Subsurface carbon modification of Ni-Ga for improved selectivity in acetylene hydrogenation reaction

Control of subsurface interstitial atoms in transition metals is an effective approach to modulate selectivity in hydrogenation reactions. In this study, nickel was alloyed with gallium to form Ni3Ga, thereby regulating the octahedral interstitial sites. Subsequently, carbon atoms were introduced into the Ni3Ga (forming Ni3GaC0.5) via thermal treatment in an acetylene atmosphere, leading to a significant enhancement in selectivity for acetylene hydrogenation reaction. The X-ray diffraction and transmission electron microscopy results demonstrate an increase in the lattice parameter due to the incorporation of carbon atoms and the uniform distribution of carbon in Ni3GaC0.5 nanoparticles. The obtained Ni3GaC0.5/oCNT catalyst exhibits significantly improved selectivity in acetylene hydrogenation reaction, with approximately 82% ethylene selectivity at 98% conversion. Furthermore, it maintains good selectivity at various hydrogen-to-alkyne ratios and displays good stability during long-term operation. The introduction of carbon suppresses the formation of the subsurface hydrogen structure under reaction conditions. Additionally, the charge transfer between carbon and nickel results in the electron deficiency of nickel, effectively inhibiting the over-hydrogenation pathway and enhancing the selectivity. These results provide insights for the design of non-precious metal catalysts in selective hydrogenation reactions.