Formation of Bronsted acid sites in the reaction of cyclohexanol on NaCeY zeolites

This study was undertaken to elucidate why the catalytic activity of NaCeY in cyclohexanol reactions carried out in a pulse reactor increases with the pulse number. We studied therefore the effect of cyclohexanol and also of ethanol and water on catalytic activity of NaCeY (of exchange degrees 36 and 72%) in cyclohexanol reactions: isomerization and disproportionation. We also studied the reaction of cyclohexanol and water with NaCeY zeolite by IR spectroscopy. Our results evidenced that new Bronsted acid sites were formed by the reaction of cyclohexanol, and water. This was shown by IR spectroscopy: the increase of Si-O1H-Al band 3638 cm(-1) and in increase of ammonium ions band (upon ammonia adsorption), The new sites were formed by hydrolysis of Ce3+ ions with water introduced in a pulse, or produced by dehydration of cyclohexanol catalyzed by acid sites. Formation of new Bronsted acid sites resulted in an increase of catalytic activity of NaCeY in cyclohexene reaction as observed in this study and also in cyclohexanol reactions.