Removal of Volatile Organic Compounds by Single-Stage and Two-Stage Plasma Catalysis Systems: A Review of the Performance Enhancement Mechanisms, Current Status, and Suitable Applications

Abstract

This paper provides a comprehensive review regarding the application of plasma catalysis, the integration of nonthermal plasma and catalysis, on VOC removal. This novel technique combinesthe advantages of fast ignition/response from nonthermal plasma and high selectivity from catalysis. It has been successfully demonstrated that plasma catalysis could serve as an effective solution to the major bottlenecks encountered by nonthermal plasma, i.e., the reduction of energy consumption and unwanted/hazardous byproducts. Instead of working independently, the combination could induce extra performance enhancement mechanisms either in a single-stage or a two-stage configuration, in which the catalyst is located inside and downstream from the nonthermal plasma reactor, respectively. These mechanisms are believed to be responsible for the higher energy efficiency and better CO2 selectivity achieved with plasma catalysis. A comprehensive discussion on the performance enhancement mechanisms is provided in this review paper. Moreover, the current status of the applications of two different plasma catalysis systems on VOC abatement are also given and compared. The catalyst plays an important role in both configurations. Especially for the single-stage type, depositing an inappropriate active component on catalytic support would decrease the VOC removal efficiency instead. To date, no definite conclusion on catalyst selection forthe single-stage plasma catalysis is available. However, MnO2 seems to be the best catalyst for two-stage configuration because it could effectively decompose ozone and generate active species toward VOC destruction. On the other hand, although the single-stage plasma catalysis has been proved to be superior to the two-stage configuration, it does not mean that the former is always the best choice. Considering the typical VOC concentrations from different sources and the characteristics of different plasma catalysis systems, the single-stage and two-stage configurations are suggested to be more suitable for industrial and indoor air applications, respectively.

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

“…Plasma catalysis is gaining increasing interest for various environmental applications, such as gaseous pollutant removal, the splitting of CO 2 , hydrogen generation and O 3 production [1][2][3][4][5][6][7][8][9]. Plasma catalysis can be regarded as the combination of a plasma with a catalyst, and often results in improved performance, in terms of selectivity and energy efficiency of the process.…”

Enhanced removal of toluene by dielectric barrier discharge coupling with Cu-Ce-Zr supported ZSM-5/TiO2/Al2O3

“…It is reported that the existence of Ce 3+ in CeO 2 implies the formation of an oxygen vacancy, and subsequently increasing catalytic activity [12]. Moreover, the generation of Cu + together with Ce 3+ is indicative of the redox equilibrium (Ce 3+ + Cu 2+ ↔ Ce 4+ + Cu + ), which is claimed to be the enhancement of reduced copper species [13].…”

Exploration of nano-surface chemistry for spectral analysis

“…Plasma catalysis technique also has the advantages of high selectivity from catalysis and the fast response from plasma technique. Reports on plasma catalysis mainly focus on environmental clean-up removing volatile organic compounds (VOCs) from gaseous pollutants [10] and hydrocarbon reforming for hydrogen production [11]. There are two ways of combination: the catalyst placed in the discharge zone (in-plasma catalysis, IPC) or the catalyst placed after the discharge zone (post-plasma catalysis, PPC).…”