Catalyst as well as preparation method and application thereof
By using a catalyst with an alumina support and zinc oxide active ingredient, combined with structural additives, the problems of toxicity and limited application range of traditional catalysts are solved, and an efficient, environmentally friendly and stable benzoic acid reduction reaction is achieved.
Patent Information
- Application Number
- CN202411856267.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-06-27
AI Technical Summary
The existing catalysts have problems with toxicity and limited application range in catalytic benzoic acid reduction.
Alumina is used as a support and zinc oxide is used as a catalyst for active ingredient, and is prepared by precipitation, aging and calcination, and combined with structural additives such as rare earth oxides, iron oxides and copper oxides, the activity and stability of the catalyst are improved.
A green, environmentally friendly, non-toxic and low-cost catalytic effect was achieved. The benzoic acid conversion rate and benzaldehyde selectivity were both above 87%, and the catalyst stability was not less than 200 hours.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of chemical engineering, and particularly relates to a catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] As an important fine chemical intermediate, benzaldehyde is widely used in the fields of medicine, food, dyes, etc. At present, the methods for synthesizing benzaldehyde mainly include toluene oxidation method, toluene halogenation hydrolysis method, benzoic acid reduction method, etc.
[0003] Among them, the benzoic acid reduction method has received wide attention due to its advantages such as high benzaldehyde yield, low pollution, and low cost. The benzoic acid reduction method generally uses the catalytic action of a catalyst to carry out a reduction reaction. Existing catalysts include, for example, Cr / ZrO2 catalyst. However, traditional catalysts are toxic to the human body and have limited application scope. Summary of the Invention
[0004] The purpose of the present invention is to provide a catalyst, a preparation method thereof, and an application thereof. The catalyst provided by the present invention is green, environmentally friendly, and non-toxic.
[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:
[0006] The present invention provides a catalyst, comprising a carrier and an active ingredient supported on the carrier; the carrier comprises alumina; the active ingredient comprises zinc oxide.
[0007] Preferably, the particle size of the carrier is 0.5 - 2000 μm; the alumina comprises one or more of α-Al2O3, β-Al2O3, and γ-Al2O3.
[0008] Preferably, the particle size of the active ingredient is 0.8 - 1200 μm.
[0009] Preferably, the mass ratio of the carrier to the active ingredient is 1 - 5:1.
[0010] Preferably, the catalyst further comprises a structural promoter supported on the carrier; the structural promoter comprises one or more of rare earth oxides, iron oxides, and copper oxides.
[0011] Preferably, the particle size of the catalyst is 0.8 - 1200 μm.
[0012] The present invention also provides a preparation method of the catalyst according to the above scheme, comprising the following steps:
[0013] Mix an active ingredient metal salt, a precipitant, a carrier, and a solvent for precipitation, and then carry out aging and calcination in sequence to obtain the catalyst.
[0014] The present invention also provides the use of the catalyst described in the above solution or the catalyst obtained by the preparation method described in the above solution in the catalytic hydrogenation of benzoic acid to produce chlorine-free benzaldehyde.
[0015] In the present invention, the method of the use includes the following steps: after the catalyst is reduced, it is mixed with vaporized benzoic acid and hydrogen to carry out a reduction reaction to obtain chlorine-free benzaldehyde.
[0016] In the present invention, the temperature of the reduction reaction is 300-400 °C; the pressure of the reduction reaction is atmospheric pressure to 1 MPa; the reduction reaction is carried out in a fixed bed.
[0017] The present invention provides a catalyst. The catalyst provided by the present invention uses alumina as a carrier and zinc oxide as an active component. Zinc oxide has a suitable metal-oxygen bond strength and can generate a suitable steady-state oxygen vacancy concentration, making the catalyst of the present invention green, environmentally friendly, non-toxic, low-cost, with a high conversion rate of benzoic acid, good selectivity for benzaldehyde, both the conversion rate of benzoic acid and the selectivity for benzaldehyde are above 87%, and it has excellent stability, and the stability is not less than 200 h.
[0018] The present invention also provides a preparation method of the catalyst described in the above solution. The preparation method provided by the present invention has simple steps, is green and pollution-free, is easy to operate, has good feasibility, has high product purity, and is easy to be industrially produced and applied on a large scale.
[0019] The present invention also provides the use of the catalyst described in the above solution or the catalyst obtained by the preparation method described in the above solution in the catalytic hydrogenation of benzoic acid to produce chlorine-free benzaldehyde. The catalyst provided by the present invention is particularly suitable for catalytic gas-phase hydrogenation of benzoic acid to produce chlorine-free benzaldehyde, and realizes the one-step hydrogenation preparation of high-value-added chlorine-free benzaldehyde from cheap benzoic acid as a raw material. Description of the Drawings
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0021] Figure 1 It is a time-variation diagram of the catalyst performance during the evaluation of the catalyst in Example 1 of the present invention;
[0022] Figure 2 It is an XRD diagram of the catalyst prepared in Example 2 of the present invention;
[0023] Figure 3 It is a high-resolution transmission electron microscope diagram of the catalyst prepared in Example 3 of the present invention; among them, ZnO(002) represents the ZnO(002) crystal plane. Detailed implementation manners
[0024] The present invention provides a catalyst, comprising a carrier and an active ingredient supported on the carrier; the carrier comprises alumina; the active ingredient comprises zinc oxide.
[0025] The catalyst provided by the present invention comprises a carrier; the particle size of the carrier is preferably 0.5 - 2000 μm, and specifically can be 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm, 1500 μm or 2000 μm.
[0026] In the present invention, the alumina preferably comprises one or more of α - Al2O3, β - Al2O3 and γ - Al2O3.
[0027] The catalyst provided by the present invention comprises an active ingredient; the particle size of the active ingredient is preferably 0.8 - 1200 μm, and specifically can be 0.8 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm or 1200 μm.
[0028] In the present invention, the mass ratio of the carrier to the active ingredient is preferably 1 - 5:1, and specifically can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or 5:1.
[0029] In the present invention, the catalyst preferably further comprises a structural aid; the structural aid preferably comprises one or more of rare earth oxides, iron oxides and copper oxides; the rare earth oxides preferably comprise one or more of cerium oxides, samarium oxides and yttrium oxides; the cerium oxide is preferably CeO2; the samarium oxide is preferably Sm2O3; the yttrium oxide is preferably Y2O3; the iron oxide is preferably Fe2O3; the copper oxide is preferably CuO. By adding the structural aid, the present invention further improves the activity of the active component.
[0030] In the present invention, the mass ratio of the carrier to the structural aid is preferably 10 - 25:1, and specifically can be 10:1, 12:1, 15:1, 18:1, 20:1, 22:1 or 25:1.
[0031] In the present invention, the particle size of the catalyst is preferably 0.8 - 1200 μm, and specifically can be 0.8 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm or 1200 μm.
[0032] The present invention also provides a preparation method of the catalyst according to the above - mentioned solution, comprising the following steps:
[0033] The active ingredient metal salt, precipitant, carrier and solvent are mixed for precipitation, followed by aging and calcination in sequence to obtain the catalyst.
[0034] In the present invention, the active ingredient metal salt, precipitant, carrier and solvent are mixed (denoted as the first mixing) for precipitation. In the present invention, the active ingredient metal salt is preferably a soluble metal salt; the soluble metal salt is preferably a zinc salt; the zinc salt preferably includes one or more of zinc sulfate, zinc nitrate and zinc oxalate.
[0035] In the present invention, the precipitant preferably includes one or more of inorganic bases, carbonates, bicarbonates and oxalic acid; the inorganic base preferably includes one or more of NaOH and NH4OH; the carbonate preferably includes one or more of NaCO3 and (NH4)2CO3; the bicarbonate preferably includes one or more of NaHCO3 and (NH4)HCO3.
[0036] In the present invention, the molar ratio of the precipitant to the metal ions in the active ingredient metal salt is preferably 1:1 to 5, and specifically can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5.
[0037] In the present invention, the mass ratio of the carrier to the total mass of the active ingredient metal salt and the precipitant is preferably 10 to 20:1, and specifically can be 10:1, 12:1, 15:1, 18:1 or 20:1.
[0038] In the present invention, the solvent is preferably water; the water is preferably pure water; the mass ratio of the solvent to the carrier is preferably 20 to 50:1, and specifically can be 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50:1.
[0039] In the present invention, the raw materials for precipitation preferably further include a structural promoter metal salt; the structural promoter metal salt is preferably an inorganic metal salt; the inorganic metal salt preferably includes one or more of cerium salts, samarium salts, yttrium salts, iron salts and copper salts; the cerium salt preferably includes one or more of cerium sulfate, cerium nitrate and cerium oxalate; the samarium salt preferably includes one or more of samarium sulfate, samarium nitrate and samarium oxalate; the yttrium salt preferably includes one or more of yttrium sulfate, yttrium nitrate and yttrium oxalate; the iron salt preferably includes one or more of iron sulfate, iron nitrate and iron oxalate; the copper salt preferably includes one or more of copper sulfate, copper nitrate and copper oxalate.
[0040] In the present invention, the molar ratio of the active ingredient metal salt to the structural aid metal salt is preferably 1:1 to 20, and specifically can be 1:1, 1:2, 1:3, 1:5, 1:7, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18 or 1:20.
[0041] In the present invention, the first mixing is preferably as follows: mixing the active ingredient metal salt, the structural aid metal salt and the first part of the solvent to obtain a mixed solution, mixing the carrier and the second part of the solvent to obtain a carrier suspension, mixing the precipitant and the remaining part of the solvent to obtain a precipitant solution, and dropping the mixed solution and the precipitant solution into the carrier suspension under stirring conditions.
[0042] In the present invention, the dropping preferably stops when the pH value of the dropping system rises.
[0043] In the present invention, the pH value of the precipitation is preferably 7 to 9, and specifically can be 8.
[0044] After the precipitation, the precipitate obtained in the present invention is aged and calcined in sequence to obtain the catalyst. In the present invention, the temperature of the aging is preferably 20 to 70 °C, and specifically can be 20 °C, 30 °C, 40 °C, 50 °C, 60 °C or 70 °C, and the heat preservation aging time is preferably 2 to 10 h, and specifically can be 2 h, 4 h, 6 h, 8 h or 10 h.
[0045] In the present invention, after the aging, it preferably further includes solid-liquid separation of the obtained product; the solid-liquid separation is preferably filtration.
[0046] In the present invention, after the solid-liquid separation, it preferably further includes washing and drying the obtained solid; the drying is preferably drying by baking; the temperature of the drying is preferably 100 to 150 °C, and specifically can be 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, and the heat preservation drying time is preferably 12 to 36 h, and specifically can be 12 h, 16 h, 20 h, 24 h, 28 h, 32 h or 36 h.
[0047] In the present invention, the temperature of the calcination is preferably 400 to 800 °C, and specifically can be 400 °C, 500 °C, 600 °C, 700 °C or 800 °C, and the heat preservation calcination time is preferably 2 to 10 h, and specifically can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h; the atmosphere of the calcination is preferably air.
[0048] In the present invention, after the calcination, it preferably further includes crushing the obtained product. In the present invention, by crushing, the catalyst is prepared into a target particle size.
[0049] The present invention also provides the use of the catalyst described in the above solution or the catalyst obtained by the preparation method described in the above solution in the catalytic hydrogenation of benzoic acid to produce chlorine-free benzaldehyde.
[0050] In the present invention, the method of the use preferably includes the following steps: after the catalyst is reduced, it is mixed with vaporized benzoic acid and hydrogen to carry out a reduction reaction to obtain chlorine-free benzaldehyde.
[0051] In the present invention, the temperature for reducing the catalyst is preferably 400-600 °C, specifically it can be 400 °C, 450 °C, 500 °C, 550 °C or 600 °C, and the holding reduction time is preferably 2-10 h, specifically it can be 2 h, 4 h, 6 h, 8 h or 10 h; the equipment for reducing the catalyst is preferably a fixed-bed reactor or a tubular reactor.
[0052] In the present invention, the molar ratio of the catalyst to benzoic acid is preferably 1-10:1, specifically it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1.
[0053] In the present invention, the molar ratio of hydrogen to benzoic acid is preferably 1:50-100, specifically it can be 1:50, 1:60, 1:70, 1:80, 1:90 or 1:100.
[0054] In the present invention, the temperature of the reduction reaction is preferably 300-400 °C, specifically it can be 300 °C, 320 °C, 350 °C, 360 °C, 380 °C or 400 °C, and the holding reaction time is preferably 2-10 h, specifically it can be 2 h, 4 h, 6 h, 8 h or 10 h; the pressure of the reduction reaction is preferably atmospheric pressure (101 kPa)-1 MPa, specifically it can be 101 kPa, 200 kPa, 300 kPa, 500 kPa, 700 kPa, 900 kPa or 1 MPa. The use conditions of the catalyst provided by the present invention are mild.
[0055] In order to further illustrate the present invention, the solution of the present invention will be described in detail below with reference to the drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0056] Example 1
[0057] (1) Preparation of the catalyst: According to the loading amount of 20 wt% (calculated based on the sum of the masses of ZnO and Y2O3), weigh the corresponding mass of β-Al2O3 support and disperse it in pure water. Weigh the corresponding masses of Zn(NO3)2·6H2O and Y(NO3)2·6H2O according to the metal stoichiometric ratio of Zn:Y = 1:12 and dissolve them in pure water. Prepare a solution with NH4OH as the precipitant. Under stirring conditions, simultaneously drop the zinc salt and yttrium salt mixture solution and the precipitant solution into the suspension and maintain a constant pH value of 8. Stop dropping when the pH value rises. Age the precipitate for 2 h, filter, wash, dry at 110 °C, and calcine at 500 °C in an air atmosphere for 6 h to obtain the catalyst.
[0058] (2) Evaluation of the catalyst: Load the catalyst of this example into a fixed-bed reactor, heat it to the reaction temperature of 350 °C, reduce it under atmospheric pressure for 2 h. After reduction, vaporize benzoic acid and introduce it into the reactor to mix with hydrogen and enter the catalyst bed for reaction for 200 h. Control the molar ratio of benzoic acid to hydrogen to be 1:65. Collect the reaction solution in a cold trap and perform off-line analysis using gas chromatography: The conversion rate of benzoic acid at the 200th h is 92.1%, and the selectivity of benzaldehyde is 92.7%.
[0059] During the evaluation process of the catalyst of this example, the time variation of the catalyst performance is as Figure 1 shown. According to Figure 1 it can be seen that the catalyst of this example has excellent stability, achieving a conversion rate of benzoic acid and a selectivity of benzaldehyde both greater than 90%, and it does not deactivate within 200 h.
[0060] Example 2
[0061] (1) Preparation of the catalyst: According to the loading amount of 30 wt% (calculated based on the sum of the masses of ZnO and Y2O3), weigh the corresponding mass of β-Al2O3 support and disperse it in pure water. Weigh the corresponding masses of Zn(NO3)2·6H2O and Y(NO3)2·6H2O according to the metal stoichiometric ratio of Zn:Y = 1:8 and dissolve them in pure water. Prepare a solution with NH4HCO3 as the precipitant. Under stirring conditions, simultaneously drop the zinc salt and yttrium salt mixture solution and the precipitant solution into the suspension and maintain a constant pH value of 7. Stop dropping when the pH value rises. Age the precipitate for 6 h, filter, wash, dry at 110 °C, and calcine at 600 °C in an air atmosphere for 4 h to obtain the catalyst.
[0062] (2) Evaluation of the catalyst: The catalyst of this example was loaded into a fixed-bed reactor, heated to the reaction temperature of 390 °C, reduced at atmospheric pressure for 2 h. After reduction, benzoic acid was vaporized and introduced into the reactor, mixed with hydrogen, and then entered the catalyst bed for reaction for 200 h. The molar ratio of benzoic acid to hydrogen was controlled at 1:65. The reaction solution was collected in a cold trap and analyzed offline using gas chromatography: The conversion rate of benzoic acid at the 200th hour was 93.8%, and the selectivity for benzaldehyde was 87.1%.
[0063] XRD analysis was performed on the catalyst prepared in this example, and the results are as Figure 2 shown. According to Figure 2 it can be seen that Zn exists in the form of hexagonal ZnO, and no diffraction peaks of the corresponding added promoter oxides appear.
[0064] Example 3
[0065] (1) Preparation of the catalyst: According to the loading amount of 10 wt% (calculated based on the sum of the masses of ZnO and Y2O3), the corresponding mass of β-Al2O3 support was weighed and dispersed in pure water. According to the metal stoichiometric ratio of Zn:Y = 1:1, the corresponding masses of Zn(NO3)2·6H2O and Y(NO3)2·6H2O were weighed and dissolved in pure water. A solution was prepared with NaCO3 as the precipitant. Under stirring conditions, the zinc salt and yttrium salt mixed solution and the precipitant solution were simultaneously dropped into the suspension and the pH value was maintained at a constant value of 7.5. When the pH value increased, the dropping was stopped. The precipitate was aged for 2 h, filtered, washed, dried at 110 °C, and calcined at 600 °C in an air atmosphere for 4 h to obtain the catalyst.
[0066] (2) Evaluation of the catalyst: The catalyst of this example was loaded into a fixed-bed reactor, heated to the reaction temperature of 400 °C, reduced at atmospheric pressure for 2 h. After reduction, benzoic acid was vaporized and introduced into the reactor, mixed with hydrogen, and then entered the catalyst bed for reaction for 200 h. The molar ratio of benzoic acid to hydrogen was controlled at 1:20. The reaction solution was collected in a cold trap and analyzed offline using gas chromatography: The conversion rate of benzoic acid at the 200th hour was 90.3%, and the selectivity for benzaldehyde was 91.2%.
[0067] High-resolution transmission electron microscopy analysis was performed on the catalyst prepared in this example, and the results are as Figure 3 shown. According to Figure 3 it can be seen that Zn exists in the form of hexagonal ZnO, and Y is an amorphous oxide.
[0068] Example 4
[0069] (1) Preparation of the catalyst: According to a loading amount of 20 wt% (calculated based on the sum of the masses of ZnO and Y2O3), weigh the corresponding mass of the β-Al2O3 support and disperse it in pure water. Weigh the corresponding masses of Zn(NO3)2·6H2O and Y(NO3)2·6H2O according to the metal stoichiometric ratio of Zn:Y = 1:12 and dissolve them in pure water. Prepare a solution with NH4OH as the precipitant. Under stirring conditions, simultaneously drip the zinc salt and yttrium salt mixture solution and the precipitant solution into the suspension and maintain a constant pH value of 8. Stop dripping when the pH value rises. Age the precipitate for 2 h, filter, wash, dry at 110 °C, and calcine at 500 °C in an air atmosphere for 6 h to obtain the catalyst.
[0070] (2) Evaluation of the catalyst: Load the catalyst of this example into a fixed-bed reactor, heat it to the reaction temperature of 350 °C, reduce it at atmospheric pressure for 2 h. After reduction, vaporize benzoic acid and introduce it into the reactor to mix with hydrogen and enter the catalyst bed for reaction for 200 h. Control the molar ratio of benzoic acid to hydrogen to be 1:65. Collect the reaction solution in a cold trap and perform off-line analysis using gas chromatography: The conversion rate of benzoic acid at the 200th h is 92.1%, and the selectivity for benzaldehyde is 92.7%.
[0071] Example 5
[0072] (1) Preparation of the catalyst: According to a loading amount of 20 wt% (calculated based on the sum of the masses of ZnO and CeO2), weigh the corresponding mass of the α-Al2O3 support and disperse it in pure water. Weigh the corresponding masses of Zn(NO3)2·6H2O and Ce(NO3)2·6H2O according to the metal stoichiometric ratio of Zn:Y = 1:1 and dissolve them in pure water. Prepare a solution with oxalic acid as the precipitant. Under stirring conditions, simultaneously drip the zinc salt and yttrium salt mixture solution and the precipitant solution into the suspension and maintain a constant pH value of 7.5. Stop dripping when the pH value rises. Age the precipitate for 2 h, filter, wash, dry at 110 °C, and calcine at 500 °C in an air atmosphere for 6 h to obtain the catalyst.
[0073] (2) Evaluation of the catalyst: Load the catalyst of this example into a fixed-bed reactor, heat it to the reaction temperature of 350 °C, reduce it at atmospheric pressure for 2 h. After reduction, vaporize benzoic acid and introduce it into the reactor to mix with hydrogen and enter the catalyst bed for reaction for 200 h. Control the molar ratio of benzoic acid to hydrogen to be 1:65. Collect the reaction solution in a cold trap and perform off-line analysis using gas chromatography: The conversion rate of benzoic acid at the 200th h is 87.3%, and the selectivity for benzaldehyde is 95.6%.
[0074] Example 6
[0075] (1) Preparation of the catalyst: According to a loading amount of 20 wt% (calculated based on the sum of the masses of ZnO, Fe2O3, and Sm2O3), weigh the corresponding mass of γ-Al2O3 support and disperse it into pure water. Weigh the corresponding masses of Zn(NO3)2·6H2O, Fe(NO3)2·9H2O, and Sm(NO3)2·6H2O according to the metal stoichiometric ratio of Zn:Y = 1:7 and dissolve them in pure water. Prepare a solution with NaHCO3 as the precipitant. Under stirring conditions, simultaneously drip the zinc salt and yttrium salt mixture solution and the precipitant solution into the suspension and maintain a constant pH value of 7. Stop dripping when the pH value rises. Age the precipitate for 2 h, filter, wash, dry at 110 °C, and calcine at 500 °C in an air atmosphere for 6 h to obtain the catalyst.
[0076] (2) Evaluation of the catalyst: Load the catalyst of this example into a fixed-bed reactor, heat it to the reaction temperature of 350 °C, reduce it at atmospheric pressure for 2 h. After reduction, vaporize benzoic acid and introduce it into the reactor to mix with hydrogen and enter the catalyst bed for reaction for 200 h. Control the molar ratio of benzoic acid to hydrogen to be 1:65. Collect the reaction solution in a cold trap and perform off-line analysis using gas chromatography: The conversion rate of benzoic acid at the 200th h is 93.5%, and the selectivity for benzaldehyde is 88.6%.
[0077] Comparative Example 1
[0078] This comparative example uses ZnO as the catalyst. Refer to Example 1 and perform off-line analysis using gas chromatography: The conversion rate of benzoic acid at the 200th h is 55.0%, and the selectivity for benzaldehyde is 54.3%.
[0079] Comparative Example 2
[0080] This comparative example uses an Al2O3 support as the catalyst. Refer to Example 1 and perform off-line analysis using gas chromatography: The Al2O3 support has no activity.
[0081] Comparative Example 3
[0082] This comparative example uses various structural aids as the catalyst. Refer to Example 1 and perform off-line analysis using gas chromatography: Various structural aids have no activity.
[0083] From the above examples, it can be seen that the present invention provides a green and environmentally friendly, non-toxic, low-cost catalyst with a high conversion rate of benzoic acid, good selectivity for benzaldehyde, both the conversion rate of benzoic acid and the selectivity for benzaldehyde are above 87%, and excellent stability, with a stability of not less than 200 h.
[0084] Although the above examples have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. Other embodiments can also be obtained based on these examples without creative efforts, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A catalyst, characterized in that The invention comprises a carrier, and an active ingredient loaded on the carrier; the carrier comprises aluminum oxide; and the active ingredient comprises zinc oxide.
2. The catalyst according to claim 1, characterized in that The particle size of the carrier is 0.5-2000 μm; the alumina includes one or more of α-Al2O3, β-Al2O3 and γ-Al2O3.
3. The catalyst according to claim 1, characterized in that The particle size of the active ingredient is 0.8 to 1200 μm.
4. The catalyst according to any one of claims 1 to 3, characterized in that The mass ratio of the carrier to the active ingredient is 1 to 5:
1.
5. The catalyst according to claim 1 or 2, characterized in that The catalyst further comprises a structural auxiliary agent supported on the carrier; the structural auxiliary agent comprises one or more of rare earth oxides, iron oxides and copper oxides.
6. The catalyst according to claim 1 or 3, characterized in that The particle size of the catalyst is 0.8 to 1200 μm.
7. The method for preparing the catalyst according to any one of claims 1 to 6, characterized in that: The following steps are involved: The active component metal salt, a precipitant, a carrier and a solvent are mixed for precipitation, and then aged and calcined in sequence to obtain the catalyst.
8. Use of the catalyst according to any one of claims 1 to 6 or the catalyst obtained by the preparation method according to claim 7 in catalyzing the hydrogenation of benzoic acid to produce chlorine-free benzaldehyde.
9. The use according to claim 8, characterized in that: The method comprises the following steps: reducing the catalyst and mixing the catalyst with gasified benzoic acid and hydrogen to carry out reduction reaction to obtain chlorine-free benzaldehyde.
10. The use according to claim 9, characterized in that: The temperature of the reduction reaction is 300-400° C.; the pressure of the reduction reaction is atmospheric pressure-1 MPa; and the reduction reaction is carried out on a fixed bed.