Exclusive Recognition of CO<sub>2</sub> from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities
Zhaoqiang Zhang, Zeyu Deng, Hayden A. Evans, Dinesh Mullangi, Chengjun Kang, Shing Bo Peh, Yuxiang Wang, Craig M. Brown, John Wang, Pieremanuele Canepa, Anthony K. Cheetham, Dan Zhao
Abstract
Exclusive capture of carbon dioxide (CO 2 ) from hydrocarbons via adsorptive separation is an important technology in the petrochemical industry, especially for acetylene (C 2 H 2 ) production. However, the physicochemical similarities between CO 2 and C 2 H 2 hamper the development of CO 2 -preferential sorbents, and CO 2 is mainly discerned via C recognition with low efficiency. Here, we report that the ultramicroporous material Al(HCOO) 3, ALF, can exclusively capture CO 2 from hydrocarbon mixtures, including those containing C 2 H 2 and CH 4 . ALF shows a remarkable CO 2 capacity of 86.2 cm 3 g –1 and record-high CO 2 /C 2 H 2 and CO 2 /CH 4 uptake ratios. The inverse CO 2 /C 2 H 2 separation and exclusive CO 2 capture performance from hydrocarbons are validated via adsorption isotherms and dynamic breakthrough experiments. Notably, the hydrogen-confined pore cavities with appropriate dimensional size provide an ideal pore chemistry to specifically match CO 2 via a hydrogen bonding mechanism, with all hydrocarbons rejected. This molecular recognition mechanism is unveiled by in situ Fourier-transform infrared spectroscopy, X-ray diffraction studies, and molecular simulations.