Plasma Regeneration of Spent Pd/Al<sub>2</sub>O<sub>3</sub> Catalysts and Their Electrochemical Performance
Liangliang Lin, Yunming Tao, Sergey A. Starostin, Chengdong Li, Hongyu Huang, Ailin He, Yingjun Wu, Volker Hessel, Kostya Ostrikov
Abstract
A dielectric barrier discharge (DBD) plasma was applied to reactivate palladium on alumina (Pd/Al 2 O 3 ) waste catalysts at extreme conditions, addressing a common problem of reusing the spent catalysts instead of discarding them. Experimental studies of the effect of gas composition in the plasma process reveal different extent of coke elimination and different electrochemical performance of the reactivated Pd/Al 2 O 3 catalysts, ranked as Ar-treated > N 2 -treated > O 2 -treated > untreated spent catalyst at fixed gas flow rate and regeneration time. The effect of the regeneration time and gas flow rate on the electrochemical performance of the reactivated Pd/Al 2 O 3 catalysts was systematically studied. The results show that for Ar and N 2 process gas, the electrochemical performance of the plasma-treated spent catalyst is improved with the increase of the gas flow rate and the treatment time. However, if O 2 is used, then the electrochemical performance of the spent catalyst decreases with the increase of the gas flow rate and the treatment time. The XPS results show that higher oxidation degrees of Pd reduces the electrochemical performance. This study demonstrates a new strategy for reusing the otherwise waste catalyst in a simple and environment-benign solvent-free manner.