Co-Fe catalyst supported on acidified bentonite for selective hydrogenation of cinnamaldehyde

The surface acidity and structure of catalysts play crucial roles in cinnamaldehyde (CAL) selective hydrogenation to manufacture cinnamyl alcohol (COL). Herein, a Co-Fe-supported acidified bentonite catalyst (Co-Fe/ACBT) was prepared via sulfuric acid treatment of bentonite (BT) and the traditional impregnation method. The combination study, including FT-IR spectra of adsorbed pyridine and ammonia temperature-programmed desorption (NH3-TPD), showed that Co-Fe/ACBT has vast acidic sites mainly originating from surface unsaturated metal sites of ACBT, which prefer to adsorb polar >C=O but not nonpolar >C=C<. X-ray photoelectron spectroscopy (XPS) verified that the effect of electron transfer was significantly enhanced when the active metal was loaded on ACBT, leading to an increase in the electron cloud density of the Co species, which promoted the activation of >C=O. Due to the modified electronic properties of Co species and abundant acidic sites, Co-Fe/ACBT exhibited a 90.5% conversion and 86.8% hydrogenation selectivity from CAL to COL, which are notably greater than those of the Co-Fe-supported bentonite catalyst (32.0% CAL conversion and 66.4% COL selectivity).