Preparation method of molecular sieve catalyst composite carrier

Abstract

The application belongs to the field of catalyst composite carrier, and discloses a preparation method of a molecular sieve catalyst composite carrier, which comprises the following steps: S1, modifying treatment of the molecular sieve; S2, preparation of inorganic oxide sol; S3, preparation of nanometer material dispersion liquid; S4, preparation of mixed material, wherein the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanometer material dispersion liquid obtained in S3 are mixed; S5, preparation of shaped particles; S6, preparation of the molecular sieve catalyst composite carrier; the shaped particles obtained in S5 are put into a calcination furnace, heated to a specified temperature, and then kept at the temperature to obtain the molecular sieve catalyst composite carrier; the preparation steps and the process are optimized and improved, the specific surface area of the composite carrier is greatly improved, the mechanical strength of the composite carrier is improved, and finally, the composite carrier has the catalytic activity of the molecular sieve, the structural stability of the inorganic oxide and the reinforcing properties of the nanometer material, and the use efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst composite carrier, in particular to a preparation method of a molecular sieve catalyst composite carrier. BACKGROUND

[0002] Molecular sieve is widely used as a catalyst carrier due to its regular pore structure, large specific surface area and good shape-selective catalytic performance. However, the traditional carrier is a single molecular sieve carrier, which has defects such as low mechanical strength, insufficient thermal stability, limited active component loading, and is prone to cause the decline of catalytic activity due to wear or high-temperature sintering in industrial applications. In order to solve the problems of the single molecular sieve carrier, the existing technology often adopts the way of combining molecular sieve with inorganic oxide (such as aluminum oxide and silicon oxide) to prepare the carrier. When combining, the basic method is to prepare by co-precipitation. The basic principle of co-precipitation is to realize the close combination of the interface of molecular sieve and inorganic oxide through synchronous precipitation based on liquid-phase uniform dispersion, and then solidify into a composite carrier with the advantages of both after treatment. Although the mechanical strength of the composite carrier prepared in this way is improved, its mechanical strength cannot fully meet the use requirements, and the use effect is poor. In addition, the molecular sieve pores are easily blocked by the oxide in the composite process, which leads to the decrease of the specific surface area, and the quality of the finished product is not high, the comprehensive quality is low, and it is difficult to meet the increasingly developing industrialization demand. SUMMARY

[0003] The present application aims to provide a preparation method of a molecular sieve catalyst composite carrier to solve the problems in the background art.

[0004] To achieve the above purpose, the present application provides the following technical scheme:

[0005] A preparation method of a molecular sieve catalyst composite carrier, comprising the following steps,

[0006] S1, modifying the molecular sieve, preparing the molecular sieve and an acid solution, the mass fraction of the acid solution is 7% to 13%, the molecular sieve is added into the acid solution, stirring for 3 to 5.5 hours, the temperature is controlled at 65 to 85℃ during stirring, and after stirring, the modified molecular sieve is obtained through filtration, washing and drying;

[0007] S2, preparing an inorganic oxide sol, preparing an inorganic oxide precursor and deionized water, adding the inorganic oxide precursor into the deionized water, then adding an acid solution dropwise to adjust the pH value of the mixed solution, adjusting the pH value of the mixed solution to 1 to 3, adjusting the mixing temperature, and stirring at 45 to 65℃ for 1 to 3 hours to obtain the inorganic oxide sol;

[0008] S3, preparing a nanomaterial dispersion liquid, preparing a dispersion container, adding water into the dispersion container, then adding a dispersant into the water, the dispersant being selected from sodium dodecyl sulfate, then adding a nanometer reinforcing material, the mass ratio of the nanometer reinforcing material to water being 1:150-220, then dispersing for 35-55 minutes through ultrasonic to obtain the nanomaterial dispersion liquid;

[0009] S4, preparing a mixture, mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanomaterial dispersion liquid obtained in S3, the mass ratio of the nanomaterial dispersion liquid, the inorganic oxide sol and the modified molecular sieve being 1:2-4:4-8, then adding a modifier, the modifier being selected from a silane coupling agent, adjusting the temperature, stirring for 2-5 hours at 30-50℃ to obtain the mixture;

[0010] S5, preparing a shaped particle, extruding the obtained mixture to obtain a particle with a shape, drying the particle at 80-130℃ for 6-12 hours to obtain the shaped particle;

[0011] S6, preparing a molecular sieve catalyst composite carrier, putting the shaped particle obtained in S5 into a calcination furnace, raising the temperature in the calcination furnace to 510-650℃, and keeping the temperature for 3.5-5.5 hours to complete the calcination modification, thereby obtaining the molecular sieve catalyst composite carrier.

[0012] Preferably, in S1, the acid solution is selected from one of nitric acid, sulfuric acid and citric acid.

[0013] Preferably, in S2, the inorganic oxide precursor is selected from one of pseudoboehmite, silica sol and tetrabutyl titanate, and the acid solution is selected from hydrochloric acid.

[0014] Preferably, in S3, the nanometer reinforcing material is selected from one of carbon nanotube and graphene, and the dispersant can also be selected from polyethylene glycol, and the mass ratio of the dispersant to the nanometer reinforcing material is 2-5:100.

[0015] Preferably, in S4, the mass ratio of the modifier to the mixture of the nanomaterial dispersion liquid, the inorganic oxide sol and the modified molecular sieve is 1-5:100.

[0016] Preferably, in S6, the temperature in the calcination furnace is first raised to 300-350℃ and kept for 1-2 hours, then the temperature in the calcination furnace is raised to 510-650℃, and nitrogen is introduced into the calcination furnace during the calcination process.

[0017] Preferably, in S6, the temperature in the calcination furnace is raised at a rate of 2-4℃ / min.

[0018] Preferably, the nitrogen gas is introduced at a rate of 50-100 mL / min.

[0019] Preferably, in S2, the mass ratio of inorganic oxide precursor to deionized water is 1:4-8.

[0020] Compared with the prior art, the technical scheme has the following beneficial effects:

[0021] (1) The technical scheme modifies the molecular sieve, modifies the molecular sieve by an acid solution, mixes the inorganic oxide in the form of sol, and fuses the nano-enhancing material with the inorganic oxide sol and other substances in the form of dispersion in the aqueous solution, thereby ensuring the compatibility of the fusion and improving the quality of the final shaped composite carrier; the nano material is introduced, thereby greatly improving the performance of the composite material; meanwhile, other preparation steps and processes are adaptively optimized and improved, thereby greatly improving the specific surface area of the composite carrier and the mechanical strength of the composite carrier; finally, the composite carrier has the catalytic activity of the molecular sieve, the structural stability of the inorganic oxide, and the enhancing properties of the nano material, thereby greatly improving the use efficiency.

[0022] (2) The design scheme completes the final treatment by the way of segmental calcination at a certain rate, converts the inorganic oxide sol into an oxide network structure, removes the organic dispersant, forms a stable composite carrier skeleton, enhances the structural stability of the composite carrier, and optimizes the active sites of the molecular sieve; meanwhile, the technical scheme has a simple process, can be prepared by using conventional production machinery, has low preparation cost, and is convenient to use. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The flowchart is a schematic diagram of the present application; DETAILED DESCRIPTION

[0024] The present application will be further described below in combination with the accompanying drawings and embodiments: Figure 1

[0025] A preparation method of a molecular sieve catalyst composite carrier, comprising the following steps,

[0026] S1, modifying the molecular sieve, preparing the molecular sieve and an acid solution, the mass fraction of the acid solution being 7%-13%, adding the molecular sieve into the acid solution, the acid solution being selected from one of nitric acid, sulfuric acid and citric acid, stirring for 3-5.5 hours, controlling the temperature during the stirring at 65-85 DEG C, and obtaining the modified molecular sieve after filtration, washing and drying; the washing is stopped until the solution is neutral, so as to prevent the residual acid from corroding the subsequent materials;

[0027] The molecular sieve in this step is selected from ZSM-5 molecular sieve;

[0028] ​S2, preparing inorganic oxide sol, preparing inorganic oxide precursor and deionized water, the mass ratio of inorganic oxide precursor and deionized water is 1:4-8, the inorganic oxide precursor is selected from one of pseudoboehmite, silica sol and tetrabutyl titanate; the inorganic oxide precursor is added into the deionized water, then an acidic solution is added dropwise to adjust the pH value of the mixed solution, the acidic solution is selected from hydrochloric acid; the pH value of the mixed solution is adjusted to 1-3, the mixed temperature is adjusted, and the stirring is carried out at 45-65℃ for 1-3 hours to obtain the inorganic oxide sol; the inorganic oxide in the sol state has better dispersibility, and can uniformly wrap the molecular sieve particles in the subsequent process, thereby improving the preparation quality;

[0029] S3, preparing nanomaterial dispersion liquid, preparing a dispersion container, adding water into the dispersion container, then adding a dispersant into the water, the dispersant is selected from sodium dodecyl sulfate or polyethylene glycol, the mass ratio of the dispersant to the nanometer reinforcing material is 2-5:100; then adding the nanometer reinforcing material, the nanometer reinforcing material is selected from one of carbon nanotube and graphene, the mass ratio of the nanometer reinforcing material to water is 1:150-220, then the ultrasonic dispersion is carried out for 35-55 minutes to obtain the nanomaterial dispersion liquid; the mixing mass ratio of the nanometer reinforcing material to water is limited, so that the added nanometer reinforcing material can ensure the reinforcing effect on the composite carrier while avoiding excessive addition of the nanometer particles to cause agglomeration and affect the subsequent quality;

[0030] S4, preparing mixed material, mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanomaterial dispersion liquid obtained in S3, the mixing mass ratio of the nanomaterial dispersion liquid, the inorganic oxide sol and the modified molecular sieve is 1:2-4:4-8, then adding a modifier, the modifier is selected from silane coupling agent, the mass ratio of the modifier to the mixed solution of the nanomaterial dispersion liquid, the inorganic oxide sol and the modified molecular sieve is 1-5:100; adjusting the temperature, and stirring at 30-50℃ for 2-5 hours to obtain the mixed material; the stirring temperature is limited to avoid rapid gelation of the inorganic oxide sol,

[0031] S5, preparing shaped particles, extruding the obtained mixed material to obtain particles with shapes, and drying the particles at 80-130℃ for 6-12 hours to obtain the shaped particles;

[0032] S6. Prepare the molecular sieve catalyst composite support. Place the shaped particles obtained in S5 into a calcination furnace. First, raise the temperature of the calcination furnace to 300℃~350℃ at a rate of 2~4℃ / min, and hold for 1~2 hours. Then, raise the temperature of the calcination furnace to 510℃~650℃ at a rate of 2~4℃ / min, and hold for 3.5~5.5 hours. During the calcination process, introduce nitrogen gas into the calcination furnace at a rate of 50~100 mL / min. After completing the calcination modification, the molecular sieve catalyst composite support is obtained.

[0033] Example 1,

[0034] S1. Modify the molecular sieve by preparing 100g of molecular sieve and 500mL of nitric acid solution. The molecular sieve used is ZSM-5 molecular sieve. Select a nitric acid solution with a mass fraction of 10%. Add the molecular sieve to the nitric acid solution and stir for 4 hours. Control the temperature at 80℃ during stirring. After stirring, filter the solution and wash it until neutral. Then dry it at 100℃ to obtain the modified molecular sieve.

[0035] S2. Prepare inorganic oxide sol. Prepare 50g of boehmite and 300ml of deionized water. Add boehmite to deionized water, then add hydrochloric acid to adjust the pH of the mixture to 2. Adjust the mixing temperature and stir at 60℃ for 2 hours to obtain inorganic oxide sol.

[0036] S3. Prepare a dispersion of nanomaterials. Prepare a dispersion container, add 1000ml of water to the dispersion container, then add 0.2g of sodium dodecyl sulfate to the water; then add 5g of carbon nanotubes. The diameter of the carbon nanotubes is controlled to be 10nm~20nm. Then disperse by ultrasonication for 45 minutes to obtain a dispersion of nanomaterials.

[0037] S4. Prepare the mixture by mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2, and the nanomaterial dispersion obtained in S3, wherein 70g of the modified molecular sieve, 30g of the inorganic oxide sol, and 10g of the nanomaterial dispersion are used, and then 3g of silane coupling agent is added; adjust the temperature and stir at 40℃ for 3 hours to obtain the mixture.

[0038] S5. Prepare shaped granules by extruding the obtained mixture to obtain shaped granules, and dry the granules at 100°C for 8 hours to obtain shaped granules.

[0039] S6, preparing the molecular sieve catalyst composite carrier, the shaped particles obtained in S5 are put into a calcination furnace, the temperature of the calcination furnace is first increased to 300 DEG C at a rate of 3 DEG C / min, after 1.5 hours of heat preservation, the temperature of the calcination furnace is then increased to 540 DEG C at a rate of 3 DEG C / min, and then heat preservation is carried out for 4 hours, in the calcination process, nitrogen is introduced into the calcination furnace at a rate of 80 mL / min, and the calcination modification is completed to obtain the molecular sieve catalyst composite carrier.

[0040] Example 2,

[0041] S1, the molecular sieve is modified, 80g of molecular sieve and 400ml of nitric acid solution are prepared, the molecular sieve is selected from ZSM-5 molecular sieve; wherein a 10% mass fraction of nitric acid solution is selected, the molecular sieve is added into the nitric acid solution, stirred for 3 hours, the temperature is controlled at 85 DEG C during stirring, after stirring, filtration is carried out, after filtration, washing is carried out until neutral, and then drying is carried out at a temperature of 100 DEG C to obtain the modified molecular sieve;

[0042] S2, preparing inorganic oxide sol, 40g of silica sol and 200ml of deionized water are prepared, the silica sol is added into the deionized water, then hydrochloric acid is added dropwise to adjust the pH value of the mixed solution, the pH value of the mixed solution is adjusted to 1.5, the mixed temperature is adjusted, and stirring is carried out at 50 DEG C for 1.5 hours to obtain the inorganic oxide sol;

[0043] S3, preparing a nanomaterial dispersion liquid, a dispersion container is prepared, 900ml of water is added into the dispersion container, then 0.3g of polyethylene glycol is added into the water, then 6g of graphene is added, and then ultrasonic dispersion is carried out for 45 minutes to obtain the nanomaterial dispersion liquid;

[0044] S4, preparing a mixture, the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanomaterial dispersion liquid obtained in S3 are mixed, wherein the modified molecular sieve is selected from 60g, the inorganic oxide sol is selected from 40g, and the nanomaterial dispersion liquid is selected from 15g, then 2g of silane coupling agent is added, the temperature is adjusted, and stirring is carried out at 30 DEG C for 4 hours to obtain the mixture;

[0045] S5, preparing shaped particles, the obtained mixture is extruded to obtain particles with shapes, and the particles are dried at 80 DEG C for 10 hours to obtain the shaped particles;

[0046] S6, preparing the molecular sieve catalyst composite carrier, the shaped particles obtained in S5 are put into a calcination furnace, the temperature of the calcination furnace is first increased to 300 DEG C at a rate of 3 DEG C / min, after 1.5 hours of heat preservation, the temperature of the calcination furnace is then increased to 540 DEG C at a rate of 3 DEG C / min, and then heat preservation is carried out for 4 hours, in the calcination process, nitrogen is introduced into the calcination furnace at a rate of 80 mL / min, and the calcination modification is completed to obtain the molecular sieve catalyst composite carrier.

[0047] Comparative Example 1,

[0048] The comparative example uses the existing coprecipitation method to prepare the composite carrier, and does not add a nano reinforcing material. When the composite carrier is prepared by the coprecipitation method, the same molecular sieve as that in Embodiment 1 and Embodiment 2 is also selected to complete the preparation of the composite carrier.

[0049] The composite carriers obtained in Embodiments 1, 2 and the comparative example are subjected to performance testing, and the results are shown in the following table,

[0050]

[0051] According to the above table, the present technical solution optimizes and improves the preparation raw materials and preparation process of the composite carrier, so that the specific surface area of the final product prepared at room temperature and the specific surface area after 800 DEG C calcination are much larger than those of the final product prepared by the existing coprecipitation method. The problem of easy plugging of the molecular sieve channel by the oxide in the coprecipitation method is solved, and the specific surface area after 800 DEG C calcination is also large, so that the composite material prepared by the present technical solution has high thermal stability; the channel is not easy to collapse at high temperature; and the compressive strength of the composite material prepared by the present technical solution is also significantly improved, the mechanical strength is improved, the use effect is enhanced, and it is further proved that the optimization and improvement of the present technical solution are effective and stable; according to the comparison of the results of Embodiments 1 and 2, the performance of the final product will change when the preparation parameters are adjusted, which shows that the optimization and limitation of the preparation parameters and the preparation method of the present technical solution are of positive significance, and not direct combination or multiple experiments can obtain.

[0052] The above-mentioned is only an embodiment of the present application, and the specific technical solutions and / or characteristics of the scheme known in the art are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent.

Claims

1. A method for preparing a composite support for a molecular sieve catalyst, characterized by: The method comprises the following steps of: S1, modifying the molecular sieve, preparing the molecular sieve and an acid solution with a mass fraction of 7-13%, adding the molecular sieve into the acid solution, stirring for 3-5.5 hours, controlling the temperature at 65-85 DEG C during stirring, and obtaining the modified molecular sieve through filtration, washing and drying after stirring; S2, preparing the inorganic oxide sol, preparing the inorganic oxide precursor and deionized water, adding the inorganic oxide precursor into the deionized water, then adding the acid solution dropwise to adjust the pH value of the mixture, adjusting the pH value of the mixture to 1-3, adjusting the mixing temperature, stirring for 1-3 hours under the condition of 45-65 DEG C, and obtaining the inorganic oxide sol; S3, preparing the nanomaterial dispersion, preparing the dispersion container, adding water into the dispersion container, then adding the dispersant selected from sodium dodecyl sulfate or polyethylene glycol into the water, then adding the nanometer reinforcing material selected from one of carbon nanotube and graphene, the mass ratio of the nanometer reinforcing material to water being 1:150-220, and then obtaining the nanomaterial dispersion through ultrasonic dispersion for 35-55 minutes; S4, preparing the mixture, mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanomaterial dispersion obtained in S3, the mass ratio of the nanomaterial dispersion, the inorganic oxide sol and the modified molecular sieve being 1:2-4:4-8, then adding the modifier selected from silane coupling agent, adjusting the temperature, stirring for 2-5 hours under the condition of 30-50 DEG C, and obtaining the mixture; S5, preparing the shaped particle, extruding the obtained mixture to obtain the particle with shape, and drying the particle at 80-130 DEG C for 6-12 hours to obtain the shaped particle; S6, preparing the molecular sieve catalyst composite carrier, putting the shaped particle obtained in S5 into the calcining furnace, raising the temperature in the calcining furnace to 510-650 DEG C, and maintaining the temperature for 3.5-5.5 hours to complete the calcination modification, and obtaining the molecular sieve catalyst composite carrier; In S1, the acid solution is selected from one of nitric acid and sulfuric acid; In S2, the inorganic oxide precursor is selected from one of pseudoboehmite, silica sol and tetrabutyl titanate, and the acid solution is selected from hydrochloric acid; In S3, the mass ratio of the dispersant to the nanometer reinforcing material is 2-5:

100.

2. The method for preparing a molecular sieve catalyst composite support as described in claim 1, characterized in that: In S4, the mass ratio of the modifier to the mixture of the nanomaterial dispersion, the inorganic oxide sol and the modified molecular sieve is 1-5:

100.

3. The method of making a composite support for a molecular sieve catalyst of claim 1 wherein: In S6, the temperature in the calcining furnace is first raised to 300-350 DEG C, and then raised to 510-650 DEG C after maintaining the temperature for 1-2 hours, and nitrogen is introduced into the calcining furnace during the calcination process.

4. The method of making a composite support for a molecular sieve catalyst of claim 1 wherein: In S6, the temperature in the calcining furnace is raised at a rate of 2-4 DEG C / min.

5. The method of making a composite support for a molecular sieve catalyst of claim 3 wherein: The introduction rate of the nitrogen is 50-100 mL / min.

6. The method of making a composite support for molecular sieve catalysts according to Claim 1 wherein: In S2, the mass ratio of the inorganic oxide precursor to the deionized water is 1:4-8.

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