Sol-gel synthesized V2O5/TiO2 catalysts for NH3-SCR: Effect of calcination temperature on performance

Ammonia-based selective catalytic reduction (SCR) is essential for removing nitrogen oxides (NO _X ) emitted from industrial furnaces and automobiles. Although commercial V ₂ O ₅ /TiO ₂ catalysts are economically viable for NH ₃ -SCR, their poor catalytic activities limit their use to operating temperatures greater than 300℃, which prevents their use under low-temperature exhaust conditions. In this study, we employed a one-step sol-gel method to produce V ₂ O ₅ /TiO ₂ catalysts and then compared their catalytic performances and physicochemical characteristics with those of a conventional impregnated V ₂ O ₅ /TiO ₂ catalyst. This one-step approach resulted in catalysts that exhibited improved NO conversions, and notably, the activity of sol-gel catalysts produced under optimized conditions was almost twice that of the conventional catalyst. In this study, catalyst calcination temperature was adjusted between 250 and 550℃. X-ray diffraction showed the crystallinity of the anatase TiO ₂ phase increased with calcination temperature, but that calcination temperatures (> 500℃) caused sintering and reduced BET surface area as determined using N ₂ adsorption-desorption isotherms. X-ray photoelectron spectroscopy and NH ₃ temperature-programmed desorption demonstrated that catalysts calcined at temperatures between 350 and 500°C had optimal amounts of V ⁴⁺ species, surface oxygen, and acidic sites, which are essential for catalytic activity. This study highlights that the one-step sol-gel technique provides a simple, cost-effective means of synthesizing high-performance V ₂ O ₅ /TiO ₂ catalysts for low-temperature NH ₃ -SCR applications.