Superior activity of Ce‐HZSM‐5 catalyst for catalytic oxidation of arsine at low oxygen

Abstract

A series of Ce modified catalysts were prepared using equivalent‐volumetric ultrasonic impregnation method for AsH3 removal. The performance of catalytic oxidation of AsH3 under dynamic conditions was studied under different synthesis and reaction conditions. Through screening tests, the optimum catalyst was impregnated by 10 wt.% Ce (CH3COO)3 precursor and subsequently calcinated at 550 °C. When the reaction temperature reached 170 °C, the Ce‐HZSM‐5 catalyst could maintain an oxidation efficiency of over 90% in 82 hrs. Furthermore, the chemical structure and properties of the catalyst and its catalytic oxidation mechanism with AsH3 were analyzed using SEM‐EDS, BET, XRD, XPS, H2‐TPR and FT‐IR. The results showed that Ce mainly existed on the catalyst surface in the forms of Ce4+ and Ce3+. In the reaction process, the chemisorbed oxygen played a key role in the transformation between the two valence states. AsH3 was firstly oxidized to elemental As with the participation of lattice oxygen. Then, the elemental As was partially blown into the rear part of the adsorption column along with the air flow and subsequently, de‐sublimed on the column wall. Herein, the elemental As remained on the surface of Ce‐HZSM‐5 catalyst, which would further oxidize to As2O3. For the recovery of As, Ce‐HZSM‐5 proved to be a promising catalyst in AsH3 removal.Highlights The CeOx modified HZSM‐5 catalyst was used to catalytic oxidation of AsH3. The Ce‐HZSM‐5 catalyst could maintain over 90% oxidation efficiency in 82 hrs. AsH3 was catalytic oxidized to elemental As and H2O on the catalyst surface and the As can be collected. The As adsorbed on the catalyst surface can be oxidized to As2O3 but cannot be further oxidized to As2O5.