Efficient natural gas upgrading using a stable Cd-based porous coordination network

Abstract

The efficient separation and purification of CH₄ from natural gas are of critical importance for the chemical industry but pose substantial challenges. Herein, we report a novel cadmium-based porous coordination polymer, Cd–TPP–^tBu-IPA, featuring a 3,6-connected network and propeller-shaped cages with narrow blades that serve as potential capture sites for C₂H₆ and C₃H₈. The ideal adsorbed solution theory (IAST) selectivities of C₂H₆/CH₄ and C₃H₈/CH₄ at 298 K and 100 kPa were 24.4 and 271.1, respectively. Grand Canonical Monte Carlo (GCMC) simulations revealed that Cd–TPP–^tBu-IPA exhibits strong affinity for C₃H₈ and C₂H₆ owing to its propeller-like cages. Dynamic breakthrough experiments demonstrated that Cd–TPP–^tBu-IPA could efficiently separate CH₄ from CH₄/C₂H₆/C₃H₈ ternary gas mixtures under ambient conditions. More importantly, the purity of CH₄ can reach 99.9%, with a high productivity of 11.49 mmol g⁻¹, which is expected to exhibit outstanding performance in practical separation. Furthermore, Cd–TPP–^tBu-IPA demonstrated excellent thermal and chemical stability.