Study On Preparation Of CuO/ZnO/Al₂O₃ Catalyst By High Gravity Co-Precipitation Method

In modern chemical production processes, the catalyst plays an increasingly important role. It is well-known that reaction performances of a catalyst are determined by its surface structure, as so is the preparation process to the formation of its surface structure. Among many preparation methods of CuO/ZnO/Al₂O₃ catalyst, sample of co-precipitation method has large surface area, small crystal size, high dispersion and low-temperature activity, as well as excellent non-toxic, non-polluting performance on the surrounding environment, so have been extensively applied to modernization chemical industry, but the structure of conventional stirred tank reactor (CSTR) resulted in the difficulty of achieving homogeneously microscopic mixing. The catalyst particles prepared by CSTR have ununiform crystal size and it is difficult to control it. The products cannot be transformed away rapidly from the precipitation system, resulting in the rise of concentration gradient and different degree of supersaturation in the precipitation system and thereby in the difference in the precipitation particle size and the difficult to achieve high dispersion of active species. We must improve the preparation method of the catalyst. Rotating Packed Bed Reactor (RPBR) is widely used to prepare a variety of nano materials. It can achieve homogenous mixing of reactant in reaction system and reaction nucleation region is divided with crystal growth region. When the catalysts were prepared using RPBR, crystal growth lies in completely macroscopic mixing region and the prepared catalysts present homogenous crystal size and high active species dispersion.In order to improve the structural restrictions of CSTR, the high gravity co-precipitation method (HGCP) was used to strengthen co-preparation process of CuO/ZnO/Al₂O₃ catalyst preparation, the rotation speed of the Packed Bed, pH of precipitation, aging time, washing times and calcination temperatures influencing the properties of the catalyst were investigated. The precursors and catalysts were characterized by various means. The catalysts prepared with HGCP show more smaller average particle size, higher copper dispersion and exhibit higher specific surface area as compared to those prepared by CSTR reactor. Based on these experimental results on the small scale RPBR, improving advice was provided and a gas-liquid separator was added and a pilot scale RPBR of 50ta^-1 was founded. Two CuO/ZnO/Al₂O₃ catalysts were prepared under different rotating rate of RPBR. The results showed that all the physical characteristics of the catalysts achieved the technical index.CuO/ZnO/Al₂O₃ catalyst was prepared by two-step high gravity co-precipitation method, support preparation and different Al salt addition methods had been experimented, the results show that the catalyst prepared by two-step method has superior internal structure, accordingly thermal stability of the catalyst can significantly increase.