The Isomerization of Propylene Oxide on Zeolite Catalysts

Abstract
The selectivity and activity of propylene oxide isomerization have been investigated over zeolite catalysts at 100°C. It has been found that the acid strength of a catalyst is a dominant factor in the selectivity and activity. The stronger the acid strength, the larger the ratio of acetone to propionaldehyde. The reaction intermediates are deduced to be a propylene oxide protonated or that adsorbed on a Lewis-acid site. It has also been found that, in the cases of HY, Silnex (SiO2), and HY treated with pyridine, the selectivity and activity correlate with the strength of the interaction between the propylene oxide and the surface hydroxyl group. Moreover, it has been clarified that the H0 value of the surface hydroxyl group observed at 3660 cm−1 on HY is −8.2–−5.6, while that found at 3540 cm−1 is +4.0–+4.8.