THE EFFECT OF COBALT AND IRON DOPANTS ON THE CATALYTIC BEHAVIOR OF V P/O CATALYSTS IN THE SELECTIVE OXIDATION OF N-PENTANE TO MALEIC AND PHTHALIC ANHYDRIDES/

V/P/O catalysts were prepared using isobutanol as solvent,which contai ned either cobalt or iron as the dopant (Me/V 0.01). The catalysts wer e characterized with several techniques, both after thermal treatment and after reaction in n-pentane/air. The catalytic performance was com pared for the selective oxidation to maleic and phthalic anhydrides un der conditions at which results were stable (i.e., after at least 200 h time-on-stream). It was found that iron had a dramatic effect on the structural evolution of the catalyst both during calcination and duri ng aging; in contrast, the effect of cobalt was much less marked. Dopi ng with 1% cobalt remarkably improved the selectivity to the phthalic anhydride at the expense of the maleic anhydride with respect to the u ndoped catalyst, while doping with iron led to a catalyst less selecti ve to phthalic anhydride and more selective to carbon oxides.