Progress in design of new amorphous alloy catalysts

Abstract

Three new kinds of Ni-based amorphous alloy catalysts, Raney type Ni–P(R–Ni–P), Ni–Co–B, and Ni–B(P)/SiO 2, have been prepared by modification of either the rapid quenching method or chemical reduction. Their amorphous structures have been determined by XRD, EXAFS, and DSC. Their catalytic activities and selectivities have been measured during the hydrogenation of various organic compounds, which demonstrate the great improvement on the catalytic properties in comparison with the corresponding amorphous alloy catalysts prepared by the rapid quenching method or chemical reduction previously reported. These new amorphous catalysts also exhibit superior catalytic properties over the traditional catalysts, such as Raney Ni, Ni/SiO 2, and Pd/C, making them possible to be used in real industrial catalysis. The relationship between the catalytic properties and the structural properties has been discussed according to various characterizations, including ICP, XPS, EXAFS, XRD, TPD, TPR, hydrogen adsorption, IR, SEM, and TEM, etc. The higher hydrogenation activity of R–Ni–P than the Ni–P amorphous catalyst obtained by rapid quenching is mainly ascribed to the increase of the surface area due to the skeleton structure; the higher activity of Ni–Co–B than the Ni–B amorphous catalyst demonstrates a promoting effect of the additive metal(s); while the higher thermal stability of supported Ni–P(B) than the corresponding unsupported catalysts can be explained by considering the stabilizing effect of the silica support on the amorphous structure.