Unusual size effect of spinel Co0.5Fe0.5Al2O4 supported Pt catalysts on the selective hydrogenation of cinnamaldehyde

Pt/Co 0.5 Fe 0.5 Al 2 O 4 catalysts with the average Pt particle size of 1.6–3.4 nm were prepared and applied to the selective hydrogenation of cinnamaldehyde (CAL). Not only the TOF was promoted from 0.19 to 2.70 s −1 , but also the selectivity to cinnamyl alcohol (COL) was improved from 68% to 94%, with the increase of Pt particle size. Stronger interaction occurred between Co 0.5 Fe 0.5 Al 2 O 4 and smaller-sized Pt particles, resulting in electron-deficient Pt particles, so that C O and C C bond could be activated simultaneously. However, electron-rich Pt species existed on Pt/Co 0.5 Fe 0.5 Al 2 O 4 with larger Pt size, which is beneficial for the preferential activation of C O bond.