Selective CO₂ Sorption

A metal-organic framework (MOF) compound composed of aminotriazole-based ligands selectively adsorbs carbon dioxide from gas mixtures at low CO₂ partial pressures, according to a study in Chemical Communications (DOI: 10.1039/b911481e). Exceptionally high CO₂ uptake has been reported previously for other MOFs, but those studies were conducted at high CO₂ pressures (tens of bars). The new study, which addresses CO₂ uptake at pressures of up to approximately 1 bar, may lead to strategies for making sorbents for gas purification. University of Calgary chemists Ramanathan Vaidhyanathan, George K. H. Shimizu, and coworkers designed MOFs with amine-lined pores to exploit that functional group’s strong affinity for CO₂. By reacting zinc carbonate, oxalic acid, and an aminotriazole under mild conditions, the team formed a porous crystalline material composed of zinc-dimer-aminotriazolate layers that are supported by oxalate pillars. The group reports that CO₂ adsorption and desorption cycles were repeated eight times at low pressures with complete reversibility. They add that the material does not exhibit appreciable uptake of nitrogen, argon, and hydrogen under similar conditions.