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e catalytic activity of various Keggin polyoxometalate catalysts has been investigated in the gas-phase partial oxidation of toluene to produce benzyl alcohol and benzaldehyde. e catalyst systems HPMo 12 O 40 , HPMo 11 VO 40 , FePMo 12 O 40 , and PMo 11 FeO 39 were prepared and characterized by FT-IR, UV-visible, SEM, XRD, TGA, and cyclic voltammetry. e acid/base properties were evaluated using the decomposition of isopropanol. Catalytic studies were carried under atmospheric pressure and over the temperature range 200°C-350°C, using carbon dioxide as a mild oxidant. Toluene conversion and product distribution depend mainly on the catalyst composition and operating conditions. In addition to benzaldehyde, benzyl alcohol is obtained with a high selectivity on the PMo 11 FeO 39 catalyst. e kinetic data show that the reoxidation of the reduced catalyst is the rate-limiting step for the partial oxidation reaction of toluene.

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Heteropolyacids of Keggin structure, H 3 PMo 12 O 40 , H 3 PMo 11 WO 40 and the salts K 3 PMo 11 WO 40 and K 2.5 Fe 0.08 H 0.26 PMo 11 WO 40 were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy, Fourier transform infrared (FTIR), low-temperature nitrogen adsorption and 31 P MAS NMR spectroscopy. The acid-base properties were evaluated using the isopropanol decomposition. They were tested in oxidative dehydrogenation (ODH) of ethylbenzene in the temperature range 300-400 • C at atmospheric pressure with the mild oxidants carbon dioxide and nitrous oxide, the major actors in the greenhouse effect. The results show that the best compromise between conversion and selectivity is obtained for the mixed K/Fe salt of PMo 11 WO 40 at a relatively low temperature, namely 350 • C.