The post plasma-catalytic decomposition of toluene over K-modified OMS-2 catalysts at ambient temperature: Effect of K+ loading amount and reaction mechanism

Abstract

The present work is devoted to study the post plasma-catalytic (PPC) degradation of toluene using packed-bed discharge (PBD) plasma over K-modified manganese oxide octahedral molecular sieve (OMS-2) catalysts at ambient temperature. Compared to plasma alone, PPC can significantly improve the toluene degradation and mineralization performance simultaneously, and the generation of discharge byproducts and organic intermediates is suppressed. The catalytic capacity of OMS-2 for toluene degradation is greatly promoted by tuning potassium ions (K+) content in OMS-2 tunnel, which might be owing to the formation of more surface active oxygen species derived from weak Mn-O bonds, plenty of oxygen vacancies, as well as more superior low-temperature reducibility. Highest toluene degradation efficiency (89.4%) and COx selectivity (88.9%) can be achieved in plasma-catalysis system over K-modified OMS-2 sample with K/Mn molar ratio of 2 at the SIE of 658 J/L. A long-term stability test has also been successfully carried out to evaluate the stability of K-modified OMS-2 with the assistance of plasma. Possible reaction mechanism for plasma-catalytic degradation of toluene on K-modified OMS-2 catalyst has been proposed based on the plasma diagnosis, catalysts characterization, and organic intermediates identification. This work aims to gaina deeperunderstandingof plasma-catalytic degradation mechanism and provides an environmentally friendly and energy-efficient method for practical volatile organic compounds (VOCs) abatement in PPC process.