Regeneration of deactivated CuO@SiO2 catalysts for catalytic oxidation of AsH3: A synergy of regeneration and modification

The recyclability of AsH3 removal catalysts is vital for industrial application and environmental protection. In this work, a series of regeneration studies based on the catalytic oxidation of AsH3 over CuO@SiO2 core–shell catalysts were carried out. Experimental results demonstrated that the nitrogen thermal regeneration (NR) and alkali rinse regeneration (AR) are promising methods for the regeneration of CuO@SiO2 catalysts. 100 % regeneration efficiency could be realized by the NR method at 500℃. The characterization results showed that oxidation products (As2O3 and As2O5) could be completely removed from the deactivated catalysts at 500℃, and highly active unsaturated Cu2+ and chemisorbed oxygen were recovered to a great extent. Surprisingly, the AR method could not only effectively regenerate the deactivated catalysts, but also modify the catalysts to a certain extent, resulting an unparalleled regeneration efficiency of 231.3 %. A synergy of regeneration and modification in the AR process was illustrated by further investigation, in which not only were the oxidation products thoroughly removed, but also the adsorption and activation sites (Si-OH) of AsH3 were increased, and the number and strength of alkaline sites were also improved. Meanwhile, this synergy enabled the regeneration efficiency still up to 172 % after five cycles of regeneration. This work provides a novel idea for the cyclic utilization of AsH3 removal catalysts.