Rational Tuning of Water Vapor and CO2 Adsorption in Highly Stable Zr-Based MOFs

摘要

We report the synthesis of a novel and highly robust monomethyl-functionalized Zr-based MOF (UiO-66-MM) by presynthesis functionalization of the BDC ligand. UiO-66-MM is isostructural to UiO-66 and is characterized by PXRD, FTIR, N2 adsorption, NMR, and TGA Grand canonical Monte Carlo (GCMC) simulations are performed to confirm the increase in adsorbate—adsorbent interactions for CO2 and CH4 observed during the experimental measurements. This enhancement is due to the presence of the methyl group in UiO-66-MM, which increases the adsorption potential by constricting the pore diameter. However, UiO-66-MM is less hydrophilic than the parent UiO-66 due to the nonpolar methyl groups and adsorbs almost 30% less water than UiO-66. This new MOF also has a much higher CO2/CH4 selectivity under dry conditions due to enhanced van der Waals interactions with CO2. Hence, we expect UiO-66-MM to exhibit superior performance over the parent MOF in humid gas separations.