Magnetic-field-assisted catalytic oxidation of arsine over Fe/HZSM-5 catalyst: Synergistic effect of Fe species and activated surface oxygen

The traditional way for arsine (AsH 3 ) removal from the reducing exhaust gas by catalytic oxidation undershot the expect goal in pollutant emission control. This laboratory scale work used magnetic field to improve the chemical environment of AsH 3 catalytic oxidation over magnetic response catalyst Fe/HZSM-5. After introducing external magnetic field at a magnetic field intensity of 0.1 T, the catalytic performance of Fe/HZSM-5 for AsH 3 removal was improved by 52%, and the turnover frequency (TOF) value increased from 4.65 × 10 −3 s −1 to 5.73 × 10 −3 s −1 . The structure–activity relationship of the catalyst in the presence of magnetic field was investigated. The characterization results showed that Fe is mainly anchored onto the surface of Fe/HZSM-5 catalyst through an oxygen bridge, while a small proportion of Fe exists in the form of iron oxides . The Fe species and surface labile oxygen (O − ) in the aluminum tetrahedra are the magnetic active sites of Fe/HZSM-5, magnetic field promotes the reaction by increasing the activity of them. It was discovered that paramagnetic O − increased by 50% in the presence of magnetic field compared with that in its absence. Therefore, a magnetic-field-assisted oxygen cycling process is proposed. In terms of the stability of catalyst, formation of more amorphous oxidized arsenic after reaction in the presence of magnetic field reduced the toxicity to the strong acid sites of the catalyst, and the holding time of excellent AsH 3 removal efficiency was prolonged from 23 h to 35 h. These results provide new insights into magnetic-field-assisted zeolite catalysis. • Magnetic-field-assisted catalytic oxidation of AsH 3 is realized for the first time. • The catalytic performance of Fe/HZSM-5 increased by 52% under magnetic field. • Paramagnetic O − and Fe species on the Fe/HZSM-5 surface are magnetic active sites. • Magnetic field promotes the arsenic poisoning resistance of Fe/HZSM-5.