Adsorption of CO, CH4 and CO2 On HKUST-1 and MIL-101 Metal Organic Frameworks

In this work we will present a comparative adsorption study of three different gases viz. CO, CH4 and CO2 on two different adsorbents viz. Cu-BTC (or HKUST-1) and Cr-BDC (or MIL-101). These three gases were chosen as probes due to their different electrostatic characteristics. Gravimetric adsorption measurements of the samples were carried out in a magnetic suspension balance (Rubotherm) at three widely different temperatures: 295, 318 and 353 K and pressures ranging between upto 100 bar. For all gases the enthalpy of adsorption at low loading was higher on MIL-101 than that on Cu-BTC. The Henry constant value for CH4 was more on HKUST-1 than on MIL-101; whereas for CO this trend was opposite. It will be shown interesting trends in behavior of adsorption isotherms at both low and high pressure regions can be well described by accounting for polarity of the gases and the number of accessible unsaturated open metal centers in the framework.