Thermal stability of SCR catalysts containing vanadia on silica-titania for the use in diesel applications
Advancing the chemical engineering fundamentals
Catalysis - II (T2-13b)
Keywords: Sintering, SCR catalyst, Diesel application
The effect of reaction temperature and vanadia content on the sintering of vanadia on 50/50 wt.% silica-titania SCR catalysts has been investigated. The variation of the surface area, the XRD spectra including crystallite size on thermal treatment in dry and moist air was investigated. The effect of water is not large for the support. When calcined at 450 oC, well within the operation range of a SCR catalyst, The supports area decreases from 267 to 230 m2/g. The support without vanadia sinters to a much lower degree than the complete catalyst. The effect of vanadia is to increase the rate of the conversion of the anatase phase of the support to rutile and to lower the transition temperature. For a 10 % catalyst a 5 hour calcination at 500, 550 , and 600 oC results in the surface areas 212, 173 and 144 m2/g. The area at 500 oC is the same as for the unsintered catalyst. A operating temperature of 550 oC thus leeds to a detrimental decrease of the surface area. Results also show the aging of a catalyst on an engine rig driven in a way to simulate normal driving for at least 500 000 km. During that time the surface area decreased by 50 %.
It is thus shown that a thermal stabilisating agent is necessary for a sucessful diesel application.
See the full pdf manuscript of the abstract.
Presented Thursday 20, 11:40 to 12:00, in session Catalysis - II (T2-13b).
