Selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde over SiO2 supported nickel phosphide catalysts

A series of SiO(2) supported transition metal (Fe, Co, Ni, Mo and W) phosphide catalysts were synthesized and tested for the selective hydrogenation of cinnamaldehyde (CMA). Among these tested catalysts, Ni(12)P(5)/SiO(2) and Ni(2)P/SiO(2) prepared with initial Ni/P ratios of 2/1.3 and 1/1 exhibited high activity and selectivity for the conversion of CMA to hydrocinnamaldehyde (HCMA). The two nickel phosphide catalysts showed selectivity to HCMA up to 90% at a conversion of 90%. The properties of the nickel phosphide catalysts were characterized by BET surface area determinations, X-ray powder diffraction (XRD) analysis, and transmission electron microscopy (TEM). The influences of reaction temperature, hydrogen pressure, Ni/P ratio, and reduction temperature were studied in detail. For comparison, Pd/SiO(2) catalyst was also used in this reaction, and the possible reasons for the different catalytic performances of the two kinds of catalysts are presented.