Unveiling the origin of enhanced catalytic performance of NiCu alloy for semi-hydrogenation of acetylene

Ni-based bimetallic catalysts are widely explored for semi-hydrogenation of acetylene due to their enhanced catalytic performance. However, the comprehensive understanding of performance promoted by Ni-based alloy still remains elusive to date. Herein, supported NiCu/ZrO2 catalysts were fabricated to unveil the origin of improved selectivity and stability. Owing to the electronic and geometric modification of active Ni sites by Cu atoms, NiCu/ZrO2 ensures weak adsorption of key intermediates and easy desorption of ethylene, leading to an improved selectivity towards ethylene. DFT calculations indicate that both the activation barriers for the acetylene deep dehydrogenation pathway and the CC bond cleavage pathway on NiCu alloy are higher, suggesting that NiCu/ZrO2 would show superior stability over Ni/ZrO2. Therefore, the ID/IG ratio obtained via in-situ Raman, which represents the anti-coking ability of catalysts, can be employed as a descriptor of catalytic stability. These findings bring new insight for designing efficient heterogeneous catalysts for selective hydrogenation.