Methane is a powerful greenhouse gas. The gas that is released from coal seams during mining has a high methane content, with molecular nitrogen making up most of the remainder. The selective capture of methane over nitrogen would, thus, be useful to reduce emissions from coal mining.

Tom K. Woo, University of Ottawa, Canada, Datong Song, University of Toronto, Canada, and colleagues have developed a highly porous, nickel-based metal–organic framework (MOF) that is promising for coal mine methane capture. The team synthesized the MOF via a hydrothermal reaction of nickel acetate with 1,1′-methylenebis(3,5-dimethyl-1H-pyrazole-4-carboxylic acid as a ligand.

The team performed gas sorption experiments and found that the ratio of adsorbed CH₄ to N₂ is 7.0. This selectivity is comparable to the best-performing previously known MOF for this application. The working capacity of the developed nickel-based MOF, however, is almost twice as high.

• 3D Porous Metal–Organic Framework for Selective Adsorption of Methane over Dinitrogen under Ambient Pressure,
  Charlie Eric William Kivi, Benjamin Sidney Gelfand, Hana Dureckova, Ha T. K. Ho, Cindy Ma, George K H Shimizu, Tom Woo, Datong Song,
  Chem. Commun. 2018.
  https://doi.org/10.1039/c8cc07756h