Hydrogen adsorption process in nanocrystalline nuclear graphite

• Published in: Nuclear technology & radiation protection Vol. 37; no. 1; pp. 11 - 17
• Main Authors: Lukic, Vladimir, Spasojevic, Milica, Lukovic, Milentije, Spasojevic, Miroslav, Maricic, Aleksa
• Format: Journal Article
• Language: English
• Published: Belgrade Vinca Institute of Nuclear Sciences 2022; VINCA Institute of Nuclear Sciences
• Subjects: Adsorption; Comminution; Crystallites; Diffusion rate; Graphite; Hydrogen; hydrogen adsorption; kinetic and mechanism; nanocrystalline nuclear graphite; Nanocrystals; porous graphite; surface area; X ray analysis
• ISSN: 1451-3994; 1452-8185
• DOI: 10.2298/NTRP2201011L

Kinetics and mechanism of hydrogen adsorption in as-obtained and ground
nuclear graphite Wendelstein 7-X are examined. In the first time interval
the adsorption process is determined by dissociation of the hydrogen
molecule, occurring at the outer surface and in open micropores of nuclear
graphite particles. However, in the second time interval, the slowest step
in the hydrogen adsorption is inter-granular and inter-crystallite diffusion
in nanopores of graphite. The X-ray analysis shows, that grinding of
as-obtained nuclear graphite results in finer particles with finer
nanocrystals and larger density of opened pores and carbon reactive sites.
The capacity and rate of adsorption increase with comminution of nuclear
graphite particles and adsorbed hydrogen does not substantially alter the
microstructure of nuclear graphite.