NOx abatement from stationary emission sources by photo-assisted SCR: Lab-scale to pilot-scale studies

Abstract

In developing a higher activity for NOx abatement from stationary emission sources, photo-assisted selective catalytic reduction (photo-SCR) was systematically investigated over TiO2 supported on a spherical α-Al2O3/γ-Al2O3. The formation of NO2 was virtually suppressed in the reaction temperature range of 110–200°C. The NOx removal efficiencies of TiO2/γ-Al2O3 photocatalyst at 120°C for real flue gas (in pilot-scale photoreactor) and simulated flue gas (in lab-scale photoreactor) were 68–75% and 43.5%, respectively, in the presence of reducing reagent (C4H10). SEM and XPS techniques revealed that sulfur temporarily occupied the active sites of the photocatalyst, causing deactivation. Spent TiO2/γ-Al2O3 photocatalyst was regenerated via desulfurization by either air or hydrogen at 400–500°C. The effects of regeneration temperature and regeneration time on the photocatalytic activity are methodically investigated, demonstrating that using hydrogen at 500°C in 1h could completely regenerate the spent photocatalyst.