A catalyst carrier with high specific surface area and preparation method thereof

Abstract

The present invention relates to the technical field of catalyst carrier materials, and in particular to a catalyst carrier with a high specific surface area and a preparation method thereof, comprising the following steps: (1) dissolving an aluminum salt, hydroxypropyl-β-cyclodextrin, and a first polyvinyl alcohol in deionized water to obtain an aluminum salt mixed solution; (2) dissolving aluminate and a second polyvinyl alcohol in deionized water to obtain aluminate mixed solution; (3) heating the aluminum salt mixed solution, and dripping the aluminate mixed solution to obtain a mixed reaction solution; (4) heating the mixed reaction solution to react to obtain a precipitate; and (5) calcining to obtain a catalyst carrier with a high specific surface area. Polyvinyl alcohol and hydroxypropyl-β-cyclodextrin work together to prepare precursors with different particle sizes and morphologies, effectively reducing the bulk density, increasing the porosity and pore size of alumina, and further increasing its specific surface area.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst carrier materials, and in particular to a catalyst carrier with a high specific surface area and a preparation method thereof. Background Art

[0002] A catalyst is a substance that can significantly increase the rate of a chemical reaction, while its composition, mass and chemical properties remain unchanged before and after the reaction. The catalyst carrier, like the catalyst, plays a wide and important role in the chemical industry. A catalyst carrier is a substance that carries a catalyst. Its main function is to ensure the application of the catalyst and improve the efficiency of the catalyst. On the other hand, it also plays a role in maintaining strength, heat resistance, corrosion resistance and other properties under harsh working conditions. It can be seen that catalyst carriers play a very important role. There are many types of catalyst carriers, mainly including alumina, activated carbon, diatomaceous earth, molecular sieves, titanium dioxide, silicon carbide, etc. Various catalyst carrier materials have their own characteristics, and among them, alumina-based catalyst carriers are the most widely used and the largest in terms of dosage.

[0003] Alumina is one of the most commonly used industrial raw materials, and has extremely important applications in the fields of ceramics, refractory materials, medicine, catalysis, etc. Alumina has become the most widely used catalyst carrier in the chemical and petroleum industries due to its advantages such as good mechanical strength, good thermal stability and chemical stability, suitable isoelectric point, adjustable surface acidity and alkalinity, and a variety of different crystal phase structures. It plays an important role in the cracking of petroleum components, hydrorefining, hydrodesulfurization, reforming of hydrocarbons to produce hydrogen, purification of gaseous oil components, and purification of automobile exhaust.

[0004] For supported catalysts, the pore structure of the carrier (including specific surface area, pore volume and pore size distribution) has an important influence not only on the dispersion of the active components loaded, but also on the diffusion and mass transfer of substances during the reaction. Therefore, the specific surface area and pore structure of the carrier are closely related to the activity, selectivity and life of the catalyst. Most of the alumina carriers commonly used in the prior art are obtained by dehydration of boehmite and pseudo-boehmite precursors. Acid-base precipitation method, sol-gel method, alcohol aluminum hydrolysis method, etc. are all preparation methods that are currently widely used in industry. However, the specific surface area of ​​alumina obtained by these methods is small, the pore size distribution is not concentrated, and there are micropores, mesopores and macropores at the same time, which limits its application range as a carrier. In this context, it is of great significance to prepare an alumina carrier with a high specific surface area. Summary of the invention

[0005] Based on the above purpose, the present invention provides a catalyst carrier with a high specific surface area and a preparation method thereof, comprising the following steps:

[0006] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0007] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:(0.1-0.2):(0-0.1);

[0008] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed solution of aluminate; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1: (0.6-0.8): (0-0.05); wherein the mass of the second polyvinyl alcohol is not 0;

[0009] (3) heating the aluminum salt mixed solution to 50-80° C., adding the metaaluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to greater than 7 to obtain a mixed reaction solution;

[0010] (4) transferring the mixed reaction solution to a reaction vessel and heating the mixture to react and obtain a precipitate;

[0011] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area.

[0012] The inventor used hydroxypropyl-β-cyclodextrin as a template and surfactant for aluminum salts and metaaluminates in previous work, and made a loose porous structure by using the internal lipophilic and external hydrophilic annular structure of hydroxypropyl-β-cyclodextrin. However, since hydroxypropyl-β-cyclodextrin is a small molecule, the specific surface area of ​​the alumina carrier is limited. In order to solve the above problems, the present invention introduces polyvinyl alcohol on the basis of hydroxypropyl-β-cyclodextrin. Hydroxypropyl-β-cyclodextrin is an organic small molecule template, which causes the aluminum source to preferentially accumulate around hydroxypropyl-β-cyclodextrin to undergo hydrolysis and polycondensation reactions. Due to the volume exclusion effect of hydroxypropyl-β-cyclodextrin, an alumina precursor can be synthesized by heating reaction. The order and stability of the sample prepared by hydroxypropyl-β-cyclodextrin are good, and its pore structure is not easy to collapse under high temperature calcination conditions, and the specific surface area loss is also small. However, since hydroxypropyl-β-cyclodextrin is a small molecular structure, the particles it forms are relatively dense, resulting in a large packing density of the carrier, which is not conducive to the improvement of the specific surface area of ​​the alumina carrier. Polyvinyl alcohol, as a macromolecular template with a long-chain structure, works together with hydroxypropyl-β-cyclodextrin to prepare precursors of different particle sizes and morphologies, effectively reducing the packing density and increasing the pore size and porosity between particles. Both polyvinyl alcohol and hydroxypropyl-β-cyclodextrin have a low thermal decomposition temperature, which can act as a pore former. In addition, polyvinyl alcohol contains a large number of hydroxyl groups on the long chain, which can form hydrogen bonds with hydroxypropyl-β-cyclodextrin, which can not only reduce the loss of polyvinyl alcohol and hydroxypropyl-β-cyclodextrin during the washing process, but also promote the formation of precipitates of different morphologies, increase the degree of precipitation anomaly, and thus increase the particle gap and specific surface area. In addition, polyvinyl alcohol has lower water solubility than hydroxypropyl-β-cyclodextrin and higher viscosity. A portion of polyvinyl alcohol will remain in the precursor and adsorb a certain amount of cyclodextrin. This part of polyvinyl alcohol and hydroxypropyl-β-cyclodextrin can act as pore formers in the subsequent calcination process, thereby increasing the porosity and pore size of alumina, and further increasing its specific surface area.

[0013] Furthermore, the present invention adds polyvinyl alcohol to the aluminum salt mixed solution in step (1) and the aluminate mixed solution in step (2) at the same time, so that the polyvinyl alcohol can play the role of dispersion and template; wherein the polyvinyl alcohol in the aluminum salt mixed solution mainly plays the role of template, and the polyvinyl alcohol in the aluminate mixed solution mainly plays the role of dispersant, and the above-mentioned role is conducive to the formation of precursors with different morphologies, and improves the porosity and particle gap of alumina. Although polyethylene is an excellent dispersant and template, the viscosity of the polyvinyl alcohol solution is large, and the amount should not be too much, otherwise it is easy to cause the precursors to agglomerate with each other. In order to accelerate the dissolution of polyvinyl alcohol, a heating treatment can be performed. Furthermore, the present invention uses polyvinyl alcohol with a degree of alcoholysis of 87-89% and a degree of polymerization of 300-600, which better promotes its dispersion performance.

[0014] Furthermore, in step (1), the aluminum salt is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; and the aluminum salt concentration in the aluminum salt mixed solution is 6-16 g / L.

[0015] Furthermore, the frequency of ultrasonic dispersion in step (1) and step (2) is 40-80 kHz, and the dispersion time is 10-30 min.

[0016] Furthermore, in step (2), the aluminate is sodium aluminate; and the aluminate concentration in the aluminate mixed solution is 5-10 g / L.

[0017] Furthermore, in step (3), the stirring rate is 150-250 r / min; and the aluminate mixed solution is added dropwise at a rate of 5-20 mL / min.

[0018] Furthermore, in step (3), the pH is 8-11.

[0019] Furthermore, the heating reaction in step (4) is carried out at 80-100° C. for 1-2 h.

[0020] Furthermore, the filtration in step (5) is carried out by using a vacuum filtration process.

[0021] Furthermore, the calcination temperature in step (5) is 500-600° C., and the calcination time is 4-6 hours.

[0022] On the other hand, the present invention also provides a catalyst carrier with a high specific surface area. Compared with the traditional alumina carrier, the alumina carrier has a large specific surface area, which can greatly improve the activity and service life of the catalyst.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The present invention introduces polyvinyl alcohol on the basis of hydroxypropyl-β-cyclodextrin. Polyvinyl alcohol, as a macromolecular template with a long chain structure, works together with hydroxypropyl-β-cyclodextrin to prepare precursors with different particle sizes and morphologies, effectively reducing the packing density and increasing the pore size and porosity between particles. In addition, polyvinyl alcohol and hydroxypropyl-β-cyclodextrin can act as pore formers, increasing the porosity and pore size of alumina, thereby further increasing its specific surface area.

[0025] 2. The alumina carrier of the present invention has a simple preparation process, and the raw materials are readily available. The surface chemical properties of the carrier can be adjusted while the pore structure of the carrier is effectively adjusted, and the application prospect is broad. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0028] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs.

[0029] It is worth noting that the raw materials used in the present invention are all common commercial products, so their sources are not specifically limited. In the following examples and comparative examples, the aluminum salt is aluminum nitrate, the aluminate is sodium aluminate, the alcoholysis degree of the first polyvinyl alcohol and the second polyvinyl alcohol are both 88% and the polymerization degree is 500; and the filtration is carried out by a vacuum filtration process.

[0030] Example 1

[0031] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0032] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.1:0.03; the aluminum salt concentration in the aluminum salt mixed solution is 14 g / L;

[0033] (2) dissolving aluminate and a second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.6:0.01; the concentration of aluminate in the mixed aluminate solution is 9 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 40 kHz, and the dispersion time is 30 min;

[0034] (3) heating the aluminum salt mixed solution to 50°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 8 to obtain a mixed reaction solution; stirring at a rate of 150 r / min; and adding the aluminate mixed solution dropwise at a rate of 5 mL / min;

[0035] (4) transferring the mixed reaction solution to a reactor and heating the reaction to obtain a precipitate; the heating reaction is carried out at 80° C. for 2 h;

[0036] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 500°C and the calcination time is 6 hours.

[0037] Example 2

[0038] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0039] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.2:0.06; the aluminum salt concentration in the aluminum salt mixed solution is 8 g / L;

[0040] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.8:0.05; the concentration of aluminate in the mixed aluminate solution is 5 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 80 kHz, and the dispersion time is 10 min;

[0041] (3) heating the aluminum salt mixed solution to 80°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 10 to obtain a mixed reaction solution; stirring at a rate of 250 r / min; and adding the aluminate mixed solution dropwise at a rate of 20 mL / min;

[0042] (4) transferring the mixed reaction solution to a reaction vessel and heating the reaction to obtain a precipitate; the heating reaction is carried out at 95° C. for 1 h;

[0043] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 600°C and the calcination time is 4 hours.

[0044] Example 3

[0045] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0046] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.1:0.06; the aluminum salt concentration in the aluminum salt mixed solution is 9 g / L;

[0047] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.8:0.01; the concentration of aluminate in the mixed aluminate solution is 6 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 50 kHz, and the dispersion time is 25 min;

[0048] (3) heating the aluminum salt mixed solution to 55°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 10 to obtain a mixed reaction solution; stirring at a rate of 180 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0049] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 96° C. for 1.1 h;

[0050] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 510°C and the calcination time is 5.6 h.

[0051] Example 4

[0052] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0053] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.2:0.03; the aluminum salt concentration in the aluminum salt mixed solution is 14 g / L;

[0054] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.6:0.04; the concentration of aluminate in the mixed aluminate solution is 10 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 80 kHz, and the dispersion time is 15 min;

[0055] (3) heating the aluminum salt mixed solution to 80°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 8 to obtain a mixed reaction solution; stirring at a rate of 220 r / min; and adding the aluminate mixed solution dropwise at a rate of 18 mL / min;

[0056] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 82° C. for 1.2 h;

[0057] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 500°C and the calcination time is 5.5 h.

[0058] Example 5

[0059] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0060] (1) Aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol are dissolved in deionized water, and ultrasonically dispersed to obtain an aluminum salt mixed solution; the mass ratio of aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.12:0.04; the aluminum salt concentration in the aluminum salt mixed solution is 13 g / L;

[0061] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.6:0.02; the concentration of aluminate in the mixed aluminate solution is 9 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 50 kHz, and the dispersion time is 25 min;

[0062] (3) heating the aluminum salt mixed solution to 60°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 9 to obtain a mixed reaction solution; stirring at a rate of 180 r / min; and adding the aluminate mixed solution dropwise at a rate of 15 mL / min;

[0063] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 86° C. for 1.8 h;

[0064] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 520°C and the calcination time is 5.4 h.

[0065] Example 6

[0066] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0067] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.18:0.05; the aluminum salt concentration in the aluminum salt mixed solution is 12 g / L;

[0068] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.7:0.04; the concentration of aluminate in the mixed aluminate solution is 9 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 70 kHz, and the dispersion time is 18 min;

[0069] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to 10 to obtain a mixed reaction solution; stirring at a rate of 230 r / min; and adding the aluminate mixed solution dropwise at a rate of 9 mL / min;

[0070] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.3 h;

[0071] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 580°C and the calcination time is 4.4 h.

[0072] Example 7

[0073] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0074] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.15:0; the aluminum salt concentration in the aluminum salt mixed solution is 10 g / L;

[0075] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.7:0.03; the concentration of aluminate in the mixed aluminate solution is 7 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 60 kHz, and the dispersion time is 20 min;

[0076] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, adjusting the pH to 9 after the addition is complete, and obtaining a mixed reaction solution; stirring at a rate of 200 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0077] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.4 h;

[0078] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 560°C and the calcination time is 4.8 h.

[0079] Example 8

[0080] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0081] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.15:0.1; the aluminum salt concentration in the aluminum salt mixed solution is 10 g / L;

[0082] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.7:0.03; the concentration of aluminate in the mixed aluminate solution is 7 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 60 kHz, and the dispersion time is 20 min;

[0083] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, adjusting the pH to 9 after the addition is complete, and obtaining a mixed reaction solution; stirring at a rate of 200 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0084] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.4 h;

[0085] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 560°C and the calcination time is 4.8 h.

[0086] Example 9

[0087] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0088] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.15:0.05; the aluminum salt concentration in the aluminum salt mixed solution is 10 g / L;

[0089] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.7:0.03; the concentration of aluminate in the mixed aluminate solution is 7 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 60 kHz, and the dispersion time is 20 min;

[0090] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, adjusting the pH to 9 after the addition is complete, and obtaining a mixed reaction solution; stirring at a rate of 200 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0091] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.4 h;

[0092] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 560°C and the calcination time is 4.8 h.

[0093] Comparative Example 1

[0094] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0095] (1) Aluminum salt, hydroxypropyl-β-cyclodextrin, the first polyvinyl alcohol, and the second polyvinyl alcohol are dissolved in deionized water, and ultrasonically dispersed to obtain an aluminum salt mixed solution; the mass ratio of aluminum salt, hydroxypropyl-β-cyclodextrin, the first polyvinyl alcohol, and the second polyvinyl alcohol is 1:0.15:0.05:0.03; the aluminum salt concentration in the aluminum salt mixed solution is 10 g / L;

[0096] (2) dissolving aluminate in deionized water and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt to aluminate is 1:0.7; the concentration of aluminate in the mixed aluminate solution is 7 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 60 kHz, and the dispersion time is 20 min;

[0097] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, adjusting the pH to 9 after the addition is complete, and obtaining a mixed reaction solution; stirring at a rate of 200 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0098] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.4 h;

[0099] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 560°C and the calcination time is 4.8 h.

[0100] Comparative Example 2

[0101] A method for preparing a catalyst carrier with a high specific surface area comprises the following steps:

[0102] (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:0.15:0.05; the aluminum salt concentration in the aluminum salt mixed solution is 10 g / L;

[0103] (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed aluminate solution; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1:0.7:0.1; the concentration of aluminate in the mixed aluminate solution is 7 g / L; the frequency of ultrasonic dispersion in step (1) and step (2) is 60 kHz, and the dispersion time is 20 min;

[0104] (3) heating the aluminum salt mixed solution to 70°C, adding the aluminate mixed solution dropwise while stirring, adjusting the pH to 9 after the addition is complete, and obtaining a mixed reaction solution; stirring at a rate of 200 r / min; and adding the aluminate mixed solution dropwise at a rate of 10 mL / min;

[0105] (4) The mixed reaction solution was transferred to a reactor and heated to obtain a precipitate; the heating reaction was carried out at 90° C. for 1.4 h;

[0106] (5) The precipitate is filtered, washed, dried, and calcined to obtain a catalyst carrier with a high specific surface area; the calcination temperature is 560°C and the calcination time is 4.8 h.

[0107] Performance test: The specific surface area, pore size and pore volume of the high specific surface area catalyst supports prepared in Examples 1-9 and Comparative Examples 1-2 were tested by the BET method.

[0108]

[0109] From Examples 1-9, it can be seen that the present invention introduces polyvinyl alcohol on the basis of hydroxypropyl-β-cyclodextrin. Polyvinyl alcohol, as a macromolecular template with a long chain structure, works together with hydroxypropyl-β-cyclodextrin to prepare precursors of different particle sizes and morphologies, effectively reducing the packing density and increasing the pore size and porosity between particles. Part of the polyvinyl alcohol and hydroxypropyl-β-cyclodextrin can act as pore formers in the subsequent calcination process, thereby increasing the porosity and pore size of alumina, and further increasing its specific surface area. Example 7 and Comparative Example 1 show that the present invention simultaneously adds polyvinyl alcohol to the aluminum salt mixed solution in step (1) and the aluminate mixed solution in step (2), so that the polyvinyl alcohol can play the role of dispersion and template, which is conducive to the formation of precursors of different morphologies and improves the porosity and particle gap of alumina. Among them, when the mass ratio of aluminum salt, hydroxypropyl-β-cyclodextrin and the first polyvinyl alcohol in step (1) is 1: (0.1-0.2): (0.03-0.06), the specific surface area is large. The amount of polyvinyl alcohol in step (2) is particularly important, and its amount cannot be 0, otherwise it will easily lead to uneven dispersion of the precursor. Comparative Example 2 shows that although polyethylene is an excellent dispersant, the viscosity of the polyvinyl alcohol solution is large, and the amount of polyvinyl alcohol in step (2) cannot be too much, otherwise it will not only fail to play a dispersing role, but will easily lead to agglomeration between the precursors.

[0110] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a catalyst carrier with a high specific surface area, characterized in that: The following steps are involved: (1) dissolving aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain an aluminum salt mixed solution; the mass ratio of the aluminum salt, hydroxypropyl-β-cyclodextrin, and the first polyvinyl alcohol is 1:(0.1-0.2):(0.03-0.06); (2) dissolving aluminate and the second polyvinyl alcohol in deionized water, and ultrasonically dispersing to obtain a mixed solution of aluminate; the mass ratio of aluminum salt, aluminate, and the second polyvinyl alcohol is 1: (0.6-0.8): (0-0.05); wherein the mass of the second polyvinyl alcohol is not 0; (3) heating the aluminum salt mixed solution to 50-80° C., adding the metaaluminate mixed solution dropwise while stirring, and after the addition is complete, adjusting the pH to greater than 7 to obtain a mixed reaction solution; (4) transferring the mixed reaction solution to a reaction vessel and heating the mixture to react and obtain a precipitate; (5) filtering, washing, drying and calcining the precipitate to obtain a catalyst carrier with a high specific surface area; The heating reaction in step (4) is carried out at 80-100° C. for 1-2 hours; The calcination temperature in step (5) is 500-600°C and the calcination time is 4-6h.

2. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: In step (1), the aluminum salt is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; and the aluminum salt concentration in the aluminum salt mixed solution is 6-16 g / L.

3. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: The frequency of ultrasonic dispersion in step (1) and step (2) is 40-80 kHz, and the dispersion time is 10-30 min.

4. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: In step (2), the aluminate is sodium aluminate; and the aluminate concentration in the aluminate mixed solution is 5-10 g / L.

5. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: In step (3), the stirring rate is 150-250 r / min; the aluminate mixed solution is added dropwise at a rate of 5-20 mL / min.

6. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: Step (3) pH is 8-11.

7. The method for preparing a catalyst carrier with a high specific surface area according to claim 1, characterized in that: The filtration in step (5) is carried out by using a vacuum filtration process.

8. A high specific surface area catalyst carrier, characterized in that: The catalyst carrier is prepared by the method for preparing a catalyst carrier with a high specific surface area according to any one of claims 1 to 7.

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