A highly efficient nano-sized Cu2O/SiO2 egg-shell catalyst for C–C coupling reactions
Mesoporous SiO2-supported Cu2O nanoparticles as an egg-shell type catalyst were prepared by impregnation method. The obtained Cu2O/SiO2 egg-shell nanocatalyst had a large surface area and narrow pore size distribution. In addition, most of the Cu2O nanoparticles, with sizes around 2.0 nm, were highly dispersed in the mesoporous silica. Accordingly, fast reactant diffusion to the active sites would occur, especially when the active metal sites are selectively located on the outer part of the support, i.e., the outer region of the egg shell. In solvent-free Sonogashira reactions for the synthesis of ynones from acyl chlorides and terminal alkynes, this catalyst exhibited a very high catalytic activity. The excellent catalytic performance can be attributed to the synergistic advantages of mesoporous structure and monodispersed Cu2O nanoparticles.