Selective Modification of the Acid-Base Properties of Ceria by Supported Au
Abstract
Au supported on CeO2 prepared by deposition-precipitation with urea leads to a basic catalyst. Au acts in two ways as surface modifier. First, Au selectively interacts with Ce4+ cations by either blocking access to or reducing Ce4+ to Ce3+. Second, the resulting Au atoms (presumably as Au+ ions) act as soft, weak Lewis acid sites stabilizing carbanion intermediates and enhancing hydride abstraction in the dehydrogenation of alcohols. In consequence, the thus-synthesized basic catalyst catalyzes the dehydrogenation of propan-2-ol to acetone with high efficiency and without notable deactivation. Additionally, the dehydration pathway of propan-2-ol is eliminated, as Au also quantitatively blocks access to strongly acidic Ce4+ ions or reduces them to Ce3+.