Influence of Pore Structure on Catalytic Properties of Mesoporous Silica-supported Co-B Amorphous Alloys in Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol

Co-B amorphous alloy catalysts supported on three kinds of mesoporous silica (common SiO(2), MCM-41 and SBA-15) have been systematically studied focusing on the effect of pore structure on the catalytic properties in liquid-phase hydrogenation of cinnamaidehyde to cinnamyl alcohol (CMO). Structural characterization of a series of different catalysts was performed by means of N(2) adsorption, X-ray diffraction, transmission electron microscopy, hydrogen chemisorption, and X-ray photoelectron spectroscopy. Various characterizations revealed that the pore structure of supports profoundly influenced the particle size, location and dispersion degree of Co-B amorphous alloys. Co-B/SBA-15 was found more active and selective to CMO than either Co-B/SiO(2) or Co-B/MCM-41. The superior catalytic activity could be attributed to the higher active surface area, because most of Co-B nanoparticles in Co-B/SBA-15 were located in the ordered pore channels of SBA-15 rather than on the external surface as found in Co-B/SiO(2) and Co-B/MCM-41. Meanwhile, the geometrical confinement effect of the ordered mesoporous structure of SBA-15 was considered to be responsible for the enhanced selectivity to CMO on Co-B/SBA-15, inhibiting the further hydrogenation of CMO to hydrocinnamyl alcohol.