A Review of Synergistic Catalytic Removal of Nitrogen Oxides and Chlorobenzene from Waste Incinerators

Emission of harmful gases, nitrogen oxides (NOx), and dioxins pose a serious threat to the human environment; so, it is urgent to control NOx and dioxin emissions. The new regulations for municipal solid waste incineration emissions set new stringent requirements for NOx and dioxin emission standards. Most of the existing pollutant control technologies focus on single-unit NOx reduction or dioxin degradation. However, the installation of separate NOx and dioxins removal units is space-consuming and costs a lot. Nowadays, the simultaneous elimination of NOx and dioxins in the same facility has been regarded as a promising technology. Due to the extremely high toxicity of dioxins, the less toxic chlorobenzene, which has the basic structure of dioxins, has been commonly used as a model molecule for dioxins in the laboratory. In this review, the catalysts used for nitrogen oxides/chlorobenzene (NOx/CB) co-removal were classified into two types: firstly, non-loaded and loaded transition metal catalysts, and their catalytic properties were summarized and outlined. Then, the interaction of the NH3-SCR reaction and chlorobenzene catalytic oxidation (CBCO) on the catalyst surface was discussed in detail. Finally, the causes of catalyst deactivation were analyzed and summarized. Hopefully, this review may provide a reference for the design and commercial application of NOx/CB synergistic removal catalysts.