Adsorption selectivity of CO2 over CH4, N2 and H2 in melamine–resorcinol–formaldehyde xerogels

Abstract

Sorptive selectivity of melamine-resorcinol-formaldehyde xerogels, towards CO 2 , CH 4 , 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 (CO 2-N 2), sour gas sweetening (CO 2-CH 4), and separation of species in the water-gas shift reaction (CO 2-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 CH 4 , 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 CO 2-CH 4 , 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.

Fine-Tuning Window Apertures in ZIF-8/67 Frameworks by Metal Ions and Temperature for High-Efficiency Molecular Sieving of Xylenes

“…This property of MOFs ZIF-8/67 was studied via GC analysis of the adsorbate (Figure S6a). Sorption selectivity ( S AB ) of components A to B was determined as where x A is the molar fraction of A in the adsorbed adsorbate, and y A is the molar fraction of A in liquid adsorbate (similarly for x B and y B ). As pore filling rates depend on temperature (Figure ), it is reasonable to investigate the corresponding selectivity vs temperature (Figure ).…”

“…This property of MOFs ZIF-8/67 was studied via GC analysis of the adsorbate (Figure S6a). Sorption selectivity (S AB ) of components A to B was determined as 45…”

Cost‐Effective Adsorption of Oxidative Coupling‐Derived Ethylene Using a Molecular Sieve

“…Subsequently, focusing on the adsorption of C 2 H 4 (i.e., gas mixture of C 2 H 4 /N 2 at 40 °C and WHSV = 9000 mL g -1 h -1 ), equilibrium studies were performed by employing four different adsorption isotherm models, namely, the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (DR) models, which are usually applied for low-temperature adsorption processes. We analyzed pure component isotherms as they can generally be measured more accurately than those obtained from mixtures, owing to issues relating to determining the composite make-up of the adsorbed phase from a multicomponent mixture [24].…”

Metal–organic frameworks for carbon dioxide capture

“…where q i and q j represent the quantity of adsorbent components, p i and p j represent their relative partial pressure, and S being derived from single-component adsorption isotherm; therefore, it does not take into consideration the competition of gas molecules for the adsorption sites on the pore surface. 38 Nevertheless, it is the best method to compare the CO 2 selectivity performance of post-combustion CCS materials. Henry's law selectivity is an alternative method to determine adsorption for wider micropores and possibly narrow mesopores (approximately <2.5 nm).…”