Boosting C<sub>3</sub>H<sub>8</sub>/C<sub>2</sub>H<sub>6</sub>/CH<sub>4</sub> Separation Performance by an Aluminum-Based Nanoporous Metal–Organic Framework with Densely Hydroxyl-Functionalized Surface
Shuyu Zeng, Guanyu Chen, Junlin Huang, Fang Lai, Mei Yang, Hongbing Ji, Kungang Chai
Abstract
The development of nanoporous metal–organic frameworks (MOFs) capable of effectively separating and purifying CH 4 is of significant importance. High surface polarity and suitable pore diameter are two key factors that can synergistically enhance separation performance. Herein, we report two hydroxyl-functionalized Al-MOFs (CAU-1-OH and CAU-1-(OH) 2 ) for the separation and purification of natural gas. They both possess two different types of nanocages as well as a densely hydroxyl-functionalized surface. Significantly, CAU-1-(OH) 2 demonstrated exceptional selectivity in separating C 3 H 8 /CH 4 (50:50, v/v) and C 2 H 6 /CH 4 (50:50, v/v), with selectivity values of 990 and 36, respectively, surpassing those of most reported porous materials. The dynamic breakthrough experiment of the ternary mixture can generate pure CH 4 exceeding 3.46 mmol g –1, which adequately demonstrates the actual CH 4 purification performance of CAU-1-(OH) 2 . Finally, molecular simulations and in situ infrared experiments verified that the high surface polarity and suitable pore diameter synergistically enhance the affinity of the frameworks toward C 3 H 8 and C 2 H 6, giving rise to the high loading capacity and selectivity for C 3 H 8 and C 2 H 6 . These results support the significant potential of the double hydroxyl-modified nanomaterial CAU-1-(OH) 2 for purifying methane from natural gas.