Unravelling the nature of the active species as well as the Mn doping effect over gamma-Al2O3 catalyst for eliminating AsH3 and PH3.

• a. Simultaneous catalytic oxidation of AsH 3 and PH 3 by Cu 1 Mn 1 -Al 2 O 3. • b. Mn doping introduces many oxygen vacancies to the Cu 1 Mn 1 -Al 2 O 3 catalyst surface. • c. The large number of Lewis acid sites produced by Mn doping promote oxygen activation. • d. Mn doping reduced the deep oxidation of PH 3 by 30.96%, inhibiting catalyst poisoning. • e. Mn doping reduced As 2 O 3 production by 44.9%, which also inhibited catalyst poisoning. To investigate the enhancing effect of Mn on the performance of simultaneous catalytic oxidation of AsH 3 and PH 3 by CuO-Al 2 O 3 in a reducing atmosphere under micro-oxygen conditions, Cu-Mn modified γ -Al 2 O 3 catalysts were prepared. The characteristics of the catalysts showed that Mn reduced the crystallinity of the active CuO component, increased the number of oxygen vacancies and acidic sites on the catalyst surface, enhanced the mobility of surface oxygen, and the interaction between copper and manganese promoted the redox cycling ability of the catalysts and improved their oxidation performance, which increased the conversion frequency (TOF) by 2.54 × 10−2 to 3.07 × 10−2 sec−1. On the other hand, the introduction of Mn reduced the production of phosphate and As 2 O 3 on the catalyst surface by 30.96% and 44.9%, which reduced the coverage and inerting of the active sites by phosphate and As 2 O 3 , resulting in an 8 hr (6 hr) improvement in the stability of PH 3 (AsH 3) removal. [Display omitted] [ABSTRACT FROM AUTHOR]