Theoretical Study of the Catalytic Activity and Anti-SO Poisoning of a MoO/VO Selective Catalytic Reduction Catalyst.

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