Direct and Selective Gas-phase Hydration of Lower Olefin to Alcohol and Ketone

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Direct hydration of lower olefins on proton-exchanged zeolite catalysts has been studied in vapor or liquid phase and the following have been observed.1. In gas-phase hydration of propylene, l-btene, and iso-butene the reactivity of iso-butene was the highest. The yield of tert-butanol amounted to ca. 20% at 383 K. The zeolites with SIO_2/Al_2O_3 = 15-20 were the most active for the hydration. On the other hands, hydrative dehydrogenation of propylene or l-butene to give acetone or methyl ethyl ketone was found to proceed on ultra-stable Y-type zeolites(HUSY). Effort has been devoted to develop more active catalyst for the ketone formation and CAO/HUSY was concluded to be the best at the present.2. Liquid-phase hydration of iso-butene has been studied under both atmospheric pressure and high pressure. The activity and selectivity of the proton-zeolites were very high. For example, the conversion and selectivity to tert-butanol were 50% and 95%, respectively, on H-ZSM-5 at 383 K, 1.5 atm, and 30 min. The catalytic activity of the zeolites was dependent on the aluminum content; the zeolites with less amount of al showed higher activity.The results strongly suggest first that the proton-zeolites are better catalysts that other catalysts such as P_2O_5/SiO_2 and ion exchange resin, secondly than one might be able to get selectively tert-butanol in hydration of mixture of propylene and butenes.