Exclusive Recognition of CO2 from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities

Zhang, Z.; Deng, Z.; Evans, H. A.; Mullangi, D.; Kang, C.; Peh, S. B.; Wang, Y.; Brown, C. M.; Wang, J.; Canepa, P.; Cheetham, A.; Zhao, D.

doi:10.1021/jacs.3c01705

Exclusive Recognition of CO₂ from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities

Z. Zhang, Z. Deng, H. A. Evans, D. Mullangi, C. Kang, S. B. Peh, Y. Wang, C. M. Brown, J. Wang, P. Canepa, A. Cheetham, and D. Zhao; J. Am. Chem. Soc. 145, 11643 (2023).

BibTeX

@article{Zhang2023exclusive,
  author  = {Zhang, Z. and Deng, Z. and Evans, H. A. and Mullangi, D. and Kang, C. and Peh, S. B. and Wang, Y. and Brown, C. M. and Wang, J. and Canepa, P. and Cheetham, A. and Zhao, D.},
  title   = {{Exclusive Recognition of CO$_{2}$ from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities}},
  journal = {Journal of the American Chemical Society},
  volume  = {145},
  pages   = {11643},
  year    = {2023},
  doi     = {10.1021/jacs.3c01705}
}

Brief summary

Removing CO₂ from hydrocarbons such as acetylene and methane is hard because the molecules are so alike. Aluminium formate captures CO₂ exclusively, with record selectivity: its small, hydrogen-lined cavities bind CO₂ through hydrogen bonds and reject every hydrocarbon, as spectroscopy, diffraction and simulations show.

Full abstract

Exclusive capture of carbon dioxide (CO₂) from hydrocarbons via adsorptive separation is an important technology in the petrochemical industry, especially for acetylene (C₂H₂) production. However, the physicochemical similarities between CO₂ and C₂H₂ hamper the development of CO₂-preferential sorbents, and CO₂ is mainly discerned via C recognition with low efficiency. Here, we report that the ultramicroporous material Al(HCOO)₃, ALF, can exclusively capture CO₂ from hydrocarbon mixtures, including those containing C₂H₂ and CH₄. ALF shows a remarkable CO₂ capacity of 86.2 cm³ g⁻¹ and record-high CO₂/C₂H₂ and CO₂/CH₄ uptake ratios. The inverse CO₂/C₂H₂ separation and exclusive CO₂ 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 CO₂ 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.