A method for preparing a catalyst for the directed polycondensation of acetone into mesitylene

Abstract

The application discloses a preparation method of a catalyst for catalyzing directional polycondensation of acetone to synthesize mesitylene, and belongs to the field of catalysis technology. The catalyst is a modified active metal supported catalyst which is composed of a catalyst carrier prepared by mixing a carbon carrier modified by nitrogen doping or a composite oxide and a molecular sieve, an active metal component, a metal modified additive component and a metal chelating agent. The active component is loaded on the composite modified carrier by an equal-volume impregnation method, and the metal modified additive component is further modified by an ion exchange method, so that the requirements of catalyzing directional deoxygenation trimerization of acetone to prepare mesitylene are met. The catalyst prepared by the method has the advantages of low price, high activity and selectivity, good stability and the like, and the problems of complicated equipment requirements in a traditional mesitylene production method and the separation cost increase caused by the separation of mesitylene and ethylbenzene with similar boiling points are avoided.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene. Background Technology

[0002] Currently, with the continuous expansion of production scale, my country's domestic phenol production capacity is expected to continue to grow in the coming years. According to 2019 data, the total phenol production capacity has reached 2.628 million tons per year (t / a). Meanwhile, since domestic phenol production mainly uses the cumene process, acetone, as a byproduct of phenol, also has a total production capacity of 1.547 million tons per year. Furthermore, in recent years, the fastest progress in commissioning cumene-to-phenol plants has been seen at Formosa Phenol (Ningbo) Co., Ltd. and Zhejiang Petrochemical Co., Ltd., which have completed and put into operation as scheduled, adding 2.54 million tons per year of phenol production capacity and 1.56 million tons per year of acetone production capacity. It is projected that by 2023, domestic phenol production capacity will reach 5.168 million tons per year, and acetone production capacity will reach 3.107 million tons per year.

[0003] The most important downstream applications of acetone in China include direct use as a solvent, production of bisphenol A, and production of methyl methacrylate (MMA) via the acetone cyanohydrin process (ACH process), accounting for 21%, 19%, and 18% of total consumption, respectively. In recent years, the applications of acetone in China have become more widespread and diversified, with significant consumption proportions in isopropanol, aliphatic water-reducing agents, and methyl isobutyl ketone (MIBK). Therefore, given the current situation of continuously expanding acetone production capacity, actively researching downstream technologies and high-value-added products is of significant practical importance in alleviating the overcapacity problem caused by the continuous expansion of acetone production capacity. Currently, the market price of acetone ranges from a minimum of 5,500 yuan / ton to a maximum of around 7,200 yuan / ton, while the market price of mesitylene reaches a maximum of 22,000 yuan / ton. This demonstrates that the technology for preparing mesitylene through acetone condensation has enormous market potential and can effectively alleviate the overcapacity problem caused by the continuous expansion of acetone production capacity.

[0004] Mesitylene (MS) is chemically highly reactive and readily undergoes halogenation, nitration, and sulfonation. It is an important chemical raw material used to prepare various fine chemical products, including the dye intermediate mesityleneamine, the antioxidant Lonox 330, and the UV-resistant antioxidant stabilizer mesitylene. It is also a crucial raw material for the production of alkyd resins and high-temperature plasticizers.

[0005] The synthesis methods for mesitylene are relatively mature. Traditional synthesis methods mainly include: extractive distillation, heavy aromatic hydrocarbon distillation separation, gas-phase isomerization of mesitylene, atmospheric-pressure liquid-phase isomerization of mesitylene, atmospheric-pressure liquid-phase alkylation of mesitylene to produce mesitylene and mesitylene, and combined isomerization and alkylation of mesitylene to produce high-purity mesitylene and mesitylene.

[0006] Taking the extraction distillation method, using dimethyl phthalate (DMT) as a solvent, as an example of the separation of C9 aromatics by Esso Chemicals in the United States, the main process involves four extraction distillation columns. From the tops of columns 1 and 2, mesitylene and m- and p-methylethylbenzene are obtained, respectively; from the bottom of column 3, the high-boiling-point solvent is recovered; from the top of column 4, o-methylethylbenzene is obtained, and from the bottom, pseudotrimethylbenzene and other heavy components are obtained. This process yields 87% mesitylene, resulting in relatively low product purity. Currently, the extraction distillation process used domestically requires fewer distillation columns than the Esso process, using only two columns. The solvent and feedstock are fed into column 1 from the top and middle sections, respectively. The distillate from the top of column 1 is high-purity mesitylene, and the mixture of o-methylethylbenzene and solvent distilled from the bottom is used as the feed for column 2. O-methylethylbenzene is distilled off from the top of column 2, and the solvent from the bottom is recycled. This method overcomes the shortcomings of the former and can achieve complete separation of ethylbenzene and mesitylene, yielding mesitylene and ethylbenzene with high purity. However, this method requires more equipment and has higher operating costs.

[0007] The isomerization method for pseudotrimethylbenzene primarily utilizes a dealaluminized mordenite zeolite catalyst impregnated with nickel-aluminate at a reaction temperature of 250℃-330℃ under hydrogen-exposed conditions. Pseudotrimethylbenzene is isomerized to mesitylene with a conversion rate of 45%, and the product can be obtained with a purity of 95-98% through distillation. In this process, if reformed oxygen is used, C3 and higher hydrocarbons must be removed beforehand; if hydrogen electrolysis is used, the reaction effect is better. This method requires hydrogen-exposed conditions and high temperature and pressure, resulting in complex reaction equipment and stringent reaction conditions, thus leading to high production costs. Furthermore, the purity of mesitylene cannot reach above 98%, clearly hindering large-scale industrial production.

[0008] The process route for preparing mesitylene from acetone via heterogeneous catalysis has advantages such as being environmentally friendly, having a high conversion rate, and being easy to scale up. However, due to the complexity of the acetone condensation process, it produces many byproducts and has low selectivity for mesitylene. Currently, catalysts for the condensation of acetone trimers are mainly divided into two categories. One category mainly consists of solid basic magnesium-aluminum composite oxides, which are used to catalyze the condensation of acetone to produce the dimer isopropenol or further trimerized isophorone and isophorone. Both domestic and foreign patents have reported this. US5153156 patent reports a catalyst obtained by spraying synthetic clay onto the surface of MgO-Al2O3. The selectivity for catalyzing the condensation of acetone to isopropylidene acetone and isophorone is relatively low at 27.3%. CN101462043A patent reports that solid alkali-modified magnesium-aluminum composite oxides are obtained by mixing, crystallizing and calcining magnesium-aluminum modified metal salt solutions in an alkaline environment. This catalyst is used for the reaction of acetone condensation to produce isophorone. The highest conversion rate under normal pressure reaches 38.2%, the selectivity of isophorone is 77.8%, and the total selectivity of isophorone and isopropylidene acetone reaches 87.8%. In patent CN109926040A, a modified metal-magnesium-aluminum composite oxide is prepared by precipitation using a template agent. In the reaction to prepare isophorone via acetone condensation, the reaction temperature is 250℃~300℃, the pressure is normal, and the acetone mass hourly space velocity is 1~8h⁻¹. -1The technology achieves a maximum acetone conversion rate of 45%, a selectivity of 75% for isophorone, and a selectivity of 90% for isopropylidene acetone and isophorone. This technology is suitable for the industrial production of isophorone. Another type of technology, primarily using solid acids such as modified aluminosilicate zeolites supported on metal oxides, can be used to catalyze the condensation of acetone with mesitylene and benzene ring-containing compounds. Numerous foreign patents report this technology. For example, US2917561A discloses a catalyst using approximately 0.05 to 5% by weight of tantalum metal as the supported active component, with aluminosilicates or porous zeolites as the catalyst for heterogeneous acetone condensation. US3201485A discloses a catalyst using chromium metal supported on an aluminosilicate gel support, doped with zinc oxide and boron, for the catalytic condensation of alkyl ketones to prepare polyalkylbenzene. US3201485A also discloses a catalyst using Pd supported on MoO3 and... The catalyst formed on a mixture of AhO3 (0.1-1% by weight of Pd) achieved an acetone conversion of 42.5% and a selectivity for mesitylene of 44.2%. US patent 5087781A improved the type of supported metal by supporting a metal Nb catalyst on a silica-alumina support. When the Nb loading was 2 wt%, an acetone conversion of 30% and a selectivity for mesitylene of 65% were achieved. Patent ES2792176A1 reported a composite solid catalyst formed by mixing a basic oxide and an acidic support in a 1 / 4 or 3 / 4 mass ratio. In this system, a mixture of TiO2 and acidic molecular sieve BEA achieved an acetone conversion of approximately 13.8% and a selectivity for mesitylene of 88.3% in the C9 product. An earlier domestic patent, CN1087280C, disclosed a process for producing high-purity mesitylene from acetone. In this process, acetone is mixed with carrier nitrogen and pumped into a fixed-bed reactor, where it undergoes catalytic condensation with a silicon-aluminum support catalyst impregnated with zirconium metal. The product in the reactor is then pumped into a cooler for gas-liquid separation to remove nitrogen. The remaining liquid is pumped into a heater for heating, and the gas-liquid mixture is finally fed into a distillation column for distillation to separate high-purity mesitylene. The catalyst used in this process has a selectivity of up to 50.1% for mesitylene.

[0009] Currently reported supported catalysts mostly use precious metals, which undoubtedly increases production costs. Furthermore, their selectivity for mesitylene products is not high, and the reaction conditions in the acetone condensation of mesitylene still require further research and optimization. Therefore, to effectively improve the selectivity of catalytic acetone condensation to produce mesitylene and reduce the production cost of traditional mesitylene, new progress is urgently needed in the modification of acidic supports for acetone condensation catalysts and the preparation of active metal-supported catalysts. This would enable the industrial-scale production of mesitylene through directional catalytic condensation of acetone and maximize the product value, demonstrating promising market application prospects. Summary of the Invention

[0010] Based on previous research and existing problems, this invention proposes a method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene after further research and analysis.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene includes the following steps:

[0013] S1. Preparation of catalyst support;

[0014] S2. Prepare a mixed solution of metal chelating agent and active component precursor salt of the required concentration as impregnation liquid, and impregnate the catalyst support in S1 using the equal volume impregnation method.

[0015] S3. After the catalyst support and impregnation solution are fully mixed, the catalyst is dried and calcined in air to obtain an active metal supported catalyst.

[0016] S4. The metal-modifying additive component is introduced into the catalyst supported in S3, and the catalyst is dried and calcined in air to obtain the modified active metal-supported catalyst.

[0017] Preferably, the catalyst support in S1 is prepared by mixing composite oxide and molecular sieve. The specific preparation method is as follows: the composite oxide, molecular sieve and zeolite are ground and mixed by ball milling in a certain mass ratio, and the catalyst support is obtained by mechanical mixing, extrusion molding, drying and calcination.

[0018] Preferably, the composite oxide is one or more of silicon dioxide, alumina, and zirconium oxide, and the molecular sieve is one or more of USY molecular sieve, SAPO molecular sieve, Beta molecular sieve, and ZSM-5 molecular sieve;

[0019] The molecular sieve content is 20–70 wt%, and the composite oxide content is 30–80 wt%.

[0020] Preferably, the catalyst support in S1 is a nitrogen-doped modified carbon support. The specific preparation method is as follows: a nitrogen modifier solution of the required concentration is prepared according to the N / C atomic ratio of 1:10 to 1:2.5 in the nitrogen-doped modified activated carbon support. The nitrogen source is introduced into the carbon support by impregnation to achieve nitrogen doping modification. The carbon support, nitrogen source and activator are calcined in a nitrogen atmosphere to obtain a nitrogen-doped modified activated carbon support.

[0021] Preferably, the carbon support is one or more of activated carbon, graphite, porous activated carbon, and activated carbon fiber;

[0022] The nitrogen-doped modifier is one or more of melamine, ammonium nitrate, dicyandiamide, N,N-dimethylformamide and urea, and the N / C atomic ratio in the nitrogen-doped modified activated carbon carrier is 1:10 to 1:2.5;

[0023] The activator is one or more of KOH, K2CO3, and ZnCl2; the mass ratio of carbon support to activator is 1:0.5 to 1:2; the calcination temperature is 500 to 900℃; the calcination heating rate is 2 to 5℃ / min; and the calcination time is 2 to 4 hours.

[0024] Preferably, in S2, the active component is one or more of the oxides or precursors of Group IVB Ti, Zr, Hf or Group VB V, Nb, Ta, and the content in the catalyst, calculated as oxide, is 0.5 to 15 wt%.

[0025] Preferably, in S2, the molar ratio of the metal chelating agent to the active component is 0.5:1 to 3:1.

[0026] Preferably, in S4, the metal modifier component is one or more of the following: oxides of Group VIB Cr, Mo, W or transition metals Fe, Co, Ni, Cu, Zn or non-metal modifier P or their precursors, and the content of the oxide in the catalyst is 1 to 10 wt%.

[0027] Preferably, in step S4, a mixed solution of metal chelating agent and metal modification auxiliary component precursor salt of the required concentration is prepared as an ion exchanger. The metal modification auxiliary component is introduced into the modified active metal supported catalyst in step S3 by ion exchange method. The ion exchange process is as follows: the active metal supported catalyst in step S3 is added to the ion exchanger, soaked for 6-12 hours, washed and filtered, evaporated to dryness in a water bath at 80-150°C, calcined at 350-550°C for 3-9 hours.

[0028] Preferably, in S4, a metal chelating agent and metal auxiliary component precursor salt solution of the required concentration are prepared as impregnation liquid, and the metal modified auxiliary component is introduced into the modified active metal supported catalyst obtained in S3 by the equal volume impregnation method.

[0029] Compared with existing technologies, this invention provides a method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene, which has the following beneficial effects:

[0030] (1) It avoids the increased separation costs caused by the complex equipment requirements and the separation problem of mesitylene and ethylbenzene at similar boiling points in the traditional mesitylene production method.

[0031] (2) The support of the supported catalyst is modified by composite modification of one or more oxides and support molecular sieves, which more rationally modulates the acid structure of the catalyst and is more conducive to the dispersion of the supported active metal.

[0032] (3) The support for the supported catalyst is a nitrogen-doped modified carbon support. By doping with nitrogen, the surface of the support is enriched with nitrogen, which is beneficial for anchoring the active metal, thereby improving the dispersion and effective utilization of the active metal.

[0033] (4) The active components of the catalyst are mainly introduced by impregnation method, which is simple and has a wide range of active metals that can be selected. The ion exchange method is innovatively used to introduce a variety of auxiliary components, which can efficiently achieve the synergistic effect between multiple active metals or between active metals and auxiliary metals. The catalyst preparation process is simple and convenient and the preparation cost is low.

[0034] (5) The acetone condensation product utilization rate is high and the waste is less in this process. The supported catalyst has high activity and selectivity, with a conversion rate of up to 44.62% under normal pressure. The selectivity of mesitylene can reach more than 90%, and the total selectivity of mesitylene and isopropylidene acetone reaches more than 95%.

[0035] (6) The prepared catalyst has a short start-up time, strong resistance to carbon deposition, and can operate stably for a long period of time. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Weigh 0.7 kg of silica and 0.3 kg of boehmite, add 2 wt% of guar gum powder as a carrier precursor powder, grind evenly, knead thoroughly into a gel, and then extrude it into cylindrical strips with a diameter of 1.6 mm on an extruder. Dry in an oven at 120 °C for 6 hours and calcine in a muffle furnace at 550 °C for 3 hours to obtain catalyst carrier S1, in which the silica content is 70 wt% and the alumina content is 30 wt%.

[0039] Weigh 100g of the catalyst support S1, mix 2.2g of hydrated citric acid, 6.4g of ammonium metavanadate, and 3.7g of tantalum ethoxide to prepare an impregnation solution, and impregnate the active component solution onto the support using an equal-volume impregnation method. The ratio of the metal chelating agent is N / metal molar ratio = 0.6 / 1, and the solution is left to stand for 2 hours. Then, dry the solution in an oven at 120°C for 6 hours and calcine it in a muffle furnace at 350°C for 3 hours to obtain the acetone condensation polymerization catalyst MC1, which has the following composition: vanadium oxide 5wt% and tantalum oxide 2wt%.

[0040] Example 2

[0041] 2.2 g of hydrated citric acid, 2.3 g of ammonium molybdate, and 1.1 g of ammonium metatungstate were measured to prepare an ion exchanger. The active metal catalyst MC1 from Example 1 was added to the prepared metal-modified ion exchanger solution and soaked for 12 h using an ion exchange method. After washing and filtration, the solution was stirred and evaporated to dryness in an 80°C water bath, and then calcined at 550°C for 3 h to obtain a modified acetone condensation polymerization catalyst TC1, with the following composition: vanadium oxide 5 wt%, tantalum oxide 2 wt%, molybdenum oxide 2 wt%, and tungsten oxide 1 wt%.

[0042] Example 3

[0043] A certain amount of 0.6 kg of USY0 molecular sieve and 0.4 kg of pseudoboehmite were weighed, and 2 wt% of guar gum powder, a precursor powder for the support, was added and ground evenly. After being fully kneaded into a gel, the mixture was extruded into cylindrical strips with a diameter of 1.6 mm on an extruder, dried in an oven at 120 °C for 6 hours, and calcined in a muffle furnace at 550 °C for 3 hours to obtain catalyst support S2, in which the content of USY molecular sieve was 60 wt% and the content of alumina was 40 wt%.

[0044] Weigh 100g of the catalyst support S2. Mix 3.6g of hydrated citric acid, 6.4g of ammonium metavanadate, 8.1g of niobium oxalate and 9.3g of tantalum ethoxide to prepare an impregnation solution. Impregnate the support with the above active component solution using an equal volume impregnation method. The ratio of metal chelating agent is N / metal molar ratio = 0.8 / 1. Let it stand for 2 hours, then dry it in an oven at 120℃ for 6 hours, and calcine it in a muffle furnace at 350℃ for 3 hours to obtain the acetone condensation polymerization catalyst MC2, with the composition of vanadium oxide 5wt%, tantalum oxide 5wt%, and niobium oxide 2wt%.

[0045] Example 4

[0046] An ion exchanger was prepared by measuring 1.8 g of hydrated citric acid, 1.6 g of ammonium molybdate, 2.5 g of nickel nitrate, and 1.3 g of diammonium hydrogen phosphate. The active metal catalyst MC2 from Example 3 was added to the prepared metal-modified ion exchanger solution and soaked for 12 h using an ion exchange method. After washing and filtration, the solution was stirred and evaporated to dryness in an 80°C water bath, and then calcined at 550°C for 3 h to obtain a modified acetone condensation polymerization catalyst TC2, with the following composition: vanadium oxide 5 wt%, tantalum oxide 5 wt%, niobium oxide 2 wt%, molybdenum oxide 1 wt%, nickel oxide 1 wt%, and phosphorus oxide 1 wt%.

[0047] Example 5

[0048] Weigh 0.8 kg of silica and 0.2 kg of zirconium oxide, add 2 wt% of guar gum powder as a carrier precursor powder, grind evenly, knead thoroughly into a gel, and then extrude it into cylindrical strips with a diameter of 1.6 mm on an extruder. Dry in an oven at 120 °C for 6 hours, and calcine in a muffle furnace at 550 °C for 3 hours to obtain catalyst carrier S3, in which the silica content is 80 wt% and the zirconium oxide content is 20 wt%.

[0049] Weigh 100g of the catalyst support S3. Mix 15.8g of hydrated citric acid, 12.8g of ammonium metavanadate, 20.2g of niobium oxalate and 18.6g of tantalum ethoxide to prepare an impregnation solution. Impregnate the support with the above active component solution using an equal volume impregnation method. The ratio of metal chelating agent is N / metal molar ratio = 1.2 / 1. After holding for 2 hours, dry in an oven at 120℃ for 6 hours and calcine in a muffle furnace at 350℃ for 3 hours to obtain the acetone condensation polymerization catalyst MC3, with the composition of 10wt% vanadium oxide, 10wt% tantalum oxide and 5wt% niobium oxide.

[0050] Example 6

[0051] An ion exchanger was prepared by measuring 2.6 g of hydrated citric acid, 3.2 g of ammonium molybdate, 2.7 g of cobalt nitrate, and 1.3 g of diammonium hydrogen phosphate. The active metal catalyst MC3 from Example 5 was added to the prepared metal-modified ion exchanger solution and soaked for 12 h using an ion exchange method. After washing and filtration, the solution was stirred and evaporated to dryness in an 80°C water bath, and then calcined at 550°C for 3 h to obtain a modified acetone condensation polymerization catalyst TC3, with the following composition: 10 wt% vanadium oxide, 10 wt% tantalum oxide, 5 wt% niobium oxide, 2 wt% molybdenum oxide, 2 wt% cobalt oxide, and 1 wt% phosphorus oxide.

[0052] Example 7

[0053] 200 mL of a urea solution with a N / C ratio of 1:5 was impregnated onto 200 g of dried activated carbon support, and dried under vacuum at 80 °C for 4 h to obtain a nitrogen-doped activated carbon support precursor. 100 g of ZnCl2 activator was then calcined with the nitrogen-doped activated carbon support precursor under a nitrogen atmosphere for 4 h at a calcination temperature of 700 °C and a calcination rate of 2 °C / min to obtain the nitrogen-doped activated carbon support NC1.

[0054] Weigh 100g of the catalyst support NC1, mix 2.2g of hydrated citric acid, 6.4g of ammonium metavanadate, and 3.7g of tantalum ethoxide to prepare an impregnation solution, and impregnate the support with the above active component impregnation solution using an equal volume impregnation method. The ratio of metal chelating agent is: N / metal molar ratio = 0.6 / 1, and leave for 2 hours. Then dry in an oven at 120℃ for 6 hours, and calcine in a muffle furnace at 350℃ for 3 hours to obtain the acetone condensation polymerization catalyst MC4, with the composition of: vanadium oxide 5wt% and tantalum oxide 2wt%.

[0055] 2.2 g of hydrated citric acid, 2.3 g of ammonium molybdate, and 1.1 g of ammonium metatungstate were weighed and mixed to prepare a metal additive impregnation solution. The metal additive impregnation solution was added to the above-mentioned active metal catalyst MC4 using an equal-volume impregnation method, wherein the metal chelating agent ratio was: N / metal molar ratio = 0.6 / 1. The mixture was allowed to stand for 2 hours, then dried in an oven at 120°C for 6 hours, and calcined in a muffle furnace at 350°C for 3 hours to obtain the modified acetone condensation polymerization catalyst TNC1, with the following composition: vanadium oxide 5 wt%, tantalum oxide 2 wt%, molybdenum oxide 2 wt%, and tungsten oxide 1 wt%.

[0056] Example 8

[0057] 200 mL of a melamine solution with an N / C ratio of 1:5 was impregnated onto 200 g of dried activated carbon support, and dried under vacuum at 80 °C for 4 h to obtain a nitrogen-doped activated carbon support precursor. 100 g of ZnCl2 activator and the nitrogen-doped activated carbon support precursor were calcined together under a nitrogen atmosphere for 4 h at a calcination temperature of 700 °C and a calcination heating rate of 2 °C / min to obtain the nitrogen-doped activated carbon support NC2.

[0058] Weigh 100g of the catalyst support NC2. Mix 3.6g of hydrated citric acid, 6.4g of ammonium metavanadate, 8.1g of niobium oxalate and 9.3g of tantalum ethoxide to prepare an impregnation solution. Impregnate the support with the above active component solution using an equal volume impregnation method. The ratio of metal chelating agent is N / metal molar ratio = 0.8 / 1. Let it stand for 2 hours, then dry it in an oven at 120℃ for 6 hours, and calcine it in a muffle furnace at 350℃ for 3 hours to obtain the acetone condensation polymerization catalyst MC5, with the composition of vanadium oxide 5wt%, tantalum oxide 5wt%, and niobium oxide 2wt%.

[0059] 1.8 g of hydrated citric acid, 1.6 g of ammonium molybdate, 2.5 g of nickel nitrate, and 1.3 g of diammonium hydrogen phosphate were weighed and mixed to prepare a metal additive component impregnation solution. The metal additive component impregnation solution was added to the above-mentioned active metal catalyst MC5 using an equal-volume impregnation method, wherein the metal chelating agent ratio was: N / metal molar ratio = 0.6 / 1. The solution was left to stand for 2 hours, then dried in an oven at 120°C for 6 hours, and calcined in a muffle furnace at 350°C for 3 hours to obtain the modified acetone condensation polymerization catalyst TNC2, with the following composition: vanadium oxide 5 wt%, tantalum oxide 5 wt%, niobium oxide 2 wt%, molybdenum oxide 1 wt%, nickel oxide 1 wt%, and phosphorus oxide 1 wt%.

[0060] Example 9

[0061] 200 mL of a melamine solution with an N / C ratio of 1:10 was impregnated onto 200 g of dried activated carbon support, which was then dried under vacuum at 80 °C for 4 h to obtain a nitrogen-doped activated carbon support precursor. 100 g of ZnCl2 activator was then calcined with the nitrogen-doped activated carbon support precursor under a nitrogen atmosphere for 4 h at a calcination temperature of 700 °C and a calcination heating rate of 2 °C / min to obtain the nitrogen-doped activated carbon support NC3.

[0062] Weigh 100g of the catalyst support NC3. Mix 15.8g of hydrated citric acid, 12.8g of ammonium metavanadate, 20.2g of niobium oxalate and 18.6g of tantalum ethoxide to prepare an impregnation solution. Impregnate the support with the above active component solution using an equal volume impregnation method. The ratio of metal chelating agent is N / metal molar ratio = 1.2 / 1. After holding for 2 hours, dry in an oven at 120℃ for 6 hours and calcine in a muffle furnace at 350℃ for 3 hours to obtain the acetone condensation polymerization catalyst MC6, with the composition of 10wt% vanadium oxide, 10wt% tantalum oxide and 5wt% niobium oxide.

[0063] 2.6 g of hydrated citric acid, 3.2 g of ammonium molybdate, 2.7 g of cobalt nitrate, and 1.3 g of diammonium hydrogen phosphate were weighed to prepare a metal additive impregnation solution. The metal additive impregnation solution was added to the above-mentioned active metal catalyst MC1 using an equal-volume impregnation method, wherein the metal chelating agent ratio was N / metal molar ratio = 0.6 / 1. The solution was left to stand for 2 hours, then dried in an oven at 120°C for 6 hours, and calcined in a muffle furnace at 350°C for 3 hours to obtain the modified acetone condensation polymerization catalyst TNC3, with the following composition: vanadium oxide 10 wt%, tantalum oxide 10 wt%, niobium oxide 5 wt%, molybdenum oxide 2 wt%, cobalt oxide 2 wt%, and phosphorus oxide 1 wt%.

[0064] Comparative Example 1

[0065] Weigh 100g of activated carbon support, mix 15.8g of hydrated citric acid, 12.8g of ammonium metavanadate, 20.2g of niobium oxalate and 18.6g of tantalum ethoxide to prepare an impregnation solution, and impregnate the support with the above active component impregnation solution using an equal volume impregnation method. The ratio of metal chelating agent is: N / metal molar ratio = 1.2 / 1, and the solution is left to stand for 2 hours. Then, dry it in an oven at 120℃ for 6 hours and calcine it in a muffle furnace at 350℃ for 3 hours to obtain acetone condensation polymerization to form mesitylene catalyst TC4, with the composition of: vanadium oxide 10wt%, tantalum oxide 10wt%, and niobium oxide 5wt%.

[0066] Comparative Example 2

[0067] 100g of silicon-aluminum monomer was weighed as a carrier. A mixing solution of 15.8g hydrated citric acid, 12.8g zirconium acetate, 20.2g niobium oxalate, and 18.6g tantalum ethoxide was prepared. The active component impregnation solution was then applied to the carrier using an equal-volume impregnation method. The metal chelating agent ratio was N / metal molar ratio = 1.2 / 1. The mixture was left to stand for 2 hours, then dried in an oven at 120℃ for 6 hours, and calcined in a muffle furnace at 350℃ for 3 hours to obtain TC5, a catalyst for the condensation polymerization of acetone to trimethylbenzene, with the following composition: 10wt% zirconium oxide, 10wt% tantalum oxide, and 5wt% niobium oxide.

[0068] The physicochemical properties of the six catalysts in Examples 1-6 above are shown in Table 1.

[0069]

[0070]

[0071] The physicochemical properties of the five catalysts in Examples 7-9 and Comparative Examples 1-2 are shown in Table 2.

[0072] catalyst <![CDATA[Specific surface area, m 2 / g]]> <![CDATA[Pore volume, cm 3 / g]]> Strength, N / cm TC4 230 0.22 180 TC5 365 0.27 180 TNC1 420 0.30 191 TNC2 435 0.32 196 TNC3 440 0.33 192

[0073] The performance of the above catalyst was evaluated using the catalytic acetone condensation process. The specific evaluation process is as follows: A micro fixed-bed pilot-scale apparatus was used, with a catalyst loading of 78 g (100 ml). First, the catalyst was subjected to a catalytic reaction at 40 °C·h. -1 The temperature was raised to 280°C, and then acetone, the evaluation raw material, was pumped in at a rate of 20°C / h. -1 The heating rate was increased to the reaction temperature of 380℃ (alternative temperatures: 350℃, 360℃, 370℃, 380℃, 390℃, 400℃). The reaction evaluation conditions were: temperature 380℃ (alternative temperatures: 350℃, 360℃, 370℃, 380℃, 390℃, 400℃), atmospheric pressure, and liquid hourly space velocity (LISH) of 2 h⁻¹. -1 After stabilization for 6 hours, samples were taken for analysis. The sampling time was 2 hours, and samples were taken twice. The samples were stored cumulatively.

[0074] The reaction evaluation results of the above six catalysts are shown in Table 3.

[0075] Table 3. Evaluation results of the reaction of six catalysts at atmospheric pressure and 380℃.

[0076]

[0077]

[0078] As shown in Table 3, the mesitylene catalyst prepared according to the method of the present invention based on acetone directional condensation polymerization has higher trimerization performance compared with the previous acetone condensation catalysts. While significantly removing oxygen atoms from the carbon-oxygen double bond of the product, it can reduce the oxygen-containing cyclized isophorone generated during the trimerization of acetone, and has stronger anti-carbon deposition ability. Furthermore, catalysts TC1, TC2, and TC3 exhibit better selectivity for the product mesitylene than catalysts MC1, MC2, and MC3. This is mainly due to the use of multiple active metal composites and the introduction of metal-modified co-catalyst components, which increases the active metal content in the support and modulates the distribution and amount of acidic sites in the catalyst. Catalysts TNC1, TNC2, and TNC3 exhibit better selectivity for the product mesitylene than catalysts TC4 and TC5. This is mainly due to the nitrogen-doping modification that enriches the support surface with nitrogen, which is beneficial for anchoring the active metal, thereby improving the dispersibility and effective utilization of the active metal, strengthening the synergistic effect between the active metal and the metal-modified co-catalyst components, and further improving the catalyst's performance in catalyzing the directional condensation polymerization of acetone into mesitylene.

[0079] Therefore, this invention utilizes a composite oxide catalyst with an active metal oxide supported on an acidic monomer. The active component of the catalyst comprises one or more of Group VB (V, Nb, Ta) or Group VIB (Cr, Mo, W). The metal modifier component comprises one or more of Group VIB (Cr, Mo, W) or transition metals (Fe, Co, Ni, Cu, Zn) or non-metal modifiers (P) oxides or precursors thereof. A metal chelating agent includes one or more of ethylene glycol, hydrated citric acid, hydrated tartaric acid, cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid, and hypoaminotriacetic acid. The support is a nitrogen-doped modified carbon support. The catalyst support is prepared by mixing the composite oxide with a molecular sieve. The main active component and the metal modifier component are introduced into the composite modified support through equal-volume impregnation and ion exchange, achieving a highly efficient synergistic effect between the active metal component and the auxiliary metal component on the composite modified support, as well as a gradient distribution of the catalyst's acid strength. The catalyst prepared by this method has advantages such as low cost, high activity and selectivity, and good stability.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene, characterized in that, Includes the following steps: S1. Preparation of catalyst support; S2. Prepare a mixed solution of metal chelating agent and active component precursor salt of the required concentration as impregnation liquid, and impregnate the catalyst support in S1 using the equal volume impregnation method. S3. After the catalyst support and impregnation solution are fully mixed, the catalyst is dried and calcined in air to obtain an active metal supported catalyst. S4. The metal-modifying additive component is introduced into the catalyst supported in S3, and the catalyst is dried and calcined in air to obtain the modified active metal-supported catalyst. The catalyst support in S1 is prepared by mixing a composite oxide with a molecular sieve. The composite oxide is one or more of silica, alumina, and zirconium oxide, and the molecular sieve is one or more of USY molecular sieve, SAPO molecular sieve, Beta molecular sieve, and ZSM-5 molecular sieve; or the catalyst support in S1 is a nitrogen-doped modified carbon support. The active component in S2 is one or more of the oxides or precursors of Group IVB Ti, Zr, Hf or Group VB V, Nb, Ta, and the content in the catalyst, calculated as oxides, is 0.5~15 wt%. The metal modifier component in S4 is one or more of the following: oxides or precursors of Group VIB Cr, Mo, W or transition metals Fe, Co, Ni, Cu, Zn or non-metal modifier P, and the content of oxides in the catalyst is 1 to 10 wt%.

2. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 1, characterized in that, The catalyst support prepared by mixing composite oxide and molecular sieve is as follows: composite oxide, molecular sieve and tianqing are ground and mixed by ball milling in a certain mass ratio, and the catalyst support is obtained by mechanical mixing, extrusion molding, drying and calcination.

3. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 1, characterized in that, The molecular sieve content is 20-70 wt%, and the composite oxide content is 30-80 wt%.

4. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 1, characterized in that, The method for preparing nitrogen-doped modified carbon support is as follows: a nitrogen modifier solution of the required concentration is prepared according to the N / C atomic ratio of 1:10 to 1:2.5 in the nitrogen-doped modified carbon support. The nitrogen source is introduced into the carbon support by impregnation method to achieve nitrogen doping modification. The carbon support, nitrogen source and activator are calcined in a nitrogen atmosphere to obtain nitrogen-doped modified carbon support.

5. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 4, characterized in that, The carbon support is one or more of activated carbon, graphite, porous activated carbon, and activated carbon fiber; The nitrogen-doped modifier is one or more of melamine, ammonium nitrate, dicyandiamide, N,N-dimethylformamide and urea, and the N / C atomic ratio in the nitrogen-doped modified carbon support is 1:10 to 1:2.5; The activator is one or more of KOH, K2CO3, and ZnCl2; the mass ratio of carbon support to activator is 1:0.5~1:2; the calcination temperature is 500~900℃; the calcination heating rate is 2~5℃ / min; and the calcination time is 2~4h.

6. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 1, characterized in that, In S2, the molar ratio of the metal chelating agent to the active component is 0.5:1 to 3:

1.

7. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 3, characterized in that, In S4, a mixed solution of metal chelating agent and metal modification auxiliary component precursor salt of the required concentration is prepared as an ion exchanger. The metal modification auxiliary component is introduced into S3 by ion exchange to obtain a modified active metal supported catalyst. The ion exchange process is as follows: the active metal supported catalyst in S3 is added to the ion exchanger, soaked for 6-12 hours, washed and filtered, evaporated to dryness in a water bath at 80-150℃, calcined at 350-550℃ for 3-9 hours.

8. The method for preparing a catalyst for the directional condensation polymerization of acetone to mesitylene according to claim 5, characterized in that, In S4, a metal chelating agent and metal auxiliary component precursor salt solution of the required concentration are prepared as impregnation liquid, and the metal modified auxiliary component is introduced into the modified active metal supported catalyst obtained in S3 by the equal volume impregnation method.

Images