Catalytic removal of gaseous HCBz on Cu doped OMS: Effect of Cu location on catalytic performance

• Cu-OMS catalysts with different Cu location were synthesized.
• Cu-OMS with framework substituted Cu exhibited high activity.
• Cu doping significantly enhanced catalyst stability.
• Surface reaction mechanism was investigated.

Hexachlorobenzene (HCBz) is a persistent organic pollutant emitted unintentionally from the flue gas of combustion and industrial processes. In this study, copper doped manganese oxide octahedral molecular sieve (Cu-OMS) was synthesized by one-step hydrothermal method and applied for the catalytic removal of low concentration gaseous HCBz. Physicochemical characterization indicates that Cu location within OMS is affected by the precursor Cu/Mn molar ratio (Cu/Mnpre). Activity tests further show that the catalytic performance of Cu-OMS is associated with Cu location. At low Cu doping level (Cu/Mnpre = 0.01–0.10), CuO is attached on the external surface of OMS. Physisorption and oxidative destruction of HCBz are hindered due to the reduction of textural properties and the amount of surface labile oxygen (SLO). At medium (Cu/Mnpre = 0.20) and high Cu doping level (Cu/Mnpre = 0.40–0.80), CuO/Cu2+ is incorporated into the framework or even enters into the tunnel structure of OMS. The textural properties and the amount of SLO are significantly promoted, resulting in the remarkable adsorption and destruction performance. Additionally, the stability of OMS is greatly enhanced by Cu doping, which can be ascribed to the rapid removal of surface chloride catalyzed by CuO.

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