Separation of CO2 from CH4 Using Mixed-Ligand Metal−Organic Frameworks

• Published in: Langmuir Vol. 24; no. 16; pp. 8592 - 8598
• Main Authors: Bae, Youn-Sang, Mulfort, Karen L, Frost, Houston, Ryan, Patrick, Punnathanam, Sudeep, Broadbelt, Linda J, Hupp, Joseph T, Snurr, Randall Q
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19.08.2008
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Interfaces: Adsorption, Reactions, Films, Forces; Surface physical chemistry; Methane; Monte Carlo method; Separation; Hydrocarbon; Theory; Microwave; Selectivity; Nitrogen; Microwave heating; Condensed benzenic compound; X ray diffraction; Powder; Naphthalene; Adsorption; Simulation; Bicyclic compound; Isotherm
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la800555x

The adsorption of CO2 and CH4 in a mixed-ligand metal−organic framework (MOF) Zn2(NDC)2(DPNI) [NDC = 2,6-naphthalenedicarboxylate, DPNI = N,N′-di-(4-pyridyl)-1,4,5,8-naphthalene tetracarboxydiimide] was investigated using volumetric adsorption measurements and grand canonical Monte Carlo (GCMC) simulations. The MOF was synthesized by two routes: first at 80 °C for two days with conventional heating, and second at 120 °C for 1 h using microwave heating. The two as-synthesized samples exhibit very similar powder X-ray diffraction patterns, but the evacuated samples show differences in nitrogen uptake. From the single-component CO2 and CH4 isotherms, mixture adsorption was predicted using the ideal adsorbed solution theory (IAST). The microwave sample shows a selectivity of ∼30 for CO2 over CH4, which is among the highest selectivities reported for this separation. The applicability of IAST to this system was demonstrated by performing GCMC simulations for both single-component and mixture adsorption.