Preparation method of hydrophobic palladium-based catalyst, hydrophobic palladium-based catalyst and application of hydrophobic palladium-based catalyst

Abstract

The invention discloses a preparation method of a hydrophobic palladium-based catalyst, the hydrophobic palladium-based catalyst and application of the hydrophobic palladium-based catalyst, and belongs to the technical field of preparation of catalytic materials. The preparation method comprises the following steps: (1) sequentially heating a pretreated carrier in nitrogen or mixed gas of acetylene, nitrogen and water vapor, and then carrying out heating treatment in a nitrogen atmosphere to obtain a surface-hydrophobized carrier; and (2) dipping the surface-hydrophobized carrier in a palladium precursor solution, drying, and roasting to obtain the hydrophobic palladium-based catalyst, the pretreated carrier is obtained by carrying out hydration treatment on silicon oxide, aluminum oxide, SBA-15 or a molecular sieve through deionized water, washing and drying; the heating temperature in the step (1) is 450-550 DEG C; the temperature of the heating treatment in the step (1) is 600-650 DEG C. The method is environment-friendly, simple to operate and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic material preparation, and in particular to a preparation method of a hydrophobic palladium-based catalyst, a hydrophobic palladium-based catalyst and applications thereof. Background Art

[0002] As an environmentally friendly oxidant, hydrogen peroxide is widely used in the fields of chemical industry, electronics, medical treatment, food, environmental protection, etc. The anthraquinone method is the mainstream industrial technology for hydrogen peroxide production, which mainly includes four stages: alkyl anthraquinone hydrogenation, oxidation, extraction and working fluid regeneration. Among them, the selective hydrogenation of anthraquinone is the key to determining the hydrogenation efficiency of the device and the hydrogen peroxide production capacity.

[0003] Supported Pd-based catalysts have become the main catalytic system for anthraquinone hydrogenation to hydrogen peroxide due to the advantages of easy recovery and high activity. However, commercial Pd / Al2O3 catalysts have high selectivity for degradation products due to poor surface hydrophobicity and the presence of acidic sites, which seriously affects the operation cycle of the hydrogen peroxide device. Studies have found that the physicochemical structure parameters and surface properties (hydrophilicity, acidity and alkalinity, etc.) of the carrier are important factors affecting the performance of anthraquinone hydrogenation. Many researchers are committed to carbon modification of the carrier surface to increase the hydrophobicity of the material and improve the catalytic performance. For example, patent CN118663258A combines microwave hydrothermal synthesis to obtain an activated carbon-alumina composite material to increase the hydrophobic strength of the alumina carrier. However, the composite material requires acid treatment during the preparation process, which affects the environmental friendliness of the process. Patent CN103623820B uses oxides to obtain carbide-modified oxide carriers by impregnation in a carbide precursor solution, but the carbide precursor solution of the patent is relatively complicated to prepare, which is not conducive to large-scale application. Patents CN116037181A and CN118002121A use solvent thermal reaction to first prepare an alumina carrier modified by a nitrogen-containing polymer, and then calcine to obtain a carbon-modified oxide carrier. However, the surface carbon content of the oxide carrier prepared by this method is low, which limits the adjustment space for the surface properties of the carrier.

[0004] Therefore, a new preparation method for modifying the hydrophobicity of the support surface is developed to improve the difficulty in preparing anthraquinone hydrogenation to hydrogen peroxide catalyst. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a preparation method of a hydrophobic palladium-based catalyst, a hydrophobic palladium-based catalyst and its application. The preparation method is simple to operate, environmentally friendly, and suitable for large-scale industrial production.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for preparing a hydrophobic palladium-based catalyst, comprising the following steps:

[0008] (1) heating the pretreated carrier in nitrogen or a mixture of acetylene, nitrogen and water vapor in sequence, and then heating the carrier in a nitrogen atmosphere to obtain a surface hydrophobic carrier;

[0009] (2) placing the surface hydrophobized carrier in a palladium precursor solution, impregnating, drying, and calcining to obtain a hydrophobic palladium-based catalyst;

[0010] The pretreated carrier is obtained by hydrating silicon oxide, aluminum oxide, SBA-15 or molecular sieve with deionized water, washing and drying.

[0011] Preferably, the heating temperature in step (1) is 450°C-550°C, more preferably 480°C-510°C. In some specific embodiments of the present invention, it is 500°C.

[0012] The heating rate is 5-10°C / min.

[0013] Preferably, the temperature of the heating treatment in step (1) is 600°C-650°C.

[0014] In the above preparation method, the acetylene in the mixed gas is bonded with the functional groups on the surface of the pretreated carrier and then chemically adsorbed on the surface of the carrier, so that the acetylene adsorbed on the surface of the carrier is decomposed into carbon at high temperature and deposited on the surface of the pretreated carrier, thereby achieving hydrophobic treatment of the carrier surface and obtaining a surface-hydrophobicized carrier.

[0015] The present invention increases the water contact angle on the carrier surface through the method, and significantly improves the hydrophobic performance.

[0016] The temperature treatment is high temperature carbonization, and its main purpose is to carbonize the acetylene molecules attached to the carrier surface through chemical adsorption. The present invention adopts nitrogen purging and then carries out temperature treatment, so that the acetylene molecules not attached to the carrier surface in the mixed gas are also carbonized, thereby avoiding the clogging of the carrier pores. The preparation method of the present invention adopts the method combined with chemical vapor deposition and high temperature carbonization, realizes the carbide modification of the carrier surface by acetylene carbonization, and then realizes the hydrophobic treatment of the carrier surface, and obtains the surface hydrophobic carrier. Then, the loading of metal palladium is carried out on the surface hydrophobic carrier, and the preparation of hydrophobic palladium-based catalyst is realized.

[0017] Preferably, the pretreatment conditions of the carrier are:

[0018] Condensation reflux at 80℃-95℃;

[0019] Processing time 10-48h;

[0020] The solid-liquid ratio of silicon oxide, aluminum oxide, SBA-15 or molecular sieve to deionized water is 1g:(5-10)mL.

[0021] The present invention has no particular limitation on the above-mentioned washing and drying, and any method well known to those skilled in the art may be used.

[0022] The drying includes but is not limited to vacuum drying and the like.

[0023] The drying temperature is preferably 70°C-120°C.

[0024] The drying time is preferably 3-8 hours.

[0025] Preferably, the volume ratio of acetylene, nitrogen and water vapor in the mixed gas in step (1) is (1-10): (90-99): (1-5); more preferably (5-10): (90-95): (2-4). In some specific embodiments of the present invention, it is preferably 5:95:3 or 10:90:3.

[0026] Preferably, the gas flow rate of the mixed gas is 50-200 mL / min, and in some specific embodiments of the present invention, it is 80 mL / min.

[0027] The present invention does not impose any special limitation on the equipment used in the above-mentioned preparation method.

[0028] In some specific embodiments of the present invention, a tube furnace device is used.

[0029] In the present invention, the immersion temperature in step (2) is preferably 25°C-60°C, and the immersion time is 2-8 hours. More preferably, the immersion temperature is room temperature, and further preferably 25°C-30°C.

[0030] In the present invention, the calcination temperature in step (2) is preferably 300°C-450°C, and the calcination time is 3-6 hours. More preferably, the calcination temperature is 320°C-400°C, and further preferably 350°C.

[0031] Preferably, in the step (2), the palladium precursor is selected from one or more of palladium acetate, palladium chloride, palladium nitrate, tetraammine palladium nitrate, tetraammine palladium chloride, and sodium chloropalladate.

[0032] The stirring method of the immersion in step (2) includes but is not limited to magnetic stirring, water bath stirring or rotary stirring.

[0033] The present invention also provides a hydrophobic palladium-based catalyst, which is prepared by the above-mentioned preparation method.

[0034] Preferably, the palladium loading in the hydrophobic palladium-based catalyst is 0.1wt%-2wt%, more preferably 0.1wt%-1wt%. In some specific embodiments of the present invention, it is preferably 0.23wt%, 0.27wt%, 0.28wt%, 0.29wt% or 0.30wt%.

[0035] Preferably, the water contact angle of the surface hydrophobized carrier in the hydrophobic palladium-based catalyst is 10°-105°, more preferably 50°-102°. In some specific embodiments of the present invention, it is preferably 53°, 65°, 78°, 92°, 98° or 102°.

[0036] The present invention also provides a hydrophobic palladium-based catalyst prepared by the above preparation method or the use of the above hydrophobic palladium-based catalyst in the production of hydrogen peroxide by hydrogenation of anthraquinone.

[0037] The reaction conditions for preparing hydrogen peroxide by hydrogenation of anthraquinone are:

[0038] The working fluid mass air velocity is 5-70h -1 , the reaction temperature is 30℃-80℃, and the reaction pressure is 0.1-0.5MPa.

[0039] Compared with the prior art, the preparation method of the hydrophobic palladium-based catalyst provided by the present invention comprises the following steps: (1) heating the pretreated carrier in nitrogen or a mixed gas of acetylene, nitrogen and water vapor in turn, and then performing a temperature treatment under a nitrogen atmosphere to obtain a surface hydrophobic carrier; (2) impregnating, drying and calcining the surface hydrophobic carrier in a palladium precursor solution to obtain a hydrophobic palladium-based catalyst; the pretreated carrier is obtained by hydrating silicon oxide, aluminum oxide, SBA-15 or molecular sieve with deionized water, washing and drying; the heating temperature in the step (1) is 450°C-550°C; the temperature of the temperature treatment in the step (1) is 600°C-650°C. The preparation method is environmentally friendly, simple to operate, and suitable for large-scale industrial production. The hydrophobic palladium-based catalyst prepared by the method has a strong activation ability for the C=O bond in the anthraquinone molecule, and exhibits a high hydrogenation efficiency and excellent stability in the production of hydrogen peroxide by hydrogenation of anthraquinone. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The hydrogenation efficiency and stability evaluation results of the catalysts prepared in Examples 3, 4, 6 and the comparative example are shown. DETAILED DESCRIPTION

[0041] To further illustrate the present invention, the preparation method of the hydrophobic palladium-based catalyst, the hydrophobic palladium-based catalyst and the application thereof provided by the present invention are described in detail below in conjunction with the embodiments.

[0042] Example 1

[0043] 1. Hydrophobic treatment of the carrier surface: Take 2.5g of SBA-15 and place it in 15mL of deionized water. After condensing and refluxing at 85℃ for 10h, place it in a 120℃ vacuum drying oven and dry it for 8h. Take an appropriate amount of the above SBA-15 and place it in a tube furnace, and heat it to 500℃ at 10℃ / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 5:95:3, flow rate of the mixture is 80mL / min) for 0.5h. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600℃ at a heating rate of 10℃ / min, treat it for 2h, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 53°.

[0044] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0045] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.7 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0046] Example 2

[0047] 1. Hydrophobic treatment of the carrier surface: Take 2.5g of SBA-15 and place it in 15mL of deionized water. After condensing and refluxing at 85℃ for 10h, place it in a vacuum drying oven at 120℃ and dry it for 8h. Take an appropriate amount of the above SBA-15 and place it in a tube furnace, and heat it to 500℃ at 10℃ / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 5:95:3, flow rate of the mixture is 80mL / min) for 2h. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600℃ at a heating rate of 10℃ / min, treat it for 2h, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 78°.

[0048] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0049] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.1 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0050] Example 3

[0051] 1. Hydrophobic treatment of the carrier surface: Take 2.5g SBA-15 and place it in 15mL deionized water. After condensing and refluxing at 85℃ for 10h, place it in a 120℃ vacuum drying oven and dry it for 8h. Take an appropriate amount of the above SBA-15 and place it in a tube furnace, and heat it to 500℃ at 10℃ / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 5:95:3, flow rate of the mixture is 80mL / min) for 3h. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600℃ at a heating rate of 10℃ / min, treat it for 2h, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 92°.

[0052] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0053] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.5 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0054] Example 4

[0055] 1. Hydrophobic treatment of the carrier surface: Take 2.5g SBA-15 and place it in 15mL deionized water. After condensing and refluxing at 85℃ for 10h, place it in a 120℃ vacuum drying oven and dry it for 8h. Take an appropriate amount of the above SBA-15 and place it in a tube furnace, and heat it to 550℃ at 10℃ / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 10:90:3, flow rate of the mixture is 80mL / min) for 3h. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600℃ at a heating rate of 10℃ / min, treat it for 2h, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 102°.

[0056] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0057] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.9 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0058] Example 5

[0059] 1. Hydrophobic treatment of the carrier surface: Take 2.5g SBA-15 and place it in 15mL deionized water. After condensing and refluxing at 85℃ for 10h, place it in a 120℃ vacuum drying oven and dry it for 8h. Take an appropriate amount of the above SBA-15 and place it in a tube furnace, and heat it to 500℃ at 10℃ / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 10:90:3, flow rate of the mixture is 80mL / min) for 3h. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600℃ at a heating rate of 10℃ / min, treat it for 2h, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 98°.

[0060] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0061] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.9 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0062] Example 6

[0063] 1. Hydrophobic treatment of the carrier surface: Take an appropriate amount of SBA-15 and place it in a vacuum drying oven at 120°C for 8 hours, and place it in a tubular furnace and heat it to 500°C at 10°C / min in 100mL / min N2. Subsequently, switch N2 to a mixture of acetylene, N2 and water vapor (volume ratio of 5:95:3, flow rate of the mixture is 80mL / min) for 3 hours. After the treatment is completed, switch the mixed gas to nitrogen, and heat it to 600°C at a heating rate of 10°C / min, treat it for 2 hours, and obtain a surface carbon-modified SBA-15 carrier. The contact angle test found that the water contact angle of the carrier was 65°.

[0064] 2. Catalyst preparation: Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven at 120℃ to dry for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h.

[0065] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.7 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0066] Comparative Example

[0067] Take 2.5g of SBA-15 and place it in 15mL of deionized water. After condensing and refluxing at 85℃ for 10h, place it in a vacuum drying oven at 120℃ and dry it for 8h. Weigh 0.015g of palladium acetate and ultrasonically disperse it in 2mL of acetone to prepare a palladium acetate precursor solution. Add the prepared solution to the above-mentioned carrier and impregnate it at room temperature for 8h using magnetic stirring. After impregnation, place the sample in an oven and dry it at 120℃ for 12h, and then place it in a muffle furnace at 350℃ for calcination for 3h. Among them, the contact angle test found that the contact angle of the carrier was 12°.

[0068] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 4.9 g / L under the reaction conditions of 0.3 MPa and 45°C.

[0069] The Pd-based catalysts prepared in the above Examples 1-6 and Comparative Examples were used in the reaction of anthraquinone hydrogenation to produce hydrogen peroxide. The catalyst evaluation method was as follows:

[0070] 80g of 2-ethylanthraquinone, 500g of trioctyl phosphate and 500g of mesitylene were mixed and added to the liquid storage tank of the horizontal flow pump. 1.0g of the prepared Pd-based catalyst was loaded into the constant temperature area of ​​the fixed bed reaction tube and reduced at 80°C for 2h at a H2 gas rate of 50mL / min. After the reduction was completed, the temperature of the reaction tube was lowered to 45°C, the pressure was adjusted to 0.5MPa, and the H2 flow rate was adjusted to 5mL / min. Subsequently, the liquid pump was turned on and the liquid flow rate was 0.3mL / min. During the reaction process, the liquid product was taken into a separatory funnel every 1h, and high-purity O2 was passed through to oxidize to light yellow, and then extracted with 20mL of deionized water multiple times. Among them, the aqueous phase was titrated with potassium permanganate solution to determine the hydrogenation efficiency of the catalyst, and the organic phase was analyzed by high-performance liquid chromatography to determine the effective anthraquinone selectivity.

[0071] Table 1 shows the anthraquinone hydrogenation reaction activity, contact angle and Pd loading of the catalysts prepared in Examples 1-6 and Comparative Examples. The results show that the water contact angle of the carrier increases after the surface is modified with carbon, and the hydrogenation efficiency and stability of the prepared Pd-based catalyst are significantly improved.

[0072] Table 1 Evaluation results of the anthraquinone hydrogenation catalytic performance of the catalysts prepared in Examples 1-6 and Comparative Examples

[0073] catalyst Pd loading (wt / %) Water contact angle (°) Hydrogenation efficiency (g / L) Example 1 0.28 53 6.7 Example 2 0.29 78 7.1 Example 3 0.27 92 7.5 Example 4 0.23 102 6.9 Example 5 0.28 98 7.9 Example 6 0.29 65 6.7 Comparative Example 1 0.30 12 4.9

[0074] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a hydrophobic palladium-based catalyst, characterized in that: The following steps are involved: (1) heating the pretreated carrier in nitrogen or a mixture of acetylene, nitrogen and water vapor in sequence, and then heating the carrier in a nitrogen atmosphere to obtain a surface hydrophobic carrier; (2) placing the surface hydrophobized carrier in a palladium precursor solution, impregnating, drying, and calcining to obtain a hydrophobic palladium-based catalyst; The pretreated carrier is obtained by hydrating silicon oxide, aluminum oxide, SBA-15 or molecular sieve with deionized water, washing and drying; The heating temperature in step (1) is 450° C.-550° C.; The temperature of the heating treatment in step (1) is 600°C-650°C.

2. The preparation method according to claim 1, characterized in that: The pretreatment conditions of the carrier are: Condensation reflux at 80℃-95℃; Processing time 10-48h; The solid-liquid ratio of silicon oxide, aluminum oxide, SBA-15 or molecular sieve to deionized water is 1g:(5-10)mL.

3. The preparation method according to claim 1, characterized in that: The volume ratio of acetylene, nitrogen and water vapor in the mixed gas in step (1) is (1-10): (90-99): (1-5).

4. The preparation method according to claim 3, characterized in that: The gas flow rate of the mixed gas is 50-200 mL / min.

5. The preparation method according to claim 1, characterized in that: The immersion temperature in step (2) is 25° C.-60° C., and the immersion time is 2-8 hours.

6. The preparation method according to claim 1, characterized in that: The calcination temperature in step (2) is 300° C.-450° C., and the calcination time is 3-6 hours.

7. The preparation method according to claim 1, characterized in that: In the step (2), the palladium precursor is selected from one or more of palladium acetate, palladium chloride, palladium nitrate, tetraammine palladium nitrate, tetraammine palladium chloride, and sodium chloropalladate.

8. A hydrophobic palladium-based catalyst, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The hydrophobic palladium-based catalyst according to claim 8, characterized in that The palladium loading in the hydrophobic palladium-based catalyst is 0.1wt%-2wt%; The water contact angle of the carrier with hydrophobic surface in the hydrophobic palladium-based catalyst is 10°-105°.

10. Use of the hydrophobic palladium-based catalyst prepared by the preparation method according to any one of claims 1 to 7 or the hydrophobic palladium-based catalyst according to claim 8 or 9 in the production of hydrogen peroxide by hydrogenation of anthraquinone.

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