Mo-containing tetragonal tungsten bronzes. The influence of tellurium on catalytic behaviour in selective oxidation of propene

Te-free and Te-containing multicomponent Mo-based catalysts presenting tetragonal tungsten bronze (TTB) structure have been prepared, characterized and tested for the selective oxidation of propene. The catalysts were prepared hydrothermally and heat treated at 700 °C. The structural characterization performed by means of XRD, FTIR, SAED and HRTEM confirms the incorporation of tellurium to the TTB structural framework and shows that its presence does not modify in essence the crystalline structure. However, the incorporation of Te strongly modifies the catalytic performance, and the highest yield to acrolein has been achieved on catalysts with Te/Mo atomic ratios in bulk of 0.03. The XPS results indicate a Te enrichment on the catalyst surface in all the studied catalysts, suggesting important modifications of the surface in Te-containing catalysts. In this way, tellurium atoms seem to be a key element in the selective oxidative activation of olefin.