Capture and Separation of SO Traces in Metal-Organic Frameworks via Pre-Synthetic Pore Environment Tailoring by Methyl Groups.

Herein, we report a pre-synthetic pore environment design strategy to achieve stable methyl-functionalized metal-organic frameworks (MOFs) for preferential SO binding and thus enhanced low (partial) pressure SO adsorption and SO /CO separation. The enhanced sorption performance is for the first time attributed to an optimal pore size by increasing methyl group densities at the benzenedicarboxylate linker in [Ni (BDC-X) DABCO] (BDC-X=mono-, di-, and tetramethyl-1,4-benzenedicarboxylate/terephthalate; DABCO=1,4-diazabicyclo[2,2,2]octane). Monte Carlo simulations and first-principles density functional theory (DFT) calculations demonstrate the key role of methyl groups within the pore surface on the preferential SO affinity over the parent MOF. The SO separation potential by methyl-functionalized MOFs has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, simulated and experimental breakthrough curves, and DFT calculations.