CO, CO2 and CH4 Gas Adsorption (Pure and Binary) on Cu-BTC and MIL-101 Metal Organic Frameworks (MOFs)

In this research article, we present a comparative study on gas adsorption of CO, CO2 and CH4 on two of the most versatile MOFs reported till date: Cu-BTC (or, HKUST-1) and MIL-101 (or, Cr-BDC). The high pressure (0-100 bar) pure gas adsorption studies were carried out gravimetrically (Rubotherm, Magnetic Suspension Balance) at varying temperatures. Virial-Langmuir and Dual Site Langmuir models were found to suitable in explaining the experimental isotherm data on Cu-BTC and MIL-101 respectively. Isotherm studies showed that the electrical properties of the probe molecules (viz. dipole moment, quadrupole moment, polarizability etc.) as well as the nature of the adsorbent surfaces influencing the adsorption. The isotherm curves of all three probe molecules showed an interesting cross-over feature, independent of temperature. Finally, any realistic process development requires estimation / prediction of mixed gas adsorption. Here, we report a binary prediction for CO2+CH4 mixture using ideal adsorption solution theory (or, LAST) on Cu-BTC.