Preparation method of eggshell type catalyst for co-production of isophorone and mesitylene

Abstract

The invention discloses a preparation method of an eggshell type catalyst for co-production of isophorone and mesitylene, and belongs to the technical field of catalysis, an acidic catalyst of an active metal composite oxide is used as a core, and an alkaline catalyst of an alkali metal doped and modified magnesium-aluminum composite oxide is used as a shell. According to the present invention, the core material and the shell material of the catalyst are respectively prepared by using the isovolumetric impregnation method and the coprecipitation method, and the uniformly mixed shell material covers the outer surface of the core by using the rolling ball molding method so as to prepare the finished product catalyst, such that the product purity of the isophorone and the mesitylene is substantially improved, and the production cost is substantially reduced; on the other hand, the acetone conversion rate is increased, the defect of low acetone conversion rate in production of a single product is overcome, and the production requirement for increasing the additional value of low-end chemical products is met.

Description

Technical Field

[0001] The invention relates to the technical field of organic catalysts, and more specifically to a method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene. Background Art

[0002] At present, the most important downstream applications of acetone in China include direct use as a solvent, use in the production of bisphenol A, and use in the production of methyl methacrylate (MMA) through the acetone cyanohydrin process (ACH process), accounting for 21%, 19% and 18% of the total consumption respectively. With the rapid development of the chemical industry, especially the synthetic resin industry, the demand for isophorone has grown rapidly. The current market price of acetone is as low as 5,500 yuan / t and as high as 7,200 yuan / t, while the market price of mesitylene is as high as 22,000 yuan / t. It can be seen that the technology of preparing mesitylene by condensation of acetone has huge market potential and can effectively alleviate the problem of overcapacity caused by the continuous expansion of acetone production capacity.

[0003] Isophorone is an important organic chemical raw material. Its derivative isophorone diisocyanate is widely used in the production of polyurethane coatings. 3,3,5-trimethylcyclohexanol generated by hydrogenation of isophorone is an intermediate for the preparation of pharmaceutical cyclomandelates and hormones. Trimethyladipic acid prepared from isophorone is an important intermediate for the synthesis of new plasticizers, lubricants, dinitriles, diamines and diols.

[0004] The preparation methods of isophorone are mostly based on the acetone gas-solid multiphase condensation method. This method has low raw material cost and broad industrial prospects. It is currently the most advantageous and relatively mature synthesis method.

[0005] Mesitylene has a wide range of uses in the market. It can be used to produce dyes such as Reactive Brilliant Blue K-3R and Pra Brilliant Blue RAW, manufacture wheat field herbicides, synthesize antioxidants such as Lonox-330, trimesic acid, 3,5-dimethylbenzoic acid, etc. It is used as an auxiliary agent in the production of resin plastics, and can also produce trimethylol formaldehyde resins, etc. As a solvent, mesitylene can be used as a developer for silicone photographic films; as an analytical reagent, mesitylene can be used to determine aromatic protons during nuclear magnetic resonance.

[0006] There are many methods for synthesizing mesitylene. Among them, the process route of preparing mesitylene from acetone through heterogeneous catalysis has the advantages of environmental protection, high conversion rate, and easy scale-up. However, due to the complexity of the acetone condensation process, it has a large number of by-products and low selectivity for mesitylene.

[0007] The process route of preparing mesitylene from acetone by heterogeneous catalysis has the advantages of environmental protection and easy industrialization. However, due to the complexity of the acetone condensation process, it has many by-products and low selectivity for mesitylene. At present, the catalysts for condensation trimer of acetone are mainly divided into two categories. One category is mainly based on solid alkaline magnesium-aluminum composite oxides, which are used to catalyze the condensation of acetone to produce dimer isoacetone alcohol or further trimerized phorone and isophorone. US5153156 patent reports a catalyst that sprays synthetic clay on the surface of MgO-Al2O3 by spraying. The selectivity for catalyzing condensation of acetone to mesitylene oxide and isophorone is low at 27.3%. In CN109926040A patent, a template agent is used to prepare a composite oxide of modified metal and magnesium-aluminum by precipitation method. In the reaction of condensation of acetone to prepare isophorone, the reaction temperature is 250℃~300℃, and the mass space velocity of acetone is 1~8h under normal pressure. -1 , the acetone conversion rate is up to 45%, the isophorone selectivity is 75%, and the mesityl oxide and isophorone selectivity is 90%. Another type of solid acid mainly based on modified aluminosilicate zeolites loaded with metal oxides can be used to catalyze the condensation of acetone with mesitylene and benzene ring-containing compounds. US2917561A patent reports an active component loaded with metal tantalum, and the carrier uses a zeolite with a porous structure as a catalyst for the heterogeneous acetone condensation process. US5087781A patent reports a metal Nb catalyst loaded on a silica-alumina carrier. When the Nb loading is 2wt%, a 30% acetone conversion rate is achieved, and the mesitylene selectivity is 65%.

[0008] Although the acetone polycondensation catalysts reported so far have a high purity for the conversion of a single product, they all have the disadvantages of low acetone conversion rate and low selectivity for mesitylene products and isophorone. At the same time, the supported catalysts mostly use precious metals, resulting in high production costs, simple catalyst structures, short lifespans, and the reaction conditions for acetone condensation still need to be studied and optimized. Therefore, in order to effectively improve the conversion rate of acetone in the catalytic acetone condensation process and reduce traditional production costs, a new eggshell catalyst for the co-production of isophorone and mesitylene is proposed, which supplements the technical gap in the catalytic acetone polycondensation co-production of isophorone and mesitylene. The key to this patented technology is the innovative use of eggshell catalysts in catalyst design to achieve efficient synergy of acid catalytic active components and base catalytic active components and rationalize the acid-base structure of the catalyst, and finally develop a new catalyst for the co-production of isophorone and mesitylene with high activity, high acetone conversion rate, high product yield and long life. Summary of the invention

[0009] Based on previous research and existing problems, the present invention proposes a method for preparing an eggshell-type catalyst for the co-production of isophorone and mesitylene after further research and analysis. The core and shell of the catalyst are respectively prepared by an equal volume impregnation method and a co-precipitation method, and then the uniformly mixed shell material is coated on the outer surface of the core by a rolling ball molding method, thereby obtaining a finished catalyst, achieving the effect of co-producing isophorone and mesitylene, and the sum of the selectivities of the two is relatively high.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene comprises the following steps:

[0012] S1, preparing catalyst core powder, and obtaining the catalyst core by a rolling molding method;

[0013] S2. Prepare catalyst shell powder, and cover the shell material on the outer surface of the catalyst core by a rolling molding method to obtain a finished catalyst.

[0014] Preferably, the catalyst core material is an acidic catalyst of an active metal composite oxide;

[0015] The active metal component is one or more oxides of Ti, Zr, Hf of Group IVB or V, Nb, Ta of Group VB or their precursors, and the content of the oxide in the catalyst is 0.5-15wt%, and the carrier is one or more of silica, USY molecular sieve, SAPO molecular sieve, Beta molecule and ZSM-5 molecular sieve.

[0016] Preferably, the catalyst shell material is an alkaline catalyst of magnesium-aluminum composite oxide doped and modified by alkali metal;

[0017] The doped alkali metal component is one or more of the oxides or hydroxides of Zn and Ca, and the content of the oxides or hydroxides in the catalyst is 0.5-15wt%. The alkaline catalyst substrate is a composite alkaline oxide of magnesium oxide and aluminum oxide, and the metal element stoichiometric molar ratio of magnesium oxide and aluminum oxide is: Mg / Al is 1:1-3:1.

[0018] Preferably, S1 specifically includes:

[0019] S11, preparing a mixed solution of active component precursor salts of a required concentration as an impregnation solution, and impregnating the catalyst core material into the carrier by an equal volume impregnation method;

[0020] S12, after the carrier and the impregnation liquid are fully mixed, the impregnated catalyst is dried, roasted, and ground to obtain an active metal-supported catalyst powder;

[0021] S13, the obtained powder is poured into the ball forming machine A, contacted with the atomized sprayed binder, and rolled into shape to obtain the catalyst core.

[0022] Preferably, S2 specifically includes:

[0023] S21, prepare a soluble mixed salt solution of magnesium, aluminum, zinc and calcium, dissolve it in water, and drip it into 70-85°C water simultaneously with ammonia water under stirring conditions, keep the pH of the reaction system at 9-10, continue stirring for 15-20 hours after the dropwise addition is completed, and then stand for 4-8 hours, precipitate and wash with water until the pH is 7.0, dry, roast and grind to obtain zinc-calcium doped modified composite alkaline oxide powder;

[0024] S22. Pour the modified composite alkaline oxide powder and the catalyst core into the ball forming machine B, and continue rolling and forming under the action of the atomized sprayed binder to obtain a finished catalyst.

[0025] Preferably, the adhesive is prepared from aluminum sol and nitric acid aqueous solution in a volume ratio of 15:1.

[0026] Preferably, in S12 and S21, the drying temperature is 100-120° C., and the drying time is 10-12 h; the roasting temperature is 550-600° C., and the roasting time is 6-10 h.

[0027] Preferably, in S21, the soluble salts of magnesium, aluminum, zinc and calcium are magnesium nitrate, aluminum nitrate, zinc nitrate and calcium nitrate.

[0028] The present invention also provides an eggshell-type catalyst for the co-production of isophorone and mesitylene, which is prepared by the above-mentioned method. The catalyst is used for catalyzing the condensation of acetone to prepare mesitylene and isophorone. The applicable reaction conditions are: the inert gas pressure in the reactor is 0.1-10MPa, the reaction temperature is 250-400°C, and the liquid hourly volume space velocity is 0.3-2.0h -1 .

[0029] Compared with the existing technology, the present invention provides a method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene, which has the following beneficial effects:

[0030] (1) Different from the traditional mesitylene production method, which has complex equipment requirements and separation problems of similar boiling point products that lead to increased separation costs, the co-production of isophorone and mesitylene through acetone polycondensation greatly improves the product purity of isophorone and mesitylene on the one hand, and on the other hand, simultaneously improves the acetone conversion rate to make up for the low acetone conversion rate in the production of a single product, which meets the production needs of increasing the added value of low-end chemical products.

[0031] (2) According to the preparation method of the core material and the shell material in the eggshell catalyst, by rationally adjusting the ratio of the acid and base components in the eggshell catalyst, the production demand of the acetone polycondensation to produce isophorone and mesitylene is controlled, and the purpose of co-producing isophorone and mesitylene is achieved efficiently.

[0032] (3) The active components of the catalyst core material are mainly introduced by impregnation, which is a simple method and has a wide range of active metals to choose from. The modified composite alkaline oxide of the catalyst shell material is innovatively coated with the acid catalyst of the core material by ball milling to achieve the coordination of the acid and base sites of the eggshell catalyst.

[0033] (4) The eggshell catalyst can efficiently catalyze the condensation of acetone to produce isophorone and mesitylene. Under normal pressure conditions, the total selectivity of isophorone and mesitylene can reach more than 95%, and the acetone conversion rate can reach more than 68%.

[0034] (5) The catalyst preparation method is simple, and the catalyst has high activity, strong resistance to carbon deposition, and good stability. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] The present invention provides a method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene, which specifically comprises the following steps:

[0037] A method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene comprises the following steps:

[0038] S1, preparing catalyst core powder, and obtaining the catalyst core by a rolling molding method;

[0039] S2. Prepare catalyst shell powder, and cover the shell material on the outer surface of the catalyst core by a rolling molding method to obtain a finished catalyst.

[0040] Among them, the catalyst core material is an acidic catalyst of active metal composite oxides; the active metal component is one or more oxides of Ti, Zr, Hf of Group IVB or V, Nb, Ta of Group VB or their precursors, and the content of the oxide in the catalyst is 0.5-15wt%; the carrier is one or more of silica, USY molecular sieve, SAPO molecular sieve, Beta molecule and ZSM-5 molecular sieve.

[0041] The catalyst shell material is an alkaline catalyst of a magnesium-aluminum composite oxide modified by alkali metal doping; the doped alkali metal component is one or more of Zn, Ca oxides or their hydroxides, and the content of the oxides or hydroxides in the catalyst is 0.5-15wt%; the alkaline catalyst substrate is a composite alkaline oxide of magnesium oxide and aluminum oxide, and the metal element stoichiometric molar ratio of magnesium oxide and aluminum oxide is: Mg / Al is 1:1 to 3:1.

[0042] In the above steps, S1 specifically includes:

[0043] S11, preparing a mixed solution of active component precursor salts of a required concentration as an impregnation solution, and impregnating the catalyst core material into the carrier by an equal volume impregnation method;

[0044] S12, after the carrier and the impregnation liquid are fully mixed, the impregnated catalyst is dried, roasted, and ground to obtain an active metal-supported catalyst powder;

[0045] S13, the obtained powder is poured into the ball forming machine A, contacted with the atomized sprayed binder, and rolled into shape to obtain the catalyst core.

[0046] S2 specifically includes the following steps:

[0047] S21, prepare a soluble mixed salt solution of magnesium, aluminum, zinc and calcium, dissolve it in water, and drip it into 70-85°C water simultaneously with ammonia water under stirring conditions, keep the pH of the reaction system at 9-10, continue stirring for 15-20 hours after the dropwise addition is completed, and then stand for 4-8 hours, precipitate and wash with water until the pH is 7.0, dry, roast and grind to obtain zinc-calcium doped modified composite alkaline oxide powder;

[0048] S22. Pour the modified composite alkaline oxide powder and the catalyst core into the ball forming machine B, and continue rolling and forming under the action of the atomized sprayed binder to obtain a finished catalyst.

[0049] The above-mentioned adhesives are all prepared from aluminum sol and nitric acid aqueous solution, with a volume ratio of 15:1. In S12 and S21, the drying temperature is 100-120°C, the drying time is 10-12h; the roasting temperature is 550-600°C, and the roasting time is 6-10h. In S21, the soluble salts of magnesium, aluminum, zinc and calcium are magnesium nitrate, aluminum nitrate, zinc nitrate and calcium nitrate.

[0050] It should be noted that the following embodiments and features in the embodiments may be combined with each other in the absence of conflict; and, based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making any creative work are within the scope of protection of the present disclosure.

[0051] Various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement a device and / or practice a method. In addition, other structures and / or functionality other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0052] Example 1

[0053] Weigh 100g of silica carrier and 8.1g of niobium oxalate to prepare an impregnation solution, and use the equal volume impregnation method to impregnate the active component impregnation solution on the carrier, and leave it for 2 hours, then dry it in an oven at 100°C for 10 hours, and calcine it at 550°C for 6 hours. Grind to obtain catalyst core powder A-1.

[0054] Weigh 140g of magnesium nitrate hexahydrate, 275g of aluminum nitrate nonahydrate, and 17g of zinc nitrate hexahydrate and dissolve them in 1000ml of deionized water. Add the mixed salt solution and ammonia water to 80°C distilled water at the same time, and adjust the dripping rate so that the pH value of the solution is about 9.0. After the addition is completed, stir for 20 hours and let it stand and cool for 6 hours. Filter and cool the precipitate, and wash with water to a pH of about 7.0. Dry at 100°C for 10 hours and then roast at 550°C for 6 hours. Grind to obtain catalyst shell powder B-1.

[0055] Weigh a certain amount of aluminum sol and nitric acid aqueous solution to prepare a binder (volume ratio 15:1), pour A-1 powder into A ball forming machine, contact with the atomized binder, roll and form, the pellets enter B ball forming machine from A ball forming machine, there is catalyst shell powder B-1 in B ball forming machine, under the action of atomized binder, roll and form. Eggshell catalyst P-1 is obtained.

[0056] Example 2

[0057] Weigh 100g of silica carrier and 9.3g of tantalum ethoxide to prepare an impregnation solution, and use the equal volume impregnation method to impregnate the active component impregnation solution on the carrier, and leave it for 2 hours, then dry it in an oven at 100°C for 10 hours, and calcine it at 550°C for 6 hours. Grind to obtain catalyst core powder A-2.

[0058] Weigh a certain amount of aluminum sol and nitric acid aqueous solution to prepare a binder (volume ratio of 15:1), pour A-2 powder into A ball forming machine, contact with the atomized binder, roll and form, the pellets enter B ball forming machine from A ball forming machine, the B ball forming machine contains the catalyst shell powder B-1 in Example 1, and roll and form under the action of the atomized binder. Eggshell catalyst P-2 is obtained.

[0059] Example 3

[0060] Weigh 210g of magnesium nitrate hexahydrate, 183g of aluminum nitrate nonahydrate, 15g of hydrated calcium nitrate, and 15g of zinc nitrate hexahydrate and dissolve them in 1000ml of deionized water. Add the mixed salt solution and ammonia water to 80°C distilled water at the same time, and adjust the dripping rate so that the pH value of the solution is about 9.0. After the addition is completed, stir for 20 hours and let it stand and cool for 6 hours. Filter and cool the precipitate, and wash with water to a pH of about 7.0. Dry at 100°C for 10 hours and then roast at 550°C for 6 hours. Grind to obtain catalyst shell powder B-3.

[0061] Weigh a certain amount of aluminum sol and nitric acid aqueous solution to prepare a binder (volume ratio of 15:1), pour the A-2 powder in Example 2 into the A ball-forming machine, contact with the atomized binder, roll and form, and the pellets enter the B ball-forming machine from the A ball-forming machine. The B ball-forming machine contains catalyst shell powder B-3, which is rolled and formed under the action of the atomized binder. The eggshell catalyst P-3 is obtained.

[0062] Comparative Example 1

[0063] Weigh 70g of magnesium nitrate hexahydrate, 550g of aluminum nitrate nonahydrate, and 26g of hydrated calcium nitrate and dissolve them in 1000ml of deionized water. Add the mixed salt solution and ammonia water to 80°C distilled water at the same time, and adjust the dripping rate so that the pH value of the solution is about 9.0. After the addition is completed, stir for 20 hours and let it stand and cool for 6 hours. Filter and cool the precipitate, and wash with water to a pH of about 7.0. Dry at 100°C for 10 hours and then roast at 550°C for 6 hours. Grind and press to obtain the alkali metal-doped modified composite magnesium aluminum oxide catalyst TC1.

[0064] Comparative Example 2

[0065] Weigh 100 g of USY molecular sieve carrier, mix 16.2 g of niobium oxalate and 9.3 g of tantalum ethoxide to form an impregnation solution, use the equal volume impregnation method to impregnate the above active component impregnation solution on the carrier and leave it for 2 hours, then dry it in an oven at 120°C for 6 hours, and calcine it at 350°C in a muffle furnace for 3 hours to obtain acetone condensation synthesis mesitylene catalyst TC2, which is composed of 5wt% of tantalum oxide and 5wt% of niobium oxide.

[0066] The present invention also evaluates the performance of the eggshell catalysts for co-producing isophorone and mesitylene prepared in Examples 1 to 3 and Comparative Examples 1 to 2. The specific evaluation process is as follows: A micro-fixed bed pilot device is used, and the catalyst loading amount is 78 grams (100 ml). First, at 40°C·h -1 The temperature was raised to 280℃, and then the raw material acetone was pumped in. At the same time, the temperature was increased at 20℃·h -1 The heating rate was raised to the reaction temperature of 380°C. The reaction evaluation conditions were: temperature 380°C, normal pressure, liquid hourly space velocity 2h -1 , sampling and analysis were carried out after stabilization for 6 hours, the sampling time was 2 hours, sampling was carried out twice, and the samples were accumulated and stored.

[0067] The reaction evaluation results of the above five catalysts are shown in Table 1:

[0068] Table 1 Reaction evaluation results of five catalysts at normal pressure and 380°C

[0069]

[0070] Combined with the data in Table 1, it can be seen that the eggshell-type catalyst for co-producing isophorone and mesitylene prepared by the method of the present invention, compared with the previous catalytic acetone condensation catalyst, adopts an eggshell-type catalyst structure, so that its shell has the benefit of catalyzing isophorone and the core has the function of catalyzing mesitylene, has higher trimerization aromatization performance, and a higher conversion rate of raw materials, and has a stronger ability to resist carbon deposition.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene, characterized in that: The following steps are involved: S1, preparing catalyst core powder, and obtaining the catalyst core by a rolling molding method; S2. Prepare catalyst shell powder, and cover the shell material on the outer surface of the catalyst core by a rolling molding method to obtain a finished catalyst.

2. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 1, characterized in that: The catalyst core material is an acidic catalyst of active metal composite oxide; The active metal component is one or more oxides of Ti, Zr, Hf of Group IVB or V, Nb, Ta of Group VB or their precursors, and the content of the oxide in the catalyst is 0.5-15wt%, and the carrier is one or more of silica, USY molecular sieve, SAPO molecular sieve, Beta molecule and ZSM-5 molecular sieve.

3. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 1, characterized in that: The catalyst shell material is an alkaline catalyst of magnesium-aluminum composite oxide doped and modified by alkali metal; The doped alkali metal component is one or more of the oxides or hydroxides of Zn and Ca, and the content of the oxides or hydroxides in the catalyst is 0.5-15wt%. The alkaline catalyst substrate is a composite alkaline oxide of magnesium oxide and aluminum oxide, and the metal element stoichiometric molar ratio of magnesium oxide and aluminum oxide is: Mg / Al is 1:1-3:

1.

4. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 1, characterized in that: S1 specifically includes: S11, preparing a mixed solution of active component precursor salts of a required concentration as an impregnation solution, and impregnating the catalyst core material into the carrier by an equal volume impregnation method; S12, after the carrier and the impregnation liquid are fully mixed, the impregnated catalyst is dried, roasted, and ground to obtain an active metal-supported catalyst powder; S13, the obtained powder is poured into the ball forming machine A, contacted with the atomized sprayed binder, and rolled into shape to obtain the catalyst core.

5. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 4, characterized in that: S2 specifically includes: S21, prepare a soluble mixed salt solution of magnesium, aluminum, zinc and calcium, dissolve it in water, and drip it into 70-85°C water simultaneously with ammonia water under stirring conditions, keep the pH of the reaction system at 9-10, continue stirring for 15-20 hours after the dropwise addition is completed, and then stand for 4-8 hours, precipitate and wash with water until the pH is 7.0, dry, roast and grind to obtain zinc-calcium doped modified composite alkaline oxide powder; S22. Pour the modified composite alkaline oxide powder and the catalyst core into the ball forming machine B, and continue rolling and forming under the action of the atomized sprayed binder to obtain a finished catalyst.

6. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 5, characterized in that: The adhesive is prepared from aluminum sol and nitric acid aqueous solution in a volume ratio of 15:

1.

7. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 5 or 6, characterized in that: In S12 and S21, the drying temperature is 100-120°C, and the drying time is 10-12 hours; the roasting temperature is 550-600°C, and the roasting time is 6-10 hours.

8. The method for preparing an eggshell-type catalyst for co-producing isophorone and mesitylene according to claim 5, characterized in that: In S21, the soluble salts of magnesium, aluminum, zinc and calcium are magnesium nitrate, aluminum nitrate, zinc nitrate and calcium nitrate.

9. An eggshell catalyst for co-producing isophorone and mesitylene, prepared by the method according to any one of claims 1 to 8, characterized in that: The catalyst is used to catalyze the condensation of acetone to prepare mesitylene and isophorone. The applicable reaction conditions are: the inert gas pressure in the reactor is 0.1-10MPa, the reaction temperature is 250-400℃, and the liquid hourly volume space velocity is 0.3-2.0h -1 .

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