Study of Dimethyl Carbonate Adsorption and Activation on Solid Bases by Fourier Transform Infrared Spectroscopy / 分析化学

ABSTRACT

The adsorption and activation of dimethyl carbonate on the surface of solid base were investigated by in situ FTIR, and the solid bases included magnesia, magnesium fluoride, Mg-Al mixed oxide and fluorine-modified Mg-Al mixed oxide. The FTIR results showed that dimethyl carbonate adsorbed on the surface of solid based by two modes of bidentate and unidentate complex. The bidentate was more active than the unidentate. Methoxyl group was formed from the adsorbed dimethyl carbonate on the surface of magnesia and Mg-Al mixed oxide. And fluomethyl group was formed from the adsorbed dimethyl carbonate on the surface of sodium fluoride. However, dimethyl carbonate on the surface of fluorine-modified Mg-Al mixed oxide showed preference for generating fluomethyl group. With the increasing of the treating temperature of samples, the methoxyl group was gradually formed on the surface. Accordingly, the fluorine-modified Mg-Al mixed oxide was found to be an excellent catalyst for methylation.