In Situ Regeneration and Deactivation of Co-Zn/H-Beta Catalysts in Catalytic Reduction of NOx with Propane

Abstract

Regeneration and deactivation behaviors of Co-Zn/H-Beta catalysts were investigated in NOx reduction with C3H8. Co-Zn/H-Beta exhibited a good water resistance in the presence of 10 vol.% H2O. However, there was a significant drop off in N2 yield in the presence of SO2. The formation of surface sulfate and coke decreased the surface area, blocked the pore structure, and reduced the availability of active sites of Co-Zn/H-Beta during the reaction of NO reduction by C3H8. The activity of catalyst regenerated by air oxidation followed by H2 reduction was higher than that of catalyst regenerated by H2 reduction followed by air oxidation. Among the catalysts regenerated by air oxidation followed by H2 reduction with different regeneration temperatures, the optimal regeneration temperature was 550 °C. The textural properties of poisoned catalysts could be restored to the levels of fresh catalysts by the optimized regeneration process. The regeneration process of air oxidation followed by H2 reduction could recover the active sites of cobalt and zinc species from sulfate species, as well as eliminate coke deposition on poisoned catalysts. The regeneration pathway of air oxidation followed by H2 reduction is summarized as initial removal of coke by air oxidation and final reduction of the sulfate species by H2.