Preparation method of catalyst for catalyzing directional polycondensation of acetone to synthesize mesitylene

Abstract

The invention discloses a preparation method of a catalyst for catalyzing directional polycondensation of acetone to synthesize mesitylene, and belongs to the technical field of catalysis. The modified active metal supported catalyst is prepared from a catalyst carrier prepared by mixing a nitrogen-doped modified carbon carrier or a composite oxide with a molecular sieve, an active metal component, a metal modification additive component and a metal chelating agent. According to the present invention, the active component is loaded on the composite modified carrier through the isovolumetric impregnation method, and the metal modification auxiliary agent component is introduced through the ion exchange method to further modify the active component, such that the requirement of the catalysis of the directional deoxidation trimerization of the acetone to prepare the mesitylene is achieved, and the catalyst prepared by the method has advantages of low price, high activity, high selectivity, good stability and the like; the problem that the separation cost is increased due to the complex equipment requirement and the separation problem of mesitylene and methyl-ethylbenzene under the similar boiling point in the traditional mesitylene production method is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a method for preparing a catalyst for catalyzing directional polycondensation of acetone to synthesize mesitylene. Background Art

[0002] At present, as the production scale of domestic phenol continues to expand, my country's phenol production capacity will continue to grow in the next few years. According to 2019 data, the total phenol production capacity has reached 2.628 million t / a. At the same time, since the domestic phenol production mainly adopts the cumene method, acetone is a by-product of phenol, and its total production capacity has reached 1.547 million t / a. In recent years, the cumene production phenol unit has been put into production faster than other units, such as Formosa Chemicals (Ningbo) Co., Ltd. and Zhejiang Petrochemical Company, which have been completed and put into production as scheduled. The domestic new phenol production capacity is 2.54 million t / a, and the new acetone production capacity is 1.56 million t / a. As of 2023, it is predicted that the domestic phenol production capacity will reach 5.168 million / a, and the acetone production capacity will reach 3.107 million t / a.

[0003] 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. In recent years, the application of acetone in China has become more extensive and diverse, and it has a certain consumption proportion in the fields of isopropanol, aliphatic water reducer, and methyl isobutyl ketone (MIBK). Therefore, from the current situation of the continuous expansion of acetone production capacity, actively studying acetone downstream technology and high value-added products has important practical significance for alleviating the growth of acetone production capacity. At present, the lowest market price of acetone is 5,500 yuan / t, and the highest is about 7,200 yuan / t. 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, which can effectively alleviate the problem of overcapacity caused by the continuous expansion of acetone production capacity.

[0004] Mesitylene (MS) is very active in chemical properties and is easily halogenated, nitrated and sulfonated. Mesitylene is an important chemical raw material that can be used to prepare a variety of fine chemical products such as dye intermediate mesitylene amine, antioxidant Lonox330, and anti-ultraviolet oxidation stabilizer mesitylene phenol. It is also an important raw material for the production of alkyd resins and high-temperature plasticizers.

[0005] The synthesis method of mesitylene is relatively mature. The traditional synthesis methods mainly include: extractive distillation method, heavy aromatic hydrocarbon distillation separation method, gas phase isomerization reaction of mesitylene, atmospheric pressure liquid phase isomerization reaction of mesitylene, atmospheric pressure liquid phase alkylation of mesitylene to produce mesitylene and co-production of mesitylene, and combined isomerization and alkylation of mesitylene to produce high-purity mesitylene and co-production of mesitylene, etc.

[0006] The extractive distillation method uses the extractive distillation method of Esso Company in the United States to separate C9 aromatics using dimethyl phthalate (DMT) as a solvent. The main process is carried out through four extractive distillation towers. From the top of tower 1 and tower 2, mesitylene and m- and p-methylethylbenzene can be obtained respectively; the high boiling point solvent is recovered from the bottom of tower 3; o-methylethylbenzene is obtained from the top of tower 4, and partial trimethylbenzene and other heavy components are obtained from the bottom of the tower. 87% of mesitylene can be obtained by this process, and the product purity is relatively low. At present, the extractive distillation process used in China is less than the distillation tower used by the process of Esso Company in the United States, and only two towers are used. The solvent and raw materials are fed in the upper and middle parts of tower 1 respectively. The distillate from the top of the tower is high-purity mesitylene, and the mixed liquid of o-methylethylbenzene and solvent distilled from the bottom of the tower is used as the feed of tower 2. O-methylethylbenzene is evaporated from the top of the tower, and the solvent at the bottom of the tower is recycled. This method overcomes the shortcomings of the former and can achieve complete separation of methyl ethyl benzene and mesitylene to obtain mesitylene and methyl ethyl benzene with higher purity. However, this method requires more equipment and has high operating costs.

[0007] The isomerization method of trimethylolbenzene is mainly to isomerize trimethylolbenzene to mesitylene on a dealuminated mordenite catalyst impregnated with aluminum and nickel at a reaction temperature of 250℃-330℃ and under hydrogen conditions, with a conversion rate of 45%. Products with a purity of 95-98% can be obtained through distillation. In this process, if reforming oxygen is used, hydrocarbons above C3 need to be removed in advance; if electrolytic hydrogen is used, the reaction effect is better. This method requires hydrogen conditions and high temperature and pressure, the reaction equipment is relatively complex, and the requirements for reaction conditions are also relatively harsh, so the production cost is relatively high, and the purity of trimethylolbenzene cannot reach more than 98%, which obviously cannot be put into large-scale production in industry.

[0008] The process route of preparing mesitylene from acetone by 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. At present, 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. Patents have been reported both at home and abroad. US5153156 patent reports a catalyst obtained by spraying synthetic clay on the surface of MgO-Al2O3 by spraying. The selectivity of catalyzing condensation of acetone to mesityl oxide and isophorone is low at 27.3%. CN101462043A patent reports that a solid alkali-modified magnesium-aluminum composite oxide is obtained by mixing, crystallizing and calcining salt solutions of magnesium-aluminum modified metals in an alkaline environment. The catalyst is used for the reaction of condensation of acetone to produce isophorone. The conversion rate under normal pressure is as high as 38.2%, the selectivity of isophorone is 77.8%, and the total selectivity of isophorone and mesityl oxide reaches 87.8%. In the patent CN109926040A, a template is used to prepare a composite oxide of a modified metal and magnesium aluminum by precipitation method. In the reaction of preparing isophorone by condensation of acetone, the reaction temperature is 250°C to 300°C, the acetone mass space velocity is 1 to 8 h under normal pressure. -1, the highest acetone conversion rate is 45%, the isophorone selectivity is 75%, and the mesityl oxide and isophorone selectivity is 90%. This technology is suitable for the industrial production of isophorone; another type of solid acid mainly based on modified aluminosilicate zeolite loaded with metal oxides can be used to catalyze the condensation of acetone with mesitylene and benzene ring-containing compounds. There are many foreign patent reports. US2917561A patent reports a metal tantalum in the range of about 0.05 to 5 weight % as the loaded active component, and the carrier uses aluminosilicate or a zeolite with a porous structure as a catalyst for the heterogeneous acetone condensation process. US3201485A patent reports a catalyst loaded with metal chromium on a silica-alumina gel carrier, and partially doped with zinc oxide and boron, which can be used for the catalytic condensation of alkyl ketones to prepare polyalkylated benzenes. US3201485A patent reports a catalyst loaded with Pd on MoO3 and The catalyst formed on a mixture of AhO3 (0.1-1% by weight of Pd) achieved an acetone conversion rate of 42.5% and a selectivity for meta-trimethylbenzene of 44.2%. The US5087781A patent improved the type of loaded metal and loaded a metal Nb catalyst on a silica-alumina carrier. When the Nb loading was 2wt%, a 30% acetone conversion rate and a 65% selectivity for mesitylene were achieved. The ES2792176A1 patent reported a composite solid catalyst formed by mixing an alkaline oxide and an acidic carrier in a mass ratio of 1 / 4 or 3 / 4, wherein in a mixed system of TiO2 and an acidic molecular sieve BEA, the acetone conversion rate was about 13.8%, and the selectivity for mesitylene in the C9 product was 88.3%. An earlier domestic patent CN1087280C discloses a production process for preparing high-purity mesitylene from acetone, in which acetone and carrier gas nitrogen are mixed and pumped into a fixed bed reactor for catalytic condensation with a silicon-aluminum catalyst impregnated with metal zirconium. The product in the reactor is then pumped into a cooler for gas-liquid separation to remove nitrogen, and the remaining liquid is pumped into a heater for heating. The gas-liquid mixed phase finally enters a distillation tower for distillation to separate high-purity mesitylene. The catalyst used in this process has a maximum selectivity of 50.1% for mesitylene.

[0009] The metals used in the supported catalysts reported so far are mostly precious metals, which undoubtedly increases the production cost. At the same time, the selectivity for the mesitylene product is not high, and the reaction conditions in the condensation of acetone to mesitylene still need to be studied and optimized. Therefore, in order to effectively improve the selectivity of catalytic condensation of acetone to prepare mesitylene and reduce the production cost of traditional mesitylene, it is urgent to make new progress in the modification of the acidic carrier of the acetone condensation catalyst and the preparation of active metal supported catalysts, so as to realize the industrial production of directional catalytic condensation of acetone to prepare mesitylene and maximize its product value, which has good market application prospects. Summary of the invention

[0010] Based on previous research and existing problems, the present invention proposes a preparation method of a catalyst for catalyzing the directional polycondensation of acetone to mesitylene after further research and analysis.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A method for preparing a catalyst for catalyzing directional polycondensation of acetone to synthesize mesitylene comprises the following steps:

[0013] S1. preparing a catalyst carrier;

[0014] S2, preparing a mixed solution of a metal chelating agent and an active component precursor salt of a required concentration as an impregnation solution, and impregnating the catalyst support in S1 by an equal volume impregnation method;

[0015] S3, after the catalyst carrier and the impregnation liquid are fully mixed, they are dried and calcined in an air atmosphere to obtain an active metal-supported catalyst;

[0016] S4, introducing the metal modification auxiliary agent component into the catalyst loaded in S3, and obtaining a modified active metal loaded catalyst after drying and calcining in an air atmosphere.

[0017] Preferably, the catalyst carrier in S1 is prepared by mixing a composite oxide and a molecular sieve. The specific preparation method is: the composite oxide, molecular sieve and Tianqing are ground and mixed in a certain mass ratio by a ball mill, and the catalyst carrier is obtained by mechanical mixing, extrusion molding, drying and calcining.

[0018] Preferably, the composite oxide is one or more of silicon dioxide, aluminum oxide, 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 20-70wt%, and the composite oxide content is 30-80wt%.

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

[0021] Preferably, the carbon carrier 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 the carbon carrier to the activator is 1:0.5 to 1:2; the calcination temperature is 500 to 900°C; the calcination heating rate is 2 to 5°C / min; and the calcination time is 2 to 4h.

[0024] Preferably, in S2, the active 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%.

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

[0027] Preferably, in S4, a mixed solution of a metal chelating agent and a precursor salt of a metal modification auxiliary component of a required concentration is configured as an ion exchanger, and the metal modification auxiliary component is introduced into S3 by an ion exchange method to obtain a modified active metal-supported catalyst. The ion exchange method treatment process is: adding the active metal-supported catalyst in S3 to the ion exchanger, soaking for 6 to 12 hours, washing and filtering, stirring in a water bath, evaporating to dryness at a temperature of 80 to 150°C, calcining at a temperature of 350 to 550°C, and calcining for 3 to 9 hours.

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

[0029] Compared with the existing technology, the present invention provides a method for preparing a catalyst for catalyzing the directional polycondensation of acetone to synthesize mesitylene, which has the following beneficial effects:

[0030] (1) It avoids the complex equipment requirements in the traditional mesitylene production method and the separation problem of mesitylene and methyl and ethyl benzene at similar boiling points, which leads to increased separation costs.

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

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

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

[0034] (5) The process has a high utilization rate of acetone condensation products and less waste. The supported catalyst has high activity and selectivity. The conversion rate can reach up to 44.62% at normal pressure, the selectivity of mesitylene can reach more than 90%, and the total selectivity of mesitylene and mesityl oxide can reach 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 DESCRIPTION

[0036] 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.

[0037] Example 1

[0038] Weigh 0.7 kg of silica and 0.3 kg of pseudo-boehmite, add 2 wt% of sesbania powder as a carrier precursor powder and grind evenly. After fully kneading into a gel state, extrude it into a cylindrical strip with a diameter of 1.6 mm on an extruder, dry it in an oven at 120°C for 6 hours, and calcine it in a muffle furnace at 550°C for 3 hours to obtain a catalyst carrier S1 with a silica content of 70 wt% and an alumina content of 30 wt%.

[0039] Weigh 100 g of the catalyst carrier S1, mix 2.2 g of hydrated citric acid, 6.4 g of ammonium metavanadate, and 3.7 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution on the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 0.6 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC1, which consists of: 5wt% vanadium oxide, 2wt% tantalum oxide.

[0040] Example 2

[0041] 2.2g of hydrated citric acid, 2.3g of ammonium molybdate and 1.1g of ammonium metatungstate were measured to prepare an ion exchanger. The active metal catalyst MC1 in Example 1 was added to the metal-modified ion exchanger solution configured above and soaked for 12h by ion exchange method, then washed and filtered, stirred and evaporated on a water bath at 80°C, and calcined at 550°C for 3h to obtain a modified acetone condensation synthesis mesitylene catalyst TC1, which was composed of 5wt% vanadium oxide, 2wt% tantalum oxide, 2wt% molybdenum oxide and 1wt% tungsten oxide.

[0042] Example 3

[0043] Weigh a certain amount of 0.6kg USY0 molecular sieve and 0.4kg pseudo-boehmite, add 2wt% of sesbania powder as the carrier precursor powder and grind evenly, after fully mixing into a gel state, extrude into cylindrical strips with a diameter of 1.6mm on an extruder, and dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 550°C for 3 hours to obtain a catalyst carrier S2, in which the USY molecular sieve content is 60wt% and the alumina content is 40wt%.

[0044] Weigh 100 g of the catalyst carrier S2, mix 3.6 g of hydrated citric acid, 6.4 g of ammonium metavanadate, 8.1 g of niobium oxalate and 9.3 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution onto the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 0.8 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC2, which consists of: 5wt% of vanadium oxide, 5wt% of tantalum oxide, and 2wt% of niobium oxide.

[0045] Example 4

[0046] 1.8g of hydrated citric acid, 1.6g of ammonium molybdate, 2.5g of nickel nitrate and 1.3g of diammonium hydrogen phosphate were measured to prepare an ion exchanger. The active metal catalyst MC2 in Example 3 was added to the metal-modified ion exchanger solution configured above and soaked for 12h by ion exchange method, then washed and filtered, stirred and evaporated on a water bath at 80°C, and calcined at 550°C for 3h to obtain a modified acetone condensation synthesis mesitylene catalyst TC2, which is composed of 5wt% of vanadium oxide, 5wt% of tantalum oxide, 2wt% of niobium oxide, 1wt% of molybdenum oxide, 1wt% of nickel oxide, and 1wt% of phosphorus oxide.

[0047] Example 5

[0048] Weigh 0.8 kg of silica and 0.2 kg of zirconium oxide, add 2 wt% of sesbania powder as a carrier precursor powder and grind evenly. After fully kneading into a gel state, extrude 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 a catalyst carrier S3, in which the silica content is 80 wt% and the zirconium oxide content is 20 wt%.

[0049] Weigh 100 g of the catalyst carrier S3, mix 15.8 g of hydrated citric acid, 12.8 g of ammonium metavanadate, 20.2 g of niobium oxalate and 18.6 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution onto the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 1.2 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC3, which is composed of: 10wt% of vanadium oxide, 10wt% of tantalum oxide, and 5wt% of niobium oxide.

[0050] Example 6

[0051] 2.6g of hydrated citric acid, 3.2g of ammonium molybdate, 2.7g of cobalt nitrate and 1.3g of diammonium hydrogen phosphate were measured to prepare an ion exchanger. The active metal catalyst MC3 in Example 5 was added to the metal-modified ion exchanger solution configured above and soaked for 12h by ion exchange method, then washed and filtered, stirred and evaporated on a water bath at 80°C, and calcined at 550°C for 3h to obtain a modified acetone condensation synthesis mesitylene catalyst TC3, which is composed of: 10wt% vanadium oxide, 10wt% tantalum oxide, 5wt% niobium oxide, 2wt% molybdenum oxide, 2wt% cobalt oxide, and 1wt% phosphorus oxide.

[0052] Example 7

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

[0054] Weigh 100 g of the catalyst carrier NC1, mix 2.2 g of hydrated citric acid, 6.4 g of ammonium metavanadate, and 3.7 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution onto the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 0.6 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC4, which is composed of: 5wt% vanadium oxide, 2wt% tantalum oxide.

[0055] Weigh 2.2g of hydrated citric acid, 2.3g of ammonium molybdate, and 1.1g of ammonium metatungstate and mix them to form a metal additive component impregnation liquid. The metal additive component impregnation liquid is added to the above-mentioned active metal catalyst MC4 by an equal volume impregnation method, wherein the ratio of the metal chelating agent is: N / metal molar ratio = 0.6 / 1, and stays for 2 hours, and 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 a modified acetone condensation synthesis mesitylene catalyst TNC1, which is composed of: 5wt% of vanadium oxide, 2wt% of tantalum oxide, 2wt% of molybdenum oxide, and 1wt% of tungsten oxide.

[0056] Example 8

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

[0058] Weigh 100 g of the catalyst carrier NC2, mix 3.6 g of hydrated citric acid, 6.4 g of ammonium metavanadate, 8.1 g of niobium oxalate and 9.3 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution onto the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 0.8 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC5, which is composed of: 5wt% of vanadium oxide, 5wt% of tantalum oxide, and 2wt% of niobium oxide.

[0059] 1.8g of hydrated citric acid, 1.6g of ammonium molybdate, 2.5g of nickel nitrate and 1.3g of diammonium hydrogen phosphate were weighed and mixed to form a metal additive component impregnation solution. The metal additive component impregnation solution was added to the above-mentioned active metal catalyst MC5 by an equal volume impregnation method, wherein the ratio of the metal chelating agent was: N / metal molar ratio = 0.6 / 1, and it was left for 2 hours, and 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 a modified acetone condensation synthesis mesitylene catalyst TNC2, which was composed of: 5wt% of vanadium oxide, 5wt% of tantalum oxide, 2wt% of niobium oxide, 1wt% of molybdenum oxide, 1wt% of nickel oxide, and 1wt% of phosphorus oxide.

[0060] Example 9

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

[0062] Weigh 100 g of the catalyst carrier NC3, mix 15.8 g of hydrated citric acid, 12.8 g of ammonium metavanadate, 20.2 g of niobium oxalate and 18.6 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution onto the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 1.2 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst MC6, which is composed of: 10wt% of vanadium oxide, 10wt% of tantalum oxide, and 5wt% of niobium oxide.

[0063] Weigh 2.6g of hydrated citric acid, 3.2g of ammonium molybdate, 2.7g of cobalt nitrate and 1.3g of diammonium hydrogen phosphate to prepare a metal additive component impregnation solution. The metal additive component impregnation solution is added to the above-mentioned active metal catalyst MC1 by an equal volume impregnation method, wherein the ratio of the metal chelating agent is: N / metal molar ratio = 0.6 / 1, and stays for 2 hours, and 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 a modified acetone condensation synthesis mesitylene catalyst TNC3, which is composed of: vanadium oxide 10wt%, tantalum oxide 10wt%, niobium oxide 5wt%, molybdenum oxide 2wt%, cobalt oxide 2wt%, phosphorus oxide 1wt%.

[0064] Comparative Example 1

[0065] Weigh 100 g of the activated carbon carrier, mix 15.8 g of hydrated citric acid, 12.8 g of ammonium metavanadate, 20.2 g of niobium oxalate and 18.6 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the above active component impregnation solution on the carrier, wherein the ratio of the metal chelator is: N / metal molar ratio = 1.2 / 1, and stay for 2 hours, then dry in an oven at 120°C for 6 hours, and calcine in a muffle furnace at 350°C for 3 hours to obtain acetone condensation synthesis mesitylene catalyst TC4, which is composed of: 10wt% of vanadium oxide, 10wt% of tantalum oxide, and 5wt% of niobium oxide.

[0066] Comparative Example 2

[0067] Weigh 100 g of silicon-aluminum monomer as a carrier, mix 15.8 g of hydrated citric acid, 12.8 g of zirconium acetate, 20.2 g of niobium oxalate and 18.6 g of tantalum ethoxide to form an impregnation solution, and use an equal volume impregnation method to impregnate the active component impregnation solution on the carrier, wherein the ratio of the metal chelating agent is: N / metal molar ratio = 1.2 / 1, and stay for 2 hours, then dry in an oven at 120° C. for 6 hours, and calcine in a muffle furnace at 350° C. for 3 hours to obtain acetone condensation synthesis mesitylene catalyst TC5, which is composed of: zirconium oxide 10wt%, tantalum oxide 10wt%, niobium oxide 5wt%

[0068] The physicochemical properties of the six catalysts in Examples 1-6 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 catalysts was evaluated by catalyzing acetone condensation. The specific evaluation process is as follows: a micro-fixed bed pilot device was used, and the catalyst loading was 78 grams (100 ml). First, at 40℃·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 (alternative temperatures of 350°C, 360°C, 370°C, 380°C, 390°C, and 400°C). The reaction evaluation conditions were: temperature of 380°C (alternative temperatures of 350°C, 360°C, 370°C, 380°C, 390°C, and 400°C), normal pressure, and liquid hourly space velocity of 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.

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

[0075] Table 3 Reaction evaluation results of six catalysts at normal pressure and 380°C

[0076]

[0077]

[0078] From the results in Table 3, it can be seen that the mesitylene catalyst prepared by the method of the present invention based on directional condensation of acetone has higher trimerization aromatization performance than the previous catalytic acetone condensation catalyst. While significantly removing the oxygen atom of the carbon-oxygen double bond of the product, it can reduce the oxygen-containing cyclized product isophorone produced in the process of acetone trimerization, and at the same time has stronger anti-carbon deposition ability. In addition, catalysts TC1, TC2, and TC3 have 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 component loading, which increases the active metal content in the carrier and adjusts the distribution of acid sites and the amount of acidity in the catalyst; catalysts TNC1, TNC2, and TNC3 have better selectivity for the product mesitylene than catalysts TC4 and TC5. This is mainly due to the nitrogen enrichment of the carrier surface through nitrogen doping modification, which is beneficial to anchoring the active metal, thereby improving the dispersion and effective utilization rate of the active metal, strengthening the synergistic effect between the active metal and the metal-modified auxiliary component, and further improving the catalyst's performance in catalyzing the directional condensation of acetone to synthesize mesitylene.

[0079] Therefore, the present invention uses an active metal oxide loaded on an acidic monomer composite oxide catalyst, the active component in the catalyst is composed of one or more of V, Nb, Ta in the VB group or Cr, Mo, W in the VI group, the metal modification auxiliary component is one or more of the oxides of Cr, Mo, W in the VI group or transition metals Fe, Co, Ni, Cu, Zn or non-metal modification auxiliary components P or its precursor, and the metal chelating agent includes one or more of ethylene glycol, hydrated citric acid, hydrated tartaric acid, cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid, and nitrilotriacetic acid, the carrier is a nitrogen-doped modified carbon carrier and the composite oxide is mixed with a molecular sieve to prepare the catalyst carrier, the main active component and the metal modification auxiliary component are introduced into the composite modified carrier by an equal volume impregnation and ion exchange method, and the active metal component and the auxiliary metal component on the composite modified carrier are efficiently synergistic and the catalyst acid strength is stepped. The catalyst prepared by the method has the advantages of low price, high activity and selectivity, good stability, etc.

[0080] 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 a catalyst for catalyzing the directional polycondensation of acetone to synthesize mesitylene, characterized in that: The steps include: S1. preparing a catalyst carrier; S2, preparing a mixed solution of a metal chelating agent and an active component precursor salt of a required concentration as an impregnation solution, and impregnating the catalyst support in S1 by an equal volume impregnation method; S3, after the catalyst carrier and the impregnation liquid are fully mixed, they are dried and calcined in an air atmosphere to obtain an active metal-supported catalyst; S4, introducing the metal modification auxiliary agent component into the catalyst loaded in S3, and obtaining a modified active metal loaded catalyst after drying and calcining in an air atmosphere.

2. The method for preparing a catalyst for catalyzing the directional polycondensation of acetone to mesitylene according to claim 1, characterized in that: The catalyst carrier in S1 is prepared by mixing a composite oxide and a molecular sieve. The specific preparation method is: the composite oxide, the molecular sieve and Tianqing are ground and mixed in a certain mass ratio by a ball mill respectively, and the catalyst carrier is obtained by mechanical mixing, extrusion molding, drying and roasting.

3. The method for preparing a catalyst for catalyzing directional polycondensation of acetone to mesitylene according to claim 2, characterized in that: The composite oxide is one or more of silicon dioxide, aluminum oxide, 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; The molecular sieve content is 20-70wt%, and the composite oxide content is 30-80wt%.

4. The method for preparing a catalyst for catalyzing the directional polycondensation of acetone to mesitylene according to claim 1, characterized in that: The catalyst carrier in S1 is a nitrogen-doped modified carbon carrier, and the specific preparation method is as follows: a nitrogen modifier solution of 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 carrier, a nitrogen source is introduced into the carbon carrier by an impregnation method to achieve nitrogen doping modification, and the carbon carrier, the nitrogen source and the activator are calcined in a nitrogen atmosphere to obtain a nitrogen-doped modified activated carbon carrier.

5. The method for preparing a catalyst for catalyzing directional polycondensation of acetone to mesitylene according to claim 4, characterized in that: The carbon carrier 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 activated carbon carrier is 1:10 to 1:2.5; The activator is one or more of KOH, K2CO3, and ZnCl2; the mass ratio of the carbon carrier to the activator is 1:0.5 to 1:2; the calcination temperature is 500 to 900°C; the calcination heating rate is 2 to 5°C / min; and the calcination time is 2 to 4h.

6. The method for preparing a catalyst for catalyzing directional polycondensation of acetone to mesitylene according to claim 1, characterized in that: In S2, the active 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%.

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

1.

8. The method for preparing a catalyst for catalyzing directional polycondensation of acetone to mesitylene according to claim 1, characterized in that: In S4, the metal modification aid component is one or more oxides of Group VIB Cr, Mo, W or transition metals Fe, Co, Ni, Cu, Zn or non-metal modification aid P or their precursors, and the content of the oxide in the catalyst is 1 to 10 wt%.

9. The method for preparing a catalyst for catalyzing directional polycondensation of acetone to mesitylene according to claim 3, characterized in that: In S4, a mixed solution of a metal chelating agent and a precursor salt of a metal modification auxiliary component of a required concentration is prepared as an ion exchanger, and the metal modification auxiliary component is introduced into S3 by an ion exchange method to obtain a modified active metal-supported catalyst. The ion exchange method treatment process is: adding the active metal-supported catalyst in S3 to the ion exchanger, soaking for 6 to 12 hours, washing and filtering, stirring in a water bath and evaporating to dryness at a temperature of 80 to 150°C, calcining at a temperature of 350 to 550°C, and calcining for 3 to 9 hours.

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

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