Exclusive Recognition of CO 2 from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities.

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.