Journal de thermodynamique et de catalyse
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Cu or Fe Modified Cs2HPMo12O40 as Catalysts for Selective Oxidation of Methacrolein

Shuo Wang, Xiaofang Liu and Lilong Zhou

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. Whereas, Fe³⁺ had no significant effect on redox ability of the catalyst. The conversion of methacrolein could reach 96% with the existence of Fe³⁺. However, the addition of Fe³⁺ had no significant effect on selectivity to methacrylic acid.