(28a) Adsorption Of Light Gases In Large-Pore Isoreticular Metal Organic Frameworks

Metal-organic frameworks (MOFs) have emerged as promising materials for separations, gas storage, catalysis, and chemical sensing. One class of widely-studied MOFs are the isoreticular metal-organic frameworks (IRMOFs), discovered by Yaghi and co-workers. Although there have been many studies of IRMOFs, most of the studies to date concentrated on the IRMOFs -1, -6, and -8. Therefore, little is known about the separation and storage characteristics of the other IRMOFs. Especially, to our knowledge, there are few experimental studies on IRMOFs -10, -12, -14, and -16, which are the non-interpenetrating counterparts of IRMOFs -9, -11, -13, and -15, respectively. This may be due to the difficulties in synthesizing these materials and the instabilities of such large-pore MOF structures. Moreover, it can be quite difficult to effectively remove all of the solvent molecules (used in the synthesis procedure) from the pores.

In this study, several large-pore IRMOFs were synthesized by the solvothermal method developed by Yaghi et al. Two solvent removal procedures were compared: the original method involving chloroform exchange suggested by Yaghi and a new procedure developed in our labs. We investigated the adsorption properties of light gases such as H2 and CO2 on IRMOFs from both procedures at cryogenic and room temperatures. In addition, grand canonical Monte Carlo (GCMC) simulations of light gases, with and without co-adsorbed solvent molecules, were used to help understand and interpret the experimental results.