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Sintering of nickel particles supported on gamma-alumina in ammonia

Johan Lif (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Magnus Skoglundh (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Lars Löwendahl (Institutionen för material- och ytkemi, Teknisk ytkemi, Keramteknologi)
Applied Catalysis A: General (0926-860X). Vol. 228 (2002), 1-2, p. 145-154.
[Artikel, refereegranskad vetenskaplig]

Sintering of nickel on gamma-alumina in hydrogen, ammonia, ammonia + hydrogen and ammonia + nitrogen was investigated isocoric in the temperature range 483 to 523 K. The sintering process was followed by hydrogen chemisorption, specific surface area measurements, X-ray diffraction and transmission electron microscopy. After exposure to ammonia + hydrogen, hydrogen chemisorption revealed a fast decline of the nickel surface area. The results from X-ray diffraction and transmission electron microscopy are consistent with the result from the chemisorption experiments. The BET analysis showed that there are no losses of the total surface area. The sintering rate was significantly slower if the heat treatment was performed in the presence of only one of the gases, ammonia or hydrogen, or in ammonia + nitrogen. This indicates that the sintering in the temperature range 483 to 523 K only occurs with reduced nickel particles in ammonia + hydrogen. The prevailing mechanism for the sintering seems to be sintering by particle migration. The kinetics of the sintering process indicates that the rate constant is correlated to more factors than the temperature.

Nyckelord: Sintering, Nickel, Alumina, Catalyst deactivation, Ammonia, Hydrogen, Chemisorption



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Denna post skapades 2007-05-03. Senast ändrad 2012-02-20.
CPL Pubid: 41152

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Teknisk ytkemi (2005-2014)
Kompetenscentrum katalys (KCK)
Institutionen för material- och ytkemi, Teknisk ytkemi, Keramteknologi (1900-2004)

Ämnesområden

Energi
Materialvetenskap
Nanovetenskap och nanoteknik
Hållbar utveckling
Kemi
Kemiteknik

Chalmers infrastruktur

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