Selective modification of the acid-base properties of ceria by supported Au

摘要

Au supported on CeO_2 prepared by deposition-precipitation with urea leads to a basic catalyst. Au acts in two ways as surface modifier. First, Au selectively interacts with Ce~(4+) cations by either blocking access to or reducing Ce~(4+) to Ce~(3+). 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 Ce~(4+) ions or reduces them to Ce~(3+).