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Oxidative Purification of Carbon Nanotubes and Its Impact on Catalytic Performance in Oxidative Dehydrogenation Reactions
Author(s) -
Rinaldi Ali,
Zhang Jian,
Frank Benjamin,
Su Dang Sheng,
Abd Hamid Sharifah Bee,
Schlögl Robert
Publication year - 2010
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.200900179
Subject(s) - dehydrogenation , catalysis , oxidative phosphorylation , chemistry , carbon nanotube , carbon fibers , photochemistry , chemical engineering , organic chemistry , nanotechnology , materials science , biochemistry , engineering , composite material , composite number
Oxidative purification with mild diluted HNO 3 followed by NaOH washing lowers the amount of amorphous carbon attached to multiwalled carbon nanotubes (CNTs). The graphitic structure improves remarkably by further annealing in argon at elevated temperatures, that is, 1173, 1573, and 1973 K. The influence of the purification treatment on the catalytic activity of the CNTs is investigated for the oxidative dehydrogenation (ODH) of ethylbenzene and propane as probe reactions. All samples tend to approach an appropriately ordered structure and Raman analysis of the used samples displays a D/G band ratio of 0.95–1.42. Oxygen functionalities are partly removed by the annealing treatment and can be rebuilt to some extent by oxygen molecules in the ODH reactant flow. The presence of amorphous carbon is detrimental to the catalytic performance as it allows for unwanted functional groups occurring in parallel with the formation of the selective (di)ketonic active sites.