Synthesis Of Core-shell CuO-Bi₂O₃@SiO₂ Catalyst And Its Catalytic Performance For Formaldehyde Ethynylation

1,4-Butynediol (BYD) is an important basic organic raw materials. The demand for BYD increases sharply with the development of downstream industries. Generally, alkyne aldehyde method uses moderate slurry bed reactor in industry and the catalyst is supported copper-bismuth catalyst. In the process of BYD production, the catalyst activity decreased after multiple cycles of reaction. However, the deactivation reasons of copper-bismuth catalyst in formaldehyde ethynylation reaction are still not clear. It has vital theoretical significance and practical value to study the deactivation mechanism of formaldehyde ethynylation catalysts and develop more efficient and stable catalysts. It has recently been realized that the research of core-shell structure provides anew way of problem solving.In this thesis, CuO-Bi2O3 catalyst was prepared by the coprecipitation method. Using CuO-Bi2O3 as the core, core-shell CCuO-Bi2O3@SiO2 catalyst was successfully fabricated by sol-gel technology. The deactivation mechanism of the copper-bismuth catalyst and the synthesis of core-shell catalyst were systematically studied. The major results of this thesis are as follows:1、The deactivation mechanism of CuO-Bi2O3/SiO2-MgO catalyst and CuO-Bi2O3 powder was investigated. The results show the aggregatin and active ingredient loss of industry catalyst and CuO-Bi2O3. These reasons led to the deactivation of the catalysts.2、CuO-Bi2O3@SiO2 catalysts were successfully fabricated by sol-gel technology. Core-shell catalysts show higher BET surface area, and the silica shell was composed of mesoporous. Compared with industrial catalyst and CuO-Bi2O3 powder, core-shell CuO-Bi2O3@SiO2 catalyst exhibits excellent stability in the reaction of formaldehyde ethynylation.Because the mesoporous silica allow dissolved chemical species to reach catalytic particles to be chemically transformed while the mesoporous shells continue to act as effective barriers against aggregation and loss of activity of the core particles.3、By changing the ratio of m(CuO-Bi2O3)/m(TEOS), different shell thickness core-shell CuO-Bi2O3@SiO2 catalysts were successfully fabricated by sol-gel technology. The formaldehyde ethynylation performance of different shell thickness core-shell CuO-Bi2O3@SiO2 catalysts were studied comparatively. The results showed that all CuO-Bi2O3@SiO2 catalysts exhibit excellent stability in the reaction of formaldehyde ethynylation.But the catalysts activity increased with decreasing of shell thickness. Because decreasing of shell thickness caused mass transfer resistance of catalytic reaction decreases.