Mobility of the acidic protons in H-ZSM-5 as studied by variable temperature 1H MAS NMR

The dynamic nature of the protons in H-ZSM-5 was examined by the temperature dependence of H-1 MAS NMR in the range 298-473 K. The line width of H-1 MAS NMR of acidic protons increased, and through maximum it decreased. The intensity of the spinning sidebands monotonically decreased, and they almost disappeared upon raising the temperature. This temperature dependence of the spectrum was explained by the thermal motion of protons. The correlation times and the activation energies for proton mobility were estimated. The estimated values of the activation energy are 17-20 kJ mol(-1).