2, University of California, Berkeley, Berkeley, California, United States
3, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Owing to their high surface areas, tunable pore dimensions, and adjustable surface functionality, metal-organic frameworks (MOFs) can offer advantages for a variety of gas storage and gas separation applications. In an effort to reduce the major energy requirements for the separation of mixtures of light hydrocarbons via cryogenic distillation, we are developing new MOFs with a high capacity for the selective adsorption of unsaturated hydrocarbons at higher temperatures. In particular, the compounds M2(dobdc) (M = Mg, Mn, Fe, Co, Ni; dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate) and M2(m-dobdc) (m-dobdc4– = 4,6-dioxido-1,3-benzenedicarboxylate), featuring open M2+ cation sites, have been evaluated for their performance in the separation of mixtures of C1-C3 hydrocarbons at 45 °C. The results indicate that these materials have significant potential for applications in adsorption-based processes for natural gas purification and olefin/paraffin separations. In addition, it will be shown that certain structural features within MOFs can enable the fractionation of hexane isomers according to the degree of branching and the separation of xylene isomers.