Mo–W-containing tetragonal tungsten bronzes through isomorphic substitution of molybdenum by tungsten

Abstract

Mixed metal oxides based in Mo(W)–Nb–V–Te with tetragonal tungsten bronze (TTB) structure have been synthesized by a hydrothermal method from aqueous solutions of the corresponding Keggin-type heteropolyacids and further heat-treatment in N 2 at 700 °C. The materials have been characterized by several physico-chemical techniques, i.e. XRD, Raman, FTIR, SEM-EDS, and TEM. This procedure allows controlling the chemical species to be distributed in the different interstices of the TTB skeleton, which is a key factor to regulate the catalytic properties of the final solid. In this sense, the isomorphic replacement of Mo by W results in lattice parameter and crystal morphology variation, although the TTB structure is preserved to different degrees of substitution. The incorporation of tellurium to the TTB framework leads to active and selective catalysts in the partial oxidation of propene to acrolein.