The effect of activation temperature on structure and properties of blue coke-based activated carbon by CO2 activation

Abstract

Blue coke-based activated carbon (BAC) was prepared via CO2 activation with disused blue coke powder as raw materials at high temperature. The factor of activation temperature was intensively studied. The properties of sample were characterized by N2 adsorption-desorption techniques, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR), and the activation mechanism was also proposed. The results showed that, with the increase of temperature, the yield of BAC decreased, while the iodine adsorption increased first and then decreased. The N2 adsorption-desorption isotherms revealed that the BAC had both micropores and mesopores, and the optimal temperature of porosity development was at 900-1000°C. When the activation temperature reached 1000°C, the maximum Brunauer-Emmett-Teller (BET) specific surface area and pore volume of BAC were 636.91 m2·g-1 and 0.3627 cm3·g-1, respectively. The FTIR results indicated that BAC surface contained large amounts of surface functional groups such as hydroxyl, ester, carboxyl, and so on. The content of them decreased with the increase of temperature. Mechanism analysis shows that radial hole-making function happen first then transverd hole-enlarging function as the temperature increases, for the formation of large amount of microporous, the radial activation was the main controlling process.