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

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 degrees 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. (C) 2012 Elsevier B.V. All rights reserved.