Preparation method of molecular sieve catalyst composite carrier

Abstract

The invention belongs to the field of catalyst composite carriers, and discloses a molecular sieve catalyst composite carrier preparation method, which comprises: S1, carrying out modification treatment on a molecular sieve, S2, preparing an inorganic oxide sol, S3, preparing a nanometer material dispersion liquid, S4, preparing a mixture, mixing the modified molecular sieve obtained in the step S1, the inorganic oxide sol obtained in the step S2 and the nano material dispersion liquid obtained in the step S3; s5, preparing formed particles; S6, preparing a molecular sieve catalyst composite carrier; s5, putting the formed particles obtained in the step S5 into a roasting furnace, raising the temperature to a specified temperature, and then performing heat preservation to obtain a molecular sieve catalyst composite carrier; according to the design scheme, the preparation steps and process are optimized and improved, the specific surface area of the composite carrier is greatly increased, meanwhile, the mechanical strength of the composite carrier is improved, the finally obtained composite carrier has the catalytic activity of a molecular sieve, the structural stability of inorganic oxide and the enhancement characteristic of a nano material, and the use efficiency of the composite carrier 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: A preparation method of a molecular sieve catalyst composite carrier, comprising the following steps, 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; 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; 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; 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; 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; 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. Preferably, in S1, the acid solution is selected from one of nitric acid, sulfuric acid and citric acid.

[0005] 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.

[0006] Preferably, in S3, the nanometer reinforcing material is selected from one of carbon nanotubes 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.

[0007] 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.

[0008] 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.

[0009] Preferably, in S6, the temperature in the calcination furnace is raised at a rate of 2-4℃ / min.

[0010] Preferably, the introduction rate of the nitrogen is 50-100 mL / min.

[0011] Preferably, in S2, the mass ratio of the inorganic oxide precursor to deionized water is 1:4-8.

[0012] Compared with the existing technology, this technical solution has the following beneficial effects: (1) This technical solution modifies the molecular sieve by using an acid solution, and the inorganic oxide is mixed in the form of a sol. The nano-reinforced material is also dispersed in an aqueous solution to complete the fusion with the inorganic oxide sol and other substances, thereby ensuring the compatibility of the fusion and improving the quality of the final composite carrier. The introduction of nanomaterials greatly improves the performance of the composite material, and at the same time, adaptive optimization and improvement are made to other preparation steps and processes, which greatly increases the specific surface area of ​​the composite carrier and the mechanical strength of the composite carrier. The composite carrier finally obtained has the catalytic activity of the molecular sieve, the structural stability of the inorganic oxide and the reinforcing characteristics of the nanomaterial, thereby greatly improving its utilization efficiency.

[0013] (2) This design scheme completes the final treatment by means of segmented roasting at a certain rate, so that the inorganic oxide sol is converted into an oxide network structure, while removing the organic dispersant to form a stable composite carrier skeleton, thereby enhancing the structural stability of the composite carrier and optimizing the molecular sieve active sites. In addition, this technical scheme has a simple process and can be prepared using conventional production machinery, with low preparation costs and easy promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the process of the present invention; DETAILED DESCRIPTION The following is combined with Figure 1 The present invention will be further described in detail with the following embodiments: A method for preparing a molecular sieve catalyst composite carrier comprises the following steps: S1. Modify the molecular sieve, prepare molecular sieve and acid solution, the mass fraction of the acid solution is 7% to 13%, add the molecular sieve to the acid solution, and select one of nitric acid, sulfuric acid and citric acid for the acid solution, stir for 3 to 5.5 hours, control the temperature at 65°C to 85°C during stirring, filter, wash and dry after stirring to obtain the modified molecular sieve; wash until neutral to prevent residual acid from corroding subsequent materials; The molecular sieve in this step is ZSM-5 molecular sieve; 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 sol state has better dispersibility, and can uniformly wrap the molecular sieve particles in the subsequent process, thereby improving the preparation quality; 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 to cause the agglomeration of nanometer particles and affect the subsequent quality; 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 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 mixture; the stirring temperature is limited to avoid the inorganic oxide sol from gelling too fast, S5, preparing shaped particles, the obtained mixture is extruded to obtain particles with shapes, and the particles are dried at 80-130℃ for 6-12 hours to obtain the shaped particles; S6, preparing a 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 300-350℃ at a rate of 2-4℃ / min, and then the temperature of the calcination furnace is increased to 510-650℃ at a rate of 2-4℃ / min after being kept at 300-350℃ for 1-2 hours, and then kept for 3.5-5.5 hours, in the calcination process, nitrogen is introduced into the calcination furnace at a rate of 50-100 mL / min, and the calcination modification is completed to obtain the molecular sieve catalyst composite carrier.

[0015] Example 1, S1, the molecular sieve is modified, 100g of molecular sieve and 500ml of nitric acid solution are prepared, the molecular sieve is selected from ZSM-5 molecular sieve; wherein a 10% by mass fraction nitric acid solution is selected, the molecular sieve is added into the nitric acid solution, stirring is carried out for 4 hours, the temperature is controlled at 80 DEG C during stirring, after stirring, filtration is carried out, after filtration, washing is carried out until neutral, then drying is carried out at 100 DEG C to obtain modified molecular sieve; S2, the inorganic oxide sol is prepared, 50g of pseudo-boehmite and 300ml of deionized water are prepared, the pseudo-boehmite is added into the deionized water, then hydrochloric acid is added dropwise to adjust the pH value of the mixture, the pH value of the mixture is adjusted to 2, the mixture temperature is adjusted, stirring is carried out at 60 DEG C for 2 hours to obtain the inorganic oxide sol; S3, the nanomaterial dispersion liquid is prepared, a dispersion container is prepared, 1000ml of water is added into the dispersion container, then 0.2g of sodium dodecyl sulfate is added into the water; then 5g of carbon nanotube is added, the diameter of the nanometer carbon tube is controlled to be 10nm-20nm, then ultrasonic dispersion is carried out for 45 minutes to obtain the nanomaterial dispersion liquid; S4, the mixture is prepared, 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 70g, the inorganic oxide sol is selected from 30g, and the nanomaterial dispersion liquid is selected from 10g, then 3g of silane coupling agent is added; the temperature is adjusted, stirring is carried out at 40 DEG C for 3 hours to obtain the mixture; S5, the shaped particles are prepared, the obtained mixture is extruded and shaped to obtain particles with shapes, the particles are dried at 100 DEG C for 8 hours to obtain the shaped particles; S6, the molecular sieve catalyst composite carrier is prepared, 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 80ml / min, and the modified calcination is completed to obtain the molecular sieve catalyst composite carrier.

[0016] Example 2, 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% by mass fraction nitric acid solution is selected, the molecular sieve is added into the nitric acid solution, stirring is carried out 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, then drying is carried out at 100 DEG C to obtain modified molecular sieve; S2, preparing inorganic oxide sol, preparing 40 g of silica sol and 200 ml of deionized water, adding the silica sol into the deionized water, then adding hydrochloric acid dropwise to adjust the pH value of the mixture, adjusting the pH value of the mixture to 1.5, adjusting the mixing temperature, stirring at 50°C for 1.5 hours to obtain the inorganic oxide sol; S3, preparing a nanomaterial dispersion, preparing a dispersion container, adding 900 ml of water into the dispersion container, then adding 0.3 g of polyethylene glycol into the water, then adding 6 g of graphene, then dispersing by ultrasonic for 45 minutes to obtain the nanomaterial dispersion; S4, preparing a mixture, mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2 and the nanomaterial dispersion obtained in S3, wherein the modified molecular sieve is selected from 60 g, the inorganic oxide sol is selected from 40 g, and the nanomaterial dispersion is selected from 15 g, then adding 2 g of silane coupling agent, adjusting the temperature, stirring at 30°C for 4 hours to obtain the mixture; S5, preparing a shaped particle, extruding the obtained mixture to obtain a particle with a shape, drying the particle at 80°C for 10 hours to obtain the shaped particle; S6, preparing a molecular sieve catalyst composite carrier, placing the shaped particle obtained in S5 into a calcination furnace, first increasing the temperature of the calcination furnace to 300°C at a rate of 4°C / min, then increasing the temperature of the calcination furnace to 570°C at a rate of 4°C / min after maintaining the temperature for 1.5 hours, then maintaining the temperature for 5 hours, and in the calcination process, introducing nitrogen into the calcination furnace at a rate of 80 mL / min, completing the calcination modification to obtain the molecular sieve catalyst composite carrier.

[0017] Comparative Example, The comparative example uses the existing coprecipitation method to prepare the composite carrier, and does not add the nanometer reinforcing material. When the composite carrier is prepared by the coprecipitation method, the same molecular sieve as in Examples 1 and 2 is also selected to complete the preparation of the composite carrier.

[0018] The performance of the composite carriers obtained in Examples 1, 2 and the comparative example is tested, and the results are shown in the following table, According to the above table, the final product prepared by optimizing and improving the raw materials and preparation process of the composite carrier has a specific surface area at room temperature and a specific surface area after calcination at 800 DEG C far greater than that of the final product prepared by the existing coprecipitation method, solves the problem that the molecular sieve channel is easily blocked by oxides in the coprecipitation method, and has a large specific surface area after calcination at 800 DEG C, so that the composite material prepared by the technical scheme 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 technical scheme is also significantly improved compared with the prior art, the mechanical strength is improved, the use effect is enhanced, and it is further proved that the optimization and improvement of the technical scheme is effective and stable; according to the comparison of the results of example 1 and example 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 technical scheme are of positive significance, and cannot be obtained by direct combination or multiple experiments.

[0019] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical scheme of the present application, some modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent.

Claims

1. A method for preparing a molecular sieve catalyst composite support, characterized in that: The following steps are included: S1. Modify the molecular sieve by preparing a molecular sieve and an acid solution with a mass fraction of 7% to 13%. Add the molecular sieve to the acid solution and stir for 3 to 5.5 hours while controlling the temperature at 65°C to 85°C. After stirring, filter, wash and dry to obtain the modified molecular sieve. S2. preparing an inorganic oxide sol, preparing an inorganic oxide precursor and deionized water, adding the inorganic oxide precursor to the deionized water, and then adding an acidic solution dropwise to adjust the pH value of the mixed solution to 1-3, adjusting the mixing temperature, and stirring at 45° C. to 65° C. for 1-3 hours to obtain an inorganic oxide sol; S3. Prepare a nanomaterial dispersion: prepare a dispersion container, add water to the dispersion container, then add a dispersant to the water, wherein the dispersant is sodium lauryl sulfate, and then add a nano-reinforcement material, wherein the mass ratio of the nano-reinforcement material to water is 1:150-220, and then ultrasonically disperse for 35-55 minutes to obtain a nanomaterial dispersion; S4, preparing a mixture, mixing the modified molecular sieve obtained in S1, the inorganic oxide sol obtained in S2, and the nanomaterial dispersion obtained in S3, wherein the mixing mass ratio of the nanomaterial dispersion, the inorganic oxide sol, and the modified molecular sieve is 1:2-4:4-8, and then adding a modifier, wherein the modifier is a silane coupling agent, adjusting the temperature, and stirring at 30° C. to 50° C. for 2-5 hours to obtain a mixture; S5, preparing shaped particles, extruding the obtained mixture to obtain shaped particles, and drying the particles at 80° C. to 130° C. for 6 to 12 hours to obtain shaped particles; S6. Prepare a molecular sieve catalyst composite carrier. Place the shaped particles obtained in S5 into a calcining furnace, increase the temperature in the calcining furnace to 510° C. to 650° C., and keep the temperature for 3.5 to 5.5 hours to complete the calcination modification to obtain a molecular sieve catalyst composite carrier.

2. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In S1, the acid solution is selected from one of nitric acid, sulfuric acid and citric acid.

3. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In the above S2, the inorganic oxide precursor is selected from one of pseudo-boehmite, silica sol, and tetrabutyl titanate, and the acidic solution is selected from hydrochloric acid.

4. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In S3, the nano-reinforcement material is selected from one of carbon nanotubes and graphene, and the dispersant can also be polyethylene glycol. The mass ratio of the dispersant to the nano-reinforcement material is 2 to 5:

100.

5. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In the step S4, the mass ratio of the modifier to the mixed solution of the nanomaterial dispersion, the inorganic oxide sol and the modified molecular sieve is 1 to 5:

100.

6. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In S6, the temperature of the calcining furnace is first raised to 300° C. to 350° C., kept at this temperature for 1 to 2 hours, and then raised to 510° C. to 650° C. During the calcining process, nitrogen is introduced into the calcining furnace.

7. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In the step S6, the temperature in the roasting furnace is increased at a rate of 2 to 4°C / min.

8. The method for preparing a molecular sieve catalyst composite support according to claim 6, wherein: The nitrogen gas introduction rate is 50-100 mL / min.

9. The method for preparing a molecular sieve catalyst composite support according to claim 1, wherein: In the S2, the mass ratio of the inorganic oxide precursor to deionized water is 1:4-8.

Images