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

ABSTRACT

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.

KEYWORDS:

• Hard coal
• activation
• heat treatment
• activated carbon
• hydrogen
• adsorption

Acknowledgments

The authors are indebted to Professor Gülşen DOĞU (Gazi University) and Professor Timur DOĞU (Middle East Technical University) Ankara/Turkey for their helpful contributions through the study. Financial supports from Zonguldak Bülent Ecevit University (BEUN Scientific Research Project 2008-13-02-02) and DPT (DPT2003K121110) (Turkey) are highly acknowledged.

Additional information

Funding

This work was supported by the State Planning Organization, Turkey [DPT2003K121110]; Zonguldak Bülent Ecevit University [BEUN Scientific Research Project 2008-13-02-02].

Notes on contributors

Fatma Oguz Erdogan

Fatma Oguz Erdogan was graduated from Zonguldak Bülent Ecevit University Faculty of Arts and Sciences, Department of Chemistry and achieved her Msc and PhD from the same university. She has been studying on production, characterization and surface modification of porous adsorbents. She is also interest in adsorption of gases, dyes and organic vapors on porous adsorbents. Now, she is Assistant professor at Kocaeli University, Kocaeli Vocational School, Department of Chemistry and Chemical Processing Technologies, Kocaeli, Turkey.

Turkan Kopac

Dr. Turkan Kopac received her B.Sc (1983) and M.Sc degrees (1985) in Chemical Engineering from the Middle East Technical University, and Ph.D in Chemical Engineering (1992) from Gazi University, Ankara Turkey. Her research activities focus on adsorption, catalysis, gas storage, nanomaterials. She has been serving as Professor since 2002 at the Department of Chemistry, Zonguldak Bülent Ecevit University, Turkey. She is currently Visiting Professor at the Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.