Influence of support composition on enhancing the performance of Ce-V on TiO₂ comprised tungsten-silica for NH₃-SCR

The roles of WO₃ and SiO₂ in Ce-V catalysts supported on TiO₂ comprised tungsten-silica were investigated systematically for NH₃-SCR (selective catalytic reduction) and NH₃-oxidation at high temperatures. When SiO₂ and WO₃ were added to TiO₂, the surface area of Ce-V/TWS was maximized and the formation of Ti[sbnd]O[sbnd]Si bond reduced nanoparticle size compared to without SiO₂. The Ce-V/TWS surface had greater abundance of catalytic defects and surface oxygen species via XPS results. Increasing the (V⁴⁺ + V³⁺) fraction increased the catalytic activity, which is attributed to the enhanced SCR performance at a wide temperature range due to the addition of WO₃ and SiO₂ to TiO₂. The catalysts using the TWS supports exhibit high catalytic activity, since WO₃ and SiO₂ can promote redox properties. It was shown that Ce-V/TWS was the most suitable catalyst for selectively producing N₂ via thermodynamically unavoidable NH₃ direct oxidation as the temperature increased. In addition, hydrothermal aging effects were investigated for the Ce-V/TWS catalyst prepared by TiO₂ supports including WO₃ and SiO₂ (comparison with vanadium-tungsten/titania). This study demonstrates the feasibility of utilizing WO₃ and SiO₂ in the TiO₂ support as a possible way to increase catalytic activity and N₂ selectivity in NH₃-SCR at high temperatures.