An environmentally-benign CeO2-TiO2 catalyst for the selective catalytic reduction of NO with NH3 in simulated diesel exhaust

Abstract

a b s t r a c tA Ce-Ti based (CeO 2 -TiO 2 ) catalyst prepared by an optimized homogeneous precipitation method showed excellent NH 3 -SCR activity, high N 2 selectivity, broad operation temperature window, and high resistance to space velocity (even under a high gas hourly space velocity (GHSV) of 500,000 h −1 ). Compared with V 2 O 5 -WO 3 /TiO 2 and Fe-ZSM-5 catalysts, the CeO 2 -TiO 2 catalyst showed better catalytic performance for NH 3 -SCR. Under a more realistic condition of simulated diesel engine exhaust, the monolith catalyst of CeO 2 -TiO 2 showed over 90% NO x conversion from 250 to 450• C under a GHSV of 20,000 h −1 in the presence of H 2 O, CO 2 , and C 3 H 6 . The high dispersion of active CeO 2 on TiO 2 in the process of homogenous precipitation and the synergistic effects between CeO 2 and TiO 2 in CeO 2 -TiO 2 are important reasons for the high NH 3 -SCR activity.

The pollutant emissions from diesel-engine vehicles and exhaust aftertreatment systems

“…Cu-PPHs, CeO 2 -TiO 2 , Cu/Al 2 O 3 , NbCe, and Fe-MFI are the other catalyst types that become a current issue. In many of the researches which were conducted on these catalysts, conversion efficiency of NO x emissions have been obtained more than 90 % rates (Shan et al 2012;Casapu et al 2011;Oliveira et al 2011). The catalysts based on TiO 2 doped by Tungsten using Vanadium as active component are the most applied catalysts for SCR because of their high activity even at low temperature and high selectivity for NO 2 as product.…”

High-efficiency reduction of NO emission from diesel exhaust using a CeWO catalyst

“…In our previous study, we have successfully developed a series of active Ce-based oxide catalysts, including the Ce-Ti, Ce-W-Ti, and Ce-W catalyst systems [29][30][31][32][33]. Among these catalysts, powder CeWO x catalyst showed nearly 100% NO x conversion from 250°C to 425°C under an extremely high GHSV of 500,000 h , which is a promising candidate for the potential application in diesel engine exhaust treatment [33].…”

The use of ceria for the selective catalytic reduction of NOx with NH3

“…Compared with the Ce-Ti oxide catalysts previously reported, this catalyst showed a remarkably improved low-temperature SCR activity and, in turn, a significantly wider reaction temperature window. Further optimization of the preparation method resulted in significantly enhanced high-temperature activity and an even further broadened temperature window [52]. In addition, the SCR activity at high space velocity conditions was also clearly improved.…”