PNNL

Abstract

Liquid-phase chemical grafting method was used to graft Zn onto TiO2 with preferentially exposed (1 0 1) or (0 0 1) facet. The obtained ZnxTiyOz 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 TiO2 (0 0 1), both terminal and bridging hydroxyls were readily titrated by Zn deposition, whereas a substantial amount of bridging hydroxyls on TiO2 (1 0 1) remained. Although dominant Zn-O-terminated surface was obtained on two ZnxTiyOz samples, bridging hydroxyls with high H-D exchange reactivity were observed on ZnxTiyOz (1 0 1) compared with ZnxTiyOz (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.