Modified Mn/ZSM-5 for Non-Thermal Plasma Mineralization of VOCs and DFT Simulation Using a Novel Y-Type ZSM-5 Model

Abstract

Using a catalyst to mineralize volatile organic compounds (VOCs) in a Non-thermal Plasma (NTP) reactor is an effective method. In many kinds of catalysts for VOCs degradation, oxygen defect is a crucial factor affecting the catalytic activity. Three different methods (steaming, doping, plasma) were used to introduce possible oxygen defects into the Mn/ZSM-5 to prepare modified catalysts, which were evaluated in VOCs degradation activity using a Double Dielectric Barrier Discharge (DDBD) plasma device. Additionally, a novel Y-type ZSM-5 model was employed in the DFT simulation. The new Y-type ZSM-5 model used in this paper is a more realistic aperiodic model. It showed that introducing possible oxygen defects can substantially enhance degradation efficiency. Taking the catalyst with oxygen defects introduced by plasma as an example, the conversion (CO2 selectivity) of the methanol, acetone, and toluene could reach 100% (100%), 97.7% (99.1%), 91.2% (93.9%), respectively, at an initial concentration of 2000 ppm and specific input energy of 9 kJ/L. The results demonstrated that modification could significantly enhance the activity of the catalyst in decomposing VOCs at room temperature using non-thermal plasma catalysis. Theoretical simulation of density functional theory (DFT) revealed that the adsorption of adsorbate on the catalyst becomes easier after possible oxygen defects are introduced.