title: Sol-gel preparation of alumina stabilized rare earth areo- and xerogels and their use as oxidation catalysts.
abstract: 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.
authors.affiliation: Institute of Applied and Physical Chemistry & Center for Environmental Research and Sustainable Technology, University of Bremen, Leobener Str., Bremen D-28359, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Neumann
authors.affiliation: Solid State Chemical Crystallography, Institute for Inorganic Chemistry, University of Bremen, Leobener Str. NW2, D-28359 Bremen, Germany.
authors.forename: Thorsten M
authors.initials: TM
authors.lastname: Gesing
authors.affiliation: Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
authors.forename: Andrii
authors.initials: A
authors.lastname: Rednyk
authors.affiliation: Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Matolin
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA. Electronic address: gash2@llnl.gov.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Gash
authors.affiliation: Institute of Applied and Physical Chemistry & Center for Environmental Research and Sustainable Technology, University of Bremen, Leobener Str., Bremen D-28359, Germany. Electronic address: mbaeumer@uni-bremen.de.
authors.forename: Marcus
authors.initials: M
authors.lastname: Bäumer
keywords: Aerogels; CO oxidation; Rare earth oxides; Sol–gel chemistry; Xerogels