In Silico Generation of Chromium-Based MOFs with Abundant Active Sites for N2/CH4 Separation

Abstract

Selective nitrogen capture from natural gas using the adsorption properties of porous materials is promising due to its environmental benefits. However, N-2 removal from N-2/CH4 mixtures has been quite challenging because of their similar physical properties. Targeting the Cr-trimer-based cluster with an open metal site, known for selective nitrogen capture through the pi-back-bonding mechanism, we screened nearly one hundred thousand chromium trimer-based metal-organic frameworks (MOFs), both experimentally synthesized and computationally constructed. Using criteria such as Cr-density, polymorphism, resistance to activation, and separation performance, we identified a promising in silico MOF. This hypothetical MOF showed a simulated nitrogen uptake of 2.13 mmol/g and a selectivity of 10.2 at 1 bar, surpassing the performance of the previously known best-performing MOF, Cr-MIL-100.