Evaluation of Supplier Catalyst Formulations for the Selective Catalytic Reduction of NO{sub}x With Ammonia

摘要

The selective catalytic reduction of NO using urea (urea-SCR) is one of the promising technologies for removing NO{sub}x from diesel engine exhaust. The engine-out NO{sub}x is reduced by ammonia (NH{sub}3) derived from urea over a catalyst to environmentally benign N{sub}2. In this paper, we investigate the effect of various reactor operating conditions on the NO{sub}x reduction performance of three different catalyst formulations (e.g., Cu-zeolite, Desolate, Vanadium-based) to obtain useful guidance in the design and operation of urea-SCR lean NO{sub}x emission control systems. We examine the effects of NO:NO{sub}2 ratio on the steady-state NO{sub}x reduction activity at typical diesel engine exhaust temperatures (150-550°C). Transient measurements were also performed to determine the impact of NH{sub}3:NO{sub}x ratio and NH{sub}3 storage on catalyst performance. The impacts of hydrocarbon poisoning and sulfur poisoning/regeneration were also examined.