• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1027-1034
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• 2007

This research was focused on the selective separation of $CO_2$ or $CH_4$ from mixture of these gases, by controlling the size of pore or pore gate. Pitch based activated carbon fibers(ACF) were used as adsorbents. The size of pore gate was controlled by the molecule having similar size to that of pore opening. After the adsorption of adsorbate on pore surface, planar molecules such as benzene and naphthalene covered the pore gate. The slow release of adsorbate from the pores covered by planar molecules makes apertures between planar molecules covering pore gate and this structure can be fixed by rapid pyrolysis. The control of pore gate using benzene as covering molecules could not accomplished due to the simultaneous volatilization of benzene and adsorbate$(CO_2)$ caused by similar temperatures of benzene volatilization and adsorbate desorption. Therefore we replaced benzene with naphthalene looking for the stability at a $CO_2$ desorption temperature. The naphthalene molecule was adsorbed on the ACF up to 15% of ACF weight and showed no desorption until $100^{\circ}C$, indicating that the molecule could be used as a good cover molecule. Naphthalene could cover almost all the pore gate, reducing BET surface area from 753 $m^2/g$ to 0.7 $m^2/g$. A mixed gas$(CO_2:CH_4=50:50)$ was adsorbed on the naphthalene treated OG-7A ACF. The amount of $CO_2$ adsorption increased with total pressure, whileas thai of $CH_4$ was not so much influenced on the pressure, indicating that $CO_2$ made more compounds on the ACF surface along with total pressure increase. The most $CO_2$ and the least $CH_4$ were adsorbed in the condition of 0.4 atm, resulting in the highly pure $CH_4$ left in ACF.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.615-618
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• 1998

The zeolite crystals were synthesized by hydrogel process into the pore of activated carbon. The effect of activated carbon in the course of the crystallization of zeolite was investigated. The phenomena of impregnation of zeolite crystals into the pore of the activated carbon were also examined. The results show that in case of the addition of 5% of activated carbon to the aluminosilicate gel including the mole composition of zeolite A, zeolite A was purely synthesized without the existence of other type of zeolite. However, in case of the addition of 20% of activated carbon, zeolite X was purely synthesized. In the pore mouth and internal of activated carbon, zeolite crystals having the size under $1{\mu}m$ was observed. From the results of the pore size and particle size distributions, it was confirmed that the synthetic sample was the composite material impregnated by the zeolite crystals into the pore of activated carbon, not the simple mixture of zeolite and activated carbon.