The effect of pore and surface characteristics of activated carbon produced by coal through N_2 and H_2O vapor/H_3PO_4 activation on a single step for CH_4 adsorption in the low pressure

摘要

In this study, activated carbons (AC) were produced by the activation of H3PO4 (with and without sonication) under N-2 and N-2+ H2O vapor at various temperatures (700-900 degrees C). These ACs have been investigated for the effect of surface and pore property on methane adsorption at low pressure (1 atm) and 298 K. The textural, surface and porosity properties of activated carbons were determined by N-2 (77 K), CO2 (273 K), and SEM-EDAX, XRD. The CH4 adsorption-desorption behavior at 298 K under low pressure was calculated using the volumetric method. According to the results obtained from N-2 adsorption at 77 K, it was determined that the increase of temperature, N-2+ H2O vapor and sonication increased BET surface area and pore volume of the ACs. The highest BET surface area and total pore volume were found in the H900N(2)+ H2O-S sample as 1881 m(2)/g and 1.12 cm(3)/g, respectively. It has been shown that narrow micropores (10 angstrom) and surface oxygen groups are effective in increasing the CH4 adsorption capacity at 298 K at low pressures. Although ACs produced by N-2+ H2O vapor have similar micropore volume to ACs generated by N-2 activation, ACs produced with N-2+ H2O vapor are found to have higher CH4 adsorption due to the lower oxygen content. The highest CH4 adsorption capacity at 298 K was found at H800N(2)+ H2O sample and it is 19.45 cm(3)/g.