A Hydrogen-Bonded Metal–Organic Framework for CO2 Capture and Natural Gas Upgrading

Abstract Efficient separation of CO2/N2 (flue gas), CO2/CH4 (natural gas), and light hydrocarbons is important in industry but remains a critical challenge. The development of versatile adsorbents capable of addressing multiple industrially relevant gas separations is therefore highly desirable. Herein, we report the synthesis of a three-dimensional (3D) hydrogen-bonded organic framework (HOF), designated ZNU-69, constructed through the interlayer hydrogen-bonding self-assembly of two-dimensional (2D) metal–organic framework (MOF) layers. Single-component adsorption isotherms reveal that ZNU-69 exhibits preferential uptake of CO2, C2H6, and C3H8 over CH4 and N2. IAST selectivity calculations at 298 K and 1 bar yield values as high as 473 for CO2/N2 (15/85), 127 for CO2/CH4 (50/50), 596 for C3H8/CH4 (50/50), and 54 for C2H6/CH4 (50/50). Theoretical calculations elucidate the microscopic adsorption mechanism, revealing that the strong binding energies, along with multiple hydrogen-bonding and van der Waals interactions with the framework, are responsible for the observed affinity and selectivity. Dynamic breakthrough experiments and cyclic tests further confirm its excellent separation performance and robust regeneration stability. This work provides a strategy for designing multifunctional MOF/HOF hybrid adsorbents that synergistically combine high selectivity with broad applicability.