Theoretical Study of the Catalytic Activity and Anti-SO2 Poisoning of a MoO3/V2O5 Selective Catalytic Reduction Catalyst

In this paper, density functional theory has been applied to study the mechanism of anti-SO 2 poisoning and selective catalytic reduction (SCR) reaction on a MoO 3 /V 2 O 5 surface. According to the calculation results, the SO 2 molecule can be converted into SO 3 on V 2 O 5 (010) and further transformed into NH 4 HSO 4 , which poisons V 2 O 5 . If V 2 O 5 and MoO 3 are combined with each other, charge separation of V 2 O 5 and MoO 3 , which are negatively and positively charged, respectively, occurs at the interface. In ammonium bisulfate liquid droplets on the MoO 3 /V 2 O 5 surface, NH 4 + tends to adhere to the V 2 O 5 (010) surface and can be removed through the SCR reaction and HSO 4 - tends to adhere to the MoO 3 (100) surface and can be resolved into SO 3 and H 2 O, which can be released into the gas phase. Thus, MoO 3 /V 2 O 5 materials are resistant to SO 2 poisoning. In the MoO 3 /V 2 O 5 material, Brønsted acid sites are easily formed on the negatively charged V 2 O 5 (010) surface; this reduces the energy barrier of the NH 3 dissociation step in the NH 3 -SCR process and further improves the catalytic activity.