Titania-supported molybdenum oxide combined with Au nanoparticles as a hydrogen-driven deoxydehydration catalyst of diol compounds

Abstract

A heterogenous catalyst for the deoxydehydration (DODH) reaction was developed using less expensive Mo than Re as the active center. The combination of Mo with anatase-rich TiO2 and Au as the support and promoter for H2 activation, respectively, can selectively convert 1,4-anhydroerythritol to 2,5-dihydrofuran, which is a typical DODH model reaction, with H2 as a reducing agent. Loading of Au on TiO2 by the deposition-precipitation method gave the more active MoOx-Au/TiO2 catalyst (MoOx-dpAu/TiO2) than that obtained by the impregnation method (MoOx-impAu/TiO2), and the activity difference is derived from the smaller size of Au particles in MoOx-dpAu/TiO2 (3-5 nm) than that in MoOx-impAu/TiO2 (>25 nm). The MoOx-dpAu/TiO2 catalyst could be applied to the DODH reaction of linear alkyl vicinal diols and cis-1,2-cyclohexanediol. The characterization with XRD, STEM, H2-TPR, XAFS and XPS revealed that the MoIV oxide cluster species on the surface of anatase TiO2 particles are responsible for the DODH reaction.