Reduction potential and oxidation catalysis of vanadium-containing H6+xP2Mo18-xVxO62 Wells–Dawson heteropolyacid (HPA) catalysts.

Vanadium-containing H6+xP2Mo18-xVxO62 (x = 0–3) Wells–Dawson heteropolyacid (HPA) catalysts were prepared. The successful formation of the Wells–Dawson HPAs was confirmed by FT-IR and ICP–AES analyses. The reduction potential of the H6+xP2Mo18–xVxO62 (x = 0–3) catalysts was determined by temperature-programmed reduction measurements. The Wells–Dawson HPA catalysts were applied to the vapor-phase oxidation of methacrolein and benzyl alcohol. The reduction potential, conversion of methacrolein, and conversion of benzyl alcohol showed volcano-shaped curves with respect to vanadium substitution, and decreased in the order of H8P2Mo16V2O62 > H7P2Mo17V1O62 > H9P2Mo15V3O62 > H6P2Mo18O62. A correlation between reduction potential and catalytic activity clearly showed that the conversion was monotonically increased with increasing reduction potential of the HPA catalyst in both oxidation reactions. [ABSTRACT FROM AUTHOR]