阅读说明：本技术 一种ecnu-24分子筛及其制备方法和应用 (ECNU-24 molecular sieve and preparation method and application thereof ) 是由 吴鹏 韩悦 徐浩 蒋金刚 何鸣元 于 2020-04-15 设计创作，主要内容包括：本发明公开了一种ECNU-24分子筛及其制备方法和应用,其特点是该分子筛为“第一氧化物”或“第一氧化物·第二氧化物”所示式的化学组成,且骨架中含有Ti和Al等催化中心的ECNU-24分子筛,其制备采用大尺寸环状有机模板剂获得前驱体后在酸性条件下进行化学处理的方法得到ECNU-24新结构分子筛,含Ti和Al的ECNU-24分子筛作为催化剂用于烯烃环氧化反应以及芳烃烷基化反应。本发明与现有技术相比具有原创性结构且为首次发现,能够丰富分子筛种类。基于该分子筛新颖的孔道结构,向其骨架中引入Al和Ti等催化中心构筑固体酸催化剂或氧化还原催化剂为开发新型环境友好催化体系提供了可能性。(The invention discloses an ECNU-24 molecular sieve and a preparation method and application thereof, and is characterized in that the molecular sieve is an ECNU-24 molecular sieve which has a chemical composition shown as a formula of 'first oxide' or 'first oxide and second oxide' and contains Ti, Al and other catalytic centers in a framework, a large-size annular organic template is adopted to obtain a precursor, then chemical treatment is carried out under an acidic condition to obtain the ECNU-24 molecular sieve with a new structure, and the ECNU-24 molecular sieve containing Ti and Al is used as a catalyst for olefin epoxidation reaction and aromatic alkylation reaction. Compared with the prior art, the invention has an original structure, is discovered for the first time and can enrich the types of molecular sieves. Based on the novel pore channel structure of the molecular sieve, Al, Ti and other catalytic centers are introduced into the framework of the molecular sieve to construct a solid acid catalyst or a redox catalyst, so that the possibility is provided for developing a novel environment-friendly catalytic system.)

1. An ECNU-24 molecular sieve, characterized in that the composition of the molecular sieve is "first oxide" or "first oxide second oxide" and has the X-ray characterized diffraction lines shown in table 1 below:

table 1: structural data table of X-ray diffraction of ECNU-24 molecular sieves

Wherein: (a) is +/-0.30 degrees; the relative intensity w of diffraction peaks is less than 20 (weak), m is 20-40 (medium), s is 40-70 (strong), and vs is more than 70 (very strong);

the compound composed of the first oxide and the second oxide contains ECNU-24 molecular sieve material with one or more than two catalytic centers of aluminum, titanium, boron, iron, gallium, tin, rare earth elements, indium and vanadium in a framework; the first oxide is silicon oxide; the second oxide is one or a mixture of more than two of aluminum oxide, titanium oxide, boron oxide, iron oxide, gallium oxide, tin oxide, rare earth oxide, indium oxide and vanadium oxide; the molar ratio of the first oxide to the second oxide is 1: 0 to 0.2.

2. A process for the preparation of the ECNU-24 molecular sieve of claim 1, wherein the ECNU-24 molecular sieve is prepared by the steps of:

preparation of (I) precursor

Mixing the first oxide with the second oxide, an organic template, an inorganic base and water according to the proportion of 1: 0-0.2: 0.05-1.0: 0-0.5: 5-30 mol ratio, aging at 35-80 ℃ for 0.5-5 hours, crystallizing at 120-180 ℃ for 4-20 days, filtering, washing and drying the crystallized product to obtain a precursor with powder, particle or film products; the first type of oxide is silicon oxide; the second oxide is one or the mixture of more than two of aluminum oxide, titanium oxide, boron oxide, iron oxide, gallium oxide, tin oxide, rare earth oxide, indium oxide and vanadium oxide; the inorganic alkali is one or a mixture of more than two of sodium hydroxide, potassium hydroxide and lithium hydroxide; the organic template agent is a quaternary ammonium salt or quaternary ammonium base form of a compound with the following structural formula A:

wherein: r₁And R₂Each independently C of different carbon chain number_1-6An alkyl group; n is 4-8;

quaternary ammonium salt form of the compound of formula A, quaternary nitrogen (N)⁺) The balance anion of the structure is halogen ion or hydroxyl ion (OH)^-) (ii) a Quaternary ammonium base forms of the compound of formula A, quaternary nitrogen (N)⁺) The counter anion of the structure is hydroxide ion (OH)^-)；

Preparation of ECNU-24 molecular sieve

Placing the precursor in an acid solution with the pH value less than 7, magnetically stirring for 5-30 minutes at room temperature, then reacting for 4-72 hours at the temperature of 120-210 ℃, carrying out suction filtration, washing and drying on a reaction solution, and roasting to obtain a roasted ECNU-24 molecular sieve, wherein the solid-liquid mass ratio of the precursor to the acid solution is 1: 10 to 100 parts; the molar concentration of the acidic solution is 0.1-5M; the roasting temperature is 500-650 ℃, and the roasting time is 4-10 hours.

3. The method of claim 2, wherein the acidic solution comprises one or more of hydrochloric acid, phosphoric acid, nitric acid, sulfuric acid, boric acid, hydroiodic acid, hydrobromic acid, and chloric acid as a solute, and one or more of water, methanol, and ethanol as a solvent.

4. The method of claim 2, wherein said ECNU-24 molecular sieve is in a calcined form selected from the group consisting of a powder, a pellet, and a membrane.

5. Use of the ECNU-24 molecular sieve of claim 1 as a catalyst in an aromatic alkylation reaction and olefin epoxidation reaction, wherein the second oxide of the catalyst in the aromatic alkylation reaction is alumina-based Al-ECNU-24 molecular sieve; the weight mol ratio of the Al-ECNU-24 molecular sieve to the aromatic hydrocarbon is 1 g: 0.01 to 0.2 mol; the second oxide of the catalyst in the olefin epoxidation reaction is a Ti-ECNU-24 molecular sieve of titanium oxide; the weight molar ratio of the Ti-ECNU-24 molecular sieve to the olefin is 1 g: 0.02 to 0.5 mol.

6. Use of the ECNU-24 molecular sieve according to claim 5, characterized in that the aromatic hydrocarbon is benzene, toluene, xylene, trimethylbenzene, phenol or naphthalene; the olefin is a C ═ C unsaturated double bond-containing linear or cyclic olefin having a carbon number of not more than 12.

Technical Field

The invention relates to the technical field of molecular sieves, in particular to a newly discovered ECNU-24 molecular sieve which has excellent catalytic performance and a novel structure, and a preparation method and application thereof.

Background

The microporous molecular sieve is TO₄Inorganic porous materials constructed by (T ═ Si, Al, Ge, Ti, Sn, B and the like) tetrahedron and having unique crystal structures, uniform pore channel structures, proper acidity and good hydrothermal stability are widely applied to the fields of adsorption separation, ion exchange, catalysis and the like. Due to the unique crystal structure and chemical composition of the molecular sieve, with the development of chemical engineering, the demand of the molecular sieve for catalysts is rapidly developed, so that the synthesis of molecular sieve materials with novel pore channel structures and novel chemical compositions is an important research direction.

Microporous molecular sieves are classified into small, medium, large and ultra-large pore molecular sieves according to the opening of the channel being 8-membered ring, 10-membered ring, 12-membered ring and > 12-membered ring. Among them, the macroporous or ultra-macroporous molecular sieves can effectively catalyze the reaction of some macromolecules by reducing the diffusion limitation of substrate molecules. Therefore, the synthesis of macroporous or ultra-macroporous molecular sieve materials has become one of the hot spots in the field of molecular sieve research. The adoption of large-size organic alkali and organic amine template agent or the addition of metal atoms with structure-directing ability, etc. is an important method for synthesizing large-aperture and new-structure molecular sieves at present. However, large pore size molecular sieves are often associated with poor structural stability, and therefore, the structure needs to be modified chemically as necessary during synthesis to improve the structure.

Disclosure of Invention

The invention aims to design an ECNU-24 molecular sieve and a preparation method and application thereof aiming at the defects of the prior art, a method for chemically treating a precursor obtained by adopting a large-size annular organic template under an acidic condition is adopted, the prepared novel molecular sieve is confirmed to have an original structure and novel pore channels through an X-ray diffraction spectrogram, and an ECNU-24 molecular sieve material with a framework containing catalytic centers such as Al, Ti and the like is used for finding and enriching the types of the molecular sieve for the first time, so that a new synthesis idea of the molecular sieve with a new structure is provided, and a possibility is provided for developing a novel environment-friendly catalytic system.

The specific technical scheme for realizing the aim of the invention is that the ECNU-24 molecular sieve is characterized in that the molecular sieve has a chemical composition shown by a formula of 'first oxide' or 'first oxide and second oxide', and has X-rays (Cu-K α,) Characterized diffraction line: table 1: structural data table of X-ray diffraction of ECNU-24 molecular sieves

Wherein: (a) is +/-0.30 degrees; the relative intensity w of the diffraction peak is less than 20 (weak), m is 20-40 (medium), s is 40-70 (strong), and vs is more than 70 (very strong).

The compound composed of the first oxide and the second oxide contains ECNU-24 molecular sieve material with one or more than two catalytic centers of aluminum, titanium, boron, iron, gallium, tin, rare earth elements, indium and vanadium in a framework; the first oxide is silicon oxide; the second oxide is one or a mixture of more than two of aluminum oxide, titanium oxide, boron oxide, iron oxide, gallium oxide, tin oxide, rare earth oxide, indium oxide and vanadium oxide; the molar ratio of the first oxide to the second oxide is 1: 0 to 0.2.

The preparation method of the ECNU-24 molecular sieve is characterized in that the ECNU-24 molecular sieve is prepared by the following steps:

preparation of (I) precursor

Mixing a first oxide source (calculated as a first oxide) and a second oxide source (calculated as a second oxide), an organic template, an inorganic alkali source and water according to the ratio of 1: 0-0.2: 0.05-1.0: 0-0.5: 5-30 mol ratio, aging at 35-80 ℃ for 0.5-5 hours, crystallizing at 120-180 ℃ for 4-20 days, filtering, washing and drying the crystallized product to obtain a molecular sieve matrix with powder, particle or membrane products; the inorganic alkali source is one or a mixture of more than two of sodium hydroxide, potassium hydroxide and lithium hydroxide; the organic template is a compound with the following structural formula A, quaternary ammonium salt or quaternary ammonium base form thereof:

wherein: r₁And R₂Each independently C of different carbon chain number_1-6Alkyl radical, R₁And R₂Preferably C_1-3An alkyl group; n is 4-8, preferably 6; the quaternary nitrogen (N) is a quaternary ammonium salt form of the compound of formula A⁺) The counter anion of the structure is a halide ion (Br)^-) Or hydroxide ion (OH)^-) Etc., but are not limited thereto; the quaternary nitrogen (N) as the quaternary ammonium base form of the compound of formula A⁺) The counter anion of the structure is hydroxide ion (OH)^-)。

Preparation of ECNU-24 molecular sieve

Placing the precursor in an acid solution with the pH value of less than 7, magnetically stirring for 5-30 minutes at room temperature, then reacting for 4-72 hours at the temperature of 120-210 ℃, carrying out suction filtration, washing and drying on the reaction liquid, and then roasting at high temperature to obtain a product which is an ECNU-24 molecular sieve, wherein the roasting temperature is 500-650 ℃, and the roasting time is 4-10 hours; the solute of the acid solution is one or a mixture of more than two of hydrochloric acid, phosphoric acid, nitric acid, sulfuric acid, boric acid, hydroiodic acid, hydrobromic acid and chloric acid, and the solvent is one or a mixture of more than two of water, methanol and ethanol; the molar concentration of the acidic solution is 0.1-5M; the solid-liquid mass ratio of the precursor to the acidic solution is 1: 10 to 100 parts; the ECNU-24 molecular sieve is in a powdery, granular or membrane product state in a roasting state.

The application of the ECNU-24 molecular sieve is characterized in that the ECNU-24 molecular sieve is used as a catalyst for aromatic alkylation reaction and olefin epoxidation reaction. The catalyst for the aromatic alkylation reaction is Al-ECNU-24 of which the second oxide in the molecular sieve is alumina, wherein the dosage ratio of the Al-ECNU-24 molecular sieve to the aromatic hydrocarbon is 1g (Al-ECNU-24): 0.01-0.2 mol (aromatic hydrocarbon), wherein the aromatic hydrocarbon is benzene, toluene, xylene, trimethylbenzene, phenol or naphthalene; the catalyst for olefin epoxidation reaction is Ti-ECNU-24 of which the second oxide in the molecular sieve is titanium oxide, wherein the dosage ratio of the Ti-ECNU-24 molecular sieve to the olefin is 1g (Ti-ECNU-24): 0.02 to 0.5 mol (olefin), wherein the olefin is a C ═ C unsaturated double bond-containing linear or cyclic olefin having a carbon number of not more than 12.

Compared with the prior art, the invention has an original structure, is discovered for the first time, can enrich the types of the molecular sieve, introduces catalytic centers such as Al, Ti and the like into the framework of the molecular sieve to construct a solid acid catalyst or an oxidation reduction catalyst based on a novel pore channel structure of the molecular sieve, and provides possibility for developing a novel environment-friendly catalytic system.

Drawings

FIG. 1 is an X-ray diffraction pattern of ECNU-24 prepared in example 1;

FIG. 2 is an X-ray diffraction pattern of Ti-ECNU-24 prepared in example 2;

FIG. 3 is an X-ray diffraction pattern of Al-ECNU-24 prepared in example 3.

Detailed Description

The preparation of the present invention is further illustrated by the following specific examples.