阅读说明：本技术 一种有序大孔非金属催化剂及其制备方法 (Ordered macroporous non-metal catalyst and preparation method thereof ) 是由 陆安慧 陆文多 李文翠 于 2019-10-21 设计创作，主要内容包括：本发明属于催化和材料技术领域,提供了一种有序大孔非金属催化剂及其制备方法。一种有序大孔非金属催化剂,其孔径为50-1000nm。一种有序大孔非金属催化剂的制备方法,选择单分散球形模板,将磷酸硼的前躯体溶液与模板混合,炭化,焙烧得到产物。本发明首次提供了一种制备有序大孔的非金属氧化物晶体的方法,制备的有序大孔催化剂可暴露更多的活性位,增强传质,应用于低碳烷烃氧化脱氢反应中催化性能显著提高。该催化剂烯烃选择性高,CO<Sub>2</Sub>生成量可忽略,与无孔催化剂相比,有序大孔催化剂达到相同转化率时,反应温度可至少降低30℃,可在高空速下得到较高产率。(The invention belongs to the technical field of catalysis and materials, and provides an ordered macroporous non-metallic catalyst and a preparation method thereof. An ordered macroporous non-metal catalyst with pore diameter of 50-1000 nm. A process for preparing the ordered macroporous non-metal catalyst includes such steps as choosing monodispersed spherical template, mixing the solution of boron phosphate precursor with said template, charring and calcining. The invention provides a method for preparing ordered macroporous non-metal oxide crystals for the first time, the prepared ordered macroporous catalyst can expose more active sites, enhance mass transfer and remarkably improve the catalytic performance when being applied to the oxidative dehydrogenation reaction of low-carbon alkane. The catalyst has high olefin selectivity and CO 2 Negligible amount of formation and no holeCompared with the catalyst, when the ordered macroporous catalyst achieves the same conversion rate, the reaction temperature can be reduced by at least 30 ℃, and higher yield can be obtained at high space velocity.)

1. An ordered macroporous non-metal catalyst with pore diameter of 50-1000 nm.

2. A preparation method of an ordered macroporous non-metallic catalyst is characterized in that a monodisperse spherical template is selected, a precursor solution of boron phosphate is mixed with the template, carbonized and roasted to obtain a product;

wherein, the mixing mode of the monodisperse spherical template and the precursor solution of the boron phosphate is a rotary evaporation method or a dipping method;

the rotary steaming method comprises the following steps: uniformly mixing a precursor solution of boron phosphate with a spherical template colloidal solution, evaporating a solvent by rotation to obtain a solid mixture, and putting the solid mixture into an oven for aging and drying; the solid content mass ratio of the spherical template colloid solution to the boron phosphate precursor solution is 0.1-5:1, the aging drying temperature is 50-200 ℃, and the aging time is 12-48 h;

the impregnation method comprises the following steps:

(1) centrifuging, filtering, settling by gravity or volatilizing the solvent to obtain a spherical template solid;

(2) soaking the spherical template solid into a precursor solution of boron phosphate, filling the precursor solution of boron phosphate into pores of the template, filling the solution soaked with the template into a hydrothermal kettle, hydrothermally growing boron phosphate crystals, filtering the template filled with boron phosphate after hydrothermal treatment, and putting the template into an oven for aging and drying; the dipping time is 0.5-3h, the hydrothermal temperature is 120-200 ℃, and the hydrothermal time is 48h-8 days; the ratio of the solid mass of the spherical template to the solid content of the boron phosphate precursor is 0.1-100:1, the aging drying temperature is 50-200 ℃, and the aging time is 12-48 h;

carbonizing and roasting to obtain a product, and carbonizing and roasting the aged and dried solid mixture to obtain the ordered macroporous non-metallic catalyst; the carbonization temperature is 500-1000 ℃, and the roasting temperature is 500-1000 ℃.

3. The method according to claim 2, wherein the monodisperse spherical template is dispersed in a solvent to obtain a spherical template colloidal solution; the monodisperse spherical template is a polymer sphere, a carbon sphere or a silicon oxide sphere; the particle size of the monodisperse spherical template is 50-1000 nm; the solvent is water or ethanol; the concentration of the spherical template colloid solution is 1-1000 mg/mL.

4. The method according to claim 3, wherein if the silica spheres are used as the template, the template is removed by using a sodium hydroxide solution or a hydrofluoric acid solution after the calcination, wherein the sodium hydroxide solution has a concentration of 5 to 40% by mass and the hydrofluoric acid solution has a concentration of 5 to 30% by mass.

5. The preparation method according to any one of claims 2 to 4, wherein the precursor solution of boron phosphate is prepared by dissolving boride and phosphide in a solvent; the boride and phosphide are respectively boric acid and phosphoric acid, and the solvent is ethanol and/or ethanol; the molar ratio of the boric acid to the phosphoric acid is 0.5-3:1, and the concentration of the boric acid is 10-1000 mg/mL.

Technical Field

The invention belongs to the technical field of catalysis and materials, and particularly relates to an ordered macroporous non-metallic catalyst and a preparation method thereof.

Background

The preparation of propylene by oxidative dehydrogenation of propane is one of the important reactions of oxidative dehydrogenation of low-carbon alkane, and has attracted attention due to the advantages of no carbon deposit generation, no thermodynamic equilibrium limitation, low energy consumption and the like. The catalysts used for this reaction are mainly concentrated on metal oxide catalysts, but there is a problem that propylene is excessively oxidized and the yield of the target product is lowered. Recently, non-metallic boron-containing materials have shown excellent activity and olefin selectivity in alkane oxidative dehydrogenation (Science,2016,354,1570; ChemCatChem,2017,9, 1718; Chinese Journal of catalysis,2017,38,389), and studies have reported that B-O sites play an important role in alkane oxidative dehydrogenation reactions, however, the boron-based catalysts reported in the literature are massive and have a low specific surface area, resulting in limited available active sites. Therefore, the porous boride is prepared to expose more active sites, enhance mass transfer and facilitate the oxidative dehydrogenation reaction of the alkane.

The ordered macroporous material has larger pore volume, higher specific surface area and ordered macroporous structure, can promote substance transfer, reduce diffusion limitation, expose more active sites, promote guest molecules to reach the active sites, and is beneficial to the catalytic conversion of the molecules, so that the application of the ordered macroporous material in the field of catalysis is widely concerned. Chinese patent ZL201510958978.3 discloses a lanthanum manganate-supported platinum tin nano-catalyst with a three-dimensional ordered macroporous structure and a preparation method thereof, and the structure is beneficial to adsorption and diffusion of reactant molecules due to the large specific surface area of the catalyst, so that the catalyst has a good catalytic effect in the aspect of catalytic purification of automobile exhaust. At present, the synthesis of ordered macroporous materials such as carbon (ZL200910220488.8, ZL201010610253.2), metal (chem. Mater.2018,30, 1617-. However, the preparation of the non-metallic oxygen-containing compound crystal with the ordered macroporous structure is not reported, and the non-metallic oxygen-containing compound crystal with the ordered macroporous structure is not applied to the alkane oxidative dehydrogenation reaction.

Disclosure of Invention

The invention provides an ordered macroporous non-metallic catalyst and a preparation method thereof, in particular to a non-metallic oxygen-containing compound crystal boron phosphate which can be prepared into an ordered macroporous structure and can obviously improve the performance of catalyzing the oxidative dehydrogenation of low-carbon alkane.

The technical scheme of the invention is as follows:

an ordered macroporous non-metal catalyst with pore diameter of 50-1000 nm.

A method for preparing ordered macroporous non-metallic catalyst, choose monodispersed spherical template, mix precursor solution of boron phosphate with template, carbonize, roast and get products;

wherein, the mixing mode of the monodisperse spherical template and the precursor solution of the boron phosphate is a rotary evaporation method or a dipping method;

the rotary steaming method comprises the following steps: uniformly mixing a precursor solution of boron phosphate with a spherical template colloidal solution, evaporating a solvent by rotation to obtain a solid mixture, and putting the solid mixture into an oven for aging and drying; the solid content mass ratio of the spherical template colloid solution to the boron phosphate precursor solution is 0.1-5:1, the aging drying temperature is 50-200 ℃, and the aging time is 12-48 h;

the impregnation method comprises the following steps:

(1) centrifuging, filtering, settling by gravity or volatilizing the solvent to obtain a spherical template solid;

(2) soaking the spherical template solid into a precursor solution of boron phosphate, filling the precursor solution of boron phosphate into pores of the template, filling the solution soaked with the template into a hydrothermal kettle, hydrothermally growing boron phosphate crystals, filtering the template filled with boron phosphate after hydrothermal treatment, and putting the template into an oven for aging and drying; the dipping time is 0.5-3h, the hydrothermal temperature is 120-200 ℃, and the hydrothermal time is 48h-8 days; the ratio of the solid mass of the spherical template to the solid content of the boron phosphate precursor is 0.1-100:1, the aging drying temperature is 50-200 ℃, and the aging time is 12-48 h;

carbonizing and roasting to obtain a product, and carbonizing and roasting the aged and dried solid mixture to obtain the ordered macroporous non-metallic catalyst; the carbonization temperature is 500-1000 ℃, and the roasting temperature is 500-1000 ℃.

Dispersing the monodisperse spherical template in a solvent to obtain a spherical template colloidal solution; the monodisperse spherical template is a polymer sphere, a carbon sphere or a silicon oxide sphere; the particle size of the monodisperse spherical template is 50-1000 nm; the solvent is water or ethanol; the concentration of the spherical template colloid solution is 1-1000 mg/mL.

If the silicon oxide spheres are used as the template, removing the template by using a sodium hydroxide solution or a hydrofluoric acid solution after roasting, wherein the concentration mass fraction of the sodium hydroxide is 5-40%, and the concentration mass fraction of the hydrofluoric acid solution is 5-30%.

The precursor solution of boron phosphate is prepared by dissolving boride and phosphide in a solvent to obtain the precursor solution of boron phosphate; the boride and phosphide are respectively boric acid and phosphoric acid, and the solvent is ethanol and/or ethanol; the molar ratio of the boric acid to the phosphoric acid is 0.5-3:1, and the concentration of the boric acid is 10-1000 mg/mL.

The invention has the beneficial effects that: the invention provides a method for preparing ordered macroporous non-metal oxide crystals for the first time, the prepared ordered macroporous catalyst can expose more active sites, enhance mass transfer and remarkably improve the catalytic performance when being applied to the oxidative dehydrogenation reaction of low-carbon alkane. The catalyst has high olefin selectivity and CO₂The amount of the generated product is negligible, and compared with a non-porous catalyst, when the ordered macroporous catalyst achieves the same conversion rate, the reaction temperature can be reduced by at least 30 ℃, and higher yield can be obtained at high space velocity.

Drawings

FIG. 1 is an SEM image of the ordered macroporous boron phosphate catalyst obtained in example 1-1.

FIG. 2 is the XRD pattern of the ordered macroporous boron phosphate catalyst obtained in example 1-1.

Detailed Description

The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.