Tungsten oxide nanomaterial interactions below monolayer coverage

Abstract

A tungsten oxide load at submonolayer coverage of alumina renders highly dispersed dimeric polytungstate (octahedral and distorted octahedral coordination) and isolated monotungstate (tetrahedral) species. The polytungstate/monotungstate proportion increases when approaching monolayer. Crystalline WO3 nanoparticles emerge at higher loads. All components display hexavalent oxidation; yet, tungsten‐ oxide (W–O–W) and tungsten‐ oxide‐ alumina (W–O–Al) interactions were discerned by X‐ ray photoelectron spectroscopy of the WOx/Al2O3 materials herein prepared with 1, 3, and 5 weight percentages. The 5 wt % sample displayed the highest intensity percentage of W–O–Al species correlated to the highest methanol conversion (45 %), ascribed to the appearance of the weak acidity disclosed by temperature‐ programmed desorption of ammonia.