Glycerol oxidehydration into acrolein and acrylic acid over W–V–Nb–O bronzes with hexagonal structure

Abstract

This paper deals with an investigation of hexagonal W–Nb–O and W–V–Nb–O bronzes as catalysts for the one-pot oxidehydration of glycerol into acrylic acid. In a previous work, we reported that the best yield to acrylic acid obtained with the W–V–O bronze was 25%; in the current work, the incorporation of Nb in the tri-component bronze structure allowed us to obtain the best acrylic acid yield of 34%. The W–Nb–O bronze was an efficient acid catalyst for the dehydration of glycerol into acrolein – more selective than WO3 at temperatures lower than 300°C –, whereas in the tri-component system the presence of V conferred to the catalyst the redox properties for the partial oxidation of acrolein into acrylic acid. The characterization of the catalysts confirmed the incorporation of Nb5+ in the hexagonal structure, and the generation of acid sites with enhanced strength compared to the bi-component W–V–O system. This also enhanced the stability of catalytic performance during short-term lifetime experiments.