Raney Ni–Si Catalysts for Selective Hydrogenation of Highly Concentrated 2-Butyne-1,4-diol to 2-Butene-1,4-diol

Abstract

Raney Ni–Si catalysts were synthesized by treating Raney Ni with silane in a fluidized bed reactor and tested in the selective hydrogenation of 2-butyne-1,4-diol (BYD) at high concentration. Structural characterizations including XRD patterns, TEM images, and X-ray photoelectron spectroscopy show that Raney Ni–Si catalysts are composed of a Ni core surrounded by nickel silicides. These species transform from Ni-rich silicide (Ni2Si) to Si-rich silicide (NiSi2) with increasing silicification temperature from 250 °C to 450 °C. The insertion of Si atoms into Raney Ni catalysts decreased the catalytic activity, but significantly improved the selectivity to 2-butene-1,4-diol (BED). The beneficial effect of Si on the selectivity hydrogenation of BYD may be caused by the presence of Si at Ni-defect sites, and the formation of the surface nickel silicide that suppress the further hydrogenation of BED. Compared with the traditional Lindlar-type catalysts, such Raney Ni–Si materials can be used extensively in organic synthesis for selective hydrogenation of alkynes, avoiding the associated hazards of toxic additives. Raney Ni–Si catalysts, synthesized by treating Raney Ni with silane, showed that the insertion of Si atoms into Raney Ni catalysts decreased the catalytic activity, but significantly improved the selectivity to 2-butene-1,4-diol.