Adsorption selectivity of CO2over CH4, N2and H2in melamine-resorcinol-formaldehyde xerogels

Sorptive selectivity of melamine-resorcinol-formaldehyde xerogels, towards CO2, CH4, N(2)and H-2, is reported, where all systems demonstrate potential for selective adsorption of CO(2)from corresponding binary gas mixtures. Selected gas mixtures represent important gas separation applications found in industry, i.e. CO(2)removal from power plant flue gases (CO2-N-2), sour gas sweetening (CO2-CH4), and separation of species in the water-gas shift reaction (CO2-H-2). All materials tested exhibit microporous character, enhancing adsorption of small molecules, however, it is the inclusion of a nitrogen-rich material into the gel matrix that results in enhanced selectivities for these systems. Despite the porous character of the gels, under the test conditions used to simulate industrial parameters, all three balance gases, i.e. H-2, N(2)and CH4, showed low affinities for the xerogels, while CO(2)adsorption was notably higher and increased with the inclusion and increased concentration of melamine. Ideal adsorbed solution theory was used to demonstrate significant differences in adsorption uptake, especially for CO2-CH4, and high selectivities for CO(2)over N-2. In all cases, selected xerogels exhibited industrially relevant adsorption timescales for CO(2)over competitor gases, demonstrating the potential of these materials for the selective adsorption of CO(2)from process streams.