Investigation of methanol adsorbed on zeolite H-ZSM-5 by carbon-13 NMR spectrometry

{sup 13}C CPMAS NMR spectra of methanol adsorbed on H-ZSM-5 samples with different Si/Al ratios indicate that aluminum content affects the conversion of methanol to dimethyl ether. Spin-lattice relaxation experiments suggest that existence of at least three adsorbed methanol species. The reorientation activation energies (E{sub a}) of these species are measured to be 10.0 ({plus minus}1.2), 1.5 ({plus minus}0.1), and 2.1 ({plus minus}0.2) kcal/mol, respectively.