Catalyst and process of oxidative dehydrogenation of propane

A catalyst for oxidative dehydrogenation of propane, characterized by being prepared by the following steps:

• a) dissolving alkali or alkaline earth metal salts of oxometallates of W, V and Nb, in water at a temperature ranging from 40 to 80° C., the molar ratios W:V and V:Nb being from 2 to 8, and such that an aqueous solution of polyoxometalates is obtained wherein the mass ratio of the oxometalates to water is between 30 and 40% m/m;
• b) adding to the aqueous solution obtained in step (a) an inorganic acid to a pH between 6.5 and 7.5, and heating the solution to temperatures of 150 to 180° C. for a period of time ranging from 3 to 4 hours;
• c) adding, under constant agitation, to the aqueous solution obtained in (b) a saturated solution of an alkali or alkaline earth metal salt, in an amount of 60 to 80% v/v of polyoxometalates solution relative to the saturated solution until precipitation of mixed salts of polyoxometalates of tungsten, vanadium and niobium occurs;
• d) filtering and drying the polyoxometalates salts obtained in step (c) at a temperature ranging from 25 to 50° C.;
• e) promoting calcination of the materials obtained in (d) under air flow at temperatures of from 350 to 550° C. for a period of time from 3 to 5 hours to obtain mixed oxides of W, V, and Nb, with structure of tungsten bronzes;
• 2. The catalyst of claim 1, wherein the mixed salts of the polyoxometalates of tungsten, vanadium and niobium, have a Keggin structure of general formula [PW12-x-yVxNbyOC40]n−Zm+, wherein 1≤x≤6, y≤3, and 4≤m≤n≤11, Z being an alkali metal of:
• Na, K or Cs or alkaline earth selected from:
• Mg, Ca, Ba;