Investigation of promotion effect of Cu doped MnO2 catalysts on ketone-type VOCs degradation in a one-stage plasma-catalysis system

摘要

Acetone and methyl ethyl ketone are two typical ketone-type VOCs which are commonly used as solvent in manufacturing factories. Their removal under plasma-catalysis over Cu-doped MnO2 catalysts were carried out in a coaxial dielectric barrier discharge (DBD) reactor in this study. The effects of Cu doping on the removal efficiency and CO2 selectivity of two ketone-type VOCs in this system are deeply investigated and compared as a function of specific energy density (SED). Experimental results show that the introduction of the Cu-doped MnO2 catalysts significantly enhances the VOCs removal performance and CO2 selectivity. Among them, Cu-0.133 Mn presents the highest removal efficiency (97% for methyl ethyl ketone and 82.1% for acetone) and the best CO2 selectivity (91.7% for methyl ethyl ketone and 89.4% for acetone) at the SED of -600 J L-1 and a high GHSV of 300,000 mL.(g.h)(-1). Based on the structure-function analysis of catalysts, it is believed that the synergistic effect between Cu and Mn in Cu-Mn solid solution can promote the amount of surface active oxygen and reducibility to improve catalytic performance. Furthermore, with the help of in situ FTIR and GC-MS, it is found that Cu-doped MnO2 catalysts can not only accelerate the VOCs degradation rate but also improve the oxygen and ozone utilization for VOCs complete oxidation. Besides, the possible degradation pathways of two ketone-type VOCs under the plasma and plasma-catalysis process have also been suggested and discussed at last.