Controllable Synthesis of Highly Dispersed Cu/SiO2 Catalysts in Supercritical CO2 and their Application in the Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

摘要

Highly dispersed Cu nanostructures were synthesized within mesoporous silica in supercritical CO2 using inorganic Cu precursors. Co-solvent was found to have significant influence on the metal loading and the nanostructure morphologies of the nanocomposites. Although the inorganic precursor has large solubility in ethanol, 1,3 propylene glycol, n-butyl alcohol and methanol, only big nanoparticles outside the nanochannels were obtained when the first three co-solvents were used, while zero metal loading was obtained when methanol was used as co-solvent. However, when ethylene glycol or the mixture of ethylene glycol and water were used as co-solvents, large amounts of short nanotubes were found inside the nanochannels with large metal loading. It indicates that the role of the co-solvent may have many aspects, such as enhancement of the precursor dissolution, change of the interaction between the precursor and the substrates and so on.