The Effect of HCl and NaOH Treatment on Structural Transformations in a Ball-Milled Anthracite after Thermal and Chemical Processing

Abstract

Nanocrystalline diamond (NCD) was observed after reactive ball milling of anthracite coal with cyclohexene, a high-temperature (1400 °C) thermal anneal, and a 4 M HCl treatment followed by a 10 M NaOH treatment. A crystalline carbon region was also observed when the thermal anneal was omitted. This crystalline region is highly unstable and converts to NCD and carbon onions via electron irradiation in the TEM. X-ray diffraction, Raman, ash content, and temperature-programmed oxidation (TPO) data suggest that tetrahedral amorphous carbon is formed during milling, iron carbides are formed during the thermal anneal step, and both the HCl and NaOH purification steps lead to changes in carbon structure. NaOH oxidizes metal carbides and this process may contribute to NCD formation.

Department(s)

Chemical and Biochemical Engineering

Sponsor(s)

Consortium for Premium Carbon Products from Coal
Pennsylvania State University. Energy Institute
Pennsylvania State University. Material Research Institute

Comments

Funding for the project has been provided by the Consortium for Premium Carbon Products from Coal (DEFC2603NT41874, Internal Agreement No. 2875- TPSU-DOE-1874), with partial support from PSU's Energy Institute and Material Research Institute.

Keywords and Phrases

Ball milling; Carbon; Hydrochloric acid; Nanocrystalline materials; Olefins; Sodium compounds; Chemical processing; NaOH treatment; Structural transformations; Thermal processing; Anthracite

International Standard Serial Number (ISSN)

0008-6223

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2007 Elsevier, All rights reserved.

Publication Date

01 Oct 2007

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