Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance as well as preparation method and application of Pt / SSZ-13 molecular sieve catalyst

Abstract

The invention belongs to the technical field of chemical catalysts, and particularly discloses a high-humidity-tolerance Pt / SSZ-13 molecular sieve catalyst and a preparation method and application thereof.The preparation method comprises the following steps that S1, a platinum metal precursor solution is prepared, specifically, platinum particles are added into a solvent according to a certain proportion, and the platinum metal precursor solution is obtained through dispersion and dissolution; s2, dipping and loading: dipping an SSZ-13 molecular sieve carrier into the platinum metal precursor solution obtained in S1 by adopting a dipping method, and uniformly stirring; s3, drying: drying at the temperature of 60-120 DEG C for 3-12 hours; s4, roasting: roasting for 1-10 hours at the temperature of 600-800 DEG C in an air atmosphere; and S5, reduction: reducing at 100-300 DEG C in a hydrogen atmosphere for 1-3 hours to obtain the Pt / SSZ-13 molecular sieve catalyst. According to the high-humidity-tolerance Pt / SSZ-13 molecular sieve catalyst as well as the preparation method and the application thereof, the Pt / SSZ-13 catalyst is obtained by utilizing a small-hole molecular sieve carrier and optimizing Pt loading and a preparation process, the high-humidity-tolerance and stability are realized, and the problem that an existing catalyst is insufficient in activity under the conditions of room temperature and high humidity is solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical catalysts, and in particular to a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance, and a preparation method and application thereof. Background Art

[0002] Exogenous ethylene elimination technologies are divided into two categories: physical and chemical elimination. Physical elimination mainly relies on the adsorption of ethylene by activated carbon, molecular sieves or other porous materials. However, adsorption materials are not suitable for large-scale applications due to the need for regular replacement and difficulty in handling. Chemical elimination mainly uses oxidation reactions to achieve efficient conversion of ethylene, which can be divided into direct oxidation of chemical reagents and catalytic oxidation technologies represented by photocatalysis, thermal catalysis and plasma catalysis. Among them, when precious metal catalysts catalyze the oxidation of ethylene, the reaction conditions are mild and no additional energy is required.

[0003] In the prior art, porous substrate catalysts (such as oxide-supported porous catalysts) are used for the oxidation reaction of low-concentration ethylene. Under low humidity conditions, such catalysts can achieve an ethylene conversion rate close to 100% at 0°C. However, the stability of such catalysts is poor, especially under high humidity or continuous reaction conditions, and they can only maintain activity for a short time, which is difficult to meet the needs of practical industrial applications.

[0004] Molecular sieve catalysts (such as ZSM-5, Beta and Y molecular sieves) are widely used in low-temperature ethylene oxidation. This type of catalyst can completely oxidize ethylene into carbon dioxide and water at room temperature, but its stability is limited and can only maintain a reaction time of about 20 hours. In addition, some studies have attempted to improve the durability of molecular sieve catalysts by doping with rare earth metals or other additives. Although the anti-deactivation ability has been improved to a certain extent, there is still a problem of long-term activity decay.

[0005] In addition, by modifying molecular sieves and introducing special additives (such as rare earth elements and precious metals), efficient modified molecular sieve catalysts for low-temperature ethylene oxidation are prepared, and their main features include:

[0006] (1) ZSM-5 catalysts can still maintain an ethylene conversion rate of 95% after 500-1000 hours of reaction, but their catalytic activity and stability at lower temperatures (such as 0°C) are relatively poor.

[0007] (2) Catalysts based on Beta molecular sieves loaded with precious metals (such as palladium and platinum) exhibit efficient ethylene oxidation ability in the low temperature range of -30°C to 0°C, and have high moisture resistance stability, and can maintain excellent catalytic activity even in a high humidity environment.

[0008] (3) The operating conditions are simple, the dosage is small, and the energy consumption is low, showing good industrial prospects.

[0009] However, the long-term stability of these modified molecular sieve catalysts under extreme humidity conditions and their adaptability to complex industrial conditions still need to be further verified to meet more demanding application requirements. Summary of the invention

[0010] The purpose of the present invention is to provide a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance, a preparation method and application thereof, and a Pt / SSZ-13 catalyst with high humidity tolerance and stability is obtained by utilizing a small-pore molecular sieve carrier and optimizing the Pt loading and preparation process, thereby solving the problem of insufficient activity of existing catalysts under room temperature and high humidity conditions.

[0011] To achieve the above object, the present invention provides a method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance, comprising the following steps:

[0012] S1. preparing a platinum metal precursor solution: adding platinum particles into a solvent in a certain proportion, dispersing and dissolving the platinum metal precursor solution;

[0013] S2, impregnation loading: impregnate the SSZ-13 molecular sieve carrier into the platinum metal precursor solution obtained in S1 by an impregnation method, and stir evenly;

[0014] S3, drying: drying at 60°C to 120°C for 5 to 12 hours;

[0015] S4, calcination: calcination at 600 ℃ ~ 800 ℃, air atmosphere for 1 ~ 10h;

[0016] S5. Reduction: reducing at 100° C. to 300° C. in a hydrogen atmosphere for 1 to 3 hours to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0017] Preferably, in S1, the platinum particles are one or more of platinum nitrate solution, tetraammineplatinum nitrate or hydroxyplatinic acid.

[0018] Preferably, in S1, the platinum content in the platinum metal precursor solution is 0.5% to 3%, calculated by mass fraction.

[0019] Preferably, in S2, the SSZ-13 molecular sieve is one or more of H-type SSZ-13 molecular sieve, ammonia-type SSZ-13 molecular sieve or low-sodium-type SSZ-13 molecular sieve.

[0020] Preferably, in S4, the calcination is specifically: calcination at 640° C. to 660° C. in an air atmosphere for 1 to 10 hours.

[0021] Preferably, in S4, the calcination is specifically: calcination at 650° C. in an air atmosphere for 1 to 10 hours.

[0022] Preferably, in S5, the reduction is specifically: reduction at 200° C. in a hydrogen atmosphere for 1 to 3 hours.

[0023] Preferably, in S5, the reduction is specifically: reduction at 200° C. in a hydrogen atmosphere for 2 h.

[0024] To achieve the above object, the present invention also provides a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance.

[0025] To achieve the above objectives, the present invention also provides an application of a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst in the purification and treatment of ethylene in industrial tail gas and indoor air under low temperature and high humidity environments.

[0026] Therefore, the present invention adopts the above-mentioned high humidity tolerance Pt / SSZ-13 molecular sieve catalyst and its preparation method and application, and the beneficial effects are as follows:

[0027] (1) The Pt / SSZ-13 molecular sieve catalyst prepared by the present invention can stably maintain an ethylene conversion rate of more than 50% (>1000h) at room temperature (20-25°C) and 50% humidity, which is significantly better than the activity performance of traditional molecular sieve catalysts in high humidity environments. It also has stable ethylene oxidation performance and does not require additional heating equipment (avoiding the dependence of traditional catalysts on high temperatures), thus reducing operating costs and energy consumption, and has significant green environmental benefits.

[0028] (2) The Pt / SSZ-13 molecular sieve catalyst prepared by the present invention can optimize the conversion rate by regulating the space velocity. The space velocity regulation is flexible and can be applied to a variety of working conditions (adapting to different industrial conditions and exhaust flow rates), meeting the catalytic oxidation needs in complex environments, and providing an effective solution for the catalytic oxidation of volatile organic compounds (ethylene) in high humidity environments (including high humidity industrial exhaust gas treatment and air purification).

[0029] (3) The present invention utilizes the pores of SSZ-13 molecular sieve to combine with Pt. The pores of SSZ-13 molecular sieve provide selective adsorption, and Pt provides active oxidation sites, which synergistically realize the oxidation of ethylene to CO2 and H2O without the generation of by-products. Compared with ZSM-5, Beta and Y molecular sieves, the CHA-type small pore structure of SSZ-13 molecular sieve enhances the anti-adsorption ability of water molecules, while improving the diffusion efficiency of reactants, and significantly enhancing its tolerance to the influence of water molecules. After an optimized preparation process (calcination at 650°C combined with hydrogen reduction at 200°C), the dispersion, activity and binding stability of Pt are effectively improved, and the migration and deactivation problems of active components are significantly reduced, ensuring the long-term operation performance of the catalyst.

[0030] (4) The present invention adopts the impregnation method and the traditional roasting reduction technology, and the process steps are mature and simple, easy to mass produce, and feasible for industrial promotion.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an electron microscope morphology image of a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst and its preparation method and application example 5 of the present invention;

[0033] Figure 2 This is a graph of ethylene removal performance of a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst and its preparation method and application example 5 of the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0035] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0036] Embodiment 1

[0037] A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance comprises the following steps:

[0038] S1. Prepare a platinum metal precursor solution: weigh 0.02 g Pt(NO3)2 and 10 ml deionized water in a beaker, disperse and dissolve to obtain a platinum metal precursor solution with a platinum content of 0.5%.

[0039] S2. Impregnation loading: 5 g of H-type SSZ-13 molecular sieve carrier is impregnated into the platinum metal precursor solution obtained in S1 by an impregnation method and stirred evenly.

[0040] S3. Drying: Dry at 120°C for 4 hours.

[0041] S4. Calcination: Calcinate at 650°C in air atmosphere for 2h.

[0042] S5. Reduction: Reduce at 200° C. in a hydrogen atmosphere for 2 h to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0043] Embodiment 2

[0044] A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance comprises the following steps:

[0045] S1. Prepare a platinum metal precursor solution: weigh 0.04 g Pt(NO3)2 and 5 ml deionized water in a beaker, and disperse and dissolve them to obtain a platinum metal precursor solution with a platinum content of 1.0%.

[0046] S2. Impregnation loading: 5 g of H-type SSZ-13 molecular sieve carrier is impregnated into the platinum metal precursor solution obtained in S1 by an impregnation method and stirred evenly.

[0047] S3. Drying: Dry at 60°C for 12h.

[0048] S4. Calcination: Calcinate at 650°C in air atmosphere for 2h.

[0049] S5. Reduction: Reduce at 100° C. in a hydrogen atmosphere for 2 h to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0050] Embodiment 3

[0051] A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance comprises the following steps:

[0052] S1. Prepare a platinum metal precursor solution: weigh 0.06 g Pt(NO3)2 and 20 ml deionized water in a beaker, disperse and dissolve to obtain a platinum metal precursor solution with a platinum content of 1.5%.

[0053] S2. Impregnation loading: 5 g of H-type SSZ-13 molecular sieve carrier is impregnated into the platinum metal precursor solution obtained in S1 by an impregnation method and stirred evenly.

[0054] S3. Drying: Dry at 120°C for 4 hours.

[0055] S4. Calcination: Calcinate at 650°C in air atmosphere for 2h.

[0056] S5. Reduction: Reduce at 200° C. in a hydrogen atmosphere for 2 h to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0057] Embodiment 4

[0058] A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance comprises the following steps:

[0059] S1. Prepare a platinum metal precursor solution: weigh 0.04 g Pt(NO3)2 and 5 ml deionized water in a beaker, and disperse and dissolve them to obtain a platinum metal precursor solution with a platinum content of 1.0%.

[0060] S2. Impregnation loading: 5 g of ammonia-type SSZ-13 molecular sieve carrier is impregnated into the platinum metal precursor solution obtained in S1 by an impregnation method and stirred evenly.

[0061] S3. Drying: Dry at 120°C for 4 hours.

[0062] S4. Calcination: Calcinate at 650°C in air atmosphere for 2h.

[0063] S5. Reduction: Reduce at 200° C. in a hydrogen atmosphere for 2 h to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0064] Embodiment 5

[0065] A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance comprises the following steps:

[0066] S1. Prepare a platinum metal precursor solution: weigh 0.04 g Pt(NO3)2 and 10 ml deionized water in a beaker, and disperse and dissolve them to obtain a platinum metal precursor solution with a platinum content of 1.0%.

[0067] S2. Impregnation loading: 5 g of low sodium SSZ-13 molecular sieve carrier is impregnated into the platinum metal precursor solution obtained in S1 by an impregnation method and stirred evenly.

[0068] S3. Drying: Dry at 120°C for 4 hours.

[0069] S4. Calcination: Calcinate at 650°C in air atmosphere for 2h.

[0070] S5. Reduction: Reduce at 200° C. in a hydrogen atmosphere for 2 h to obtain a Pt / SSZ-13 molecular sieve catalyst.

[0071] Experimental Testing

[0072] The structure of the Pt / TiO2 catalyst prepared in Example 5 was analyzed. Figure 1 It can be seen that the Pt particles are uniformly dispersed on the SSZ-13 molecular sieve carrier. The Pt / TiO2 catalyst prepared in Example 5 was tested for ethylene oxidation catalysis. Experimental conditions: 6000mL / (hg), 50ppmC2H4, 21%O2, 20°C, relative humidity 50%. Figure 2 As shown, the ethylene conversion performance of the Pt / SSZ-13 molecular sieve catalyst is stably maintained at above 60%.

[0073] The Pt / SSZ-13 molecular sieve catalyst prepared in Examples 1 to 5 was used to carry out ethylene oxidation catalytic test.

[0074] The specific test conditions and results are shown in Table 1.

[0075] Table 1 Ethylene conversion rate and duration results statistics

[0076]

[0077]

[0078] As can be seen from Table 1, the catalytic oxidation performance of the Pt / SSZ-13 molecular sieve catalyst prepared by Examples 1 to 5 for ethylene is stably maintained at more than 50% under the conditions of 20°C to 25°C and 50% humidity. When the space velocity increases, the conversion rate decreases, but its stability is not affected.

[0079] Therefore, the present invention adopts the above-mentioned high humidity tolerance Pt / SSZ-13 molecular sieve catalyst and its preparation method and application, utilizes a small pore molecular sieve carrier, and obtains a Pt / SSZ-13 catalyst by optimizing the Pt loading and preparation process. The catalyst has high humidity tolerance and stability, and solves the problem of insufficient activity of existing catalysts under room temperature and high humidity conditions.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance, characterized in that: The following steps are involved: S1. preparing a platinum metal precursor solution: adding platinum particles into a solvent in a certain proportion, dispersing and dissolving the platinum metal precursor solution; S2, impregnation loading: impregnate the SSZ-13 molecular sieve carrier into the platinum metal precursor solution obtained in S1 by an impregnation method, and stir evenly; S3, drying: drying at 60°C to 120°C for 3 to 12 hours; S4, calcination: calcination at 600 ℃ ~ 800 ℃, air atmosphere for 1 ~ 10h; S5. Reduction: reducing at 100° C. to 300° C. in a hydrogen atmosphere for 1 to 3 hours to obtain a Pt / SSZ-13 molecular sieve catalyst.

2. The method for preparing a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst according to claim 1, characterized in that: In S1, the platinum particles are one or more of platinum nitrate solution, tetraammineplatinum nitrate or hydroxyplatinic acid.

3. The method for preparing a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst according to claim 1, characterized in that: In S1, the platinum content in the platinum metal precursor solution is 0.5% to 3%, calculated by mass fraction.

4. The method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance according to claim 1, characterized in that: In S2, the SSZ-13 molecular sieve is one or more of H-type SSZ-13 molecular sieve, ammonia-type SSZ-13 molecular sieve or low-sodium-type SSZ-13 molecular sieve.

5. The method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance according to claim 1, characterized in that: In S4, the calcination is specifically: calcination at 640° C. to 660° C. in an air atmosphere for 1 to 10 hours.

6. The method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance according to claim 5, characterized in that: In S4, the calcination is specifically: calcination at 650° C. in an air atmosphere for 1 to 10 hours.

7. The method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance according to claim 1, characterized in that: In S5, the reduction is specifically: reduction at 200° C. in a hydrogen atmosphere for 1 to 3 hours.

8. The method for preparing a Pt / SSZ-13 molecular sieve catalyst with high humidity tolerance according to claim 7, characterized in that: In S5, the reduction is specifically: reducing at 200° C. in a hydrogen atmosphere for 2 h.

9. A Pt / SSZ-13 molecular sieve catalyst prepared by the method for preparing a high humidity tolerance Pt / SSZ-13 molecular sieve catalyst according to any one of claims 1 to 8.

10. Use of the high humidity tolerance Pt / SSZ-13 molecular sieve catalyst as claimed in claim 9 in the purification of ethylene from industrial tail gas and indoor air under low temperature and high humidity environment.

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