CN102614907B - Molecular sieve catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a molecular sieve catalyst, which is characterized in that the catalyst contains 60-90 wt% of β molecular sieve and 10-40 wt% of inorganic oxide carrier, and the said β molecular sieve is based on molecular sieve and contains 0.01 ~10 wt% copper and Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) > 50 wt% on the surface of the beta molecular sieve. The catalyst is used in the process of synthesizing ethylbenzene by the liquid-phase alkylation reaction of benzene and ethylene, and has high activity and ethylbenzene selectivity under low temperature conditions.

Description

A kind of molecular sieve catalyst and preparation method thereof

technical field

The invention relates to a molecular sieve catalyst and a preparation method thereof, in particular to a catalyst suitable for preparing ethylbenzene by liquid-phase alkylation of benzene and ethylene and a method for preparing the catalyst.

Background technique

Ethylbenzene is an important organic chemical raw material. In industry, it is mainly produced through the alkylation reaction of benzene and ethylene and the transalkylation reaction of polyethylbenzene and benzene. The relatively mature preparation processes mainly include: aluminum chloride method, molecular sieve Gas-phase alkylation and molecular sieve liquid-phase alkylation. At present, the use of molecular sieve liquid-phase alkylation to produce ethylbenzene has become the development trend of this industry.

U.S. Patent No. 4,891,458 first reported the use of a β molecular sieve catalyst to synthesize ethylbenzene under liquid-phase alkylation conditions. The catalyst was composed of a β molecular sieve and an alumina carrier obtained through ammonium and rare earth ion exchange.

U.S. Patent No. 59890859 proposes that β molecular sieve treated with water steam and molecular sieve modified by ammonium ion exchange method are used for liquid-phase alkylation to produce ethylbenzene, so as to obtain good alkylation activity and selectivity. The β molecular sieve is first roasted at 540-650°C to remove the organic amine template, and then treated with water vapor at 500-800°C, preferably 550-700°C, and then carries out ammonium ion exchange at a pH of 1.0-3.5 to remove Non-skeleton aluminum.

U.S. Patents US5723710, US6162416 and US6440886 have reported surface-modified β molecular sieves and their application in the alkylation of aromatic hydrocarbons. The β molecular sieves that have not been deaminated by roasting are treated with acid at a pH of 0 to 2 and below 125 ° C. Down treatment changed the chemical environment of Al but did not cause dealumination of β molecular sieve. After surface modification, the 2P binding energy of Al on the surface of molecular sieve reached above 74.8 electron volts.

Chinese patent CN1098028A discloses a β molecular sieve catalyst for toluene disproportionation and transalkylation reactions and a preparation method thereof. The catalyst is composed of 10-90% by weight of β molecular sieve, 5-90% by weight of binder, and 0.05-5% by weight of metal promoters selected from Ni, Co, Cu, Ag, Sn, Ca, etc., and has a high Activity and selectivity for disproportionation and transalkylation. . In the preparation method of the catalyst, firstly, the β molecular sieve is deaminated by roasting, and then the deaminated molecular sieve and binder are extruded and roasted to shape, exchanged with ammonium ions, then impregnated and exchanged by metal salt solution, and finally prepared by roasting hydrogen reduction. have to.

Chinese patent CN1872685A discloses a modified β molecular sieve, which is modified by phosphorus and transition metals Fe, Co, Ni, Cu, Mn, Zn and Sn. , and then introduce phosphorus and transition metal aqueous solution impregnation modification. The modified β molecular sieve is used in the catalytic cracking process as a catalyst or auxiliary active component.

The above methods are to remove the template agent in the β molecular sieve first, and then adjust the acidity and acidity of the molecular sieve through hydrothermal treatment or rare earth and transition metal modification, or modify the pores to meet the requirements of different reactions.

European patent EP1690831A1 discloses a method for preparing molecular sieves. In this method, an organic template is first added to a silicon source and an aluminum source, crystallized to obtain a molecular sieve powder, and then the molecular sieve powder is added to an aqueous solution containing an oxidizing agent and a transition metal ion. , deamination treatment was performed at 100°C, and ion exchange was performed during deamination to prepare molecular sieve samples containing different metal components. The oxidizing agent used includes hydrogen peroxide, ozone, nitric acid and peroxyacid, wherein hydrogen peroxide is preferred, and transition metal ions are more preferably Fe ³⁺ ions. This method proposes to combine solvent oxidative deamination and liquid ion exchange to prepare molecular sieves. The low-temperature deamination method not only protects the molecular sieve framework from damage, inhibits the framework dealumination, but also simplifies the molecular sieve treatment process; its disadvantage is that ion exchange The process is limited by the deamination process. Insufficient deamination will also lead to insufficient ion exchange, and in order to cooperate with the use of oxidants, other metal ions are often introduced, which limits the types of ion exchange.

Contents of the invention

The purpose of the present invention is to provide a molecular sieve catalyst and its preparation method which is different from the metal distribution on the surface of the prior art. It has higher activity and ethylbenzene selectivity under the conditions.

The molecular sieve catalyst provided by the present invention is characterized in that the catalyst contains 60 to 90 wt% of β molecular sieve and 10 to 40 wt% of inorganic oxide carrier, and the said β molecular sieve is based on molecular sieve and contains 0.01 to 10 wt% of CuO. % copper and Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) on the surface of the β molecular sieve ≥ 50wt%.

The present invention also provides the preparation method of molecular sieve catalyst, and this method comprises:

(1) Ammonium-type β-molecular sieves are obtained by ammonium-exchanging the β-molecular sieve containing the template agent, so that the content of Na ₂ O therein is less than 0.3wt%;

(2) The ammonium-type β molecular sieve obtained in step 1 is contacted and mixed with the aqueous solution or gel of a copper-containing compound at room temperature, and dried and roasted to obtain a copper-containing β molecular sieve; or the ammonium-type β molecular sieve of step (1) Contacting and mixing with an aqueous solution or gel of a copper-containing compound at room temperature, drying and roasting, cooling the roasted sample, contacting with an aqueous ammonium salt solution with a concentration of 2 to 5% by weight to exchange part of the copper ions, filtering the copper-containing solution, and then Wash the filter cake, heat to 110°C and dry to obtain copper-containing β molecular sieve;

(3) Kneading and kneading the copper-containing β molecular sieve with the inorganic oxide carrier, drying, heating to 250-600° C. and calcining for 1-10 hours in an air atmosphere to obtain the β molecular sieve catalyst.

The catalyst provided by the invention has the advantage of being used in the process of synthesizing ethylbenzene by the liquid-phase alkylation reaction of benzene and ethylene, and has high activity and ethylbenzene selectivity under low temperature conditions.

Description of drawings

Fig. 1, Fig. 2, Fig. 3, and Fig. 4 are the X-ray photoelectron spectra of the surface copper elements of the samples S1, S2, S3, and S4 of the embodiment respectively.

Fig. 5 is the X-ray photoelectron spectrum of the copper element on the surface of sample D1 of the comparative example.

Fig. 6 is a peak-splitting spectrum of the X-ray photoelectron spectrum of the copper element on the surface of the sample S1 of the embodiment.

Detailed ways

The molecular sieve catalyst provided by the invention contains 60-90 wt% of β molecular sieve and 10-40 wt% of inorganic oxide carrier,

The β molecular sieve is obtained by copper modification, based on the molecular sieve, it contains 0.01-10 wt%, preferably 0.2-8 wt% copper in terms of CuO; the _Na2O content is less than 0.3%, preferably less than 0.2% , more preferably less than 0.1%. The silicon-aluminum molar ratio of the β molecular sieve calculated by SiO ₂ and Al ₂ O ₃ is 5-80, preferably 10-60, more preferably 15-50.

The molecular sieve catalyst provided by the present invention, the copper-containing β molecular sieve, is obtained by copper ion catalyzed low-temperature deamination and copper ion solid-state ion exchange coupling treatment technology, specifically is to remove the organic amine template at low temperature and at the same time by copper It is obtained by solid-state ion exchange modification of ions and molecular sieves. The molecular sieve copper ion exchange modification process and its low-temperature deamination process are carried out simultaneously, and the prepared copper-containing β molecular sieve is also different from the β molecular sieve of the conventional copper-modified molecular sieve, and the chemical environment of copper is also affected by deamination. The inventor noticed that, according to the molecular sieve catalyst of the present invention, the relationship between the content of monovalent copper ions and divalent copper ions on the surface of said β molecular sieve (1-10nm depth) is Cu ⁺ /(Cu ⁺ +Cu ²⁺ )≥ 50 wt%, in a preferred case Cu ⁺ /(Cu ⁺ +Cu ²⁺ )≥60 wt%, in a more preferred case Cu ⁺ /(Cu ⁺ +Cu ²⁺ )≥80 wt%. The qualitative determination of the valence state of copper on the surface of molecular sieves (1-10nm depth) is based on the binding energy corresponding to Cu 2P _3/2 in the photoelectron spectrum and the Auger kinetic energy of Cu LMM. The Cu 2P3/2 spectrum peak is divided into peaks by the energy shift, and then the Cu 2p _3/2 spectrum peak and the Cu 2p _3/2 shake up spectrum peak are normalized to obtain the monovalent copper and divalent copper The calculation method is as follows: (Refer to "Material Surface Science", Cao Lili, Tsinghua University Press, 2007)

Cu ⁺¹ /Cu ⁺² ＝Cu 2p _3/2 (+1)/[Cu 2p _3/2 (+2)+Cu 2p _3/2 shake up]

Molecular sieve catalyst provided by the present invention, wherein said inorganic oxide carrier is known to those skilled in the art, such as alumina, silica, silica-alumina, magnesium oxide, titania, zinc oxide, zirconia and alkaline earth metal One or more of conventional inorganic oxide supports such as oxides can be prepared by a coprecipitation method known to those skilled in the art, or can be obtained commercially. In preferred cases, the preferred inorganic oxides are alumina or silica.

The shape of the molecular sieve catalyst is a catalyst shape commonly used in the art, such as a strip or spherical catalyst with a circular or clover-shaped cross section, which is not particularly limited in the present invention.

The present invention also provides the preparation method of above-mentioned molecular sieve catalyst, comprises following several steps:

(1) The conventionally synthesized β molecular sieve containing a template is subjected to ammonium exchange so that the content of Na ₂ O therein is less than 0.3 wt%.

(2) Stir and mix the ammonium-type β molecular sieve and the aqueous solution or gel of the copper-containing compound at room temperature, and after drying at room temperature to 120°C, heat to 200-450°C in an air atmosphere and roast for 2-8 hours to obtain the copper-containing β-molecular sieve or mix the ammonium-type β molecular sieve with the aqueous solution or gel of copper-containing compound at room temperature, dry at room temperature to 120°C, heat to 200-450°C in an air atmosphere and roast for 2-8 hours, and add the roasted sample after cooling Stir the ammonium salt aqueous solution with a concentration of 2-5 wt%, exchange part of the copper ions, filter the copper-containing solution, then wash the filter cake, heat to 110°C and dry to obtain the copper-containing β molecular sieve;

(3) Copper-containing β molecular sieve and inorganic oxide carrier are kneaded and formed, after drying, heated to 250-600° C. for 1-10 hours in an air atmosphere to obtain a copper-containing β molecular sieve catalyst.

In the preparation method provided by the present invention, in the step (1), the conventional synthetic process of β molecular sieve is a hydrothermal synthesis process, and the conventional synthetic method of β molecular sieve can refer to documents US3308069, EP159846, EP164208, etc.

In the method provided by the present invention, the template agent refers to the organic amine compound introduced in the molecular sieve synthesis process, which can be tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetramethylamine One or more of amine hydroxide, tetramethylammonium bromide, etc., preferably one or more of tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride.

In step (1), the ammonium exchange is to exchange the β molecular sieve through an aqueous solution of ammonium salts such as ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium acetate, etc. at room temperature to 100°C to reduce the sodium ion content in the molecular sieve , making the content of Na ₂ O therein less than 0.3wt%, preferably less than 0.1wt%.

In the preparation method provided by the present invention, in step (2), the copper-containing compound is selected from copper nitrate, copper chloride, cuprous chloride, copper sulfate, copper acetate, copper ammonia solution, copper hydroxide, etc. One or more of valent or divalent copper compounds, preferably copper chloride and copper hydroxide, more preferably copper hydroxide. The molar ratio of the ammonium type β molecular sieve to the copper-containing compound is 1:0.5 to 1:10, preferably 1:0.5 to 1:4. The ammonium type β molecular sieve is calculated as aluminum, and the copper-containing compound is Measured in copper.

In the method provided by the present invention, the preparation method of the copper-containing compound gel is to add an alkaline solution such as ammonia water to an aqueous solution of metallic copper dropwise according to a certain stoichiometric ratio to form a flocculent gel containing copper hydroxide.

In the preparation method provided by the present invention, in the step (3), the mixing ratio of the copper-containing β molecular sieve and the inorganic oxide carrier is 50:50-90:10 by weight. A weight ratio of 60:40-85:15 is preferred.

The inorganic oxide carrier described in step (3) is a conventional inorganic oxide carrier, such as aluminum oxide, silicon oxide, silicon oxide-alumina, magnesium oxide, titanium oxide, zinc oxide, zirconium oxide and alkaline earth metal oxides, etc. The carrier material of the present invention is not particularly limited; wherein the preferred inorganic oxide carrier is alumina and silicon oxide.

The highest calcining temperature for catalyst shaping in step (3) is 250-600°C, preferably 350-550°C.

The present invention will be further described below by way of examples, but the present invention is not limited thereto.

In the embodiment, the X-ray photoelectron spectrometer (XPS for short) used is Quantera type X-ray photoelectron spectrometer of ULVCA-PHI Company of the United States. The quality of the valence state of copper on the surface is determined based on the binding energy corresponding to Cu 2P _3/2 in the photoelectron spectrum and the Auger kinetic energy of Cu LMM. Spectrum peaks are divided into peaks, and then the ratio of monovalent copper to divalent copper is obtained by performing area normalization on Cu 2p _3/2 peaks and Cu 2p _3/2 shake up peaks. The calculation method is as follows: (Refer to "Material Surface Science", Cao Lili, Tsinghua University Press, 2007)

Cu ⁺¹ /Cu ⁺² ＝Cu 2p _3/2 (+1)/[Cu 2p _3/2 (+2)+Cu 2p _3/2 shake up]

The instrument used for the analysis method of copper content is Japan Rigaku Electric Co., Ltd. 3013 X-ray fluorescence spectrometer. After the sample is pressed into tablets, the intensity of the characteristic lines of Si, Al, Na, Cu and other elements is measured, and the SiO in the molecular sieve is obtained. ₂ , the content of Al ₂ O ₃ and other elements in the β molecular sieve catalyst.

The analysis method of the silicon-aluminum molar ratio, first measure the mass percentage of SiO ₂ and Al ₂ O ₃ in the molecular sieve, and divide the measured mass fraction by the molar mass ratio of SiO ₂ and Al ₂ O ₃ to get the silicon-aluminum molar ratio Compare.

The sodium type β molecular sieve (Naβ) containing organic amine template used in the examples and comparative examples is produced by Sinopec Changling Catalyst Co., Ltd. The template is tetraethylammonium hydroxide, which accounts for about 15% to 25%. . The mass fraction of Al ₂ O ₃ in the dry basis is 7.28%, the mass fraction of SiO ₂ is 92.5%, the mass fraction of Na ₂ O is 0.034%, and the ratio of silicon to aluminum in the skeleton is 11.26.

Example 1

Take Naβ zeolite and add 10% (weight) ammonium nitrate solution, liquid/solid = 4:1, ion exchange for 2 hours under the condition of stirring in a water bath at 90°C, filter and wash, dry at 110°C, repeat the exchange to obtain a template containing organic amine The NH ₄ β molecular sieve of the agent is used so that the content of Na ₂ O therein is less than 0.3wt%.

Weigh 0.61g of copper chloride dihydrate, add 500g of water to form an aqueous solution of copper chloride, add dropwise 0.48g of concentrated ammonia water with a mass fraction of 25%, and prepare a copper hydroxide gel. Weigh 20g of NH ₄ β molecular sieve and mix it with it at room temperature, filter, wash, dry the filter cake and put it in a muffle furnace, in an air atmosphere, heat up from room temperature to 400°C, and roast at a constant temperature of 400°C for 4 hours, sample S1 was obtained.

Sample S1 was analyzed by X-ray fluorescence method, wherein the copper content was 2.06wt% calculated as CuO.

The X-ray photoelectron spectrum of sample S1 is shown in Figure 1, and the peak spectrum is shown in Figure 6, where the ratio of Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) is 81.78.

Example 2

Weigh 2.43g of copper chloride dihydrate, add 500g of water to form a copper chloride aqueous solution, add 1.94g of concentrated ammonia water with a mass fraction of 25% dropwise, and prepare a copper hydroxide gel. Add 20g of the NH ₄ β molecular sieve obtained by the treatment in Example 1, stir and mix at room temperature, filter, wash, dry the filter cake and place it in a muffle furnace, raise the temperature to 350°C in an air atmosphere, and keep the temperature constant at 350°C Calcined for 4 hours to obtain sample S2a.

Grind the roasted sample S2a into powder in a quartz grinder, add 100 mL of ammonium acetate aqueous solution with a mass fraction of 10%, and adjust the pH to about 7.0 with ammonia water. Stir at room temperature for 120-180 minutes, filter, wash, and dry to obtain the final sample S2.

Sample S2 was analyzed by X-ray fluorescence method, wherein the copper content was 1.14wt% calculated as CuO.

The X-ray photoelectron spectrum of sample S2 is shown in Figure 2, wherein the ratio of Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) is 85.31.

Example 3

Weigh 0.81g cupric chloride dihydrate, add 20g water to form a cupric chloride aqueous solution, add 20g _NH4β molecular sieve obtained through the treatment of Example 1, stir and mix at room temperature, place in a muffle furnace after drying, The temperature was raised to 380° C. in the atmosphere, and then fired at a constant temperature of 380° C. for 4 hours to obtain sample S3.

Sample S3 was analyzed by X-ray fluorescence method, wherein the copper content was 2.55 wt% calculated as CuO.

The X-ray photoelectron spectrum of sample S3 is shown in Figure 3, where the ratio of Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) is 81.59.

Example 4

Weigh 0.81g cupric chloride dihydrate, prepare 20g cupric chloride aqueous solution, add 20g NH ₄ β molecular sieves obtained through the treatment of Example 1, stir and mix at room temperature, place in a muffle furnace after drying, under oxygen The temperature was raised to 380° C. in the atmosphere, and it was roasted at a constant temperature of 380° C. for 4 hours.

Grind the calcined sample into powder in a quartz grinder, add 100 mL of ammonium nitrate aqueous solution with a mass fraction of 10%, and adjust the pH to about 7.0 with ammonia water. Stir at room temperature for 120-180 minutes, filter, wash, and dry to obtain the final sample S4.

Sample S4 was analyzed by X-ray fluorescence method, wherein the copper content was 0.8 wt% calculated as CuO.

The X-ray photoelectron spectrum of sample S4 is shown in Figure 4, where the ratio of Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) is 89.1.

Comparative example 1

This comparative example illustrates the process of preparing β-copper-containing molecular sieves from deaminated β-molecular sieves by solution impregnation according to the method provided by the patent CN1098028A.

Weigh 20g of the NH ₄ β molecular sieve obtained by the treatment in Example 1, place it in a muffle furnace, and in an air atmosphere, heat up from room temperature to 400°C over 2 hours, calcinate for 2 hours, and then heat up to 600°C over 2 hours. Roast at constant temperature for 5 hours to carry out deamination treatment.

Weigh 0.61g of copper chloride dihydrate, add 500g of water to form an aqueous solution of copper chloride, add dropwise 0.48g of concentrated ammonia water with a mass fraction of 25%, and prepare a copper hydroxide gel. Weigh 20g of deaminated β-molecular sieve, stir and mix with it at room temperature, filter, wash, dry the filter cake and put it in a muffle furnace. In an air atmosphere, heat up from room temperature to 400°C, and roast at a constant temperature of 400°C. After 4 hours, comparative sample D1 was obtained.

Sample D1 was analyzed by X-ray fluorescence method, wherein the copper content was 2.53% as CuO.

The X-ray photoelectron spectrum of sample D1 is shown in Figure 5, wherein the ratio of Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) is 38.35.

Example 5

This example illustrates the preparation of catalyst CA1 by the method provided by the present invention.

Weigh 20g (dry basis weight) of molecular sieve S1, add 10g (dry basis weight) of silica sol (containing 40wt% SiO ₂ , produced by Changling Catalytic Agent Factory), mix evenly with an appropriate amount of deionized water, and roll into a 2mm The spherical particles were dried at 120°C and calcined at 400°C for 4 hours to obtain catalyst CA1.

Example 6

This example illustrates the preparation of catalyst CA2 by the method provided by the present invention.

Take by weighing 20g (dry basis weight) molecular sieve S2, add 9g (dry basis weight) pseudoboehmite (produced by Changling Catalyst Factory), mix well and add 0.5 citric acid, 0.25g Tianqing powder and an appropriate amount of nitric acid aqueous solution, Then extrude the strips with a clover orifice plate of Φ1.5 to form a strip-shaped catalyst with a diameter of 1.6mm, dry at 120°C, and roast at 500°C for 4 hours to obtain the catalyst CA2.

Example 7

This example illustrates the preparation of catalyst CA3 by the method provided by the present invention.

The sample S3 was prepared as a catalyst according to the method for preparing the catalyst in S1 above, which was denoted as catalyst CA3.

Example 8

This example illustrates the preparation of catalyst CA4 by the method provided by the present invention.

The sample S4 was prepared as a catalyst according to the method for preparing the catalyst in S2 above, and it was recorded as catalyst CA4.

Comparative example 2

This comparative example illustrates the preparation of comparative catalysts DC1 and DC2.

Molecular sieve D1 was used to prepare a comparative catalyst according to the preparation method of catalyst C1 in Example 5, which was recorded as DC1.

Comparative example 3

Molecular sieve D1 was prepared as a comparison catalyst according to the preparation method of catalyst C2 in Example 7, which was recorded as DC2.

test case

This test example simulates the process conditions of an industrial device to evaluate the low-temperature activity evaluation results of the catalysts CA1-CA4 and the comparative catalysts DC1 and DC2 for the liquid-phase alkylation of benzene and ethylene.

Break the catalyst obtained above into 16-20 mesh particles, take 8mL and put it into a Φ12.5mm stainless steel reactor. After the catalyst is purged with nitrogen at 110°C, use a feed pump to continuously enter analytically pure benzene. The volume of the feed liquid is The space velocity is 3 hours ^-1 , the system rises to 250°C at a rate of 50°C/hour, and then enters the polymerization grade ethylene, the reaction pressure is 3.5Mpa, the benzene/ethylene molar ratio is 12, and after 48 hours of stable operation, respectively to 200°C, 190°C, and 180°C temperature points, each reacted for 48 hours, and samples were taken for chromatographic analysis. The results of the conversion rate of ethylene and the selectivity of ethylbenzene are listed in Table 1.

Table 1

It can be seen from Table 1 that after low-temperature deamination and simultaneous copper ion exchange treatment, the low-temperature reaction activity of the β molecular sieve catalyst in the liquid-phase alkylation reaction of benzene and ethylene is greatly improved, and it has better ethylbenzene selectivity.

Claims (10)

1. A molecular sieve catalyst, characterized in that the catalyst contains 60-90wt% beta molecular sieve and 10-40wt% inorganic oxide carrier, and the molecular sieve is used as a benchmark in said beta molecular sieve, and the copper contained is 0.01% in terms of CuO ~10wt%, and Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) on the surface of the β molecular sieve ≥ 60wt%. 2. The catalyst according to claim 1, wherein said beta molecular sieve contains 0.2 to 8 wt% of copper calculated as CuO based on the molecular sieve. 3. The catalyst according to claim 1, wherein Cu ⁺ /(Cu ⁺ +Cu ²⁺ ) on the surface of said beta molecular sieve is ≥ 80 wt%. 4. The catalyst according to claim 1, wherein the SiO ₂ /Al ₂ O ₃ of the β molecular sieve is 5-80. 5. The catalyst according to claim 1, wherein said inorganic oxide support is selected from the group consisting of one or more mixtures of alumina, silica, magnesia, titania and zirconia. 6. The catalyst according to claim 5, wherein said inorganic oxide support is alumina or silica. 7. A preparation method of a molecular sieve catalyst, characterized in that the method comprises: (1) β containing one or more templating agents in tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetramethylammonium hydroxide, tetramethylammonium bromide Molecular sieve, ammonium type β molecular sieve obtained through ammonium exchange, so that the content of _Na2O is less than 0.3wt%; (2) The ammonium-type β molecular sieve obtained in step 1 is contacted and mixed with the aqueous solution or gel of a copper-containing compound at room temperature, and dried and roasted to obtain a copper-containing β molecular sieve; or the ammonium-type β molecular sieve of step (1) Contacting and mixing with an aqueous solution or gel of a copper-containing compound at room temperature, drying and roasting, cooling the roasted sample, contacting an aqueous ammonium salt solution with a concentration of 2 to 5% by weight to exchange part of the copper ions, filtering the copper-containing solution, and then Wash the filter cake, heat to 110°C and dry to obtain copper-containing β molecular sieve; (3) Knead and knead copper-containing β molecular sieve and inorganic oxide carrier, after drying, heat to 250-600°C in air atmosphere and roast for 1-10 hours to obtain β-molecular sieve catalyst, said β-molecular sieve catalyst contains 60-90wt % of β molecular sieve and 10 to 40wt% of inorganic oxide carrier, said β molecular sieve is based on molecular sieve, and the copper contained is 0.01 to 10wt% as CuO, and the Cu ⁺ /(Cu ⁺ + on the surface of β molecular sieve Cu ²⁺ )≥60wt%. 8. According to the preparation method of claim 7, wherein, the said copper-containing compound in step (2) is selected from one or more of the compounds containing monovalent or divalent copper. 9. According to the preparation method of claim 8, wherein, said copper-containing compound is selected from copper nitrate, copper chloride, cuprous chloride, copper sulfate, copper acetate, copper ammonia solution or copper hydroxide. 10. According to the preparation method of claim 7, in step (2), the molar ratio of the ammonium type β molecular sieve to the copper-containing compound is 1: 0.5 to 1: 10, and said ammonium type β molecular sieve is calculated as aluminum, and said The copper-containing compounds are calculated as copper.

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