Efficient liquid-phase hydrogenation of cinnamaldehyde to cinnamyl alcohol with a robust PtFe/HPZSM-5 catalyst

HPZSM-5 with hierarchical porous structure obtained via partial desilication of commercial ZSM-5 was proved to be a suitable support for Pt nanoparticles towards the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to yield cinnamyl alcohol (COL). Compared with Pt/ZSM-5, Pt/HPZSM-5 showed improved catalytic performance although the improvement seems to be very limited. After doping Fe to Pt/HPZSM-5 with a Fe/Pt molar ratio of 0.25, the PtFe/HPZSM-5 catalyst gave much further enhanced CAL conversion. Under the optimized conditions, a 97.9% CAL conversion with 87.6% selectivity to COL was achieved with the PtFe/HPZSM-5 catalyst. The initial activity (in terms of TOF value, defined as molecules of CAL converted per surface atom of Pt per second) reached about 3.41 s⁻¹ with the PtFe/HPZSM-5 catalyst, one of the highest values up to now to our best knowledge. Moreover, the PtFe/HPZSM-5 catalyst can be recycled for at least 9 times without obvious loss in activity or selectivity to COL. The effect of partial desilication and Fe doping on the catalytic performance of PtFe/HPZSM-5 was discussed based on the characterization results using a series of techniques.