Abstract
Production of biomethane from raw biogas requires the removal of impurities, such as CO(2) and H(2)S. To accommodate the variety of biogas sources, a modular separation design with a small footprint is desired. In this work, we report three diamine-impregnated metal-organic frameworks (MOFs), MIL-101(Cr) (diamines: diethylethylenediamine, ee-2; 2,2-dimethyl-1,3-propanediamine, dmpn; N-methylethylenediamine, m-2) for simultaneous removal of H(2)S and CO(2) from simulated binary and ternary biogas mixtures. The H(2)S and CO(2) separation performance and regeneration conditions were investigated by dynamic column breakthrough and temperature-programmed desorption experiments. While all three diamine-impregnated MIL-101(Cr) samples were H(2)S-selective over CO(2) in the mixture compositions studied, MIL-101(Cr)-ee-2 displayed the highest H(2)S/CO(2) adsorption selectivity of ∼7. Also, it showed distinct desorption temperatures for H(2)S and CO(2) that allows for concentrated H(2)S collection during adsorbent regeneration, which can potentially simplify the biogas separation process to achieve concentrated biomethane and H(2)S collection using the same adsorption module.