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Activation and Decomposition of Methane over Cobalt‐, Copper‐, and Iron‐Based Heterogeneous Catalysts for CO x ‐Free Hydrogen and Multiwalled Carbon Nanotube Production
Author(s) -
Dasireddy Venkata D. B. C.,
Likozar Blaž
Publication year - 2017
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201600633
Subject(s) - catalysis , bimetallic strip , cobalt , materials science , inorganic chemistry , carbon fibers , hydrogen production , thermogravimetric analysis , hydrogen , carbon nanotube supported catalyst , carbon nanofiber , chemistry , organic chemistry , composite material , composite number
Monometallic 50 wt % Cu/Al 2 O 3 catalyst and bimetallic catalysts containing 25 wt % Co/25 wt % Cu, 25 wt % Co/25 wt % Fe, and 25 wt % Cu/25 wt % Fe, supported on Al 2 O 3 , were prepared by impregnation and coimpregnation methods. For bimetallic catalysts, metal oxides were in the form of spinel oxides, which exhibited a strong metal–support interaction. The decomposition of methane over these catalysts led to the formation of pure hydrogen and carbon nanotubes on their surfaces. The activation energy, total carbon yield, and amount of hydrogen formed, by using the prepared catalysts, were in agreement with the metal dispersion and acid–base site ratio on the surface of the catalysts. Cu−Fe/Al 2 O 3 catalyst exhibited a stable hydrogen formation rate of 58 mmol min −1 g −1 at a temperature of 650 °C. All catalysts exhibited deactivation after 500 min, which occurred due to the formation of carbon on the surface of the catalysts. The carbon material deposited predominantly assumed the form of multiwalled carbon nanotubes, as evidenced by high‐resolution TEM and Raman spectroscopy. Thermogravimetric analysis finally confirmed that Cu−Fe/Al 2 O 3 exhibited a higher yield of multiwalled carbon nanotubes.