Coating of catalyst supports : links between slurry characteristics, coating process and final coating quality

• Main Author: Adegbite, Stephen Ademola
• Other Authors: Barigou, M. ; Simmons, M. J. H.
• Published: University of Birmingham 2010
• Subjects: 530.417; TP Chemical technology
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519930

Tightening legislation for vehicles across the world has caused the use of monolith catalysts in automotive emission control to become ubiquitous. Control of the adherence and homogeneity of the platinum group metal (PGM) coating onto the monolith block, to maximise catalytic performance for a minimum PGM loading, is therefore paramount. In this study, an automatic film application is used for coating γ–alumina slurries onto Fecralloy®, an integral component of metallic monolith catalysts, to achieve the desired coating properties. Upon coating of the Fecralloy® coupons, the samples preoxidised for 10 h gave the best performance in terms of coating loading (7.94 mass %) and adherence (< 10 mass % loss) based on ultrasonic vibration test. These conditions produced the optimal surface topography, typified by conspicuous and randomly-oriented α–alumina whiskers which promote coating adherence. The optimal coating loading and adherence were achieved at a pH of 4 and solids concentrations not exceeding 40 wt%. A newly devised technique using the electromechanical testing system showed that finest particle coatings of 40 wt% solids concentration produced the best coating adherence. At solids concentration of 45 wt% the coating adherence was poor and insensitive to the blends of different particle size distributions.