Comparison of Activated Carbons Produced from Zonguldak Kozlu and Zonguldak Karadon Hard Coals for Hydrogen Sorption

A series of activated carbons prepared using hard coals from two different mines, Kozlu and Karadon in Zonguldak, with heat treatment and chemical activation (KOH, NaOH, ZnCl,2 and H3PO4) were evaluated for their hydrogen sorption performances at −196°C. The analysis of the porous structure of the resulting activated carbons was accomplished through the use of the BET, Langmuir, DFT, and t-plot methods utilizing the nitrogen adsorption-desorption data (−196°C). The analysis results have shown that the carbons, according to the type of the applied chemical activation could be ranked in the order H3PO4 < ZnCl2 < NaOH < KOH in terms of their yielded surface area and total pore volume. Heat treatment only without any chemical treatment yielded the smallest pore volume and surface area, on the other hand, highly microporous structure containing microporores in between 74.84% and 97.78% occured by chemical activation. The effects of pore volume and surface area on hydrogen sorption were examined. The highest hydrogen sorption capacity attained was 5.43 wt% and 5.21 wt% for the samples obtained from Zonguldak Karadon hard coal with KOH treatment at 700°C, and with ZnCl2 activation at 400°C, respectively.