Insight into the mechanism of CO2 adsorption on Cu-BTC and its composites with graphite oxide or aminated graphite oxide

CO2 adsorption on Cu-BTC and its composites with graphite oxide or aminated graphite oxide was evaluated at 273 K and 295 K under the pressure up to similar to 0.1 MPa. The samples before and after CO2 adsorption were characterized using X-ray diffraction, FT-IR spectroscopy and thermal analysis. The isosteric heats of adsorption were calculated from the experimental adsorption isotherms. The results indicate that CO2 is physically adsorbed on Cu-BTC and its composites with graphite oxide or aminated graphite oxide. The primary adsorption sites are open copper centers and cage window sites. The composite of Cu-BTC and modified graphite oxide with the highest degree of structural and chemical heterogeneity (MOE/GO-U3) shows the highest CO2 capacity (8.45 mmol/g at 273 K and 4.78 mmol/g at 295 K) and excellent regenerability with a relatively low and constant over a broad range of surface coverage isosteric heat of adsorption (average value similar to 24.8 kJ/mol). (C) 2013 Elsevier B.V. All rights reserved.