Sorbitol-derived carbon overlayers encapsulated Cu nanoparticles on SiO2: Stable and efficient for the continuous hydrogenation of ethylene carbonate.

An ultrastable and efficient Cu@C/SiO2 nanocatalyst was fabricated for the hydrogenation of ethylene carbonate, in which Cu nanoparticles are encapsulated by sorbitol-derived graphitized carbon overlayers. During the calcination of Cu-sorbitol/SiO2 precursors under N2 atmosphere, sorbitol decomposed to CO and CO2. The in situ generated CO not only reduced Cu2+ to Cu0/Cu+, but also formed graphitized carbon overlayers on the Cu surface via the disproportionation of CO. The Cu@C/SiO2 catalyst exhibited superior catalytic performance (91% MeOH yield and 43.6 h-1 TOF) at a H2/EC molar ratio of 20. Of particular note, the Cu@C/SiO2 catalyst showed remarkable long-term stability during 736 h time-on-stream test without any deactivation. The graphitized carbon overlayers on the surface of Cu nanoparticles not only functioned synergistically with the surface Cu0/Cu+ sites to promote the EC hydrogenation but also suppressed the sintering of Cu nanoparticles. Furthermore, the interaction of Cu nanoparticles and graphitized carbon overlayers stabilized the surface Cu+/(Cu0+Cu+) ratio.