Acetone to isobutene conversion on ZnxTiyOz: Effects of TiO2 facet.

[Display omitted] • Zn x Ti y O z with well-defined surface were synthesized by liquid-phase grafting using (1 0 1) or (0 0 1) facet dominant anatase. • Site requirements of acetone to isobutene reaction at molecular level were studied by faceted mixed metal oxides. • The bridging OHs with rapid proton transfer efficiently stabilize a transition state in the acetone to isobutene conversion. Liquid-phase chemical grafting method was used to graft Zn onto TiO 2 with preferentially exposed (1 0 1) or (0 0 1) facet. The obtained Zn x Ti y O z materials were characterized using various techniques (e.g., XRD, Raman, DRIFTS etc.) and evaluated for the acetone-to-isobutene reaction. It was found that over TiO 2 (0 0 1), both terminal and bridging hydroxyls were readily titrated by Zn deposition, whereas a substantial amount of bridging hydroxyls on TiO 2 (1 0 1) remained. Although dominant Zn-O-terminated surface was obtained on two Zn x Ti y O z samples, bridging hydroxyls with high H-D exchange reactivity were observed on Zn x Ti y O z (1 0 1) compared with Zn x Ti y O z (0 0 1). The bridging hydroxyls showing rapid proton transfer efficiently stabilizes a transition state of diacetone alcohol intramolecular rearrangement for isobutene production as opposed to the diacetone alcohol dehydration. [ABSTRACT FROM AUTHOR]