Surface reactions of acetone on Al2O3, TiO2, ZrO2, and CeO2: IR spectroscopic assessment of impacts of the surface acid-base properties

Adsorption and surface reactions of acetone vapor were observed on the titl e oxides at room and higher temperatures (up to 400 degreesC), using in sit u infrared spectroscopy The results were correlated with results of infrare d spectroscopy of adsorbed pyridine, to assess impacts of the surface acid- base properties. It was found that the availability of Lewis acid sites is essential for anchoring acetone molecules to the surface: Coexisting Lewis base sites catalyze condensation of the acetone molecules into mesityl oxid e surface species, via formation and subsequent decomposition of enolate an d diacetone alcohol species. When intimately coupled, the Lewis acid and ba se sites generate pair sites of particularly strong adsorption capacity tow ard condensation products thus formed. Consequently, surface active sites a re blocked and adsorptive and catalytic interactions of acetone are largely suppressed.