A Distinct Microporous Metal–Organic Framework with Multiple Accessible Adsorption Sites for Separation of C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub>/CH<sub>4</sub> Mixtures
Xiaoxia Zhang, Shui-Sheng Chen, Meng-Yu Huo, Ziyou Zhang, Lei Hou, Chao Li
Abstract
Acetylene (C 2 H 2 ), as a crucial chemical feedstock, and its purification from multicomponent light hydrocarbon mixtures is industrially challenging. Herein, we used the 3-methyl-4-(4 H -1,2,4-triazol-4-yl) benzoic acid (HL) ligand and CoSO 4 ·7H 2 O to assemble a novel metal–organic framework (MOF), [Co 3 (L) 2 (OH) 2 (SO 4 ) (H 2 O)]·DMA·4H 2 O ( 1 ), with porous channels decorated with accessible active sites including an open metal center, an uncoordinated carboxylate group, functional methyl groups, and sulfate anions. The adsorption capacities are 64.1, 30.3, and 9.4 cm 3 g –1 for C 2 H 2, CO 2, and CH 4, respectively, with an excellent adsorption selectivity of C 2 H 2 /CH 4 (56.2), C 2 H 2 /CO 2 (5.6), and CO 2 /CH 4 (6.7). During the breakthrough time intervals (Δτ) of 12.4, 3.5, and 3.3 min g –1 for the equimolar C 2 H 2 /CH 4, CO 2 /CH 4, and ternary C 2 H 2 /CO 2 /CH 4 mixtures, the productivities of 50.8, 10.4, and 8.2 L kg –1, respectively, for high purity of CH 4 (≥99.9%) can be obtained. Particularly, 10.3 L kg –1 of C 2 H 2 (>99%) was recovered by a regenerated test for the equimolar ternary C 2 H 2 /CO 2 /CH 4 mixture. Moreover, the grand canonical Monte Carlo (GCMC) simulations revealed that the selective separation of C 2 H 2, CO 2, and CH 4 mixtures is attributed to the synergistic effect from multiple accessible adsorption sites.