Liquid Coordination Environment-Induced Liquid-Like Metal Behavior: Mobile Single-Atom Copper Catalytic Centers

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Heterogeneous single-atom catalysts traditionally rely on rigid supports, limiting their adaptability.
• Dynamic response of catalysts under reaction conditions is crucial for optimizing performance.
• Static anchoring restricts the dynamic behavior of active sites in single-atom catalysis.

Purpose of the Study:

• To develop a heterogeneous single-atom catalyst with liquid-metal-like dynamic behavior.
• To create dynamically reconfigurable active centers using a liquid coordination environment.
• To achieve high selectivity and activity in acetylene hydrogenation via dynamic coordination.

Main Methods:

• Introduction of an ionic liquid membrane onto Al2O3 to create a high-loading single-ion Cu catalyst.
• Spectroscopic analyses (e.g., X-ray absorption spectroscopy) to characterize active species and coordination environment.
• Acetylene-selective hydrogenation reactions with kinetic and operando spectroscopic studies.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• A single-ion Cu catalyst with a liquid coordination environment was successfully constructed.
• Dynamically reconfigurable active centers were generated through reversible N-heterocyclic carbene (NHC) and Cu coordination exchange.
• The catalyst exhibited high acetylene conversion (98%) and ethylene selectivity (92%) at 200 °C with low Cu loading (0.25 wt%).
• A 35 °C lower half-conversion temperature and stable performance over 200 hours were observed compared to CuCl/Al2O3.
• Mechanistic studies revealed strengthened acetylene adsorption, weakened ethylene binding, and altered H2 dissociation barriers.

Conclusions:

• Coordination dynamics in a liquid environment offer a new strategy for dynamic, self-adaptive single-atom catalysis.
• This approach overcomes limitations of static anchoring, enabling tunable catalytic behavior.
• The developed catalyst demonstrates superior performance in selective acetylene hydrogenation, paving the way for advanced catalytic systems.