A zinc oxide catalyst for benzoic acid hydrogenation reaction, a preparation method and application thereof

Abstract

The application discloses a preparation method and application method of a zinc oxide catalyst for benzoic acid hydrogenation reaction and belongs to the technical field of catalyst synthesis. The preparation method and application method of the zinc oxide catalyst for benzoic acid hydrogenation reaction can realize recovery and value-added utilization of zinc elements in waste zinc oxide desulfurizer, are simple in process, safe and environmentally-friendly, and can recycle and reuse sulfur and zinc in the waste zinc oxide desulfurizer through only two hydrothermal reactions. Tetraethyl orthosilicate is added in the hydrothermal process for synthesizing zinc oxide, zinc silicate primary products are obtained through hydrothermal reaction, and the supported zinc oxide catalyst is obtained after calcination, so that the active component has good dispersity; the catalyst has a flower sheet shape with a thickness of about 10 nm and a large specific surface area; the catalyst has excellent performance and can efficiently catalyze the gas-phase hydrogenation reduction of benzoic acid to produce benzaldehyde; and a small amount of transition metals such as manganese contained in the waste zinc oxide desulfurizer can bring beneficial effects of improving the activity of the zinc oxide catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and in particular to a method for preparing and applying a zinc oxide catalyst for the hydrogenation reaction of benzoic acid. Background Technology

[0002] Zinc oxide is widely used as a desulfurizing agent in petrochemical, coal chemical, and fertilizer production. During the desulfurization process, it mainly reacts with hydrogen sulfide in the material to generate zinc sulfide, thereby solidifying the gaseous sulfur in the material to be desulfurized and achieving the purpose of desulfurization. Zinc oxide desulfurizing agent has high desulfurization precision and large sulfur capacity, and is currently the most widely used fine desulfurizing agent. The industrial consumption is large. As the desulfurization process proceeds, most of the zinc oxide gradually transforms into ZnS and loses its activity. When its sulfur capacity is broken through, it is replaced and becomes waste agent. Waste zinc oxide desulfurizers have a high zinc content, and most of them are not well recycled, resulting in a waste of resources and potentially causing environmental pollution problems. In existing technologies, the regeneration of waste zinc oxide desulfurizing agents mainly falls into two categories: dry methods and wet methods. The dry process involves calcining and decomposing waste zinc oxide desulfurizer in air to regenerate zinc oxide. While the dry process is widely used, it generates sulfur-containing waste gas during calcination, causing secondary pollution. Furthermore, the zinc oxide obtained from calcination has low activity and cannot be directly reused as a desulfurizer. It often requires acid treatment to obtain products such as zinc salts, as proposed in invention patents CN201610946195.8 and CN201310616051.2.

[0003] The wet process is a regeneration process that regenerates waste zinc oxide desulfurizing agent through acid dissolution, precipitation, and calcination. In the wet process, zinc sulfide reacts with acid. To prevent the release of hydrogen sulfide gas, oxidants such as oxygen and hydrogen peroxide need to be added. The process requires high control and improper handling can easily lead to environmental pollution. For example, the invention patent with patent application number CN202210354823.9 proposes a method to produce copper sulfide by reacting waste zinc oxide desulfurizing agent with a copper source in an acidic environment. This method effectively removes and utilizes the sulfur element in the waste zinc oxide desulfurizing agent, but it does not treat the zinc-containing solution.

[0004] In the above process, waste zinc oxide desulfurizing agent is processed through multiple steps to obtain zinc salt or regenerated zinc oxide desulfurizing agent. Most of these processes are quite complex, pose a risk of secondary pollution, and do not significantly improve the utilization value of zinc. Therefore, it is essential to develop environmentally friendly and high-value-added methods for recycling waste zinc oxide desulfurizing agent. Summary of the Invention

[0005] The purpose of this invention is to solve the problems mentioned in the background art, and to provide a method for preparing and applying a zinc oxide catalyst for the hydrogenation reaction of benzoic acid.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid mainly includes the following steps: Step 1: After hydrothermal reaction of waste zinc oxide desulfurizing agent with copper source and inorganic acid, the generated copper sulfide solid is removed by filtration to obtain zinc-containing solution; Step 2: Add triblock copolymer P123 to the obtained zinc-containing solution until completely dissolved, and then add tetraethyl orthosilicate; Step 3: Adjust the pH of the solution using ammonia water, adjusting the pH range to 3.5-7.5; Step 4: Add urea, stir well, and then carry out a hydrothermal reaction; Step 5: After washing and drying the solid product obtained by hydrothermal treatment, calcine it at a certain temperature to obtain zinc oxide catalyst.

[0007] Preferably, the copper source in step one is either copper oxide or a copper salt.

[0008] Preferably, the inorganic acid in step one is one of sulfuric acid, nitric acid, or hydrochloric acid.

[0009] Preferably, in step two, the molar ratio of tetraethyl orthosilicate to zinc ions in the zinc-containing solution is 0.5:1 to 3:1, and the mass ratio of the triblock copolymer P123 to tetraethyl orthosilicate is 0.25:1 to 1.5:1.

[0010] Preferably, the molar ratio of urea to zinc ions in the zinc-containing solution in step four is 5:1 to 15:1.

[0011] Preferably, the hydrothermal reaction temperature in step four is 100-200℃.

[0012] Preferably, the roasting temperature in step five is 400-650℃, and the roasting time is 1-12 hours.

[0013] A zinc oxide catalyst for the hydrogenation reaction of benzoic acid is prepared using a method for preparing zinc oxide catalysts for the hydrogenation reaction of benzoic acid. The zinc oxide catalyst is in the form of flakes, has a thickness of 8-12 nm, and a specific surface area of ​​not less than 100 m². 2 / g.

[0014] Application of a zinc oxide catalyst for the hydrogenation reaction of benzoic acid, used for the gas-phase hydrogenation reduction of benzoic acid to benzaldehyde.

[0015] Preferably, the catalyst is loaded into a fixed-bed reactor, and hydrogen and gasified benzoic acid are introduced into the reactor, wherein the molar ratio of hydrogen to benzoic acid is 20:1-100:1; the space velocity of the fixed-bed reactor is 200-2000 h⁻¹. -1 The reaction temperature is 300-500℃.

[0016] Compared with the prior art, the present invention provides a method for preparing and applying a zinc oxide catalyst for the hydrogenation reaction of benzoic acid, which has the following beneficial effects: 1. The preparation method and application method of the zinc oxide catalyst for the hydrogenation reaction of benzoic acid, through... 2. The preparation method and application method of the zinc oxide catalyst for the hydrogenation reaction of benzoic acid, through... 3. The preparation method and application method of the zinc oxide catalyst for the hydrogenation reaction of benzoic acid, through... The parts of this device not described herein are the same as or can be implemented using existing technology. The beneficial effects of this invention are: 1. Turning waste into treasure, realizing the recovery and value-added utilization of zinc element in waste zinc oxide desulfurizing agent; 2. The process is simple, safe and environmentally friendly. It only requires two hydrothermal reactions to recover and reuse both sulfur and zinc in the waste zinc oxide desulfurizing agent. 3. Tetraethyl orthosilicate is added during the hydrothermal synthesis of zinc oxide to obtain zinc silicate primary product by hydrothermal treatment. After calcination, a supported zinc oxide catalyst is obtained with good dispersion of active components. 4. The catalyst exhibits a flower-like morphology with a thickness of about 10 nm and a large specific surface area; 5. The catalyst has excellent performance and can efficiently catalyze the gas-phase hydrogenation reduction of benzoic acid to benzaldehyde; 6. The trace amounts of transition metals such as manganese contained in the waste zinc oxide desulfurizer have a beneficial effect on improving the activity of the zinc oxide catalyst. Attached Figure Description

[0017] Figure 1 The XRD pattern of the catalyst prepared by the method for preparing zinc oxide catalyst for the hydrogenation reaction of benzoic acid proposed in this invention; Figure 2 This is a SEM image of the catalyst prepared by the method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid proposed in this invention. Figure 3 The nitrogen adsorption isotherm and pore size distribution diagram of the zinc oxide catalyst prepared by the method for preparing zinc oxide catalyst for benzoic acid hydrogenation reaction proposed in this invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example

[0019] A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid mainly includes the following steps: Step 1: After hydrothermal reaction of waste zinc oxide desulfurizer with copper source and inorganic acid, the generated copper sulfide solid is removed by filtration to obtain zinc-containing solution. The copper source is either copper oxide or copper salt. When using copper salt, copper sulfate, copper acetate, copper nitrate or copper chloride can be used. The inorganic acid is either sulfuric acid, nitric acid or hydrochloric acid. Sulfuric acid is used in this case. Step 2: Add triblock copolymer P123 to the obtained zinc-containing solution until completely dissolved, then add tetraethyl orthosilicate, wherein the molar ratio of tetraethyl orthosilicate to zinc ions in the zinc-containing solution is 0.5:1 to 3:1, preferably 0.75:1 to 1.5:1, and the mass ratio of triblock copolymer P123 to tetraethyl orthosilicate is 0.25:1 to 1.5:1, preferably 0.5:1 to 1:1; Step 3: Adjust the pH value of the solution using ammonia water, with the pH range being 3.5-7.5, preferably 5.0-6.0; Step 4: Add urea, stir evenly, and carry out hydrothermal reaction. The molar ratio of urea to zinc ions in the zinc-containing solution is 5:1 to 15:1, preferably 8:1-12:1, and the hydrothermal reaction temperature is 100-200℃. Step 5: After washing and drying the solid product obtained by hydrothermal treatment, calcinate it at a certain temperature to obtain zinc oxide catalyst. The calcination temperature is 400-650℃, preferably 500-600℃, and the calcination time is 1-12 hours, preferably 2-4 hours. The performance evaluation method and application of the catalyst involves loading the catalyst into a fixed-bed reactor, and then introducing hydrogen and vaporized benzoic acid into the reactor. The molar ratio of hydrogen to benzoic acid is 20:1-100:1, and the space velocity of the fixed-bed reactor is 200-2000 h⁻¹. -1 The reaction temperature is 300-500℃. Example

[0020] Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid mainly includes the following steps: Step 1: Dissolve 20 mL of concentrated sulfuric acid in 200 mL of water and add it to a hydrothermal reactor with a polytetrafluoroethylene liner. Then weigh 20 mmol each of the crushed waste zinc oxide desulfurizer and copper oxide and add them to the hydrothermal reactor containing sulfuric acid solution while stirring continuously. Step 2: The reaction is carried out at 100℃ for 24 hours, and then naturally cooled to room temperature. The resulting solid substance is copper sulfide, which is filtered and separated for other uses. Step 3: Add 2.5g of P123 to the zinc-containing solution obtained after separation and dissolve it completely. Then add 4.42g of tetraethyl orthosilicate, dissolve it, add ammonia water to adjust the pH value to 5.5, add 6g of urea, stir for 30min, and then perform hydrothermal reaction at 180℃ for 12h. Step 4: After washing and drying the solid product obtained by hydrothermal treatment, calcine it at 550℃ for 3 hours to obtain the catalyst. The XRD pattern of the catalyst is shown in the figure. Figure 1 As shown, the SEM image of the catalyst is as follows. Figure 2 As shown, the nitrogen adsorption isotherm and pore size distribution of the catalyst are as follows: Figure 3 As shown; The method for evaluating catalyst performance is as follows: the catalyst is loaded into a fixed-bed reactor, and the gasified reactants are passed through the reactor at a hydrogen:benzoic acid ratio of 60:1, with a space velocity of 700 h⁻¹. -1 The reaction temperature is 360℃; The reaction products were detected by gas chromatography. The conversion rate of benzoic acid and the selectivity of benzaldehyde were defined as follows:

[0021] The conversion rate of benzoic acid was measured to be 80.1%, and the selectivity of benzaldehyde was 93.7%. Example

[0022] Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is basically the same as that in Example 2, except that the amount of tetraethyl orthosilicate added in step 3 is 6.63 g and the hydrothermal reaction temperature is 150 °C.

[0023] The obtained catalyst was used in the process of Example 2 for the hydrogenation reduction of benzoic acid to benzaldehyde, with the hydrogen to benzoic acid ratio changed to 50:1 and the space velocity changed to 900 h⁻¹. -1 .

[0024] Gas chromatography analysis showed that the benzoic acid conversion rate was 80.1% and the benzaldehyde selectivity was 93.7%. Comparative Example 1: Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is basically the same as that in Example 2, except that P123 is not added in step three. The resulting catalyst is used in the process of Example 2 for the hydrogenation reduction of benzoic acid to benzaldehyde. The reaction effect is detected by gas chromatography, and the conversion rate of benzoic acid is 71.2% and the selectivity of benzaldehyde is 76.3%. Comparative Example 2: Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is presented, which is basically the same as that in Example 2, except that tetraethyl orthosilicate is not added in step three. The resulting catalyst is used in the hydrogenation reduction of benzoic acid to benzaldehyde reaction using the process of Example 2. The reaction effect is detected by gas chromatography, and the conversion rate of benzoic acid is 60.1%, and the selectivity of benzaldehyde is 85.2%. Example

[0025] Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is basically the same as that in Example 2, except that the amount of urea added in step three is 4g, the hydrothermal reaction temperature is 210℃, and the calcination temperature in step four is 500℃.

[0026] The obtained catalyst was used in the process of Example 2 for the hydrogenation reduction of benzoic acid to benzaldehyde, with the hydrogen to benzoic acid ratio changed to 70:1 and the space velocity changed to 1000 h⁻¹. -1 The reaction temperature becomes 375℃.

[0027] The reaction was detected by gas chromatography, and the conversion rate of benzoic acid was 88.6%, while the selectivity of benzaldehyde was 90.8%. Example

[0028] Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is basically the same as that in Example 2, except that the amount of concentrated sulfuric acid used in step one is 15 mL, and copper oxide is replaced with an equimolar amount of copper sulfate.

[0029] The obtained catalyst was used in the process of Example 2 for the hydrogenation reduction of benzoic acid to benzaldehyde. The reaction effect was detected by gas chromatography. The conversion rate of benzoic acid was 86.5%, and the selectivity of benzaldehyde was 93.1%. Example

[0030] Reference Figure 1-3 A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid is basically the same as that in Example 2, except that in step three, the pH value is adjusted to 6.5 with ammonia water, and the amount of urea added is changed to 2g. The obtained catalyst is used in the process of Example 2 for the hydrogenation reduction of benzoic acid to benzaldehyde, with a benzoic acid conversion rate of 89.3% and a benzaldehyde selectivity of 86.6%. Example

[0031] Reference Figure 1-3A zinc oxide catalyst for the hydrogenation reaction of benzoic acid is prepared by a method for preparing zinc oxide catalysts for the hydrogenation reaction of benzoic acid. The zinc oxide catalyst is in the form of flakes, the thickness of the zinc oxide catalyst is 8-12 nm, and the specific surface area of ​​the zinc oxide catalyst is not less than 100 m2 / g.

[0032] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a zinc oxide catalyst for the hydrogenation reaction of benzoic acid, characterized in that, Includes the following steps: Step 1: After hydrothermal reaction of waste zinc oxide desulfurizing agent with copper source and inorganic acid, the generated copper sulfide solid is removed by filtration to obtain zinc-containing solution; Step 2: Add triblock copolymer P123 to the obtained zinc-containing solution until completely dissolved, and then add tetraethyl orthosilicate; Step 3: Adjust the pH of the solution using ammonia water, adjusting the pH range to 3.5-7.5; Step 4: Add urea, stir well, and then carry out a hydrothermal reaction; Step 5: After washing and drying the solid product obtained by hydrothermal treatment, calcine it at a certain temperature to obtain zinc oxide catalyst.

2. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, The copper source in step one is either copper oxide or a copper salt.

3. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, The inorganic acid in step one is one of sulfuric acid, nitric acid, or hydrochloric acid.

4. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, In step two, the molar ratio of tetraethyl orthosilicate to zinc ions in the zinc-containing solution is 0.5:1 to 3:1, and the mass ratio of the triblock copolymer P123 to tetraethyl orthosilicate is 0.25:1 to 1.5:

1.

5. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, In step four, the molar ratio of urea to zinc ions in the zinc-containing solution is 5:1 to 15:

1.

6. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, The hydrothermal reaction temperature in step four is 100-200℃.

7. The method for preparing the zinc oxide catalyst for the hydrogenation reaction of benzoic acid according to claim 1, characterized in that, The roasting temperature in step five is 400-650℃, and the roasting time is 1-12 hours.

8. A zinc oxide catalyst for the hydrogenation reaction of benzoic acid, characterized in that, The zinc oxide catalyst for the hydrogenation reaction of benzoic acid is prepared by the method described in any one of claims 1-7. The zinc oxide catalyst is in the form of flakes, has a thickness of 8-12 nm, and a specific surface area of ​​not less than 100 m². 2 / g.

9. An application of the zinc oxide catalyst of claim 8 for the hydrogenation reaction of benzoic acid, characterized in that, Used for the gas-phase hydrogenation reduction of benzoic acid to produce benzaldehyde.

10. The application of the zinc oxide catalyst according to claim 9 for the hydrogenation reaction of benzoic acid, characterized in that, The catalyst is loaded into a fixed-bed reactor, and hydrogen and vaporized benzoic acid are introduced into the reactor, wherein the molar ratio of hydrogen to benzoic acid is 20:1-100:1; the space velocity of the fixed-bed reactor is 200-2000 h⁻¹. -1 The reaction temperature is 300-500℃.

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