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-SO2 poisoning and selective catalytic reduction (SCR) reaction on a MoO3/V2O5 surface. According to the calculation results, the SO2 molecule can be converted into SO3 on V2O5(010) and further transformed into NH4HSO4, which poisons V2O5. If V2O5 and MoO3 are combined with each other, charge separation of V2O5 and MoO3, which are negatively and positively charged, respectively, occurs at the interface. In ammonium bisulfate liquid droplets on the MoO3/V2O5 surface, NH4+ tends to adhere to the V2O5(010) surface and can be removed through the SCR reaction and HSO4- tends to adhere to the MoO3(100) surface and can be resolved into SO3 and H2O, which can be released into the gas phase. Thus, MoO3/V2O5 materials are resistant to SO2 poisoning. In the MoO3/V2O5; material, Bronsted acid sites are easily formed on the negatively charged V2O5(010) surface; this reduces the energy barrier of the NH3 dissociation step in the NH3-SCR process and further improves the catalytic activity.