Effect of SiO addition on NHHSO decomposition and SO poisoning over VO-MoO/TiO-CeO catalyst.

The deposition of NHHSO and the poisoning effect of SO on SCR catalyst are the main obstacles that restrict the industrial application of CeO-doped SCR catalysts. In this work, deposited NHHSO decomposition behavior and SO poisoning over VO-MoO/TiO catalysts modified with CeO and SiO were investigated. By the means of characterization analysis, it was found that the addition of SiO into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NHHSO. Temperature-programmed methods and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments indicated that the doping of SiO promoted the decomposition of deposited NHHSO on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NHHSO and enhancing the NHHSO reactivity with NO in low temperature. And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NHHSO deposition. Accompanied with cerium sulfate species generated over catalyst surface, the conversion of SO to SO was inhibited in SiCe mixed catalyst. The addition of SiO could promote the decomposition of cerium sulfate, which may be a potential strategy to enhance the resistance of SO poisoning over CeO-modifed catalysts.