Abstract：Comparative studies of the structure and catalysis of the oxidation of glycerol over Pt/CNTs and Pt-Sb/CNTs catalysts under base-free conditions were performed and the corresponding possible reaction pathways were proposed by using the transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and other characterization techniques. The addition of Sb to the catalyst has been found to have almost no effects on the particle size and electronic properties of Pt. However, Sb may be selectively deposited on the surface of Pt atom and sterically control the conversion of glycerol in an orientation favorable to its secondary hydroxyl group, thus changing the selectivity of the reaction path. The monometallic Pt/CNTs catalyst preferred to oxide the primary hydroxyl groups of glycerol, generating glyceraldehyde (GLYD) and then glyceric acid (GLYA), which was further oxidized into hydroxypyruvic acid (HPYA) and tartronic acid (TA), while the bimetallic Pt-Sb/CNTs catalyst favored for the oxidation of the secondary hydroxyl group of glycerol, generating dihydroxyacetone (DHA) and was further transformed into HPYA. Both the produced HPYA and TA during the two reaction routes could eventually be oxidized to glycolic acid (GLYCA) and other products by the cleavage of C-C bond.
