A Study of Catalyst Design by Use of Molecular or Crystalline Mixed Oxides

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Catalyst design based on molecular or crystalline mixed oxides was attempted. Heteropoly compounds, perovskite-type mixed oxides and V-P oxides were examined for this purpose by elucidating reaction mechanism and the interaction between reactants and the active sites under the working conditions. Furthermore, the effects of the formation of their thin films and ultrafine particles on the catalytic performance were studied.(1) In situ measurement of pseudoliquid phase Chemical shifts of molecules in the pseudoliquid phase was analyzed by FT-IR and solid state NMR. Protonated ethanol monomer, dimer, and ethoxy group, which are important intermediates for the dehydration, were directly detected by ^1H and ^<13>C NMR. In situ FT-IR measurement supports the presence of these species. Catalyst for selective oxidation of aldehyde was designed. Control of acidity by substitution of alkali for H^+ and increase of oxidation ability by partial substitution of V for Mo (polyatom) were found to be effective for the design of selective catalyst.(2) Catalytic properties of thin films of perovskites The surface structure of LaCoO_3/ZrO_2, which was highly active for catalytic combustion, was characterized by XPS, TEM, SEM, EDX, and NO adsorption. It was shown that monolayer thin film of LaCoO_3 or the like covered uniformly the surface of ZrO_2.(3) Control of morphology of V-P-oxides The effect of morphology of (VO)_2P_2O_7, which is efficient catalyst for the selective oxidation of butane to maleic anhydride, was studied. It was concluded that large crystallites grown in the direction of [020] was high selective and was stable under the working conditions.