Palladium nanoparticles supported on a Ni-Based MOF for low-temperature acetylene semi-hydrogenation: breaking the activity-selectivity trade-off

Abstract The semi-hydrogenation of acetylene in excess ethylene is of great importance in the petrochemical industry. Conventional catalysts typically rely on Pd sites that simultaneously activate H2 and C2H2, often resulting in a trade-off effect between activity and selectivity. In this work, Pd nanoparticles are stabilized by a Ni-based metal-organic framework (Ni-MOF) to afford a Pd/Ni-MOF composite. The Ni-MOF not only selectively concentrates and activates acetylene, but also modulates the electronic structure of Pd, suppressing its inherent acetylene activation ability and enabling it to preferentially activate hydrogen. This design establishes separated activation sites for hydrogen and acetylene, thereby achieving high ethylene selectivity while maintaining excellent catalytic activity even at low temperatures. This Pd/Ni-MOF achieves > 99.6% acetylene conversion with 92% ethylene selectivity at 80°C, surpassing most Pd-based catalysts. This synergistic mechanism effectively suppresses over-hydrogenation while preserving high activity, offering a promising strategy for rational design of heterogeneous catalysts for selective hydrogenation.