Molecular sieve effect in the hydration of olefins on zeolites

A study of the hydration of these alkenes on high,silicon zeolite ZHM displayed an unusual reactivity order: ethylene = propylene > isobutylene. The optimum temperature for the hydration of ethylene and propylene is 250-280~ and the molar yields of ethanol and 2-propanol were 5-6%. The molar yield of tert-butyl alcohol in the hydration of isobutylene at 150-200~ did not exceed 1%. Carbonization of the catalyst and the formation of isobutylene oligomers increased at higher temperature; the yield of tert-butyl alcohol did not increase. These results may be explained by a molecular sieve effect for olefin hydration and not by sample deactivation and side reactions since even a partially carbonized catalyst did not display reduced activity in olefin hydration.