Synthesis and Characterization of Silica-Supported Cobalt Phosphide Catalysts for CO Hydrogenation

A series of silica supported cobalt phosphides with different metal/P molar ratios were synthesized by means of a temperature programmed reduction (TPR) method. Their catalytic performances of CO hydrogenation were tested in a fixed-bed reactor under conditions of 553 K, 5.0 MPa, and H-2/CO = 2 (molar). The catalytic activity of the phosphides ranked in the following order: Co2P/SiO2 < Co4P/SiO2 < Co8P/SiO2 (x denotes the molar ratio of metal to P). It is interesting to find that C-2(+) oxygenates were the main product over the CoxP catalysts. Evidence from X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) measurements proved that the Co delta+ species might be the active sites for the formation of higher oxygenates during CO hydrogenation.