V. Martin et al., THERMOGRAVIMETRIC ANALYSIS OF VANADIUM PHOSPHORUS OXIDE CATALYSTS DOPED WITH COBALT AND IRON, JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, 53(1), 1998, pp. 111-121
The transformation of VOHPO4. 0.5H(2)O (VPO) precursor doped with coba
lt or iron for n-butane oxidation to maleic anhydride was investigated
by thermogravimetric analysis under air and nitrogen, with and withou
t n-butane in the flow. While almost no effect was observed in nitroge
n or air, a strong influence of the doping was observed when n-butane
was added to the nitrogen or air. This resulted in a delay of the deco
mposition of the precursor and a further reoxidation of the VPO cataly
st, particularly for doping with cobalt at low percentage (1%). This s
hows that doping can change the oxidation state of vanadium phosphorus
oxide catalysts, which can explain differences in their catalytic per
formances and the favourable effect of doping by cobalt.