Selective hydrogenation of acetylene on carbon-encapsulated Ni-Co-Cu trimetallic nanoparticles: Synergizing electronic effects and spatial confinement

Achieving high ethylene selectivity and activity simultaneously for acetylene selective hydrogenation still remains challenging. Here, the challenge of the trade-off between activity and selectivity was solved by synergizing electronic effects and spatial confinement, which was achieved by confining the Ni-Co-Cu trimetallic nanoparticles in a carbon layer (NixCuyCoz@C/Al2O3). Compared to the catalyst without carbon encapsulation (NixCuyCoz/Al2O3), NixCuyCoz@C/Al2O3 showed superior catalytic performance in terms of enhanced activity, selectivity and stability. Under optimal conditions, acetylene conversion of 100% and ethylene selectivity of 89% were achieved, whereas NixCuyCoz/Al2O3 exhibited lower acetylene conversion (92%) and ethylene selectivity (21%). Detailed characterizations reveal that the electronic structure can be regulated flexibly by controlling the composition of Ni-Co-Cu nanoparticles. The enhanced activity and selectivity were attributed to the weakened adsorption of acetylene and ethylene on the electron-rich Ni. The improved stability was related to the carbon layer, which suppressed the acetylene coupling by the acidic sites on the Al2O3 surface.