H beta molecular sieve catalyst as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of an H beta molecular sieve catalyst, which comprises the following steps: carrying out acid-base alternate etching on a roasted H beta molecular sieve according to an acid-base sequence by adopting an acid-base alternate etching method, and optionally carrying out ion exchange and roasting on a product obtained after alkali etching to obtain the H beta molecular sieve catalyst. According to the method disclosed by the invention, the H beta molecular sieve is modified through acid-base alternate etching, so that not only is abundant binary micro / mesopores constructed, the specific surface area of the molecular sieve increased and the mass transfer effect enhanced, but also the required acid strength and appropriate L and B acid sites are provided by changing the acid strength and the acid type on the pore channel and the surface of the catalyst subjected to acid-base etching. The prepared H beta molecular sieve catalyst is applied to Friedel-Crafts acylation reaction of anisole and acetic anhydride, and the catalytic activity is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst and fine chemical intermediate production, and particularly relates to an Hβ molecular sieve catalyst and a preparation method thereof, and application of the catalyst in the synthesis of p-methoxyacetophenone by Friedel-Crafts acylation reaction. Background Art

[0002] p-Methoxyacetophenone ( P -MOAP) is an important aromatic ketone fine chemical product. At present, the industry mainly uses homogeneous catalysts such as Lewis acids (AlCl3, FeCl3, etc.) to produce it through Friedel-Crafts acylation reaction using intermittent reaction process. P -MOAP. Although the process has a high yield of acylation products, mild reaction conditions, and cheap and readily available raw materials, it also has problems such as catalyst corrosion equipment, difficulty in product refining, difficulty in catalyst regeneration, and complex process flow. Therefore, the development of efficient solid acid catalysts and corresponding fixed bed production processes is crucial to achieving P -The green industrial production of MOAP is of great significance.

[0003] At present, not only in the fields of medicine and beauty, but also in the fields of new energy vehicles, chip semiconductors and other industries, innovation and development are constantly taking place. The scale and demand of aromatic ketones in China are constantly increasing, and the production, safety and environmental problems brought about by the use of homogeneous catalytic processes such as anhydrous AlCl3 are becoming increasingly prominent. First, anhydrous AlCl3 is not easy to store as a catalyst, and it is easy to lose its catalytic effect due to water absorption. Secondly, the aromatic ketones produced by the FC acylation reaction (Friedel-Crafts) combine with anhydrous AlCl3 to form a relatively stable complex. As the reaction proceeds, the amount of anhydrous AlCl3 participating in the reaction decreases. Therefore, before the reaction, a stoichiometric ratio greater than that required for the reaction must be input, resulting in the use of a large amount of AlCl3 catalyst. In addition, a large amount of water must be added to the reactor. A large amount of heat and HCl gas are released when the aromatic ketone-AlCl3 complex is hydrolyzed, resulting in a decrease in the yield of the aromatic ketone product. In the end, the waste liquid aqueous phase containing aluminum ions is not easy to separate and recover, so a large amount of waste liquid is generated. This traditional BSTR (boiler-type intermittent) process has problems such as complex process flow, high catalyst consumption and difficulty in regeneration, and serious pollution of three wastes. There is an urgent need to develop a new process that is green, pollution-free, and has a recoverable catalyst to replace the traditional process that uses homogeneous catalysts such as anhydrous AlCl3.

[0004] At present, p-methoxyacetophenone ( PThe synthesis method of p-methoxyacetophenone (-MOAP) is to use Friedel-Crafts acylation reaction, which uses acid catalysts to react aromatic hydrocarbons with acyl chlorides or anhydrides at a certain temperature and pressure. At present, clay catalysts, solid superacid catalysts, heteropolyacid catalysts, composite metal oxide catalysts, zeolite molecular sieve catalysts and other catalysts have been tried for p-methoxyacetophenone ( P -MOAP) production.

[0005] Although traditional Lewis acid catalysts have high activity and good selectivity in Friedel-Crafts acylation reactions, their main disadvantage is that they cannot be recycled and seriously pollute the environment. Solid acid catalysts as alternatives to traditional homogeneous catalysts can reduce pollution to a certain extent, have excellent catalytic activity and are easy to recycle. Solid superacids such as trifluoromethanesulfonates are expensive and difficult to prepare, and have limitations in actual industrial production. Although modified heteropolyacids can effectively catalyze acylation reactions, further research is needed to achieve sustainable catalytic performance of the catalyst. Composite metal oxide catalysts are non-toxic, harmless, cheap and easy to obtain, but they deactivate quickly. Zeolite molecular sieves, as environmentally friendly catalysts, have attracted widespread attention in Friedel-Crafts acylation reactions of aromatic rings because of their advantages such as high uniformity of pores, easy tunability and selectivity for reactant and product molecules, which are difficult to match with other catalytic materials. Among them, Hβ molecular sieve has shown excellent catalytic performance in the acylation reactions of various substrates due to its special three-dimensional macroporous structure and suitable acid center strength. It is a very potential Friedel-Crafts acylation catalyst and has also attracted increasing attention from researchers.

[0006] However, commercial Hβ molecular sieves have low activity and still need to be post-modified to improve their activity. Acid-base etching is the simplest, most economical and effective method. Different types of acid or base etching, such as single inorganic acid or inorganic base etching, can change its structural characteristics, acid strength, etc. Methods for modifying Hβ molecular sieves include hydrothermal treatment and the like.

[0007] Zhao Dishun et al. (Catalysis Letters, 2008, 126: 188) used acetic anhydride as the acylating agent and carried out the acylation reaction of anisole under the catalysis of Hβ molecular sieves modified with different acids. They found that the catalytic activity and stability of Hβ molecular sieves modified with hydrochloric acid were improved.

[0008] Li Guohua et al. (Study on the acylation reaction of anisole and acetic anhydride catalyzed by multi-level pore Hβ molecular sieve, [J]. Modern Chemical Industry, 2019(002):039.), obtained multi-level pore Hβ molecular sieve by treating Hβ (25) molecular sieve with 0.2mol / L NaOH solution. Relevant characterization showed that the alkali treatment did not change the crystal structure of the molecular sieve, and the treated molecular sieve had a larger mesoporous structure, which improved the mass transfer effect. The acylation reaction of anisole and acetic anhydride was used as a probe to test the catalytic effect of the Hβ molecular sieve after alkali treatment. Under the conditions of reaction time of 2h, reaction temperature of 120℃, catalyst mass of 2g, and reactant molar ratio of 1.5, the conversion rate of anisole was 89.27% ​​and the selectivity was 97.2%. The conversion rate of this catalyst needs to be improved. Summary of the invention

[0009] The purpose of the present invention is to provide a method for preparing Hβ molecular sieve catalyst by acid-base alternating etching method and the prepared catalyst, through the acid-base step-by-step alternating etching process, binary micro / mesopores are constructed to modify it, while increasing its specific surface area and enhancing the mass transfer effect, and at the same time obtaining suitable acid strength and acid type, thereby improving its catalytic activity in Friedel-Crafts acylation reaction.

[0010] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: A method for preparing a Hβ molecular sieve catalyst, characterized by comprising the following steps performed in sequence: (1) calcining the Hβ molecular sieve; (2) Acid etching: Add the calcined Hβ molecular sieve into an acid solution, stir or ultrasonicate it to dissolve it, heat it under reflux for reaction, cool it to room temperature after the reaction is completed, wash, dry and grind the product into powder; (3) Alkali etching: adding the product obtained in step (2) into an alkaline solution, stirring or ultrasonicating it to dissolve it, heating it under reflux for reaction, cooling it to room temperature after the reaction is completed, washing, drying and grinding the product into powder; (4) calcining the product after alkali etching in step (3), or calcining after ion exchange, to obtain an Hβ molecular sieve catalyst.

[0011] The Hβ molecular sieve is Hβ (25), Hβ (55), Hβ (75), Hβ (120) or all-silicon Hβ molecular sieve.

[0012] Preferably, the reaction temperature of the acid etching is 60-90° C., the reflux reaction is heated for 2-6 hours, and the molar concentration of the acid solution is 0.5 mol / L-1.5 mol / L.

[0013] Preferably, the reaction temperature of the alkaline etching is 40-60° C., the heating reflux reaction is 0.5-2 h, and the molar concentration of the alkaline solution is 0.1 mol / L-0.5 mol / L.

[0014] Preferably, the solvent of the acid solution or the alkaline solution includes, but is not limited to, one or more of water, methanol, ethanol, acetonitrile, hexane and cyclohexane.

[0015] Preferably, the acid solution includes, but is not limited to, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, etc., and organic acids such as tartaric acid, citric acid and acetic acid, one or more of which are preferably inorganic hydrochloric acid or nitric acid.

[0016] The alkaline solution includes, but is not limited to, inorganic bases such as alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, ammonia water, etc., and organic bases are quaternary ammonium hydroxide salts, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylethylammonium hydroxide, tetrapropylammonium hydroxide (TPAOH), etc., preferably one or more selected from sodium hydroxide, sodium carbonate, TPAOH, and ammonia water. More preferably, the organic base TPAOH. When the base is an alkali metal oxide, carbonate (bicarbonate) salt, etc. containing metal ions, the product after alkaline etching needs to be ion exchanged and then roasted.

[0017] In the steps (2) and (3), the mass ratio of the acid solution, the alkaline solution and the Hβ molecular sieve is 10 to 50:1, preferably 20 to 25:1.

[0018] Furthermore, the ion exchange in step (4) is to add the product after alkali etching into an ion exchanger solution, stir or ultrasonicate to dissolve it, heat and reflux to react, cool to room temperature after the reaction is completed, wash, dry and grind the product into powder; the ion exchanger is selected from ammonium chloride, ammonium nitrate, etc.; preferably, the ion exchanger is ammonium chloride, the molar concentration is 0.5-1 mol / L, the exchange temperature is 60-80°C, and the exchange time is 2-4h.

[0019] In step (1), preferably, the calcination temperature is 550° C. and the calcination time is 3 to 6 h.

[0020] The invention also relates to an Hβ molecular sieve catalyst prepared by the acid-base alternating etching method.

[0021] The present invention also provides the use of the Hβ molecular sieve catalyst prepared by acid-base alternating etching in the Friedel-Crafts acylation reaction of anisole and acetic anhydride.

[0022] In the Friedel-Crafts acylation reaction, the reaction temperature is 110-120° C., the molar ratio of anisole to acetic anhydride is (3-3.5) / 1, the acetic anhydride is 0.1 mol, and the Hβ molecular sieve catalyst is 1 g.

[0023] Beneficial effects: The Hβ molecular sieve catalyst prepared by the acid-base alternating etching method of the present invention is modified by constructing binary micro / mesopores through the acid-base step-by-step alternating etching process, and a binary pore is constructed to enhance the mass transfer effect while increasing its specific surface area. The acid-base alternating etching also changes the acid strength and acid type on the catalyst pores and surface, providing the acid strength and suitable L and B acid sites required for the reaction, thereby promoting the improvement of catalytic activity. The prepared Hβ molecular sieve has improved its catalytic activity in the Friedel-Crafts acylation reaction. The method for preparing the Hβ molecular sieve catalyst by acid-base etching of the present invention is simple and has a low preparation cost. The catalyst obtained after acid-base alternating etching has significantly improved catalytic activity for anisole and acetic anhydride. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Example 1 BET diagram of Hβ (75) molecular sieve catalyst prepared by acid-base alternating etching method.

[0025] Figure 2 Example 1 NH3-TPD diagram of Hβ (75) molecular sieve catalyst prepared by acid-base alternating etching method.

[0026] Figure 3 Example 1 FI-IR image of Hβ (75) molecular sieve catalyst prepared by acid-base alternating etching method. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is described in detail below through specific embodiments. However, it is necessary to point out that the following embodiments are only used to describe the content of the present invention and do not constitute a limitation on the protection scope of the present invention.

[0028] In the following examples, the activity test method of the catalyst in the Friedel-Crafts acylation reaction of anisole and acetic anhydride is as follows: the molecular sieve catalyst obtained after acid-base alternating etching is ground into a powder larger than 100 mesh, and 1 g is weighed for standby use. 32.442 g (0.3 mol) of anisole and 10.209 g (0.1 mol) of acetic anhydride are weighed in a three-necked flask with a magnet using an analytical balance, and the magnetic stirring speed is controlled to be 600 r / min. A condenser, a thermometer, and a nitrogen replacement gas path are installed on the three-necked flask. Set the temperature of the oil bath pot, and when the temperature displays the set value, add the pre-weighed catalyst to the three-necked flask, followed by nitrogen replacement. Then start timing. During the experiment, samples are taken at regular intervals, filtered through a 0.22 um organic filter head, and then chromatographed, and the catalyst activity is evaluated using the internal standard method.

[0029] Example 1 A method for preparing Hβ (75) molecular sieve catalyst by acid-base alternating etching, the specific steps are as follows: Weigh 5g of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and heat it up (heating rate is 5℃ / min) to 550℃ and roast it for 5h. After cooling to room temperature, take out 4g of the roasted Hβ (75) molecular sieve and place it in a dry, refluxed 250ml flask, and add 80g of pre-prepared 1.0mol / L hydrochloric acid, then ultrasonicate for 10min to dissolve it completely, then place it in a water bath pot with mechanical stirring at 80℃, heat and reflux for 4h, quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and place it in a drying dish for use.

[0030] Accurately weigh 3g of the powder obtained above and put it into a 200ml dry flask with reflux, then add 60g of pre-prepared 0.1mol / L TPAOH (tetrapropylammonium hydroxide), then ultrasonicate for 10min to dissolve it completely, then put it into a water bath with mechanical stirring at 60℃, heat and reflux for 0.5h, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve).

[0031] The solid powder was calcined at 550°C and cooled to room temperature to obtain the acid-base alternating etching Hβ (75) molecular sieve catalyst, which was placed in a drying dish for later use.

[0032] The BET data of the catalyst prepared by acid-base alternating etching Hβ (75) are as follows: Figure 1 As shown in the figure, after acid-base alternating etching, an obvious hysteresis loop appears in the relative pressure region of 0.85-0.95, a binary channel is constructed, the number of micro-mesopores increases, and its specific surface area is increased, thereby increasing the mass transfer effect. Figure 2 , 3 As shown in the figure, the desorption peaks of NH3-TPD at medium and low temperature and high temperature regions and the Py-IR at 1540 cm -1 and 1450cm -1 The characterization results show that the acid strength and acid type in the catalyst pores and on the surface change after acid-base etching. Alternating acid-base etching also provides the acid strength and suitable L and B acid sites required for the reaction.

[0033] Example 2 A method for preparing Hβ (75) molecular sieve catalyst by acid-base alternating etching, the specific steps are as follows: Weigh a certain amount of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h. After cooling to room temperature, take out a certain amount of roasted Hβ (75) molecular sieve into a dry, refluxed 250ml flask, and add pre-prepared 1.0mol / L hydrochloric acid, the mass ratio of hydrochloric acid to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath pot with mechanical stirring at 80℃, heat and reflux for 4h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for use.

[0034] Accurately weigh a certain mass of the powder obtained above into a 200ml dry flask with reflux, then add the pre-prepared 0.2mol / L NaOH, the mass ratio of NaOH solution to Hβ molecular sieve is 20:1, and then ultrasonicate for 10 minutes to dissolve it completely. Then put it into a water bath with mechanical stirring at 60℃, heat and reflux for 0.5h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it into a drying dish for use.

[0035] Take a certain amount of the above powder in a flask with reflux, add the pre-prepared 1.0 mol / L NH4Cl, and then ultrasonicate for 10 minutes to dissolve it completely. Then put it in a water bath with mechanical stirring at 80°C, heat it under reflux for 3 hours, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110°C for 12 hours. Grind the dried solid into powder (pass through a 100 mesh sieve), and calcine it at 550°C to obtain the acid-base alternating etching Hβ (75) molecular sieve catalyst.

[0036] Example 3 A method for preparing a Hβ (75) molecular sieve catalyst by acid-base alternating etching, the specific steps are as follows: Weigh a certain amount of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h. After cooling to room temperature, take out a certain amount of roasted Hβ (75) molecular sieve into a dry, refluxed 250ml flask, and add pre-prepared 1.5mol / L hydrochloric acid, the mass ratio of hydrochloric acid to Hβ molecular sieve is 25:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat and reflux for 4h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for use.

[0037] Accurately weigh a certain mass of the powder obtained above into a 200ml dry flask with reflux, then add the pre-prepared 0.2mol / L TPAOH, the mass ratio of TPAOH solution to Hβ molecular sieve is 25:1, then ultrasonicate for 10 minutes to dissolve it completely and put it into the flask with reflux. Then put it into a water bath with mechanical stirring at 60°C, heat it under reflux for 0.5h, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110°C for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve), and calcine it at 550°C to obtain the acid-base alternating etching Hβ (75) molecular sieve catalyst.

[0038] Example 4 A preparation method of an acid-base alternating etching Hβ (75) molecular sieve catalyst, the specific steps are as follows: Weigh a certain amount of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h. After cooling to room temperature, take out a certain amount of roasted Hβ (75) molecular sieve into a dry, refluxed 250ml flask, and add pre-configured nitric acid with a concentration of 1.5mol / L or 1.0mol / L. The mass ratio of nitric acid to Hβ molecular sieve is 30:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat and reflux for 4h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for use.

[0039] Accurately weigh a certain mass of the powder obtained above into a 200ml dry flask with reflux, then add TPAOH with a pre-configured concentration of 0.2mol / L or 0.1mol / L, and the mass ratio of TPAOH solution to Hβ molecular sieve is 25:1, then ultrasonicate for 10 minutes to dissolve it completely and put it into the flask with reflux. Then put it into a water bath with mechanical stirring at 60°C, heat it under reflux for 0.5h, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110°C for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve), calcine it at 550°C to obtain the acid-base alternating etching Hβ (75) molecular sieve catalyst, and put it in a drying dish for use.

[0040] Example 5 A method for preparing a Hβ (75) molecular sieve catalyst by acid-base alternating etching, the specific steps are as follows: Weigh a certain amount of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h. After cooling to room temperature, take out a certain amount of roasted Hβ (75) molecular sieve into a dry, refluxed 250ml flask, and add it to the pre-prepared 1.0mol / L nitric acid. The mass ratio of nitric acid to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat it under reflux for 4h, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for use.

[0041] Accurately weigh a certain mass of the powder obtained above into a 200ml dry flask with reflux, then add the pre-prepared 0.2mol / L NaOH, the mass ratio of NaOH solution to Hβ molecular sieve is 15:1, and then ultrasonicate for 10 minutes to dissolve it completely. Then put it into a water bath with mechanical stirring at 60℃, heat and reflux for 0.5h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for later use.

[0042] Take a certain amount of the above powder in a flask with reflux, add the pre-prepared 1.0 mol / L NH4Cl, and then ultrasonicate for 10 minutes to dissolve it completely. Then put it in a water bath with mechanical stirring at 80 ° C, heat it under reflux for 3 hours, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110 ° C for 12 hours. Grind the dried solid into powder (pass through a 100 mesh sieve), and calcine it at 550 ° C to obtain the acid-base alternating etching Hβ (75) molecular sieve catalyst.

[0043] The different types of acid-base alternating etching Hβ (75) molecular sieve catalysts prepared above were tested for the activity of the catalysts. Table 1 shows the activity data of different types of acid-base alternating etching Hβ (75) molecular sieve catalysts in the reaction of anisole and acetic anhydride. As shown in Table 1, the catalysts obtained by first etching with hydrochloric acid or nitric acid and then etching with TPAOH or NaOH and acid-base alternating etching achieved better catalytic effects. Among them, the catalyst obtained by first etching with 1.0 mol / L hydrochloric acid and then acid-base alternating etching with 0.1 mol / L TPAOH achieved the best catalytic activity.

[0044] Table 1 Activity of Hβ(75) molecular sieve catalyst etched by acid-base alternation in the reaction of anisole and acetic anhydride.

[0045]

[0046] Comparative Example 1 Weigh a certain mass of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h, cool it to room temperature, take out the roasted Hβ (75) molecular sieve and place it in a dry, refluxed 250ml flask, and add pre-prepared 1.0mol / L hydrochloric acid, the mass ratio of hydrochloric acid to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat it under reflux for 4h, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100 mesh sieve), roast it at 550℃, and test the catalytic activity of the product in the reaction of anisole and acetic anhydride.

[0047] Comparative Example 2 Weigh a certain mass of Hβ (75) molecular sieve into a 300ml crucible of the original powder, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h, and then cool it to room temperature. Take out the roasted Hβ (75) molecular sieve and put it in a dry, refluxed 300ml flask, then add the pre-prepared 0.1mol / L TPAOH (tetrapropylammonium hydroxide), the mass ratio of TPAOH to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it in a 60℃ water bath with mechanical stirring, heat reflux for 0.5h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. The dried solid is ground into powder (passed through a 100 mesh sieve), roasted at 550℃, and the Hβ (75) molecular sieve catalyst is prepared, and its catalytic activity in the reaction of anisole and acetic anhydride is tested.

[0048] Comparative Example 3 Weigh a certain mass of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h, and cool it to room temperature. Take out the roasted Hβ (75) molecular sieve and place it in a dry, refluxed 300ml flask, and then add the pre-prepared 0.1mol / L TPAOH (tetrapropylammonium hydroxide), the mass ratio of TPAOH to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a 60℃ water bath with mechanical stirring, heat and reflux for 0.5h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve).

[0049] Weigh a certain amount of alkaline-etched Hβ (75) molecular sieve in the above step into a 300ml flask, add pre-prepared 1.0mol / L hydrochloric acid, the mass ratio of hydrochloric acid to Hβ molecular sieve is 20:1, and then ultrasonicate for 10 minutes to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat it under reflux for 4 hours, then quickly cool it to room temperature, then centrifuge it, wash it with water until it is neutral, and dry the washed product at 110℃ for 12 hours. Grind the dried solid into powder (pass through a 100-mesh sieve), calcine it at 550℃, and test its catalytic activity in the reaction of anisole and acetic anhydride.

[0050] Table 2 Catalytic activity of Hβ(75) molecular sieve prepared by etching method in the reaction of anisole and acetic anhydride.

[0051]

[0052] Example 6 The Hβ (75) molecular sieve catalyst was prepared by alternating etching with different types of acid and base, and the steps are as follows: Weigh a certain amount of Hβ (75) molecular sieve powder into a 300ml crucible, place it in a muffle furnace and roast it at 550℃ (heating rate of 5℃ / min) for 5h. After cooling to room temperature, take out a certain amount of roasted Hβ (75) molecular sieve into a dry, refluxed 250ml flask, and add a pre-configured acid solution with a concentration of 1.0mol / L, selected from hydrochloric acid, nitric acid, acetic acid, tartaric acid, citric acid, and the mass ratio of acid solution to Hβ molecular sieve is 20:1, and then ultrasonicate for 10min to dissolve it completely. Then put it into a water bath with mechanical stirring at 80℃, heat and reflux for 4h, then quickly cool it to room temperature, then centrifuge and wash it with water until neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve) and put it in a drying dish for use.

[0053] Accurately weigh a certain mass of the powder obtained above and put it into a 200ml dry flask with reflux, then add a pre-prepared 0.1mol / L alkaline solution selected from TPAOH, NH3H2O ​​and NaOH, and the mass ratio of the alkaline solution to the Hβ molecular sieve is 20:1, then ultrasonicate for 10 minutes to dissolve it completely and put it into the flask with reflux. Then put it into a 60℃ water bath with mechanical stirring, heat and reflux for 0.5h, then quickly cool it to room temperature, then centrifuge and wash it with water until it is neutral, and dry the washed product at 110℃ for 12h. Grind the dried solid into powder (pass through a 100-mesh sieve).

[0054] When the base is TPAOH or NH3H2O, the solid is calcined at 550°C to obtain an acid-base alternating etching Hβ (75) molecular sieve catalyst. When the base is NaOH, 1.0 mol / L NH4Cl is used for ion exchange and then calcined at 550°C to obtain an acid-base alternating etching Hβ (75) molecular sieve catalyst.

[0055] The activity of the catalyst was tested and the results are shown in Table 3.

[0056] Comparative Example 4 The Hβ (75) molecular sieve catalyst was prepared by acid etching in a method substantially the same as that in Comparative Example 1, except that the acid solution was 1.0 mol / L nitric acid, acetic acid, or 0.5 mol / L tartaric acid, or 0.75 mol / L citric acid. The activity of the catalyst was tested, and the results are shown in Table 3.

[0057] Comparative Example 5 The Hβ (75) molecular sieve catalyst was prepared by alkaline etching in a method substantially the same as that in Comparative Example 2, except that the alkaline solution was 0.1 mol / L NH3H2O ​​or NaOH (ion exchange). The activity of the catalyst was tested, and the results are shown in Table 3.

[0058] Table 3 Catalytic activity of different types of acid-base etched Hβ (75) molecular sieve catalysts in the reaction of anisole and acetic anhydride.

[0059]

[0060] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any substantial or formal sense. It should be noted that, for a person skilled in the art, several improvements can be made without departing from the purpose of the present invention, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a Hβ molecular sieve catalyst, characterized in that: The method includes the following steps: (1) calcining the Hβ molecular sieve; (2) Acid etching: Add the calcined Hβ molecular sieve into an acid solution, stir or ultrasonicate it to dissolve it, heat it under reflux for reaction, cool it to room temperature after the reaction is completed, wash, dry and grind the product into powder; (3) Alkali etching: adding the product obtained in step (2) into an alkaline solution, stirring or ultrasonicating it to dissolve it, heating it under reflux for reaction, cooling it to room temperature after the reaction is completed, washing, drying and grinding the product into powder; (4) calcining the product after alkali etching in step (3), or calcining after ion exchange, to obtain an Hβ molecular sieve catalyst.

2. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The Hβ molecular sieve is Hβ (25), Hβ (55), Hβ (75), Hβ (120) or all-silicon Hβ molecular sieve.

3. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The reaction temperature of the acid etching is 60-90° C., the heating reflux reaction is 2-6 hours, and the molar concentration of the acid solution is 0.5 mol / L-1.5 mol / L.

4. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The reaction temperature of the alkaline etching is 40-60° C., the heating reflux reaction is 0.5-2 hours, and the molar concentration of the alkaline solution is 0.1 mol / L-0.5 mol / L.

5. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The acid solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, tartaric acid, citric acid or acetic acid.

6. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The alkaline solution is selected from one or more of sodium hydroxide, sodium carbonate, tetrapropylammonium hydroxide and ammonia water.

7. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: In the steps (2) and (3), the mass ratio of the acid solution or the alkaline solution to the Hβ molecular sieve is 10 to 50:

1.

8. The method for preparing the Hβ molecular sieve catalyst according to claim 1, characterized in that: The ion exchange described in step (4) refers to when the alkaline solution contains metal ions, adding the product after alkaline etching to an ion exchanger solution selected from ammonium chloride or ammonium nitrate, stirring or ultrasonicating it to dissolve it, heating it under reflux reaction, cooling it to room temperature after the reaction is completed, and washing, drying and grinding the product into powder.

9. The Hβ molecular sieve catalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the Hβ molecular sieve catalyst according to claim 9 in the Friedel-Crafts acylation reaction of anisole and acetic anhydride.

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