SO42-immobilization regulated by reaction atmosphere over ABS poisoned α-Fe2O3 catalysts for efficient NOx removal

SO42-immobilization is pivotal for boosting the catalytic performance of iron oxides in NH3-SCR. However, the critical issue related to sulfate species enrichment on alpha-Fe2O3 is still elusive. Herein, by employing ammonium bisulfate (ABS) as the source of SO42-, we conducted a detailed investigation on the effect of reaction atmospheres (NH3, NO + O2 and NH3 + NO + O2) on the immobilization of sulfate species and their consequence for ABS poisoned Fe2O3/SiO2 (ABS/FeSi) catalysts in NH3-SCR. Results showed sulfate group could be transferred from ABS to FeSi under thermal treatment and the efficiency actually exhibited an atmosphere-dependent feature. The promotion effect from NO/O2 was most prominent due to accelerated consumption of NH4+, whereas NH3 treatment retarded ABS pyrolysis, resulting in reduced sulfate immobilization on FeSi surface. Besides, an un-expected effect on Fe2O3 disintegration was exhibited by NH3, which was detrimental to activity enhancement due to disruption of electronic property. By correlating catalytic performance with adsorption feature, we pro-pose the occurrence of reaction via E-R pathway over sulfated FeSi catalysts. The result of present study can enrich our understanding on the controlled sulfate immobilization for robust SCR denitration.