RE-NiOx (RE=Ce, Y, La) composite oxides coupled plasma catalysis for benzene oxidation and by-product ozone removal

Abstract

Plasma-coupled catalysis is a promising volatile organic compounds (VOCs) removal technology because of its interactional principles of plasma decomposition and catalytic oxidation. However, the problem of harmful by-products is still in trouble. A series of rare earth doped RE-NiOx (RE = Ce, Y, La) composite oxides were synthesized by metal organic frameworks (MOFs)-derived method for coupled plasma oxidation of benzene and by-product ozone removal. Compared with plasma alone, the 1%La-NiOx catalyst shows the best enhancement of 50% for benzene conversion with complete removal of a maximum of 800 ppm ozone. The energy consumption for 90% benzene removal efficiency (η90%) is also reduced from 3600 to 1200 J/L. Characterization results of RE-NiOx catalysts indicate that the doping of La causes interaction and synergistic effect between La and Ni, and the surface oxygen and lattice oxygen with defects play crucial roles in benzene oxidation and ozone decomposition, respectively. In addition, the decomposition mechanism of benzene and ozone under plasma is proposed. Plasma is responsible for the indiscriminate bond breaking in benzene and oxygen to form a variety of organic intermediates and ozone, while the La-NiOx catalyst selectively oxidizes the intermediates to COx/H2O and decomposes the ozone into oxygen.