Stabilization of Supramolecular Frameworks by Surface-Confined Polymerization for Natural Gas Purification

Abstract

High-porosity supramolecular frameworks (SMFs) show potential as natural gas purification adsorbents, but their instability and tendency to collapse after activation limit their practical value. Here, we adopt the strategy of surface-confined polymerization to overcome this problem, using trimethylhexamethylene diisocyanate (TMDI) to coat the surface of a new SMF, NUT-130, which allows obtaining NUT-130@PolyTMDI with permanent porosity. Compared to the uncoated material NUT-130, the specific surface area of NUT-130@PolyTMDI increased 3.25 times from 627 m²·g^–1 to 2668 m²·g^–1. The coated samples showed a more favorable separation performance due to the retained mesopores, which favored the adsorption of C₂H₆ and C₃H₈. Breakthrough experiments showed that NUT-130@PolyTMDI was significantly superior to NUT-130 for the ternary mixture CH₄/C₂H₆/C₃H₈ (85:10:5, v:v:v) separation, and the performance was almost unchanged after three cycles. This work provides a strategy for preserving the mesopores of SMF, which enhances the separation efficiency for natural gas purification and provides ideas for the subsequent synthesis of novel adsorbents for natural gas purification.