Kinetic studies of the dehydration of methanol over aluminosilicate and gallosilicate offretites

Abstract

The kinetics of the dehydration of CH ₃ OH by the hydrogen forms of three offretites with different contents of framework Al and Ga have been monitored by ¹³ C magic-angle-spinning (MAS) NMR spectroscopy. No reaction takes place at room temperature. At 150 °C methanol is dehydrated to dimethyl ether. As expected, the catalytic activity of offretite for this reaction is lower than that of zeolite ZSM-5, and it decreases with increasing framework gallium content. The rates of the dehydration reaction are 0.045, 0.863 and 1.136 a.u. ⁻¹ s ⁻¹ for Ga-, Al,Ga- and Al-offretites, respectively.