A Highly Chemically Robust 2D Zn-MOF as Promising Adsorbent for One-Step Methane Purification from Multicomponent Gas Mixtures.

Abstract

One-step CH4 purification from C2-hydrocarbons and CO2 gas impurities is essential in the quest for clean energy resources amidst the growing energy crisis. While MOF materials have demonstrated significant progress in binary C2H2/CH4, C2H4/CH4, C2H6/CH4, and CO2/CH4 separations, there is a growing emphasis on purification of CH4 from multicomponent gas mixtures using a single adsorbent. Toward this direction, a 2D MOF: IITKGP-27, {[Zn(MBPz)(SO2DBA)]·4H2O}n featuring rhombus pores decorated with polar functionalities has been strategically constructed displaying remarkable chemical robustness in water for 7 days, across wide pH range (pH=2-12), and in open air for 30 days. Interestingly, IITKGP-27 selectively adsorb C2 hydrocarbons (C2H2, C2H4 and C2H6) and CO2 over CH4, attributed to the synergistic effect of favorable host-guest interactions due to the presence of accessible surface functionalities and optimal pore apertures. Moreover, an excellent trade-off between high sorption capacities and moderate separation selectivities were achieved. Transient breakthrough simulations further validated it's feasibility toward unexplored CH4 purification from a blend of all such five gases, demonstrating its viability for this critical application. In addition, the bulk scalability, ease of regeneration, excellent recyclability and outstanding structural stability highlight its potential as a robust solution for efficient CH₄ purification from natural gas streams.