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 TiO 2 supported on a spherical α-Al 2 O 3 /γ-Al 2 O 3 . The formation of NO 2 was virtually suppressed in the reaction temperature range of 110–200 °C. The NOx removal efficiencies of TiO 2 /γ-Al 2 O 3 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 (C 4 H 10 ). SEM and XPS techniques revealed that sulfur temporarily occupied the active sites of the photocatalyst, causing deactivation. Spent TiO 2 /γ-Al 2 O 3 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 1 h could completely regenerate the spent photocatalyst.