Heteropoly acid salt catalyst and its preparation method

A heteropoly acid salt catalyst having the following general formula:

• x(Mo12PaKbVcDdEeOf)/yZ,
• wherein
• D represents at least one element selected from the group consisting of copper, magnesium, manganese, stibium and zinc;
• E represents at least one element selected from the group consisting of tungsten, silicon, nickel, palladium, ferrum and plumbum;
• Z is a carrier/diluting thermal-conductive agent, which is one selected from the group consisting of SiC, MoO3, WO3, TiO2 and ZrO2;
• the weight ratio y/x=15-50:100;
• a=0.1-3;
• b=0.01-5;
• c=0.01-5;
• d=0.01-3;
• e=0.01-2;
• and
• f is the atom ratio of oxygen balancing the valence for each component described above,
• wherein the catalyst is prepared by the following procedures:
• (i) dissolving molybdenum, phosphorus, and vanadium compounds in a solvent to formulate Solution A;
• dissolving potassium compound and a D-containing compound in a solvent to formulate Solution B;
• and dissolving an E-containing compound in a solvent to formulate Solution C;
• (ii) mixing Solutions A, B and C under a temperature of −5-10° C.;
• (iii) pre-calcinating under an oxygen-containing gas flow to obtain a catalyst precursor;
• (iv) adding into the catalyst precursor 1-5 wt % of graphite powder and a diluting thermal-conductive agent, wherein the weight ratio between the diluting thermal-conductive agent and the catalyst precursor (y/x) is 15-50:100;
• and
• (v) calcinating in an oxygen-containing atmosphere.