Radiotracers were used to monitor the molecular diffusion (tables 6 and 7) of ethyl and n-butyl alcohols in LTA zeolite crystallites under conditions of liquid-phase sorption. Evidence for a two-stage process was found. In the case of ethyl alcohol movement, this prevented the estimation of energy barriers to molecular migration. Estimates were possible when n-butyl alcohol was the labeled species. The effect of the presence of Mg, Ca, Sr, Zn, Na, Li, K and H cations was studied. It was concluded that the mobility of unbound alcohol molecules contributed to the initial diffusion process and that the second process was associated with alcohol molecules in some form of solvation shield around the cations present in the larger zeolite cages.

Self-Diffusion of Simple Alcohols in Heteroionic Forms of LTA Zeolites. A.Dyer, S.Amin: Microporous and Mesoporous Materials, 2001, 46[2–3], 163–76

Table 7

Activation Energies for Self-Diffusion

of Butanol in Zeolites at 298K