Adsorption of CH4 and CO2 on Cu-BDC Metal-Organic Frameworks Synthesized Using Different Solvent Separation Routes

Abstract

Energy storage is one of the major challenges during the last decades. Natural gas adsorption on porous materials has notable advantages in comparison with the other approaches. Due to the lack of adsorption information about Cu-BDC (copper terephthalate), it was synthesized by two different solvent separation procedures and identified using X-ray diffraction (XRD), Brunauer-Emmet-Telller (BET) and thermogravimetric analysis (TGA) techniques. Moreover, equilibrium adsorption measurements were performed for CH4 and CO2 gases in the pressure range 0-50 bar at two various temperatures (293 and 323 K), and experimental adsorption data were modeled with adsorption isotherms. Also, the sample synthesized by the new solvent separation procedure had 918 m2/gr surface area and 0.42 cm3/gr pore volume which were respectively 45% and 50% higher than the traditional method. In addition, this sample has shown CO2 and CH4 adsorption capacity (16.72 and 13.23 mmol gr-1) were desirable in comparison with other conventional Metal-Organic Frameworks (MOFs) and its methane adsorption value was close to DOE (Department of Energy) targets. To investigate the application of the synthesized materials, the selectivity of CO2/CH4 was determined by IAST (ideal adsorbed solution theory) according to the sorption test information of the single components. Finally, adsorption enthalpy of the adsorbates on the two samples was computed using the Clausius-Clapeyron equation and the results were in accordance with the isotherms at two various temperatures (293 and 323 K).

Keywords

• metal-organic frameworks (mof)
• adsorbed natural gas (ang)
• methane
• carbon dioxide
• adsorption