(621ch) Structure Regulation of Hollow Cylindrical EO Catalyst and Effective Diffusion Coefficient

Ethylene oxide synthesis process in fixed-bed is a multiple and strong exothermic reaction and belongs to surface control reaction. The shape of silver catalysts have changed gradually from the spherical particle, hollow cylinder, three-hole cylindrical catalyst to seven-hole spherical particle to improve the selectivity. The thin-wall multi-hole catalyst can shorten the diffusion path, and reduce temperature rise in the grain, thus improve the reaction selectivity and intra-granular effective diffusion coefficient.

In this paper, the theoretical analysis-experiment-mathematical simulation method was applied to investigate the effect of the engineering parameters, such as catalyst size, thin wall thickness, hole number etc., on the epoxy ethane selectivity and effective diffusivity. The three-dimensional reaction-mass transfer-heat transfer model inside the hollow cylindrical particles was developed and solved by COMSOLand verified by the literature data. The calculated results from COMSOL algorithm are in good agreement with the dada of the orthogonal collocation method from the literature. Some multi-hole catalysts were calculated and the structure regulation strategy was proposed. The results obtained can provide a scientific basis for the structure regulation of the EO catalyst, even for strong exothermic reaction catalysts.