Environmental Engineering Reference
In-Depth Information
Figure 6.29: Log
K
versus 1/
T
correlations for reactions of carbon with various oxidizing and
reducing agents [From ref.
423
. Reprinted with permission].
presence of reducing conditions in the regeneration system. It follows from
Fig. 6.29 [423]
that for these reactants, much higher temperatures were necessary for achieving desirable rates
of coke removal. For example, the study on the CO
2
regeneration of the catalyst used for
hydroprocessing of the vacuum residue derived from Athabasca bitumen revealed that the
formation of CO via Boudart reaction, i.e.:
CO
2
+
C
=
2CO
just began above 800 K
[425]
. More than 1000 K was necessary for removing most of the
carbon in pure CO
2
.As
Fig. 6.30
shows, there was a significant effect of the CO
2
concentration on carbon removal as indicated by the increase in CO yield by increasing the
