Efficient Methane Purification Using a Robust and Recoverable Hydrogen-Bonded Organic Framework

Abstract

Efficient separation and purification of methane is a key step in promoting its wide application as an environmentally friendly energy carrier and an important chemical raw material. Development of single solid adsorbents simultaneously combining robust structure, high separation capacity, and easy performance recovery is highly desired but quite a challenge for realizing methane depuration. In the present study, we report an ultramicroporous hydrogen-bonded organic framework compound constructed from a tetracyano bithiophene-functionalized ligand. Similar to the acting principle of enzymes, multisite supramolecular interactions endow the material with not only extraordinary chemical stability in wide pH range including 12 M HCl and 20 M NaOH solutions but also highly selective recognition of acetylene and carbon dioxide over methane. The packing densities and adsorption selectivities toward acetylene and carbon dioxide are the highest reported for the hydrogen-bonded organic framework materials. Dynamic breakthrough experiments demonstrate its highly efficient methane purification ability from binary and even ternary mixed gases, with not only methane productivities up to 2.34 mol kg-1 but also moderate regeneration energy. Furthermore, the title compound can be easily regenerated in almost quantitative yield via simple rato-evaporation of its dichloromethane solution once its activity is attenuated or lost.