Conversion of methanol to dimethyl ether and formaldehyde over alumina intercalated in a montmorillonite Original Research Article

Catalytic and acid properties of alumina activated by an intercalation in a montmorillonite, which is effective catalyst for the conversion of a methanol to dimethyl ether, were studied by temperature-programmed desorption of NH3, FTIR measurements of adsorbed pyridine species and the HD exchange reaction of hydroxyl groups on the alumina surface with deuterium in D2O. For practical purpose, a montmorillonite pillared with an alumina was prepared in a very shortened time: the alumina was prepared from sodium-free polynuclear complex ions. The intercalation gives significantly active effects for a partial oxidation and dehydration of methanol to formaldehyde and dimethyl ether. The intercalated species of alumina were determined to have [Al6.0O7.5(OH)2.0]+ as the average chemical formula from chemical analysis, and weight loss of catalyst dehydration. The intercalation enhances HD exchange reactivity of the hydroxyl groups on intercalated alumina. The NH3-TPD data and FTIR data of the adsorbed pyridine species indicate that the intercalation increases significantly amount of adsorbed ammonia, and modifies the acid properties of alumina. Thus, the intercalation gives activation of alumina, and a remarkable promotion of the methanol dehydration and partial oxidation.