The Cu2+ or Fe3+
substituted Cs2HPMo12O40 was synthesized to study the effect of transitional
metal cations on selective catalytic oxidation of methacrolein by
polyoxometalates.
Adding of Cu2+
could reduce acidity and enhance oxidizing ability of the catalyst. The catalytic
experiments showed that the addition small amount of Cu2+ to the
catalyst could increase the conversion of methacrolein from 65% to 96% and the
selectivity to methacrylic acid to 55%, at 300-340°C.
It is found
adding of Cu2+ could promote the reduction process of catalysts should be the
main reason of the performance enhancement. Adding of Fe3+ to the catalyst
could induce some new weak acidic sites due to the formation of iron aqua
complexes.
