Exploring the efficient catalytic decomposition behavior of AsH3 over HZSM-5 molecular sieve based on in situ DRIFTS characterization

Existing processes for transforming arsine (AsH 3 ) into toxic arsenic oxides (As x O y ) through catalytic oxidation do not meet economic requirements. In contrast, the catalytic decomposition method stands out due to its ability to both remove AsH 3 and obtain elemental arsenic (As 0 ) as a valuable product. A series of blank molecular sieves (HZSM-5, 13X, MCM-41, and TS-1) was applied to the catalytic decomposition performance of AsH 3 . At a catalytic decomposition temperature of 100 ℃, the HZSM-5 zeolite exhibited exceptional performance, achieving a D 90% value (the duration for which the AsH 3 removal efficiency remained above 90 %) exceeding 40 h. Moreover, up to 83.1 % of the product was As 0 . Comprehensive characterization revealed that the surface of the HZSM-5 zeolite contained a large number of strong acid sites, which played a key role in As 0 generation. In situ diffuse reflectance infrared spectroscopy further revealed the activation behavior of O 2 at the Brønsted acid sites on HZSM-5. To assess its suitability in industrial applications, the AsH 3 removal performance of the HZSM-5 molecular sieve was investigated in the presence of actual gas components (CO, H 2 S, PH 3 ). This study provides new ideas for the effective catalytic decomposition of AsH 3 and the recovery of valuable products in industry.