A systematic review of intermediates and their characterization methods in VOCs degradation by different catalytic technologies

In the process of volatile organic compounds (VOCs) catalytic oxidation, the search of the reaction mechanism and the reaction rate-controlling part are the key and difficult elements of research. In this work, the intermediate products in the process of eliminating various VOCs by different catalytic technologies are systematically reviewed. Based on intermediates analysis, the advantages and disadvantages of various catalytic technologies in the control of by-products are described in detail. The paper also focuses on the detection techniques of characteristic intermediates in VOCs elimination, and discusses the characterization methods and their usage conditions. Finally, several factors are provided that affect the formation and conversion of intermediates. Especially, the effects of catalysts surface metal capacity and oxygen species on intermediates are discussed. It is believed that the review will provide a good basis and reference point for the exploration of VOCs catalytic oxidation pathways and the analysis of intermediate products.