Adsorption and diffusion of CO2 and CH4 on Cu-BTC powder

Adsorption equilibrium and diffusion of CO2 and CH4 on Cu-BTC powder were experimentally studied by gravimetric method and ZLC technique respectively, at 308, 343, and 373 K and pressures up to 7 bar. It was found that Cu-BTC powder has CO2 and CH4 adsorption capacities of 3.7 mol/kg and 0.79 mol/ kg respectively, at 308 K and 1 bar. Also, Langmuir adsorption isotherm equation can fit well CO2 and CH4 adsorption isotherms on Cu-BTC powder, with isosteric heat of adsorption at about 22.8 and 14.9 kJ/mol, respectively. The adsorption kinetic measurements showed that diffusion coefficient of CO2 and CH4 in the Cu-BTC powder is in the range of 0.5-0.8*10-8 and 1.1-1.8*10-8 cm2/s and in 308-373 K with activation energy of 18 and 6.6 kJ/mol, respectively. CH4 showed relatively faster adsorption kinetics than CH4. From these results it can be concluded that Cu-BTC has good adsorption properties as an adsorbent for separation of CO2 from natural gas.

Keywords:

Adsorption equilibrium , Cu-BTC powder , diffusion , CO2 , CH4