Non-thermal plasma-enhanced urea-SCR treatment of diesel exhaust for low-temperature NOx reduction

摘要

Test bench measurements were performed demonstrating low-temperature non-thermal plasma-enhanced selective catalytic reduction of NOx in the exhaust of a 1.9-liter direct injection diesel engine. The plasma-catalytic hybrid system consisted of an oxidation catalyst, a modular dielectric barrier discharge reactor for plasma treatment, a semiconductor switched pulse voltage source for electrical excitation, and an urea SCR system based on a monolithic V{sub}2O{sub}5-WO{sub}3/TiO{sub}2 catalyst. In a test cycle simulating urban driving conditions the average NOx-mass flow was reduced from 27 g/h down to 11.5 g/h. Maximum NOx-reduction rates of 28 g/h were obtained at an energy cost of 10 Wh/g NOx. The ammonia storage capability of the catalyst was utilized for reduction at temperatures below 140°C.