Wej. Van Kooten et al., Ce-ZSM-5 catalysts for the selective catalytic reduction of NOx in stationary diesel exhaust gas, APP CATAL B, 21(3), 1999, pp. 203-213
Citations number
45
Categorie Soggetti
Physical Chemistry/Chemical Physics","Environmental Engineering & Energy
This paper describes the preparation of Ce-ZSM-5 SCR catalysts for stationa
ry diesel engine applications, such as marine diesels, and the performance
of these catalysts with ammonia as a reducing agent in both simulated and r
eal diesel exhaust gas. Catalysts prepared by ion exchange in aqueous solut
ion, show an increasing NOx conversion with increasing cerium ion-exchange
level at all temperatures tested (NOx conversion > 80% in the temperature r
ange 350-500 degrees C at a gas hourly space velocity (GHSV) of 40.000 h(-1
) with simulated diesel exhaust). Ce-ZSM-5 does not convert nitric oxide or
ammonia into the greenhouse gas nitrous oxide. Moreover, Ce-ZSM-5 does not
exhibit ammonia slip up to ammonia/nitric oxide feed ratios of 1.4, the ex
cess ammonia being converted to nitrogen. Ce-ZSM-5 extrudates with 50 wt.%
alumina binder do not show ammonia slip up to ammonia/nitric oxide feed rat
ios of at least 1.1. With diesel exhaust gases of a three-cylinder, 10 kW d
iesel engine, Ce-ZSM-5 can reach about 70% NOx conversion at 500 degrees C
at a GHSV of 50.000 h(-1). Deactivation of the catalysts in real diesel exh
aust occurs mainly in the first 60 h of operation resulting in stable catal
ysts which show about 40% NOx conversion at 450 degrees C, at a GHSV of 32.
000 h(-1). The preparation of Ce-ZSM-5 via solid-state ion exchange results
in a remarkably active catalyst. (C) 1999 Elsevier Science B.V. All rights
reserved.