The used 3J1 catalyst was recovered at 1, 4, 10, 20 and 45 h on
stream and characterized using TPO and XPS to study the growth
of carbon deposition with time on stream. Fig. 11a presents some
of the TPO profiles of catalysts recovered after steam reforming
at different times on streams. The catalysts did not show appreciable
carbon deposition until 20 h time on stream. The large
peak observed for 45 h run above 450 ◦C was attributed to carbon
that was deposited on the catalyst support. The peak was
observed much earlier in case of catalysts not containing Rh and
corresponded to an earlier onset of deactivation during reforming.
Further characterization of the used catalysts using XPS can be seen
in Fig. 11b. The results were in agreement with that of TPO where
only 45 h run used catalysts displayed a peak, which corresponds
to aromatic and/or polymeric type of species.