Tuning the pore architecture of HKUST-1 via Polyvinylpyrrolidone for superior CH4 capture

The structure-property relationship between MOFs and CH 4 capture was clarified. • PVP served as template and structure-directing agent to tailor the pore of HKUST-1. • PVP-assisted HKUST-1-P x display volcano-like CH 4 adsorption behavior. • GCMC simulation was used to reveal the CH 4 adsorption mechanism on different MOFs. Efficient CH 4 capture from low-concentration coal mine gas is of great significance. Metal–organic frameworks (MOFs) are promising adsorbents owing to high porosity and structural tunability. Nevertheless, regulating the relationship between the MOFs structure and CH 4 capture performance, as well as developing rational strategies to overcome the adsorption bottleneck of MOFs, remain critical challenges. Herein, we present a systematic investigation of pore environments and adsorption sites on CH 4 capture, employing representative MOFs with diverse metal centers (Zr, Zn, Fe, Co, and Cu) and different topological structures. Interestingly, HKUST-1(Cu), with a matched pore size and open-metal sites, exhibited the highest adsorption capacity. Furthermore, by leveraging polyvinylpyrrolidone(PVP)-assisted pore modulation, HKUST-1-P x exhibited concentration-dependent growth. At low PVP concentrations, it selectively modulates the growth kinetics of crystallographic facets through coordination and steric effects, whereas at high concentrations, excessive PVP preferentially forms a dense layer that stabilizes the crystal dimensions and promotes isotropic growth. Moreover, the CH 4 adsorption capacity of HKUST-1-Pₓ follows an intriguing volcano-type trend with varying PVP content. Notably, HKUST-1-P 0.4 affords the best adsorption performance—30% higher than HKUST-1. Grand Canonical Monte Carlo simulations reveal that the coordination between PVP and Cu nodes reconstructs the pore distribution of HKUST-1-P x and strengthens CH 4 binding, as evidenced by the decrease in the adsorption energy of the CH 4 molecule from −18.05 kJ/mol (HKUST-1) to −27.15 kJ/mol (HKUST-1-P 0.4 ). Finally, the cyclic and breakthrough tests further validated the application potential of HKUST-1-P 0.4. This study provides innovative polymer-induced strategies for designing high-performance CH 4 -capture adsorbents for low-concentration coal mine gas. Download: Download high-res image (203KB) Download: Download full-size image