Mesoporous Tungsten Carbide Synthesis

Nano-tungsten carbide (WC) is a kind of non-noble metal catalytic material with excellent performance. It has been reported that the surface electron layer of WC is similar to platinum (Pt) and has Pt-like catalytic activity in some reactions. WC not only has the characteristics of replacing platinum and other precious metal catalysts and good anti-poisoning ability, but also has strong acid resistance and good electrocatalytic activity. However, how to further improve the catalytic activity of WC is one of the main problems in the preparation of WC catalyst.

Porosity and pore size distribution of catalysts are the main factors affecting the basic properties of catalysts, such as specific surface area, gas-liquid diffusion, etc. How to prepare catalysts with well-developed pores and suitable pore size distribution becomes the precondition for their catalytic activity. The structure and morphology of precursor will have a great effect on the structure of WC particles prepared in the later stage.

Some scholars have provided a preparation method of Mesoporous Tungsten Carbide (WC). The Mesoporous Tungsten carbide is composed of nano-sized tungsten carbide particles. The crystal length is controllable, the preparation process is simple, the pores are developed, and it can be well used in the catalytic field. The main processes are:

Control the ambient temperature to 10 C, take 10 g of ammonium metatungstate and 10 g of ammonium carbonate, put them into a bowl and mix evenly. After grinding for 3 minutes, pour the mixed powder into an open incubator, add 200 ml deionized water, stir the glass rod for 3 minutes, and then centrifuge for 18 hours. Wash them three times with deionized water and dry them at room temperature. The crystal of ammonium meta tungstate is needle like long crystal. The crystal of the ammonium tungstate crystal is photographed. It can be seen from the diagram that the obtained crystal is needle shaped long crystal. The surface is smooth and the crystal is ideal. Mesoporous acicular tungsten carbide was obtained by one-step carbonization at a programmed heating rate of 6 C / min for 4 hours at 800 C. The average length of mesoporous acicular tungsten carbide was 2.1 mm, and the surface pore diameter was about 50 nm.

The characteristics of the new process are that ammonium metatungstate crystals were synthesized by self-growing ammonium metatungstate crystals in liquid phase at room temperature. The self-growing acicular ammonium metatungstate crystals were prepared by incorporating ammonium carbonate, a low-temperature decomposable compound, into the crystallization process. The structure and morphology of ammonium tungstate composite crystals are controlled and the crystal structure and particle size are controlled. Then the characteristics of the composite crystals are fully utilized. During the carbonization process, ammonium carbonate in ammonium metatungstate composite crystals is decomposed into gas to form voids at high temperature, which makes tungsten carbide particles accumulate in nano-scale and obtain mesoporous structure. The acicular tungsten carbide particles with high specific surface area were obtained.

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