Catalytic Elimination of Typical Halogenated Volatile Organic Compounds (HVOCs): A Critical Review

Halogenated volatile organic compounds (HVOCs) represent a class of highly toxic, stable, and recalcitrant organic compounds among the volatile organic compounds (VOCs), posing big threats to air quality and human health. Catalytic elimination is a promising approach for HVOCs purification. However, catalytic elimination of HVOCs generates highly reactive and corrosive HX and X2 (X = F, Cl, and Br), giving rise to the poisoning and deactivation of catalysts. Moreover, the formation of numerous halogen-containing byproducts can induce secondary pollution issues. Therefore, the development of catalysts with high stability, good catalytic performance, and low selectivity towards toxic byproducts has been the primary research focus in the past years. Modifying geometric and electronic structures of the catalysts and constructing bifunctional catalysts with synergistic acidity and redox properties have demonstrated good catalytic performance and resistance towards poisoning. Depending on the category of HVOCs, different catalytic reaction systems are often required. The present review article summarizes recent progresses in catalysts preparation and their catalytic HVOCs elimination performance. By categorizing HVOCs removal into several specific reaction systems, we discuss the deep elimination efficiency of HVOCs, the selectivity of inorganic halogen species, and the migration pathways and removal mechanisms of halogens on the catalysts surface, thereby establishing the structure–performance relationships. Furthermore, we outline the prospects and challenges of catalytic HVOCs elimination technologies in the future work and practical applications. It is expected that the findings summarized in this review will inspire more researchers to develop catalytic systems capable of effectively eliminating HVOCs.