Preparation Of CuO-Bi₂O₃/SiO₂-MgO Catalyst And Its Ethynylation Performance

1,4-Butanediol (BDO) is a versatile basic organic raw materials. The demand for BDO increases sharply with the development of downstream industries and has reached1.5million t/year by2011. Reppe method is a classical process for the synthesis of BDO. In this method,1,4-butynediol (BD) is synthesized firstly by acetylene and formaldehyde over the ethynylation catalyst, and then BD was further hydrogenated to BDO. As the source reaction, the synthesis of BD through the ethynylation of formaldehyde becomes a key step for the whole industry chain. Our country has mastered BD production technology; however, the catalyst is still dependent on importation. This restricts the development of the BDO industry chain. Thus, it is of great importance to develope the ethynylation catalysts with independent intellectual property rights. In our preliminary work, the ethynylation catalysts were researched and developed. SiO2-MgO complex was prepared by sol-gel technology combined with supercritical drying and then impregnated with the solution containing active component. The obtained CuO-Bi2O3/SiO2-MgO catalyst had a better ethynylation performance in the synthesis of1,4-butynediol reaction.In the present thesis, the CuO-Bi2O3/SiO2-MgO catalysts were prepared by different preparation methods and charactered by a variety of means. The inherent relationship of the structure, texture and catalytic activity was discussed. Also, more extensive reseach about the effects of preparation conditions on the catalyst structure and activity were developed. These studies will provide the necessary theoretical support for the further development of industrial ethynylation catalyst. The major results of this thesis are as follows:1,The CuO-Bi2O3/SiO2-MgO catalysts were prepared by impregnation method, deposition precipitation method and coprecipitation method, respectively. The characterization and evaluation results showed that the CuO species of catalyst prepared by impregnation method gathered, and formed a strong interaction with the support. Deposition precipitation method weakened the interaction of CuO with the support, while the CuO metal size was still large. And coprecipitation method simultaneously improved the dispersion and reduction ability of CuO species. So this CuO species were reduced efficiently to Cu+, and thus more activity centers were generated. This made the catalysts show the high catalytic performance.2,The CuO-Bi2O3/SiO2-MgO catalysts were prepared by coprecipitation methods using silica sol, sodium silicate, TEOS respectively, and evaluated for the ethynylation performance. The results showed that CuO species were not well dispersed over the catalysts prepared with the silica sol because of its rapid hydrolysis and polymerization rate; the hydrolysis rate of sodium silicate was slow, the dispersion of CuO species was good, while the weak interaction was formed between CuO and the support; TEOS with slow hydrolysis rate allowed the silicon species and the active component mix fully, and the CuO species were highly dispersed on the support and simultaneously formed appropriate interaction with the support, and catalysts demonstrated the high ethynylation performance.3,The CuO-Bi2O3/SiO2-MgO catalysts were prepared by different precipitants, precipitation methods and pre-hydrolysis time. The ethynylation performance was influenced by different dispersion and reduction of CuO induced by different preparation conditions.