阅读说明：本技术 一种多孔层状过渡金属硫族化合物及其制备方法和应用 (Porous layered transition metal chalcogenide compound and preparation method and application thereof ) 是由 王程 徐伟明 郑慧琳 章鹏飞 沈鸿云 李小玲 于 2020-05-20 设计创作，主要内容包括：本发明涉及催化剂领域,提供了一种多孔层状过渡金属硫族化合物及其制备方法和应用。本发明提供的制备方法包括以下步骤：(1)将二氧化硅微球、过渡金属盐和硫族单质混合后进行压制处理,得到压片；所述二氧化硅微球为单一粒径的二氧化硅微球或由不同粒径的二氧化硅微球组成；(2)将所述压片在氢气氛围中进行烧结,然后除去二氧化硅微球,得到多孔层状过渡金属硫族化合物。采用本发明方法制备的多孔层状过渡金属硫族化合物晶格层边缘暴露量增加,具有更多的活性位点,催化活性较高,在可见光照射下,能够有效催化醇氧化成醛或者催化硫醚氧化成亚砜。(The invention relates to the field of catalysts, and provides a porous layered transition metal chalcogenide compound and a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: (1) mixing the silica microspheres, the transition metal salt and the sulfur group simple substance, and then performing pressing treatment to obtain a pressed sheet; the silica microspheres are silica microspheres with single particle size or consist of silica microspheres with different particle sizes; (2) and sintering the pressed sheet in a hydrogen atmosphere, and then removing the silicon dioxide microspheres to obtain the porous layered transition metal chalcogenide. The porous layered transition metal chalcogenide crystal lattice layer prepared by the method has the advantages of increased edge exposure, more active sites, higher catalytic activity and capability of effectively catalyzing the oxidation of alcohol into aldehyde or the oxidation of thioether into sulfoxide under the irradiation of visible light.)

1. A preparation method of a porous layered transition metal chalcogenide compound comprises the following steps:

(1) mixing the silica microspheres, the transition metal salt and the sulfur group simple substance, and then performing pressing treatment to obtain a pressed sheet; the silica microspheres are silica microspheres with single particle size or consist of silica microspheres with different particle sizes;

(2) and sintering the pressed sheet in a hydrogen atmosphere, and then removing the silicon dioxide microspheres to obtain the porous layered transition metal chalcogenide.

2. The preparation method according to claim 1, wherein the diameter of the silica microspheres in the step (1) is 5-200 nm.

3. The method according to claim 1, wherein the transition metal salt in step (1) comprises one or both of phosphotungstic acid, ammonium metatungstate and ammonium molybdate.

4. The method according to claim 1, wherein the chalcogen in the step (1) includes one or both of S, Se and Te.

5. The preparation method according to any one of claims 1 to 4, wherein the mass ratio of the silica microspheres to the transition metal salt in the step (1) is 1:0.05 to 1; the mass ratio of the silica microspheres to the sulfur family simple substance is 1: 0.05-1.

6. The preparation method according to claim 1, wherein the sintering temperature in the step (2) is 400-900 ℃, and the holding time is 2-5 h.

7. The method according to claim 1, wherein the reagent for removing the silica microspheres in the step (2) comprises an aqueous hydrofluoric acid solution, an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution; the mass concentration of the hydrofluoric acid aqueous solution is 10-40%; the mass concentration of the sodium hydroxide aqueous solution is 5-40%; the mass concentration of the potassium hydroxide aqueous solution is 5-40%.

8. A porous layered transition metal chalcogenide compound produced by the production method according to any one of claims 1 to 7.

9. Use of a porous layered transition metal chalcogenide as claimed in claim 8 as a photocatalyst in photocatalytic selective oxidation reactions; the photocatalytic selective oxidation reaction comprises the oxidation of an alcohol to an aldehyde or the oxidation of a thioether to a sulfoxide.

10. Use according to claim 9, characterized in that the oxidation of the alcohol to the aldehyde is in particular the oxidation of alkoxybenzyl alcohol to alkoxybenzaldehyde and the oxidation of the thioether to the sulfoxide is in particular the oxidation of 5-fluoro-2-methyl-1- (4-methylthiobenzylidene) -3-indeneacetic acid to (Z) -5-fluoro-2-methyl-1- [ [4- (methylsulfinyl) phenyl ] methylene ] -3-indeneacetic acid.

Technical Field

The invention relates to the field of catalysts, in particular to a porous layered transition metal chalcogenide compound and a preparation method and application thereof.

Background

The chemical formula of the layered transition metal chalcogenides (TMDs) is generally MX₂Wherein M is transition metal mainly including Mo, W, V, etc., and X is chalcogen element (S, Se, Te). Layered transition metal chalcogenides have a graphite-like layered lattice layer, which is generally a sandwich structure consisting of three atomic layers: the middle layer is a transition metal atomic layer, and the two sides are chalcogenide layers which are generally abbreviated as X-M-X lattice layers; in the X-M-X lattice layer, metal atoms and chalcogen atoms are bonded together by strong chemical bonds, and the lattice layers are stacked together only by weak van der Waals forces. In TMDS materials, the band Structure of semiconductor materials is relatively special, the electron transition mainly comes from d orbital electrons of metal elements in the materials but not valence electrons of chalcogen elements, the anti-photo-corrosion capability of S/Se/Te elements is greatly improved, and the material has good stability (R.Coehoron, C.Haas, J.Dijkstra, C.J.F.Flaps, R.A.D.Groot, A.wold.electronic Structure of MoSe)₂,MoS₂,and WSe₂.I.Band-structure Calculations and Photoelectron Spectroscopy[J]Phys.Rev.B,1987,35(12), 6195-6202); furthermore, the forbidden bandwidth of the TMDs material is relatively narrow (<2.4eV) can undergo a photocatalytic reaction under irradiation of visible light. However, for the common TMDs, because atom bonding in the lattice layer is saturated, the catalytic activity sites are few, and the catalytic performance is poor.

Study ofIt is shown that the catalytic activity of the material is greatly improved due to the existence of a large number of dangling bonds (dangling bonds), and the atoms are theoretically considered to be active sites in various catalytic reactions (t.f. jamamilo, k.p).J.Bonde,J.H.Nielsen,S.Horch,I.Chorkendorff.Identification ofActive Edge Sites for Electrochemical H₂Evolution from MoS₂Nanocatalysts[J]Science,2007,317, 100-102.). However, because the TMDS crystal has a strong spontaneous tendency of reducing the surface energy in the growth process, the material always reduces the exposure proportion of the edges of the lattice layer by forming a lamellar shape, curling into a nanotube shape and the like. How to overcome the thermodynamic spontaneous tendency of reducing the surface energy in the crystal growth process, the design and synthesis of TMDS materials with high lattice layer edge exposure becomes the key for developing the higher-performance catalysts.

Disclosure of Invention

The invention provides a porous layered transition metal chalcogenide compound and a preparation method and application thereof.

The invention provides a preparation method of a porous layered transition metal chalcogenide compound, which comprises the following steps:

(1) mixing the silica microspheres, the transition metal salt and the sulfur group simple substance, and then performing pressing treatment to obtain a pressed sheet; the silica microspheres are silica microspheres with single particle size or consist of silica microspheres with different particle sizes;

(2) and sintering the pressed sheet in a hydrogen atmosphere, and then removing the silicon dioxide microspheres to obtain the porous layered transition metal chalcogenide.

Preferably, the diameter of the silica microspheres in the step (1) is 5-200 nm.

Preferably, the transition metal salt in step (1) includes one or two of phosphotungstic acid, ammonium metatungstate and ammonium molybdate.

Preferably, the chalcogen in step (1) includes one or both of S, Se and Te.

Preferably, the mass ratio of the silicon dioxide microspheres to the transition metal salt in the step (1) is 1: 0.05-1; the mass ratio of the silica microspheres to the sulfur family simple substance is 1: 0.05-1.

Preferably, the sintering temperature in the step (2) is 400-900 ℃, and the heat preservation time is 2-5 h.

Preferably, the reagent for removing the silica microspheres in the step (2) comprises hydrofluoric acid aqueous solution, sodium hydroxide aqueous solution or potassium hydroxide aqueous solution; the mass concentration of the hydrofluoric acid aqueous solution is 10-40%; the mass concentration of the sodium hydroxide aqueous solution is 5-40%; the mass concentration of the potassium hydroxide aqueous solution is 5-40%.

The invention provides a porous layered transition metal chalcogenide compound prepared by the preparation method in the scheme.

The invention provides the application of the porous layered transition metal chalcogenide compound in the scheme as a photocatalyst in photocatalytic selective oxidation reaction; the photocatalytic selective oxidation reaction comprises the oxidation of an alcohol to an aldehyde or the oxidation of a thioether to a sulfoxide.

Preferably, the oxidation of the alcohol to the aldehyde is in particular the oxidation of alkoxybenzyl alcohol to alkoxybenzaldehyde and the oxidation of the thioether to the sulphoxide is in particular the oxidation of 5-fluoro-2-methyl-1- (4-methylthiobenzylidene) -3-indeneacetic acid to (Z) -5-fluoro-2-methyl-1- [ [4- (methylsulphinyl) phenyl ] methylidene ] -3-indeneacetic acid.

Advantageous effects

The invention provides a preparation method of a porous layered transition metal chalcogenide compound, which comprises the following steps: (1) mixing the silica microspheres, the transition metal salt and the sulfur group simple substance, and then performing pressing treatment to obtain a pressed sheet; the silica microspheres are silica microspheres with single particle size or consist of silica microspheres with different particle sizes; (2) and sintering the pressed sheet in a hydrogen atmosphere, and then removing the silicon dioxide microspheres to obtain the porous layered transition metal chalcogenide. According to the invention, the silica microspheres with single particle size or different particle sizes are used as the template of the layered transition metal chalcogenide porous structure, and after the template is removed, the adjustable range of the pores of the catalyst is large, so that the catalyst is very easy to adsorb molecules with various sizes, and the catalytic activity is high. In the sintering process, hydrogen reacts with the chalcogen simple substance to generate gases such as hydrogen sulfide, hydrogen selenide or hydrogen telluride, the generated gases such as the hydrogen sulfide, the hydrogen selenide or the hydrogen telluride react with the transition metal salt to spontaneously generate the layered transition metal chalcogen compound, and the generated layered transition metal chalcogen compound contains the silica microspheres. After the silica microspheres are removed, all the positions originally occupied by the silica microspheres become gaps to form porous layered transition metal chalcogenide compounds with different sizes, and the existing pore structures improve the edge exposure of the lattice layer and have more active sites, so that the porous layered transition metal chalcogenide compounds have higher catalytic activity.

Drawings

FIG. 1 shows WSe prepared in example 1₂Scanning electron microscope images of;

FIG. 2 shows MoSe prepared in example 3₂Scanning electron microscope images of;

FIG. 3 is a nuclear magnetic hydrogen spectrum of p-3-methyl-4-methoxybenzaldehyde prepared in application example 3;

fig. 4 is a nuclear magnetic hydrogen spectrum of sulindac prepared in application example 5.

The results of the examples show that the porous layered transition metal chalcogenide compounds with different sizes prepared by the method have the characteristics of more active sites and high specific surface area.

In addition, the preparation method of the invention also has the advantage of simple steps.

The porous layered transition metal chalcogenide compound provided by the invention has the characteristics of high specific surface area and more active sites, and can effectively catalyze the oxidation of alcohol into aldehyde or the oxidation of thioether into sulfoxide. The results of the examples show that the specific surface area of the layered transition metal chalcogenide can be as high as 29m²/g。