Studies on the Selective Oxidation of Methane over Magnesium and Rare Earth Molybdatcs

Abstract

Abstract: The ABO₄ type of Mg, Ln(La, Ce, Eu)molybdates has been used as catalysts to convert CH₄ to HCHO. ESR, TPR and XRD measurements show that molybdenum near the neighbour oxygen ions take part in oxidation reaction. When molybdenum ions were fixed as the atom Band the atomic ratio A/B was changed, the atoms at site A were substituted by Mg,La,Ce,Eu, the structure of catalysts take varied type, such as, a-MgMoO₄, a-La₂(MoO₄)₃, Eu₂(MoO₄)₃ etc. The selectivity of formaldehyde increased according to the following. order MgMoO₄<Eu₂(MoO₄)₃<La₂(MoO₄)₃< Ce₂(MoO₄)₃. The catalysts of the CeMoO₄ series gave a higher selectivity for formaldehyde, which well coordinate oxygen inserting and dehydrogenation functions, but showed no selectivity for both CO₂ and coupling products. The befunctional effect for oxygen inserting and dehydrogenation was dependent to the electronegativity of A and B atoms, and the lattice structure of catalysts.

Key words: Methane, Formaldehyde, Cerium molybdate.

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Cui Xianghao, Wei Quan, Li Xiangwei, Ma Yingde. Studies on the Selective Oxidation of Methane over Magnesium and Rare Earth Molybdatcs[J]. Chem. J. Chinese Universities, 1990, 11(10): 1158.

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Studies on the Selective Oxidation of Methane over Magnesium and Rare Earth Molybdatcs

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