New Insights into the Decomposition Behavior of NH(4)HSO(4) on the SiO(2)-Decorated SCR Catalyst and Its Enhanced SO(2)-Resistant Ability

[Image: see text] This article illustrates the detailed decomposition behavior of NH(4)HSO(4) on the TiO(2) and TiO(2)–SiO(2) supports, along with the effect of SiO(2) addition on the sulfur resistance of the corresponding V(2)O(5)-based catalysts. For TiO(2) support, sulfate species selectively occupied its surface basic hydroxyl groups, while Si–OH groups functioned as the main sites for the accommodation of NH(4)HSO(4) over the TiO(2)–SiO(2) mixed support, enabling its surface sulfate species with higher thermal stability. Compared with NH(4)(+) on the TiO(2) surface, NH(4)(+) on the TiO(2)–SiO(2) mixed support was much easier to be consumed during the heating process, hence causing some variations in the decomposition behavior of NH(4)HSO(4). Finally, adding SiO(2) enhanced the SO(2) tolerance properties of the catalysts to a certain extent. When exposed to the SO(2)-containing flue gas, the deposition of NH(4)HSO(4) mainly caused serious deactivation of SiO(2)-free catalyst, while the as-accumulated SO(4)(2–) also contributed to the declined activity of SiO(2)-added catalyst. These results ensured the potential commercialization of TiO(2)–SiO(2)-based catalysts in the typical low-temperature selective catalytic reduction systems in the short run and pointed out a strategy to design new catalysts with superior activity and enhanced SO(2)-tolerant ability.