Bulk defect-dependent initial steps of acetone oxidation on rutile TiO₂(110)

Abstract

Systematic model investigations revealed that defects, particularly bulk Ti³⁺ interstitials, play a crucial role in directing reactions of alcohols and aldehydes at rutile Titania (TiO₂), a cheap, nontoxic and earth abundant catalyst. Coadsorption with oxygen may enhance the population of certain reaction paths. As systematic studies on the reactivity of ketones are rare, we studied the interaction of acetone with slightly (∼5%) and highly (∼20%) reduced rutile TiO₂(110) surfaces by Temperature Programmed Desorption (TPD) and polarised Fourier-Transform Infrared Reflexion Absorption Spectroscopy (FT-IRRAS) to elucidate surface intermediates and reaction products. For low defect densities the only reaction observed occurs at high temperatures resulting in the formation of propane and propene of less than 1%. At high Ti³⁺ defect densities a stabilisation of acetone on the surface by the formation of a diolate was observed. In the presence of oxygen, the partial formation of a tilted acetone species is apparent in FT-IRRAS. A concomitant activation of the CH-bond can be attributed to the interaction with O_ad atoms and can relate to thermally induced low temperature decomposition to water and carbon dioxide. However, in contrast to alcohols and aldehydes, both intermediates do not react to other more valuable products.

GRAPHICAL ABSTRACT

KEYWORDS:

• Rutile TiO₂(110)
• FT-IRRAS
• defects
• acetone
• total oxidation

Acknowledgement

The funding of the DFG research training group GRK 2226 “Chemical Bond Activation’ is appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).