Competitive I₂ Sorption by Cu-BTC from Humid Gas Streams

Abstract

Competitive sorption of molecular iodine gas from a mixed stream containing iodine and water vapor is identified and characterized for the hydrophilic Cu-BTC metal–organic framework. By combining simulation (Grand Canonical Monte Carlo and molecular dynamics simulations) with crystallography (high-energy synchrotron-based powder X-ray diffraction data and pair distribution function analyses), we show that I2 substantially adsorbs, in preference to water vapor, into two principal areas. First, it adsorbs in the smallest cage close to the copper paddle wheel. Second, it adsorbs within the main pore with close interactions with the benzene tricarboxylate organic linker. Analysis suggests that I2 forms an effective hydrophobic barrier to minimize water sorption. The finding is relevant to mixed gas streams in nuclear energy industrial processes and accident remediation. This also represents the highest reported I2 sorption by a metal–organic framework (175 wt % I2 or 3 I/Cu).

Water Stability and Adsorption in Metal–Organic Frameworks

“…150 Interestingly, Nenoff et al found that HKUST-1 also possesses properties that are relevant to nuclear energy industrial processes. 156 Despite the hydrophilic nature of the structure the authors found molecular iodine, a long-lifetime product that is released during the processing of spent nuclear fuel, is preferentially adsorbed over water in HKUST-1 under 1:1 I 2 :H 2 O conditions. This behavior was attributed to the formation of hydrophobic I 2 barriers in the structure which reduce water's ability to adsorb into the pores.…”

Recent advances in the application of total scattering methods to functional materials

“…the host-guest correlations. Furthermore, the intensity of the PDF peaks is correlated to the relative abundance of a given atom-atom pair: thus the intensity of the peaks due to Cu-O and I-I bonds (at about 2 and 2.7 Å, respectively) provides an estimation of the Cu/I ratio which is monitored during the room temperature isotherm for iodine sorption, as reported in Figure 11 43 .…”

Thermally Robust 3-D Co-DpyDtolP-MOF with Hexagonally Oriented Micropores: Formation of Polyiodine Chains in a MOF Single Crystal

“…[102][103][104][105][106][107][108] Interestingly, when the robust solvent-free framework I was immersed into a solution of iodine in cyclohexane, its hexagonally-arranged channels allowed iodine to form very intriguing polyiodine chains. The iodine-captured framework of I, I_I 2 , was structurally characterized by X-ray crystallography ( Table 1).…”