CN119608227A

CN119608227A - A multi-level pore Zr-Beta molecular sieve and its preparation method and application

Info

Publication number: CN119608227A
Application number: CN202510151738.6A
Authority: CN
Inventors: 朱美华; 严华鹏; 杨琴; 段媛; 陈祥树
Original assignee: Jiangxi Normal University
Current assignee: Jiangxi Normal University
Priority date: 2025-02-12
Filing date: 2025-02-12
Publication date: 2025-03-14
Anticipated expiration: 2045-02-12
Also published as: CN119608227B

Abstract

The invention discloses a multi-level pore Zr-Beta molecular sieve and its preparation method and application, and relates to the preparation and application technical field of molecular sieve. The preparation method of the multi-level pore Zr-Beta molecular sieve includes: preparing the multi-level pore Zr-Beta molecular sieve by a hydrothermal synthesis-etching-recrystallization method; the multi-level pore Zr-Beta molecular sieve includes a Beta molecular sieve and Zr loaded on its surface and skeleton, with an average particle size of 100nm~500nm, and micropores, mesopores and/or macropores are present inside; the multi-level pore Zr-Beta molecular sieve is used to catalyze the Friedel-Crafts acylation reaction (isophenylene dimethyl ether and acetic anhydride) under solvent-free conditions to prepare 2,4-dimethoxyacetophenone. The multi-level pore Zr-Beta molecular sieve of the present invention has a multi-level pore structure and an acidic molecular sieve catalytic active site, and has a synergistic catalytic effect. The method for preparing 2,4-dimethoxyacetophenone is green and environmentally friendly, easy to operate, and has high catalytic efficiency.

Description

Hierarchical pore Zr-Beta molecular sieve and preparation method and application thereof

Technical Field

The invention relates to the technical field of preparation and application of molecular sieves, in particular to a hierarchical pore Zr-Beta molecular sieve, and a preparation method and application thereof.

Background

2, 4-Dimethoxy acetophenone (2, 4-Dimethoxyacetophenone) is an organic compound with multiple applications, and is widely used in the industries of perfume, medical intermediate, cosmetics and the like. Because of its special fragrance properties, it is widely used as a fragrance ingredient in the perfume industry, and at the same time has potential in the pharmaceutical field as an intermediate for the synthesis of other organic compounds. At present, the synthesis of 2, 4-dimethoxy acetophenone mainly adopts traditional chemical synthesis methods, such as methylation reaction of aldehyde compounds, however, the methods generally require higher temperature and pressure under the reaction conditions, and can lead to the generation of a large amount of harmful byproducts, thereby polluting the environment.

To address these challenges, researchers are actively looking for more efficient, environmentally friendly alternative catalysts and synthetic routes. In the synthesis of aromatic ketones, friedel-Crafts acylation is a widely established synthetic method. However, the conventional Lewis acid catalyst generally has the problems of difficult catalyst recovery, excessive acid waste liquid, complicated post-treatment process and the like. In order to solve these problems, in recent years, researchers have proposed the use of solid acid catalysts as an alternative. Beta molecular sieve as one kind of material with relatively high acidity and pore canal structure has shown superiority and potential in Friedel-crafts acylation reaction. Previous studies indicate that Beta molecular sieves are capable of catalyzing acylation reactions at lower temperatures, and have higher catalytic activity and recyclability. Therefore, the Beta molecular sieve not only can replace the traditional Lewis acid catalyst, but also has the advantages of easy recovery, simple post-treatment and reaction cost, and the service life and recovery efficiency of the catalyst. Chinese patent CN110860307A proposes a technical route for synthesizing aromatic ketone compounds by catalyzing Friedel-crafts acylation reaction by using Beta molecular sieve, and further verifies the potential of the aromatic ketone compounds in the fields of high efficiency and environmental protection catalysis. The reaction is carried out under the action of a Lewis acid catalyst, and acyl can be directly introduced into an aromatic ring to obtain the required aromatic ketone compound. In order to develop efficient and environment-friendly catalysts, researchers have explored a variety of materials such as ionic liquids, cation exchange resins, solid superacids, heteropolyacids, and the like. However, under mild reaction conditions, the development of a catalyst which is low in cost, high in efficiency and easy to recycle remains a key to the production of 2, 4-dimethoxyacetophenone.

Disclosure of Invention

The invention aims to at least solve one of the technical problems in the prior art, provides a hierarchical pore Zr-Beta molecular sieve and a preparation method and application thereof, and particularly relates to a synthesis method of a hierarchical pore heteroatom molecular sieve and an aromatic ketone compound, and more particularly relates to a hierarchical pore Zr-Beta molecular sieve and a preparation method thereof, and a method for synthesizing 2, 4-dimethoxy acetophenone.

The invention synthesizes a hierarchical pore Zr-Beta molecular sieve by a hydrothermal synthesis-etching-recrystallization method, aims to optimize the synthesis process of 2, 4-dimethoxy acetophenone, fully considers the potential of combining a molecular sieve catalyst with a hierarchical pore structure with metal oxide, and deeply discusses the application prospect of a solid acid catalyst. By optimizing the structure and reaction conditions of the catalyst, it is desirable to increase the yield and selectivity of the target product while extending the service life of the catalyst, thereby promoting the feasibility thereof in industrial applications.

On the one hand, the invention solves the problems of insufficient activity and slower reaction rate of the traditional catalyst in the reaction process. By adopting the etching method to treat the Zr-Beta molecular sieve, the structure of the internal pore canal of the catalyst is optimized, the activity and the reaction rate of the catalyst are obviously improved, and the yield of the target product is obviously improved. On the other hand, the method solves the problems that the Lewis catalyst cannot be recovered, the post-treatment is complex, the environment is polluted and the like in the traditional Friedel-crafts acylation reaction. The catalyst prepared by the invention not only improves the synthesis efficiency of 2, 4-dimethoxy acetophenone, but also realizes a green and sustainable production process, and effectively promotes the high-yield synthesis of 2, 4-dimethoxy acetophenone.

The technical scheme of the invention is as follows:

in a first aspect, the invention provides a preparation method of the hierarchical pore Zr-Beta molecular sieve, which comprises the following steps:

s1, taking a Beta molecular sieve as a seed crystal, synthesizing sol SiO ₂:Na₂O: TEAOH:Al₂O₃: H₂O: ZrO₂ with a molar ratio of 1:0.03-0.10:0.10-0.35:0.005-0.015:20-50:0.01-0.05, heating and synthesizing to obtain a crystallized Zr-Beta molecular sieve, and cleaning, drying and roasting the crystallized Zr-Beta molecular sieve;

s2, fully mixing the crystallized Zr-Beta molecular sieve with a TEAOH solution for etching to obtain the Zr-Beta molecular sieve with a multistage pore structure;

and S3, recrystallizing the Zr-Beta molecular sieve with the hierarchical pore structure and TEAOH solution, and then centrifuging, drying and calcining to obtain the hierarchical pore Zr-Beta molecular sieve.

Optionally, in step S1, the molar ratio of the synthetic sol SiO ₂:Na₂O: TEAOH:Al₂O₃: H₂O: ZrO₂ is 1:0.04-0.08:0.15-0.33:0.007-0.012:25-40:0.015-0.04, more preferably 1:0.06:0.28:0.01:28.8:0.02;

The temperature and time of the heating synthesis are 120-180 ℃ and 12-48 hours respectively, and more preferably 140-160 ℃ and 20-28 hours;

the temperature and time of the roasting are 450-550 ℃ and 4-12 hours respectively, and more preferably 480-520 ℃ and 4-8 hours.

Optionally, in the step S2, the adding ratio of the crystallized Zr-Beta molecular sieve to the TEAOH solution is 1g:15 mL-40 mL, more preferably 1g:25 mL-35 mL;

the concentration of the TEAOH solution, the etching temperature and the etching time are respectively 0.05M-1.5M, 30-110 ℃ and 1-10 h. More preferably, the concentration of the TEAOH solution is 0.15M-1.3M, and the etching temperature and the etching time are 40 ℃ to 100 ℃ and 1h to 8h respectively.

Optionally, in step S3, the adding ratio of the Zr-Beta molecular sieve with a hierarchical pore structure to the TEAOH solution is 1g:20 ml-35 ml, more preferably 1g:25 ml-35 ml;

The concentration of the TEAOH solution, the temperature and the time of the recrystallization are respectively 0.1-1.3M, 90-170 ℃ and 1-10 h, more preferably, the concentration of the TEAOH solution is 0.15-1.3M, and the temperature and the time of the recrystallization are respectively 100-160 ℃ and 1-8 h.

The temperature and time of calcination are 450-550 ℃ and 6-10 hours respectively.

In a second aspect, the invention provides a hierarchical pore Zr-Beta molecular sieve prepared by the method, which comprises a Beta molecular sieve and Zr loaded on the surface and skeleton of the Beta molecular sieve, wherein the average particle size of the hierarchical pore Zr-Beta molecular sieve is 100-500 nm, and micropores, mesopores and/or macropores are formed in the hierarchical pore Zr-Beta molecular sieve.

In a third aspect, the invention provides a method for preparing 2, 4-dimethoxy acetophenone by using the hierarchical pore Zr-Beta molecular sieve, which comprises the following steps:

And taking the hierarchical pore Zr-Beta molecular sieve as a catalyst, performing Friedel-crafts acylation reaction on the catalytic reaction raw material of m-xylylene ether and acetic anhydride, recovering the hierarchical pore Zr-Beta molecular sieve after the reaction is finished, and washing and purifying a reaction product to obtain the 2, 4-dimethoxy acetophenone.

The reaction formula is as follows:

optionally, the temperature and time of the reaction are respectively 80-150 ℃ and 1-10 hours.

More preferably, the temperature and time of the reaction are 80 ℃ to 120 ℃ and 4 hours to 10 hours respectively.

Optionally, the molar ratio of the m-xylylene ether to the acetic anhydride is 1:1-5, and the ratio of the hierarchical pore Zr-Beta molecular sieve to the reaction solution (the total mass of the m-xylylene ether and the acetic anhydride) is 0.5-20 wt%.

More preferably, the molar ratio of the m-xylylene ether to the acetic anhydride is 1:2-4, and the ratio of the hierarchical pore Zr-Beta molecular sieve to the reaction solution is 0.8wt% -18 wt%

More preferably, the preparation method comprises the steps of:

(1) A hierarchical pore Zr-Beta molecular sieve is adopted to catalyze Friedel-crafts acylation reaction of m-xylylene ether and acetic anhydride.

(2) Recovering the hierarchical pore Zr-Beta molecular sieve by a centrifugal separation technology after the Friedel-crafts acylation reaction is finished, analyzing the components of a reaction product by adopting gas chromatography, and calculating the conversion rate of the reactant and the selectivity of a main product;

(3) The reaction product was washed with distilled water and the aromatic ketone as the main product was purified by distillation under reduced pressure.

In a fourth aspect, the present invention provides 2, 4-dimethoxyacetophenone obtained by the process.

The invention has at least one of the following beneficial effects:

1. The hierarchical pore Zr-Beta molecular sieve is prepared by a hydrothermal synthesis-etching-recrystallization method, and has good advantages and application prospects. On one hand, a plurality of empty nests are etched in the crystal after the template agent etching treatment, so that the distribution of active sites of pore channel sizes is obviously increased, a micro-mesoporous concurrent multistage pore channel system is formed to improve the molecular mass transfer diffusion rate of the molecular sieve, on the other hand, metal catalytic active sites are formed on the surface of the molecular sieve and are packaged in the empty nests and the pore channels in the molecular sieve crystal by a recrystallization method, and the catalytic reaction efficiency of the molecular sieve is further enhanced, so that the multistage pore Zr-Beta molecular sieve not only has a multistage pore channel structure, but also has an acidic molecular sieve catalytic active site, thereby having a synergistic catalytic effect and greatly enhancing the conversion efficiency of the m-xylylene dimethyl ether.

2. When the prepared hierarchical pore Zr-Beta molecular sieve is used for catalyzing m-xylylene ether and acetic anhydride to synthesize 2, 4-dimethoxy acetophenone, the 2, 4-dimethoxy acetophenone has 100 percent selectivity, the conversion efficiency of m-xylylene ether is high, the yield of target products can be improved, the problems of irrecoverable and poor stability of the traditional catalyst are solved, and the environment pollution is effectively caused. In addition, the preparation process of the catalyst is green and environment-friendly, the post-treatment is simple, the reaction is stable, the benefit is high, and the catalyst has wide application prospect.

Drawings

FIG. 1 is a schematic illustration of the preparation of a hierarchical pore Zr-Beta molecular sieve according to example 1.

FIG. 2 is a representation of a hierarchical pore Zr-Beta molecular sieve prepared in example 1, wherein (a) is an SEM photograph, (b) is an XRD pattern, (c) is an N ₂ adsorption-desorption curve, and (d) is an FTIR spectrum.

FIG. 3 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 1.

FIG. 4 is a nuclear magnetic resonance spectrum of 2, 4-dimethoxyacetophenone prepared in example 1.

FIG. 5 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 2.

FIG. 6 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 3.

FIG. 7 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 4.

FIG. 8 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 5.

FIG. 9 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 6.

FIG. 10 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 7.

FIG. 11 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 8.

FIG. 12 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in comparative example 1.

FIG. 13 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in comparative example 2.

FIG. 14 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in comparative example 3.

FIG. 15 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in comparative example 4.

FIG. 16 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 9.

FIG. 17 is a gas chromatography chart of 2, 4-dimethoxyacetophenone prepared in example 10.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Example 1

The embodiment provides a preparation method of a hierarchical pore Zr-Beta molecular sieve, and FIG. 1 is a schematic diagram of a preparation process of the hierarchical pore Zr-Beta molecular sieve, comprising the following steps of firstly adopting a commercial Beta molecular sieve (Tianjin southward catalyst Co., ltd., average grain size of 200 nm) as a seed crystal, preparing the Zr-Beta molecular sieve by a secondary hydrothermal synthesis method, synthesizing a synthetic gel with a sol molar ratio of 1SiO ₂:0.06Na₂O:0.28TEAOH:0.01Al₂O₃:28.8H₂O:0.02ZrO₂, and respectively synthesizing at a synthesis temperature of 150 ℃ and a synthesis time of 24 h. The crystallized Zr-Beta molecular sieve is cleaned, dried and baked for 6 hours under 823K for standby. And secondly, transferring the roasted Zr-Beta molecular sieve and 0.75M TEAOH solution into a PP bottle together according to the proportion of 30 ml/g, wherein the reaction temperature and the reaction time are respectively 80 ℃ and 3h, and etching to obtain the Zr-Beta molecular sieve with a multistage pore structure. Finally, the Zr-Beta molecular sieve with the hierarchical pore structure and 0.25M TEAOH solution are transferred into a reaction kettle together according to the proportion of 30 ml/g for recrystallization, the synthesis temperature and the synthesis time are respectively 150 ℃ and 2h, and after recrystallization, the hierarchical pore Zr-Beta molecular sieve is collected through centrifugation, drying and calcination (550 ℃ and 10 hours).

FIG. 2 is a representation of the results of a hierarchical pore Zr-Beta molecular sieve. In FIG. 2, (a) is an electron microscopic image of a hierarchical pore Zr-Beta molecular sieve, the surface is rough, and the average particle diameter is about 200 nm. FIG. 2 (b) is an XRD pattern of a hierarchical pore Zr-Beta molecular sieve, and the sample shows characteristic peaks of a typical Beta molecular sieve. In FIG. 2, (c) is an N ₂ adsorption-desorption curve and a pore size distribution diagram of the hierarchical Zr-Beta molecular sieve, an isothermal adsorption curve of a sample is biased to a y axis in a low specific pressure region, the existence of micropores is indicated, the hierarchical Zr-Beta molecular sieve has obvious hysteresis in a high specific pressure region, the existence of mesopores/macropores is indicated, in FIG. 2, (d) is an FTIR spectrum of the hierarchical Zr-Beta molecular sieve, and the FTIR analysis result indicates that the structure of the hierarchical Zr-Beta molecular sieve is obviously influenced by the introduction of zirconium (Zr). In the Zr-Beta-0.75-0.25 samples, the absorption peaks at 3700 cm ^-1 and 3500 cm ^-1 are respectively related to the telescoping vibration of the silicon hydroxyl group (Si-OH) and the zirconium hydroxyl group (Zr-OH), which proves that zirconium is successfully introduced into the surface of the molecular sieve. 1650 The absorption peak of cm ^-1 is associated with adsorbed water molecules, 1100 cm ^-1 with internal tetrahedrally coordinated oxygen (O-T-O), and 1000 cm ^-1 with vibration of silicon-oxygen-zirconium bonds (Si-O-Zr), indicating that zirconium has been incorporated into the molecular sieve framework. 1200 The absorption peak of cm ^-1 may reflect the interaction of zirconium with surface hydroxyl groups.

The embodiment also provides a method for preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using a hierarchical pore Zr-Beta molecular sieve, which comprises the following steps:

Firstly, catalyzing Friedel-crafts acylation reaction of the isophthalate dimethyl ether and acetic anhydride by using a hierarchical pore Zr-Beta molecular sieve, wherein the reaction temperature and the reaction time are 120 ℃ and 6 hours, the molar ratio of the isophthalate dimethyl ether to the acetic anhydride is 1:3.5, and the mass of the hierarchical pore Zr-Beta molecular sieve accounts for 1wt% of the total mass of the reaction liquid.

And secondly, recovering the hierarchical pore Zr-Beta molecular sieve by a centrifugal separation technology after the Friedel-crafts acylation reaction is finished, analyzing the components of a reaction product by adopting gas chromatography, and calculating the conversion rate of the reactant and the selectivity of a main product.

Under the reaction conditions, the conversion rate of the m-xylylene is 71.64%, the selectivity of the 2, 4-dimethoxy acetophenone is 100%, the figure 3 is a gas chromatographic chart of a reaction product, 4 peaks are shown in the figure 3, the retention time is 1.98 min, the retention time is 2.02 min, the retention time is 2.73 min, the retention time is 5.51 min, and the retention time is 2, 4-dimethoxy acetophenone. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Finally, the reaction product was washed with distilled water and the main product 2, 4-dimethoxyacetophenone was purified by distillation under reduced pressure.

FIG. 4 is a nuclear magnetic resonance spectrum of the purified main product 2, 4-dimethoxyacetophenone. The nuclear magnetic resonance hydrogen spectrum (& lt 1H NMR) of 2, 4-dimethoxyacetophenone shows its characteristic chemical shift and peak shape, which are consistent with the structure of the compound. In the spectra, the peaks at chemical shifts 7.84 ppm and 7.83 ppm correspond to hydrogen atoms on the aromatic ring, while the peaks at chemical shifts 3.90 ppm and 3.89 ppm may correspond to hydrogen atoms attached to oxygen atoms. Peaks for chemical shifts 2.58 ppm and 2.57 ppm may then correspond to hydrogen atoms on the alkyl chain attached to the aromatic ring. Fewer inconsistent additional signals can be observed in the spectra, indicating higher purity of the product. The area of the integral curve is consistent with the theoretical proportion of hydrogen atoms in the compound, and the purity of the product is further confirmed.

Example 2

The Zr-Beta molecular sieve with the multi-stage pore structure is prepared differently from the example 1 in that the concentration of TEAOH solution in the process of preparing the Zr-Beta molecular sieve with the multi-stage pore structure by etching is 0.25M.

The process of preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using a hierarchical pore Zr-Beta molecular sieve is consistent with the process of the embodiment 1, wherein the catalytic performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of m-phenylene dimethyl ether is 60.65 percent, and the selectivity of 2, 4-dimethoxy acetophenone is 100 percent. FIG. 5 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 5, retention time 1.97 min assigned to the acetic acid response, retention time 2.01 min assigned to the acetic anhydride response, retention time 2.73 min assigned to the isophthaloyl ether response, and retention time 5.47 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 3

The Zr-Beta molecular sieve with the multi-stage pore structure is prepared by the method which is different from the embodiment 1 in that the etching temperature and the etching time in the process of preparing the Zr-Beta molecular sieve with the multi-stage pore structure are respectively 100 ℃ and 2 h.

The process of preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using a hierarchical pore Zr-Beta molecular sieve is consistent with the process of example 1, wherein the catalytic performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of m-phenylene dimethyl ether is 64.95%, and the selectivity of 2, 4-dimethoxy acetophenone is 100%. FIG. 6 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 6, retention time 1.96 min assigned to the acetic acid response, retention time 2.01 min assigned to the acetic anhydride response, retention time 2.70 min assigned to the isophthaloyl ether response, and retention time 5.35 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 4

The Zr-Beta molecular sieve with the hierarchical pore structure is prepared differently from example 1 in that the concentration of TEAOH solution in the recrystallization process of preparing the hierarchical pore Zr-Beta molecular sieve is 0.5M.

The process of preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using a hierarchical pore Zr-Beta molecular sieve is consistent with the process of the embodiment 1, wherein the catalytic performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of m-phenylene dimethyl ether is 64.10 percent, and the selectivity of 2, 4-dimethoxy acetophenone is 100 percent. FIG. 7 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 7, retention time 2.02 min attributed to the acetic acid response, retention time 2.05 min attributed to the acetic anhydride response, retention time 2.78 min attributed to the isophthaloyl ether response, and retention time 5.57 min attributed to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 5

The Zr-Beta molecular sieve with the hierarchical pore structure is prepared differently from the embodiment 1 in that the synthesis temperature and the synthesis time in the recrystallization process of preparing the hierarchical pore Zr-Beta molecular sieve are 130 ℃ and 5 h respectively.

The process of preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using a hierarchical pore Zr-Beta molecular sieve is consistent with the process of the embodiment 1, wherein the catalytic performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of m-phenylene dimethyl ether is 57.57 percent, and the selectivity of 2, 4-dimethoxy acetophenone is 100 percent. FIG. 8 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 8, retention time 1.96 min assigned to the acetic acid response, retention time 2.00 min assigned to the acetic anhydride response, retention time 2.73 min assigned to the isophthaloyl ether response, and retention time 5.46 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 6

The Zr-Beta molecular sieve preparation with the multistage pore structure is the same as that of the example 1.

The process for preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction with a hierarchical Zr-Beta molecular sieve is different from example 1 in that the reaction temperature is 100 ℃. The catalyst performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of the isophthaloyl dimethyl ether is 64.14 percent, and the selectivity of the 2, 4-dimethoxy acetophenone is 100 percent. FIG. 9 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 9, retention time 1.95 min assigned to the acetic acid response, retention time 1.99 min assigned to the acetic anhydride response, retention time 2.69 min assigned to the isophthaloyl ether response, and retention time 5.28 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 7

The process for preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction with a hierarchical pore Zr-Beta molecular sieve is different from that of the embodiment 1 in that the molar ratio of the reaction intermediate dimethyl ether to acetic anhydride is 1:1. The catalyst performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of the isophthaloyl dimethyl ether is 29.95 percent, and the selectivity of the 2, 4-dimethoxy acetophenone is 100 percent. FIG. 10 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 10, retention time 1.95 min assigned to the acetic acid response, retention time 1.99 min assigned to the acetic anhydride response, retention time 2.73 min assigned to the isophthaloyl ether response, and retention time 5.36 min assigned to the 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 8

The process for preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction with a hierarchical Zr-Beta molecular sieve is different from the process of the embodiment 1 in that the mass ratio of the hierarchical Zr-Beta molecular sieve to reactants (isophthaloyl dimethyl ether and acetic anhydride) is 4 wt%. The catalyst performance of the hierarchical pore Zr-Beta molecular sieve is that the conversion rate of the m-xylylene is 100 percent, and the selectivity of the 2, 4-dimethoxy acetophenone is 100 percent. FIG. 11 is a gas chromatograph of the reaction product. In FIG. 11 there are 3 peaks with a retention time of 2.01 min for acetic acid response, a retention time of 2.05 min for acetic anhydride response and a retention time of 5.58 min for product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Comparative example 1

A method for preparing 2, 4-dimethoxy acetophenone by using a commercial Beta molecular sieve (Tianjin southbound catalyst Co., ltd., average grain size of 200 nm) is provided, wherein the process of preparing 2, 4-dimethoxy acetophenone by catalyzing Friedel-crafts acylation reaction by using the commercial Beta molecular sieve is consistent with the process of example 1, and the catalytic performance of the commercial Beta molecular sieve is that the conversion rate of m-phenylene dimethyl ether is 32.15%, and the selectivity of 2, 4-dimethoxy acetophenone is 92.49%. FIG. 12 is a gas chromatograph of the reaction product, with 5 peaks in FIG. 12, retention time 2.01 min attributed to acetic acid response, retention time 2.24 min acetic anhydride response, retention time 2.86 min attributed to isophthaloyl ether response, retention time 4.33 min attributed to product 2, 6-dimethoxyacetophenone response, and retention time 5.73 min attributed to product 2, 4-dimethoxyacetophenone response.

Comparative example 2

A process for the preparation of a homemade Zr-Beta molecular sieve (Zr ₂/SiO₂ =0.1, average particle size 200 nm) is provided, which differs from example 1 in that the homemade Zr-Beta molecular sieve in comparative example 2 is not etched and recrystallized.

The preparation method of the self-made Zr-Beta molecular sieve in the comparative example 2 comprises the following steps:

The Zr-Beta molecular sieve is prepared by adopting a commercial Beta molecular sieve (Tianjin southward catalyst Co., ltd., average grain size is 200 nm) as seed crystal through a secondary hydrothermal synthesis method, and the synthetic gel with the molar ratio of 1SiO ₂:0.06Na₂O:0.28TEAOH:0.01Al₂O₃:28.8H₂O:0.02ZrO₂ of the synthetic sol is synthesized at the synthesis temperature of 150 ℃ and the synthesis time of 24 h respectively. The crystallized Zr-Beta molecular sieve is cleaned, dried and baked for 6 hours under 823K for standby.

The process of preparing 2, 4-dimethoxy acetophenone by adopting a self-made Zr-Beta molecular sieve to catalyze Friedel-crafts acylation reaction is the same as that of the example 1, wherein the self-made Zr-Beta molecular sieve has the catalysis performance that the conversion rate of the isophthaloyl dimethyl ether is 56.25 percent, and the selectivity of the 2, 4-dimethoxy acetophenone is 100 percent. FIG. 13 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 13, retention time 1.99 min assigned to the acetic acid response, retention time 2.03 min assigned to the acetic anhydride response, retention time 2.76 min assigned to the isophthaloyl ether response, and retention time 5.49 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Comparative example 3

A method for preparing a self-made hierarchical pore Beta molecular sieve (average particle size 200 nm) is provided, which is different from example 1 in that the self-made hierarchical pore Beta molecular sieve in comparative example 3 does not contain Zr and is not recrystallized.

The preparation method of the self-made hierarchical pore Beta molecular sieve in the comparative example 3 comprises the following steps:

firstly, a commercial Beta molecular sieve (Tianjin southward catalyst Co., ltd., average grain size of 200 nm) is used as seed crystal, the Beta molecular sieve is prepared by a secondary hydrothermal synthesis method, the synthetic gel with the mol ratio of 1SiO ₂:0.06Na₂O:0.28TEAOH:0.01Al₂O₃:28.8H₂ O of the synthetic sol is synthesized, and the synthesis temperature and the synthesis time are respectively 150 ℃ and 24 h. The crystallized Zr-Beta molecular sieve is cleaned, dried and baked for 6 hours under 823K for standby. And secondly, transferring the calcined Beta molecular sieve and 0.75M TEAOH solution into a PP bottle together according to the proportion of 30 ml/g, wherein the reaction temperature and the reaction time are respectively 80 ℃ and 3 h, and etching to obtain the Beta molecular sieve with the hierarchical pores.

The process of preparing 2, 4-dimethoxy acetophenone by adopting self-made hierarchical pore Beta molecular sieve to catalyze Friedel-crafts acylation reaction is the same as that of example 1, and the self-made hierarchical pore Beta molecular sieve has the catalysis performance that the conversion rate of m-phenylene dimethyl ether is 53.22% and the selectivity of 2, 4-dimethoxy acetophenone is 100%. FIG. 14 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 14, retention time 1.96 min assigned to the acetic acid response, retention time 2.00 min assigned to the acetic anhydride response, retention time 2.69 min assigned to the isophthaloyl ether response, and retention time 5.29 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Comparative example 4

The preparation method of the Zr-Beta molecular sieve is different from the preparation method of the embodiment 1 in that 'the Zr-Beta molecular sieve with a multistage pore structure is obtained after etching', the recrystallization process is not carried out, and calcination is directly carried out (550 ℃ and 10 hours) to obtain the Zr-Beta-0.75.

The procedure for preparing 2, 4-dimethoxyacetophenone was as in example 1, with a conversion of 60.53% of isophthaloyl dimethyl ether and a selectivity of 2, 4-dimethoxyacetophenone of 100%, using Zr-Beta-0.75 as catalyst, which was prepared without recrystallization. FIG. 15 is a gas chromatograph of the reaction product, 4 peaks in FIG. 15, response to acetic acid with retention time 2.03 min, response to acetic anhydride with retention time 2.07 min, response to isophthaloyl dimethyl ether with retention time 2.79min, and response to product 2, 4-dimethoxyacetophenone with retention time 5.55 min. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 9

The preparation method of the Zr-Beta molecular sieve is different from the preparation method of the embodiment 1 in that the etching time is changed to 1h, and the Zr-Beta molecular sieve is obtained by other steps in the embodiment 1.

The method for preparing 2, 4-dimethoxy acetophenone by using the Zr-Beta molecular sieve obtained in the etching time of 1h as a catalyst is the same as that of the example 1, the conversion rate of the m-anisole is 46.14%, and the selectivity of the 2, 4-dimethoxy acetophenone is 100%. FIG. 16 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 16, retention time 1.95 min assigned to the acetic acid response, retention time 1.99 min assigned to the acetic anhydride response, retention time 2.69 min assigned to the isophthaloyl ether response, and retention time 5.28 min assigned to the 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

Example 10

The preparation method of the Zr-Beta molecular sieve is different from the preparation method of the embodiment 1 in that the etching time is changed to 8h, and the other steps are the same as those of the embodiment 1, so that the Zr-Beta molecular sieve is obtained.

The method for preparing 2, 4-dimethoxy acetophenone by using the Zr-Beta molecular sieve obtained in the etching time of 8 hours as a catalyst is the same as that of the example 1, the conversion rate of the m-anisole is 71.26%, and the selectivity of the 2, 4-dimethoxy acetophenone is 100%. FIG. 17 is a gas chromatograph of the reaction product, with 4 peaks in FIG. 17, retention time 1.98 min assigned to the acetic acid response, retention time 2.02 min assigned to the acetic anhydride response, retention time 2.73 min assigned to the isophthaloyl ether response, and retention time 5.51 min assigned to the product 2, 4-dimethoxyacetophenone response. The final product of this example was shown to be 2, 4-dimethoxyacetophenone.

TABLE 1 Friedel-crafts acylation reaction conditions and corresponding catalytic Properties in the examples and comparative examples

As can be seen from Table 1, the selectivity of 2, 4-dimethoxyacetophenone in examples 1-10 of the present invention is 100%, which indicates that the hierarchical pore Zr-Beta molecular sieve prepared by the present invention has high selectivity to 2, 4-dimethoxyacetophenone, and the selectivity is superior to commercial Beta (comparative example 1).

In the invention, the conversion rate of the intermediate anisole is 100 percent (in the embodiment 8) and 29.95 percent (in the embodiment 7) at the highest, which shows that the molar ratio of the reactant raw materials can influence the conversion rate of the intermediate anisole. Also, as can be seen by comparing example 1, example 8 and example 9, the etching time also affects the conversion of isophthalamide. When the molar ratio of reactant raw materials is 1:3.5, the conversion rate of the isophthalate of the hierarchical pore Zr-Beta prepared under a plurality of reaction conditions is superior to that of commercial Beta (comparative example 1) and that of a self-made Zr-Beta molecular sieve (comparative example 2), and under the same reaction conditions, the conversion rate of the isophthalate of the hierarchical pore Zr-Beta prepared in the embodiment 1 is superior to that of the self-made hierarchical pore Beta molecular sieve (comparative example 3), which shows that the catalytic performance of the hierarchical pore Zr-Beta prepared in the invention is superior to that of the hierarchical pore Beta prepared by other methods.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims

1. The preparation method of the hierarchical pore Zr-Beta molecular sieve is characterized by comprising the following steps of:

2. The method according to claim 1, wherein in the step S1, the molar ratio of the synthetic sol SiO ₂:Na₂O: TEAOH:Al₂O₃: H₂O: ZrO₂ is 1:0.04-0.08:0.15-0.33:0.007-0.012:25-40:0.015-0.04;

the temperature and time of the heating synthesis are 120-180 ℃ and 12-48 hours respectively;

the temperature and time of the roasting are 450-550 ℃ and 4-12 hours respectively.

3. The preparation method according to claim 1, wherein in the step S2, the addition ratio of the crystallized Zr-Beta molecular sieve to the TEAOH solution is 1g:15 mL-40 mL;

the concentration of the TEAOH solution, the etching temperature and the etching time are respectively 0.05M-1.5M, 30-110 ℃ and 1-10 h.

4. The preparation method of claim 1, wherein in the step S3, the adding ratio of the Zr-Beta molecular sieve with a multi-stage pore structure to the TEAOH solution is 1g:20 ml-35 ml;

The concentration of the TEAOH solution, the temperature and the time of recrystallization are respectively 0.1-1.3M, 90-170 ℃ and 1-10 h;

5. The hierarchical pore Zr-Beta molecular sieve obtained by the preparation method according to any one of claims 1-4, which is characterized by comprising a Beta molecular sieve and Zr loaded on the surface and skeleton of the Beta molecular sieve, wherein the average particle size of the hierarchical pore Zr-Beta molecular sieve is 100-500 nm, and micropores, mesopores and/or macropores exist in the hierarchical pore Zr-Beta molecular sieve.

6. A method for preparing 2, 4-dimethoxy acetophenone by using the hierarchical pore Zr-Beta molecular sieve according to claim 5, comprising the steps of:

Taking the hierarchical pore Zr-Beta molecular sieve as a catalyst, catalyzing m-xylylene ether and acetic anhydride to carry out Friedel-crafts acylation reaction, obtaining a reaction product after the reaction is finished, recycling the hierarchical pore Zr-Beta molecular sieve,

And washing and purifying the reaction product to obtain the 2, 4-dimethoxy acetophenone.

7. The method of claim 6, wherein the friedel-crafts acylation reaction is performed at a temperature of 80 ℃ to 150 ℃ and for 1h to 10 h, respectively.

8. The method according to claim 6, wherein the molar ratio of the isophthalate to the acetic anhydride is 1:1-5, and the ratio of the hierarchical pore Zr-Beta molecular sieve to the reaction solution is 0.5wt% to 20 wt%.

9. A 2, 4-dimethoxyacetophenone obtained by the method of any one of claims 6-8.