A new sol-gel synthesis route for rare earth (Ce and Pr) alumina hybrid aero- and xerogels is presented which is based on the so-called epoxide addition method. The resulting materials are characterized by TEM, XRD and nitrogen adsorption. The results reveal a different crystallization behavior for the praseodymia/alumina and the ceria/alumina gel. Whereas the first remains amorphous until 875°C, small ceria domains form already after preparation in the second case which grow with increasing calcination temperature. The use of the calcined gels as CO oxidation catalysts was studied in a quartz tube (lab) reactor and in a (slit) microreactor and compared to reference catalysts consisting of the pure rare earth oxides. The Ce/Al hybrid gels exhibit a good catalytic activity and a thermal stability against sintering which was superior to the investigated reference catalyst. In contrast, the Pr/Al hybrid gels show lower CO oxidation activity which, due to the formation of PrAlO3, decreased with increasing calcination temperature.

Charles University Faculty of Mathematics and Physics Department of Surface and Plasma Science 5 Holešovičkách 2 18000 Prague 8 Czech Republic

Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology University of Bremen Leobener Str Bremen D 28359 Germany

Physical and Life Sciences Directorate Lawrence Livermore National Laboratory Livermore CA 94551 USA

Solid State Chemical Crystallography Institute for Inorganic Chemistry University of Bremen Leobener Str NW2 D 28359 Bremen Germany

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