Environmentally benign selective hydrogenation of α, β-unsaturated aldehydes and reduction of aromatic nitro compounds using Cu based bimetallic nanoparticles supported on multiwalled carbon nanotubes and mesoporous carbon

Bimetallic catalysts of Cu with Fe, Co, Ni, Zn or Ru supported on multiwalled carbon nanotubes (MWCNT) and mesoporous carbon (MC) were prepared by in situ reduction of CuCl2 and the metal chlorides using NaBH4. The catalytic activity of these materials was investigated in the hydrogenation of alpha, beta-unsaturated aldehydes and reduction of aromatic nitro compounds using different hydrogen sources. Cu-Ni and Cu-Ru supported on MWCNT catalysts were found to be better than MC supported catalysts in terms of yield of the expected product and recyclability. Among the different hydrogen sources used, molecular H-2 was found to be the best for the hydrogenation of alpha, beta-unsaturated aldehydes to corresponding alcohols (conversion 83-86%, selectivity 72-78%), whereas NaBH4 was the best for the reduction of aromatic nitro compounds to corresponding amines (conversion 100%, selectivity 98%). The reaction conditions were optimised for good yield and selectivity of the product. Generality of the catalysts was also investigated in the reduction of different alpha, beta-unsaturated aldehydes and aromatic nitro compounds. The relationship between catalytic activity and physico-chemical properties was investigated by characterising the catalytic materials using powder X-ray diffraction (powder XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM).