In order to determine if the size of the iron oxide clusters in the
composite structure could have an effect on the reactivity of the
OCMs, a preliminary study was carried out in the TGA. Iron oxide
particles of different sizes (40–80 lm, 80–160 lm) and
sub-micron powder were tested feeding carbon monoxide during
the reduction and carbon dioxide during the oxidation at 850 C
and atmospheric pressure. Fig. 4 shows the normalised weight gain
during the reduction and the oxidation, respectively, during the
first and the third redox cycle. The weight variation was normalised
by dividing by the expected available oxygen in the iron