Molding method of general molecular sieve catalyst carrier

Abstract

The invention belongs to the technical field of molecular sieve catalyst molding, and discloses a general molecular sieve catalyst carrier molding method, which comprises: synthesizing a molecular sieve raw material; performing gel crystallization; forming is conducted; aging is performed; according to the technical scheme, multi-stage crystallization treatment is carried out, and the temperature, time and temperature increase rate of each stage of crystallization treatment are limited, so that the growth rate and final size of crystals can be controlled, the crystal form can be better controlled, and most of crystal impurities can be removed; morphological control on the molecular sieve is improved, and the performance of the finally formed molecular sieve is improved; tetrapropylammonium hydroxide and metal salt are added, so that formed metal complex ions are extremely easy to combine with hydroxyl on the surface of the molecular sieve, and subsequent crystallization is facilitated; the pore channel smoothness of the molecular sieve is ensured by optimizing the whole steps, and the structural strength of the molecular sieve is improved.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve catalyst molding, and in particular to a molding method for a universal molecular sieve catalyst carrier. Background Art

[0002] Molecular sieve is a kind of aluminosilicate material with uniform pore size and regular crystal structure. It has rich pore system, large specific surface area and good thermal stability. It is regarded as an excellent industrial material in removing oxygen-containing compounds from olefins, catalytic cracking reaction and adsorbing harmful gases. In the gas separation industry, molecular sieve can efficiently extract specific components such as oxygen, nitrogen or carbon dioxide from mixed gases. Its relatively large specific surface area provides numerous active sites for adsorption, thereby enhancing the adsorption performance of molecular sieve. These characteristics of molecular sieve not only have great potential in traditional fields such as chemical industry, oil and natural gas processing, but also show broad application prospects in emerging fields such as environmental protection, clean energy and biological science.

[0003] In the prior art, the method for preparing molecular sieves includes using silica sol as a silicon source and using a specific directing agent for preparation; preparing the molecular sieve mother liquor by mixing water glass, sodium hydroxide, aluminum hydroxide or sodium aluminate, and then adding the directing agent thereto, and finally obtaining the molecular sieve after aging and adding a weakly polar dispersant.

[0004] However, the existing preparation methods have the problems of low silicon source utilization, difficult to control size and morphology of the prepared molecular sieve products, and insufficient dispersion, which results in poor performance of the molecular sieves finally obtained and makes it difficult to meet the growing industrial needs. Summary of the invention

[0005] The present invention is intended to provide a method for forming a universal molecular sieve catalyst carrier to solve the technical problems raised in the above background technology.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for forming a universal molecular sieve catalyst carrier comprises the following steps: S1, synthesizing molecular sieve raw materials, mixing silica sol, deionized water and sodium hydroxide and stirring them evenly for 1 hour to obtain a silicon source gel, wherein the concentration of the silicon source in the silicon source gel is 50wt% to 99wt%; mixing sodium aluminate and deionized water and stirring them evenly for 1 hour to obtain an aluminum source gel, wherein the concentration of the aluminum source in the aluminum source gel is 17wt% to 99wt%; slowly dripping the silicon source gel into the aluminum source gel and mixing, stirring them evenly at a temperature of 25°C to 40°C for 5 hours to 7 hours to obtain a mixed gel; S2, gel crystallization, adding the obtained mixed gel into an autoclave lined with polytetrafluoroethylene, controlling the hydrothermal crystallization temperature and time, firstly raising the crystallization temperature from room temperature to 95°C to 155°C at a heating rate of 2°C / min to 8°C / min, maintaining the condition of 95°C to 155°C for continuous crystallization for 6.5h to 7.5h, then continuing to increase the temperature for crystallization, and continuing to increase the processing purification temperature to 150°C to 180°C at a heating rate of 2°C / min to 8°C / min, maintaining the condition of 150°C to 180°C for continuous crystallization for 12h to 18h, to obtain a crystallized product; S3, forming, mixing the crystallized product, silica gel, tetrapropylammonium hydroxide, metal salt and deionized water to obtain a mixed liquid, and crystallizing the mixed liquid again to obtain a formed molecular sieve; S4, aging, mixing the formed molecular sieve with polyvinyl alcohol to obtain a mixed solution, aging the mixed solution at an aging temperature of 30°C to 90°C; maintaining the aging condition of 30°C to 90°C for 5h to 20h; and then continuing crystallization to obtain a preliminary molecular sieve; S5, obtaining molecular sieve powder, filtering, washing, separating and drying the preliminary molecular sieve to obtain molecular sieve powder, filtering the obtained preliminary molecular sieve to obtain a molecular sieve mixture, washing the molecular sieve mixture to obtain a molecular sieve condensate free of other impurities, and then separating the molecular sieve condensate to obtain a pure molecular sieve solid-liquid mixture, and subjecting the molecular sieve solid-liquid mixture to microwave drying by a microwave dryer, wherein the microwave dryer comprises a conveyor belt conveyor, a microwave generator and a dehumidification system, and the molecular sieve solid-liquid mixture is spread on the conveyor belt conveyor, and the molecular sieve solid-liquid mixture moves along the conveyor belt conveyor and then passes under the microwave generator, and the microwave generator emits microwaves to dry the molecular sieve solid-liquid mixture passing under the microwave generator, and the drying time can be controlled by controlling the transmission speed of the conveyor belt conveyor, and the water in the molecular sieve solid-liquid mixture evaporates and is extracted through the suction system, thereby obtaining molecular sieve powder; S6, particle preparation, preparing the molecular sieve powder into spherical molecular sieves through an enameling machine or preparing the molecular sieve powder into columnar molecular sieves through an extruder.

[0007] Preferably, the molar ratio of the components in the crystallized product is: silicon oxide: aluminum oxide: sodium oxide: water = 1: 0.5-1.5: 0.1-0.8: 20-30.

[0008] Preferably, the pH value of the mixed gel is 9 to 11.5.

[0009] Preferably, in step S3, the re-crystallization temperature is 110° C. to 175° C., and the re-crystallization is performed for 12 h to 40 h while maintaining the temperature at 110° C. to 175° C.

[0010] Preferably, in step S4, the temperature for continuing crystallization is 150° C. to 180° C., and the crystallization is carried out at the temperature of 150° C. to 180° C. for 12 h to 30 h.

[0011] Preferably, in step S1, one or more of ethyl orthosilicate, coarse-pore silica gel or silicon powder can be selected and mixed with deionized water and sodium hydroxide to prepare silicon source gel, and one or more of activated pseudo-boehmite, aluminum sulfate or aluminum nitrate can be selected and mixed with deionized water to prepare aluminum source sol.

[0012] Preferably, the metal salt is one of Fe salt, Pt salt, Au salt, Ag salt, Cu salt and Ga salt.

[0013] Preferably, in step S4, the mass ratio of the formed molecular sieve to polyvinyl alcohol is 1:0.02-0.07.

[0014] The beneficial effects of this technical solution are: (1) The technical solution proposed in the present invention performs multi-stage crystallization treatment on the mixed gel, and at the same time limits the temperature, time and temperature increase rate of each stage of crystallization treatment, which can control the growth rate and final size of the crystal, and thus better control the crystal form, remove most of the crystal impurities, improve the morphology control of the molecular sieve, and improve the performance of the molecular sieve finally formed.

[0015] (2) The technical solution proposed in the present invention performs an aging operation on the formed molecular sieve. Polyvinyl alcohol can serve as a structure directing agent and a growth regulator, which can further assist crystallization and improve the structural stability of the molecular sieve. After aging, the molecular sieve is crystallized again, so that the molecular sieve is incorporated with micropores and mesopores, which improves the silicon source conversion rate, increases the specific surface area and pore capacity of the molecular sieve, increases the adsorption points of the molecular sieve, and thus improves the performance of the molecular sieve, greatly improving the application range of the molecular sieve.

[0016] (3) The technical solution proposed in the present invention facilitates accelerating the subsequent crystal formation rate and improving production efficiency by limiting the ratio of silicon source gel and aluminum source gel, stirring temperature and time, and regulating the pH value during gel mixing; the metal complex ions formed by adding tetrapropylammonium hydroxide and metal salts are very easy to combine with the hydroxyl groups on the surface of the molecular sieve, which is beneficial to the subsequent crystallization; and the pore patency of the molecular sieve is guaranteed by optimizing the overall steps, thereby improving the structural strength of the molecular sieve.

[0017] (4) The present invention adopts microwave drying to carry out drying, which greatly improves the drying speed and can also evenly dry the molecular sieve powder to achieve deep drying. Microwave drying can avoid contact with the molecular sieve and avoid contamination of the molecular sieve. The drying environment temperature will not be very high, which improves the comfort of the working environment. The drying time can be adjusted by controlling the running speed of the conveyor belt. The operation is simple and convenient, which greatly improves the quality of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 A statistical diagram of the performance of the final product of different embodiments provided by the present invention; DETAILED DESCRIPTION The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Embodiment 1, A method for forming a universal molecular sieve catalyst carrier comprises the following steps: S1, synthesizing molecular sieve raw materials, mixing silica sol, deionized water and sodium hydroxide and stirring them evenly for 1 hour to obtain a silicon source gel, and controlling the addition amounts of silica sol, deionized water and sodium hydroxide to make the concentration of silicon source in the silicon source gel 72wt%; mixing sodium aluminate and deionized water and stirring them evenly for 1 hour to obtain an aluminum source gel, and controlling the addition amount of sodium aluminate to make the concentration of aluminum source in the aluminum source gel 65wt%; slowly dripping the silicon source gel into the aluminum source gel and mixing, and stirring them at a temperature of 32°C for 6 hours to obtain a mixed gel; adjusting the pH value of the mixed gel to 10, and the pH value of the mixed gel can be adjusted by controlling the addition ratio of sodium hydroxide and sodium aluminate; S2, gel crystallization, adding the obtained mixed gel into an autoclave lined with polytetrafluoroethylene, controlling the hydrothermal crystallization temperature and time, firstly raising the crystallization temperature from room temperature to 120°C at a heating rate of 5°C / min, maintaining the condition of 120°C for continuous crystallization for 7h, then continuing to increase the temperature for crystallization, and further increasing the processing purification temperature to 160°C at a heating rate of 5°C / min, maintaining the condition of 160°C for continuous crystallization for 12h, to obtain a crystallized product; S3, forming, mixing the crystallized product, silica gel, tetrapropylammonium hydroxide, metal salt and deionized water to obtain a mixed liquid, and re-crystallizing the mixed liquid to obtain a formed molecular sieve; the re-crystallization temperature is 150° C., and the re-crystallization is carried out for 12 hours under the condition of maintaining 150° C.; the metal salt is selected from Pt salt, specifically, chloroplatinic acid; S4, aging, mixing the formed molecular sieve with polyvinyl alcohol to obtain a mixed solution, aging the mixed solution at an aging temperature of 80°C; maintaining the aging condition of 80°C for 12 hours; then continuing to crystallize to obtain a preliminary molecular sieve; continuing the crystallization temperature at 160°C, maintaining the crystallization condition at 160°C for 24 hours; the mass ratio of the formed molecular sieve to the polyvinyl alcohol is 1:0.05; S5, obtaining molecular sieve powder, filtering, washing, separating and drying the preliminary molecular sieve to obtain molecular sieve powder, filtering the obtained preliminary molecular sieve to obtain a molecular sieve mixture, washing the molecular sieve mixture to obtain a molecular sieve condensate free of other impurities, and then separating the molecular sieve condensate to obtain a pure molecular sieve solid-liquid mixture, and subjecting the molecular sieve solid-liquid mixture to microwave drying in a microwave dryer, wherein the microwave dryer comprises a conveyor belt conveyor, a microwave generator and a dehumidification system, wherein the microwave generator is arranged above the conveyor belt conveyor, and the molecular sieve solid-liquid mixture is spread on the conveyor belt conveyor, and the molecular sieve solid-liquid mixture moves along the conveyor belt conveyor and then passes under the microwave generator, wherein the microwave generator emits microwaves to dry the molecular sieve solid-liquid mixture passing under the microwave generator, and the drying time can be controlled by controlling the transmission speed of the conveyor belt conveyor, and the water in the molecular sieve solid-liquid mixture evaporates and is extracted through the suction system, thereby obtaining molecular sieve powder; S6, particle preparation, preparing the molecular sieve powder into spherical molecular sieves through an enameling machine or preparing the molecular sieve powder into columnar molecular sieves through an extruder.

[0019] Embodiment 2, The difference between Example 2 and Example 1 is that the crystallization time and purification temperature are adjusted. Step S1 is the same as in Example 1. S2, gel crystallization, adding the obtained mixed gel into an autoclave lined with polytetrafluoroethylene, controlling the hydrothermal crystallization temperature and time, firstly raising the crystallization temperature from room temperature to 140°C at a heating rate of 3°C / min, maintaining the condition of 140°C for continuous crystallization for 6.5h, then continuing to increase the temperature for crystallization, and further increasing the processing purification temperature to 150°C at a heating rate of 8°C / min, maintaining the condition of 150°C for continuous crystallization for 18h, to obtain a crystallized product; S3, forming, mixing the crystallized product, silica gel, tetrapropylammonium hydroxide, metal salt and deionized water to obtain a mixed liquid, and re-crystallizing the mixed liquid to obtain a formed molecular sieve; the re-crystallization temperature is 130° C., and the re-crystallization is carried out at 130° C. for 24 hours; the metal salt is selected from Pt salt, specifically, chloroplatinic acid; The subsequent steps S4, S5 and S6 are the same as those in Example 1.

[0020] Embodiment 3, The difference between Example 3 and Example 1 is that step S3 is no longer performed, and the crystallized product obtained in step S2 is directly aged.

[0021] Embodiment 4, The difference between Example 4 and Example 1 is that multi-stage crystallization is no longer performed; Step S1 is the same as in Example 1. S2, gel crystallization, adding the obtained mixed gel into an autoclave lined with polytetrafluoroethylene, controlling the hydrothermal crystallization temperature and time, firstly increasing the crystallization temperature from room temperature to 150°C at a heating rate of 8°C / min, maintaining the temperature at 150°C for 7.5h, and obtaining a crystallized product; S3, forming, mixing the crystallized product, silica gel, tetrapropylammonium hydroxide, metal salt and deionized water to obtain a mixed liquid, and re-crystallizing the mixed liquid to obtain a formed molecular sieve; the metal salt is selected from Pt salt, specifically, chloroplatinic acid; the time and temperature of the re-crystallization are the same as those in Example 1; S4, aging, mixing the formed molecular sieve with polyvinyl alcohol to obtain a mixed solution, aging the mixed solution at an aging temperature of 80° C.; maintaining the aging condition of 80° C. for 12 hours; then continuing to crystallize to obtain a preliminary molecular sieve; the time and temperature for continuing crystallization are the same as those in Example 1; Steps S5 and S6 are the same as those in Example 1.

[0022] Instruction Manual Figure 2 Here, micropores refer to pores with a pore diameter of less than 2 nm, and mesopores refer to pores with a pore diameter of 2 to 50 nm, and a supplementary explanation is given here.

[0023] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for forming a general molecular sieve catalyst carrier, characterized in that: The following steps are involved: S1, synthesizing molecular sieve raw materials, mixing silica sol, deionized water and sodium hydroxide and stirring them evenly for 1 hour to obtain a silicon source gel, wherein the concentration of the silicon source in the silicon source gel is 50wt% to 99wt%; mixing sodium aluminate and deionized water and stirring them evenly for 1 hour to obtain an aluminum source gel, wherein the concentration of the aluminum source in the aluminum source gel is 17wt% to 99wt%; slowly dripping the silicon source gel into the aluminum source gel and mixing, stirring them evenly at a temperature of 25°C to 40°C for 5 hours to 7 hours to obtain a mixed gel; S2, gel crystallization, adding the obtained mixed gel into an autoclave lined with polytetrafluoroethylene, controlling the hydrothermal crystallization temperature and time, firstly raising the crystallization temperature from room temperature to 95°C to 155°C at a heating rate of 2°C / min to 8°C / min, maintaining the condition of 95°C to 155°C for continuous crystallization for 6.5h to 7.5h, then continuing to increase the temperature for crystallization, and continuing to increase the processing purification temperature to 150°C to 180°C at a heating rate of 2°C / min to 8°C / min, maintaining the condition of 150°C to 180°C for continuous crystallization for 12h to 18h, to obtain a crystallized product; S3, forming, mixing the crystallized product, silica gel, tetrapropylammonium hydroxide, metal salt and deionized water to obtain a mixed liquid, and crystallizing the mixed liquid again to obtain a formed molecular sieve; S4, aging, mixing the formed molecular sieve with polyvinyl alcohol to obtain a mixed solution, aging the mixed solution at an aging temperature of 30°C to 90°C; maintaining the aging condition of 30°C to 90°C for 5h to 20h; and then continuing crystallization to obtain a preliminary molecular sieve; S5, obtaining molecular sieve powder, filtering, washing, separating and drying the preliminary molecular sieve to obtain molecular sieve powder, filtering the obtained preliminary molecular sieve to obtain a molecular sieve mixture, washing the molecular sieve mixture to obtain a molecular sieve condensate free of other impurities, and then separating the molecular sieve condensate to obtain a pure molecular sieve solid-liquid mixture, and subjecting the molecular sieve solid-liquid mixture to microwave drying by a microwave dryer, wherein the microwave dryer comprises a conveyor belt conveyor, a microwave generator and a dehumidification system, and the molecular sieve solid-liquid mixture is spread on the conveyor belt conveyor, and the molecular sieve solid-liquid mixture moves along the conveyor belt conveyor and then passes under the microwave generator, and the microwave generator emits microwaves to dry the molecular sieve solid-liquid mixture passing under the microwave generator, and the drying time can be controlled by controlling the transmission speed of the conveyor belt conveyor, and the water in the molecular sieve solid-liquid mixture evaporates and is extracted through the suction system, thereby obtaining molecular sieve powder; S6, particle preparation, preparing the molecular sieve powder into spherical molecular sieves through an enameling machine or preparing the molecular sieve powder into columnar molecular sieves through an extruder.

2. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: The molar ratio of each component in the crystallized product is: silicon oxide: aluminum oxide: sodium oxide: water = 1: 0.5-1.5: 0.1-0.8: 20-30.

3. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: The pH value of the mixed gel is 9-11.

5.

4. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: In the step S3, the re-crystallization temperature is 110° C. to 175° C., and the re-crystallization is carried out for 12 h to 40 h while maintaining the temperature at 110° C. to 175° C.

5. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: In the step S4, the temperature for continuing crystallization is 150° C. to 180° C., and the crystallization is carried out at the temperature of 150° C. to 180° C. for 12 h to 30 h.

6. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: In step S1, one or more of ethyl orthosilicate, macroporous silica gel or silicon powder may be selected and mixed with deionized water and sodium hydroxide to prepare silicon source gel, and one or more of activated pseudo-boehmite, aluminum sulfate or aluminum nitrate may be selected and mixed with deionized water to prepare aluminum source sol.

7. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: The metal salt is one of Fe salt, Pt salt, Au salt, Ag salt, Cu salt and Ga salt.

8. The method for forming a universal molecular sieve catalyst carrier according to claim 1, characterized in that: In the step S4, the mass ratio of the formed molecular sieve to the polyvinyl alcohol is 1:0.02-0.07.

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