the ribulose formation rate is 31.42%, and the selectivity is 5,0.32%.

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

[0287] Weigh 30 g of ribose and dissolve it in 100 ml of deionized water. Add 6 g of 20% CdO-SiO2-Cal-400, and stir and react at 130 °C for 60 min, then cool to room temperature. After the reaction solution is centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form The 120 ion exchange resin is used to remove the residual cadmium ions in the solution, and then a high-purity ribulose product is obtained through concentration and refinement. The ribose reaction rate is 68.82%, the ribulose formation rate is 28.56%, and the selectivity is 41.51%.

[0288] Example 137 Optimization of ribulose synthesis through solvent effect

[0289] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 1g of ribose was weighed and dissolved in 100ml of the above solution. 0.2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 35.17%, the ribulose production rate was 33.58%, and the selectivity was 95.48%.

[0290] Example 138 Effect of Ribose Concentration on Ribulose Synthesis Efficiency in Water-Isopropanol System

[0291] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 5g of ribose was weighed and dissolved in 100ml of the above solution. 1g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 40.77%, the ribulose production rate was 37.67%, and the selectivity was 92.40%.

[0292] Example 139 Effect of Ribose Concentration on Ribulose Synthesis Efficiency in Water-Isopropanol System

[0293] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 10g of ribose was weighed and dissolved in 100ml of the above solution. 2g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 43.45%, the ribulose production rate was 39.58%, and the selectivity was 91.08%.

[0294] Example 140 Effect of Ribose Concentration on Ribulose Synthesis Efficiency in Water-Isopropanol System

[0295] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 15g of ribose was weighed and dissolved in 100ml of the above solution. 3g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 50.73%, the ribulose production rate was 39.70%, and the selectivity was 78.26%.

[0296] Example 141 Effect of Ribose Concentration on Ribulose Synthesis Efficiency in Water-Isopropanol System

[0297] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 20g of ribose was weighed and dissolved in 100ml of the above solution. 4g of 20% CdO-SiO2-Cal-400 was added and stirred at 150°C 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 56.80%, the ribulose production rate was 33.70%, and the selectivity was 59.34%.

[0298] Example 142 Effect of Ribose Concentration on Ribulose Synthesis Efficiency in Water-Isopropanol System

[0299] Water and isopropanol were thoroughly mixed in a mass ratio of 8:2 to prepare a solution. 30g of ribose was weighed and dissolved in 100ml of the above solution. 6g of 20% CdO-SiO2-Cal-400 was added and 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-type 120 ion exchange resin was used to remove residual cadmium ions from the solution, and then concentrated and purified to obtain a high-purity ribulose product. The ribose reaction rate was 62.07%, the ribulose production rate was 29.33%, and the selectivity was 47.26%.

[0300] Example 143: Reusing Catalyst to Synthesize Xylulose

[0301] The performance stability of the catalyst during multiple recycling processes was tested (Table 1) to evaluate its reusability. Weigh 5 g of xylose and dissolve it in 100 ml of deionized water to prepare a solution. Add 1 g of CdO-Cal-700 and stir at 120 °C for 50 min, then cool to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form 120 ion exchange resin was added to the obtained solution to remove the residual cadmium ions, and then a high-purity xylulose product was obtained through concentration and purification.

[0302] Under the above reaction conditions, the catalyst was reused for continuous catalytic reactions. After each catalytic reaction, the catalyst was recovered by filtration, washed three times with ethanol and water, and dried at 80 °C, and then used for the next reaction cycle. During ten consecutive catalytic tests, the xylulose yield remained constant, maintaining at about 20%, and the relevant data are shown in Table 1. The results fully demonstrate that the catalytic performance of CdO-Cal-700 was maintained during continuous catalytic reactions, and it has good reusability characteristics.

[0303] Table 1

[0304]

[0305]

[0306] Example 144 Reuse of the catalyst for the synthesis of xylulose

[0307] The performance stability of the catalyst during multiple recycling processes was tested (Table 2) to evaluate its reusability. Weigh 5 g of xylose and dissolve it in 100 ml of deionized water to prepare a solution. Add 1 g of 20% CdO-SiO2-Cal-400 and stir at 130 °C for 40 min, then cool to room temperature. After the reaction solution was centrifuged at 10,000 r / min and filtered to remove the solid catalyst, 30 g of hydrogen-form 120 ion exchange resin was added to the obtained solution to remove the residual cadmium ions, and then a high-purity xylulose product was obtained through concentration and purification.

[0308] Under the above reaction conditions, the catalyst was reused for continuous catalytic reactions. After each catalytic reaction, the catalyst was recovered by filtration, washed three times with ethanol and water, and dried at 80 °C, and then used for the next reaction cycle. During ten consecutive catalytic tests, the xylulose yield remained constant, maintaining at about 24%, and the relevant data are shown in Table 2. The results fully demonstrate that the catalytic performance of 20% CdO-SiO2-Cal-400 was maintained during continuous catalytic reactions, and it has good reusability characteristics.

[0309] Table 2

[0310]

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

[0312] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An aqueous-phase-stable cadmium-based catalyst for aldose isomerization reaction, characterized in that, The cadmium-based catalyst is cadmium oxide or a supported cadmium oxide catalyst; the carrier of the supported cadmium oxide catalyst is one or more of TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, and SiO2.

2. The water-phase stable cadmium-based catalyst for aldose isomerization reaction according to claim 1, wherein The preparation method of cadmium oxide is the precursor calcination method or the precipitation method.

3. The water-phase stable cadmium-based catalyst for aldose isomerization reaction according to claim 2, characterized in that, The preparation method of the precursor calcination method is as follows: Place solid Cd(NO3)2·4H2O in a muffle furnace and calcine it at 400 - 900 °C for 4 - 10 hours. After cooling, obtain CdO, grind it, and use it as a catalyst.

4. The aqueous phase-stable cadmium-based catalyst for aldose isomerization reaction according to claim 2, wherein The preparation method of the precipitation method is as follows: Dissolve solid Cd(NO3)2·4H2O in deionized water to prepare a solution. Gradually add concentrated ammonia water dropwise to the above solution until the pH of the solution is neutral and white flocculent precipitates appear in the solution. Stir the mixture solution at room temperature to allow the precursor to react fully. Then, filter and wash to obtain white flocculent precipitates. Dry and grind them, and calcine them in a muffle furnace at 400 - 900 °C for 4 - 10 hours. Further grind the obtained solid powder and use it as a catalyst.

5. The aqueous-phase stable cadmium-based catalyst for aldose isomerization reaction according to claim 1, characterized in that, The preparation method of the supported cadmium oxide catalyst is as follows: Dissolve cadmium nitrate in deionized water to form a solution. Disperse the carrier in the above solution, stir and mix, and then dry. Calcine the dried solid at a temperature of 400 °C - 900 °C for 4 - 10 hours to obtain supported cadmium-based catalyst powder.

6. The water-phase stable cadmium-based catalyst for aldose isomerization reaction according to claim 1, wherein In the supported cadmium oxide catalyst, cadmium oxide accounts for 10 - 50% of the mass of the carrier.

7. The water-phase stable cadmium-based catalyst for aldose isomerization reaction according to claim 1, wherein, The carrier of the supported cadmium oxide catalyst is SiO2.

8. Use of the cadmium-based catalyst according to any one of claims 1 - 7 in the aldose isomerization reaction.

9. The application according to claim 8, wherein: The aldose includes xylose, glucose, ribose, or mannose.

10. A method for a sugar isomerization reaction, characterized in that, It includes the following steps: Mix the cadmium-based catalyst according to any one of claims 1 - 7 with an aldose reactant in a mass ratio of 1:1 - 1:50 in deionized water; React at a reaction temperature of 80 °C - 150 °C for 10 minutes - 240 minutes; After the reaction, separate and recover the cadmium-based catalyst, and evaporate and concentrate the treated reaction solution to obtain an isomerization product.

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