Effect of Silica on Nitrate-Incorporated Vanadia Catalysts in Low-Temperature Selective Catalytic Reduction of Nitrogen Oxides

Developing shaped catalysts for the low-temperature selective catalytic reduction (SCR) of NOx often results in severe physical detachment and efficiency loss. Building on our previous development of highly active nitrate-incorporated V2O5–WO3/TiO2 powder catalysts, we investigated the effect of SiO2 as a structural binder for coating these catalysts onto glass fiber sheets. Coatings with 0–30 wt % SiO2 were prepared and evaluated. The addition of 10 wt % SiO2 significantly improved catalyst dispersion, coating uniformity, and mechanical adhesion, successfully preventing the structural degradation typically observed under highly humid operating conditions. Consequently, the SiO2-containing catalyst demonstrated enhanced physical stability, maintaining consistent NOx removal efficiencies for at least 80 h, whereas the SiO2-free coating showed progressive deactivation due to physical peeling. The optimized catalyst (10 wt % SiO2, 4 wt % V2O5) achieved a 98.7% NOx removal efficiency at 180 °C under dry conditions and 95.2% in the presence of 10 vol % H2O. These findings clearly demonstrate that SiO2 acts as an exceptionally robust structural binder, effectively bridging the gap between highly active fundamental powders and macroscopically stable industrial applications.