Ketonization of carboxylic acids is an important reaction relevant for upgrading biomass-derived compounds through C-C bond formation and oxygen removal. Titania is particularly active for acetic acid ketonization. However, clear structure-activity relationships remain obscured by the “materials gap” of applying polymorphic and/or multi-faceted titania under realistic reaction conditions and the “pressure gap” of studying well-defined single-crystal titania surfaces under ultrahigh vacuum, far from relevant conditions for ketonization catalysis. We studied well-defined faceted nanoparticle anatase TiO2 exposing &gt;90% of the (101) surface under atmospheric and UHV conditions to bridge these materials and pressure gaps. The reaction mechanism was probed by a combination of in situ temperature-programmed-DRIFTS and TPSR-MS under both atmospheric and UHV conditions with protium- and deuterium-labeled acetic acid. It is revealed that acetic acid adsorbs both molecularly and as bidentate acetate at 300 K. Increasing surface coverages of acetic acid under UHV conditions favor ketonization to acetone rather than dehydration to ketene, and ketene is not observed during TPSR at atmospheric pressure. Evaluation of energetic barriers and kinetic isotope effects provide insight into the reaction mechanism. These results highlight the role of well-defined faceted nanoparticles to bridge the materials and pressure gaps between surface science and catalysis with technical materials.

Acetic acid ketonization over faceted nanoparticle anatase TiO2(101) surfaces

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