Ranulfo Allen, John Baglin, et al.
J. Photopolym. Sci. Tech.
The separation of C2H2 from CO2 is an important process for industrial achievement of gaseous precursor C2H2, which is yet challenged by the well-known trade-off between capacity and selectivity derived from their close physical properties (such as the nearly identical kinetic molecular sizes). Herein, we experimentally screen a series of Hoffman-type metal organic frameworks (MOFs) and regulate the pore size and functionality by introducing different metal cation and organic linkers. We find that among the obtained MOFs, a Ni2+ based MOF (termed as Ni-Pz) shows the best performance of efficient C2H2 separation from CO2, featuring both high capacity (106 cm3/g) and selectivity (10.8). Moreover, to the best of our knowledge, Ni-Pz has never been explored in C2H2 related separation before and is the only MOF that balances the adsorption capacity (>100 cm3/g), selectivity (>10), adsorption heat (<45 kJ/mol) and stability (>400 °C; pH = 1–12). Grand Canonical Monte Carlo (GCMC) simulations reproduce the experimental results and reveal several typical binding configurations of C2H2/CO2 in Ni-Pz. Density functional theory calculations corroborate that the binding configurations from GCMC are very stable and that C2H2 has stronger binding affinity inside the cavity of Ni-Pz than CO2. Practical separation performance is further demonstrated by dynamic breakthrough experiments with good recyclability. Overall, our findings highlight that the Ni-Pz MOF screened from various Hoffman-type MOFs is an excellent candidate for industrial application.