Kinetic Separation of Butane Isomers Using a Formate Metal-Organic Framework.

n-butane (n-C4H10) and isobutane (i-C4H10) are important raw materials in chemical industry. The separation of the two hydrocarbon isomers via distillation is challenging and energy-consuming. Herein we report the adsorption behavior of a microporous cobalt formate framework [Co3(HCOO)6] for potential kinetic separation of butane isomers. Under ambient condition, [Co3(HCOO)6] shows near adsorption capacity for n-C4H10 (1.77 mmol g-1) and i-C4H10 (1.36 mmol g-1) with different adsorption kinetics. Study on the adsorption kinetic for butane indicates that the smaller isomer is adsorbed at a higher diffusion rate, resulting in a high kinetic selectivity of 193 for n-C4H10/i-C4H10 separation. Analyses of adsorption kinetics and breakthrough experiment have validated the separation potential of [Co3(HCOO)6] for butane purification.