Phase composition of Mg—Al mixed oxides, their activity and selectivity in the ethanol condensation reaction

Resumo

Layered hydroxides with a molar ratio of metals Mg: Al: M = 3: 1: 1 (M = Fe, Ce, Zr, Cr) were prepared and served as a basis to obtain the mixed oxides MgAlO_x, MgAlCrO_x, MgAlCeO_x, MgAlZrO_x, and MgAlCrO_x. Powder X-ray diffraction was used to study the phase composition of the oxides. It was suggested that the catalyst active surface is related to the presence of spineltype X-ray amorphous compounds. Ammonia adsorption was used to determine the total acidity, and deuterated acetonitrile adsorption was applied to estimate the strength of acid sites. The catalytic properties of complex oxides were studied in the ethanol condensation reaction. An attempt was made to correlate the catalyst activity and selectivity and the distribution of acid and base sites on the catalyst surface.