Moderate Temperature Control for a Catalyst Bed with Unique Structure Packing in Gas-Phase Propene Oxidation

Abstract

Decreasing the maximum temperature and dispersing the high-temperature zone in a catalyst bed can inhibit the generation of local high-temperature zones (hot spot, denoted as HTS) and resolve unbalanced reaction load on a catalyst in vapor-phase oxidation over a fixed-bed tubular reactor. Towards this, the catalyst volume in the high-temperature zone could be decreased and reactant gases could be fed to the volume-decreased catalyst evenly by the optimum feed amount. For our specific strategy, we conceived a type of structure packing with a decreased volume or cross-sectional area and a flow path through which a reactant gas passes and wherein the cross-sectional area decreases continuously or stepwise from the inlet to the outlet. Upon installing any of four types of structure packing, remarkable effects on HTS restriction and the expansion of a moderate-temperature zone were observed in gas-phase propene oxidation. The temperature distribution, maximum temperature in the catalyst bed, and propene conversion were significantly affected by the size and shape of the structure packing. These results indicated that a reactor tube with a longer diameter compared to those of conventional ones may be used, and this would make it possible to reduce pressure loss, facilitate catalyst loading, increase the catalyst loading amount, and improve productivity.