ABSTRACT

The systematic studies of the supported metal-metalloid amorphous alloy catalysts are summarized in the present paper. Various catalysts, such as Ni-B/SiO₂, Ni-B/Al₂O₃,  Ni-B/TiO₂-Al₂O₃, Co-B/SiO₂, Pd-B/SiO₂, Ru-B/SiO₂, Ni-P/SiO₂, Co-P/SiO₂, Ni-Co-B/SiO₂, Ni-Ru-B/SiO₂, Ni-W-B/SiO₂, Ni-Pd-P/SiO₂, etc., are prepared by chemical reduction of the transition-metal ions dispersed on the support with BH₄^- or H₂PO₂^-. The preparation conditions are discussed for obtaining the optimum catalysts. The amorphous structure is determined by XRD, EXAFS and DSC analysis. The catalytic properties of those catalysts are evaluated during the hydrogenation of various unsaturated groups, such as C=C, C=O, N=O C≡N. In comparison with those corresponding crystalline catalysts, such as Raney metal and supported metal catalysts prepared by hydrogen reduction, the following advantages of the as-prepared supported amorphous catalysts during the catalysis can be concluded: (1) the higher activity and selectivity and sulfur resistance than the corresponding crystalline catalysts; (2) the higher thermal stability than the corresponding unsupported amorphous alloy catalysts; (3) the less pollution than the Raney Ni catalyst. According to various characterizations, including ICP, XPS, EXAFS, XRD, TPD, TPR, hydrogen adsorption, IR, SEM, and TEM etc, the aforementioned excellent catalytic properties are elucidated based on the promoting effect of the amorphous structure, the alloying metalloid, the metal additives and the interaction between the alloys and the supports.