Effects of coexisting components in waste gas on the catalytic oxidation of CVOCs

Chlorinated volatile organic compounds (CVOCs), a major class of volatile organic compounds (VOCs), are highly toxic, persistent, and bio-accumulative pollutants that pose serious threats to both environmental and human health. The widespread emission of CVOCs from industrial production and waste incineration contributes significantly to ozone depletion, photochemical smog, and haze formation. Various abatement technologies—such as adsorption, absorption, photocatalysis, plasma treatment, and thermal incineration—have been explored for CVOC removal. Among these, catalytic oxidation is considered the most efficient and promising strategy due to its high activity, selectivity, stability, and low energy consumption under mild conditions. However, during catalytic oxidation, chlorine radicals generated from CVOC decomposition can deactivate catalysts and induce the formation of toxic polychlorinated byproducts, leading to secondary pollution. Therefore, developing highly efficient catalysts with strong resistance to chlorine poisoning is crucial for practical industrial applications. However, industrial waste gas possesses a highly complex composition, in which multiple coexisting components such as H2O, SO2, and NOx are simultaneously emitted along with CVOCs. These species can significantly influence the adsorption, activation, and oxidation behaviors of CVOCs on catalyst surfaces, thereby altering catalytic performance and reaction pathways. For instance, water vapor may compete with CVOCs for active sites or induce reversible surface hydroxylation, while SO2, and NOx can react with surface oxygen species to form sulfates or nitrates, leading to active-site blockage and catalyst deactivation. Moreover, the coexistence of these gases may also change the redox equilibrium and surface acidity of the catalyst, further affecting the efficiency and selectivity of CVOC oxidation. Therefore, to realize green, efficient, and stable purification of industrial CVOCs, it is essential to conduct an in-depth investigation into the synergistic or antagonistic interactions between H2O, SO2, NOx, and CVOCs during the catalytic oxidation process. Herein, this review focuses on CVOCs, systematically details the inhibitory and promoting effects of the industrial coexisting component H2O on the catalytic oxidation of CVOCs; summarizes the interaction between SO2 and active sites and its interference with the CVOC reaction process; analyzes the dual effects of the synergistic treatment of NOx and CVOCs on CVOC degradation efficiency, by-products, and conversion pathways; and generalizes the effects of non-chlorinated VOCs on the oxidation efficiency of CVOCs. This review aims to gain a deeper understanding of the influence of coexisting components of industrial waste gas and CVOCs on the catalytic oxidation of CVOCs, a clarification of the mechanisms by which the coexisting components and CVOCs affect the oxidation and acidic sites of the catalytic system, thereby providing a theoretical basis and technical guidance for designing efficient catalysts for reducing CVOC emission in complex industrial atmospheres.