阅读说明：本技术 一种有序介孔过渡金属氮化物的制备方法 (Preparation method of ordered mesoporous transition metal nitride ) 是由 程之星 阿里萨阿德 刘思奇 杨明辉 于 2019-08-14 设计创作，主要内容包括：本发明提供一种有序介孔过渡金属氮化物的制备方法,包括以下步骤：将二氧化硅SBA-15介孔模板填充过渡金属离子,高温氧化后用碱去除模板,生成带有介孔结构的介孔氧化物,然后将介孔氧化物高温氮化处理合成有序介孔过渡金属氮化物；本发明基于SBA-15模板衍生的前体,可用于各种类型的TMN材料。一方面,通过促进NH<Sub>3</Sub>的气体扩散,能够有效地降低反应时间,有利于合成高结晶度的刚性介孔结构。另一方面,快速氮化工艺可节省一般温度编程加热和冷却时间,从而抑制介孔结构的封闭和塌陷。(The invention provides a preparation method of ordered mesoporous transition metal nitride, which comprises the following steps: filling a silicon dioxide SBA-15 mesoporous template with transition metal ions, removing the template by using alkali after high-temperature oxidation to generate mesoporous oxide with a mesoporous structure, and then performing high-temperature nitridation treatment on the mesoporous oxide to synthesize ordered mesoporous transition metal nitride; the present invention is based on SBA-15 template-derived precursors, useful for various types of TMN materials. In one aspect, by promoting NH 3 The gas diffusion of (2) can effectively reduce the reaction time, and is beneficial to synthesizing a rigid mesoporous structure with high crystallinity. On the other hand, the rapid nitridation process can save the time for programming heating and cooling at common temperature, thereby inhibiting the closing and collapse of the mesoporous structure.)

1. The preparation method of the ordered mesoporous transition metal nitride is characterized by comprising the following steps of: filling transition metal ions in a silicon dioxide SBA-15 mesoporous template, removing the template by using alkali after high-temperature oxidation to generate mesoporous oxide with a mesoporous structure, and then performing high-temperature nitridation treatment on the mesoporous oxide to synthesize the ordered mesoporous transition metal nitride.

2. The method for preparing an ordered mesoporous transition metal nitride according to claim 1, wherein the transition metal ions are one or more of cobalt ions, tungsten ions, chromium ions, nickel ions, and iron ions.

3. The method of preparing an ordered mesoporous transition metal nitride according to claim 1, wherein the mesoporous oxide is one or more of cobalt oxide, tungsten oxide, chromium oxide, and nickel iron oxide.

4. The method for preparing the ordered mesoporous transition metal nitride according to claim 1, wherein the method for preparing the mesoporous template of silicon dioxide SBA-15 comprises:

1) adding a nonionic triblock copolymer Pluronic P123 into hydrochloric acid with the pH value less than 1, and stirring at 30-50 ℃ until the solute is completely dissolved;

2) adding tetraethyl orthosilicate into the solution prepared in the step 1) under the condition of stirring, uniformly mixing and standing for 10-30 h; heating in an oven at 80-90 ℃ for 10-24h under the standing condition, filtering, washing and drying the precipitate obtained by filtering by using deionized water, and finally calcining at the temperature of more than 500 ℃ to obtain the silicon dioxide SBA-15 mesoporous template.

5. The method of preparing an ordered mesoporous transition metal nitride according to claim 1, wherein the method of preparing the mesoporous oxide comprises:

1) adding a silicon dioxide SBA-15 mesoporous template and an oxide precursor into ethanol, uniformly mixing, stirring at room temperature for 30-50min, heating to 60-80 ℃, and evaporating to remove ethanol to obtain a mesoporous silicon composite material;

2) putting the mesoporous silicon composite material into a porcelain boat, heating for 3-4h at the temperature of 250 ℃ in a muffle furnace at 230 ℃, removing the silicon dioxide SBA-15 mesoporous template by using NaOH solution, washing by using deionized water and ethanol, and drying in vacuum at the temperature of 60-80 ℃ to obtain the mesoporous oxide.

6. The method of preparing an ordered mesoporous transition metal nitride according to claim 5, wherein the oxide precursor is a metal salt corresponding to a metal oxide; the metal oxide is one or more of cobalt oxide, chromium oxide, tungsten oxide and nickel iron oxide.

Technical Field

The invention relates to the field of nano-structure functional materials, in particular to a preparation method of ordered mesoporous transition metal nitride.

Background

Transition Metal Nitrides (TMN) are intermetallic filling compounds produced by insertion of nitrogen into a transition metal lattice, having properties of covalent compounds, ionic crystals and transition metals. TMN has unique physical and chemical properties, such as high strength, strong acid and alkali resistance, high chemical stability, good conductivity, etc., and thus has wide applications in the fields of superhard materials, protective materials, superconductors, and structural materials. In addition, a great deal of research shows that TMN shows good catalytic activity in a plurality of hydrogen-involved reactions, and even has the performance which is not inferior to the performance of noble metals such as Pt, Rh and the like, so that the TMN has important significance for carrying out extensive and intensive research on the formation mechanism, the preparation condition and the catalytic performance of the TMN and developing the application prospect.

It is well known that specific surface area and pore structure have a great influence on catalytic reactions, whereas a large number of metal active sites and increased pore volume are provided by a high specific surface area and a regular pore structure. The preparation of the transition metal nitride is a local regular reaction, and particularly when a material with high specific surface area is synthesized, the transition metal nitride with high specific surface area can be generated under the condition that the crystal structure of a transition metal oxide precursor is not basically damaged by strictly controlling the reaction conditions. However, most of the existing methods for preparing Transition Metal Nitrides (TMN) involve high temperature heating or high pressure for a long time, and high interfacial energy and pressure exist in such reaction systems, so that the porous structure is inevitably aggregated, closed and collapsed during the transformation and recrystallization processes. Therefore, it is very necessary to use a new method to prepare ordered porous TMN with high specific surface area.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art: provides a new method for preparing ordered mesoporous transition metal nitride by a rapid nitridation synthesis method. The method is based on SBA-15 template-derived precursors and can be used for various types of TMN materials. In one aspect, by promoting NH₃The gas diffusion of (2) can effectively reduce the reaction time, and is beneficial to synthesizing a rigid mesoporous structure with high crystallinity. On the other hand, the rapid nitridation process can save the time for programming heating and cooling at common temperature, thereby inhibiting the closing and collapse of the mesoporous structure.

The technical solution of the invention is as follows: a method for preparing ordered mesoporous transition metal nitride comprises the following steps: filling transition metal ions in a silicon dioxide SBA-15 mesoporous template, removing the template by using alkali after high-temperature oxidation to generate mesoporous oxide with a mesoporous structure, and then performing high-temperature nitridation treatment on the mesoporous oxide to synthesize the ordered mesoporous transition metal nitride.

The transition metal ions are one or more of cobalt ions, tungsten ions, chromium ions, nickel ions and iron ions.

The mesoporous oxide is one or more of cobalt oxide, tungsten oxide, chromium oxide and nickel iron oxide.

The preparation method of the silicon dioxide SBA-15 mesoporous template comprises the following steps:

1) adding a nonionic triblock copolymer Pluronic P123 into hydrochloric acid with the pH value less than 1, and stirring at 30-50 ℃ until the solute is completely dissolved;

2) adding tetraethyl orthosilicate into the solution prepared in the step 1) under the condition of stirring, uniformly mixing and standing for 10-30 h; heating in an oven at 80-90 ℃ for 10-24h under the standing condition, filtering, washing and drying the precipitate obtained by filtering by using deionized water, and finally calcining at the temperature of more than 500 ℃ to obtain the silicon dioxide SBA-15 mesoporous template.

The preparation method of the mesoporous oxide comprises the following steps:

1) adding a silicon dioxide SBA-15 mesoporous template and an oxide precursor into ethanol, uniformly mixing, stirring at room temperature for 30-50min, heating to 60-80 ℃, and evaporating to remove ethanol to obtain a mesoporous silicon composite material;

2) putting the mesoporous silicon composite material into a porcelain boat, heating for 3-4h at the temperature of 250 ℃ in a muffle furnace at 230 ℃, removing the silicon dioxide SBA-15 mesoporous template by using NaOH solution, washing by using deionized water and ethanol, and drying in vacuum at the temperature of 60-80 ℃ to obtain the mesoporous oxide.

The oxide precursor is metal salt corresponding to metal oxide; the metal oxide is one or more of cobalt oxide, chromium oxide, tungsten oxide and nickel iron oxide.

The invention has the beneficial effects that: the invention can synthesize a series of binary and ternary TMN materials (Co) within 30minN, WN, CrN and Ni₃FeN) and avoids pore collapse, and a perfect mesoporous structure is maintained, so that the catalyst has a high specific surface area and can provide more active sites in a catalytic reaction. The successful preparation of the series of materials shows that the invention has universality and wide application prospect. In addition, the preparation method has the advantages of simple operation, simple equipment, uniform product and short overall reaction time.

Drawings

FIG. 1: the X-ray diffraction pattern of the example is shown.

FIG. 2: the X-ray diffraction pattern spectrum in the example is shown.

FIG. 3: CoN, WN, CrN and Ni prepared in the examples₃A mesoporous morphology map of a FeN transmission electron microscope.

FIG. 4: CoN, WN, CrN and Ni prepared in the examples₃FeN high resolution transmission electron microscope lattice diagram.

Detailed Description

The present invention will be described in further detail with reference to the following examples, but the present invention is not limited to the following examples.