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Abstract
Dry/CO2 reforming is one the hydrocarbon processes that recently has been
interesting due to it is ability of producing a lower synthesis gas ratio (H2/CO).
This synthesis gas is a highly significant product since it costs more than 50%
of the total capital cost of gas to liquid (GTL) process. However, since this
reaction is thermodynamically limited, higher temperature or lower pressure is
required to achieve higher conversion. Typically, reaction temperatures
between 1073 and 1173 K are used for catalytic dry reforming reactions.
Consequently, these extreme temperatures lead to a severe carbon
deposition causing a catalyst deactivation which is the major difficulty related
to CO2 reforming reaction. This has pushed the efforts to be focused mainly
on the development of new catalysts. In fact, dry reforming of propane is an
equilibrium-limited reaction which can be shifted to the product side by
removing one of the products out of the system which can be achieved using
a selective membrane reactor.
This research is dedicated to investigate and study the catalytic performance
of dry reforming of propane over cobalt-nickel catalyst under the temperature
range of 773-973 K. This bimetallic catalyst supported on δ-Al2O3 has been
utilized in this research since it exhibits better activity, selectivity, and
deactivation resistance than monometallic catalysts. Based on this, the
primary aims of this thesis are to examine this catalyst and to study the impact
of using membrane reactor. In addition, the reaction mechanism and kinetic
are investigated using a fixed-bed reactor.
Experimental observations have exposed that the catalyst is offering good
results under this reaction. The catalysts analysis has confirmed the presence
of metal oxides in the catalyst. However, only at a lower carbon dioxide to
propane ratio, i.e. lower than 3.5, a carbon signal has been reported. The
activation energy study indicates that the process is unlimited by diffusion.
The reaction order for propane and carbon dioxide has been found to be zero
and 1.17 respectively. This in turn has indicated that C3H8 activation reaction
is taking place rapidly and carbon dioxide is suggested to be involved in the
rate determining step. In membrane reactor operation, the production rates for
H2 and CO have been reported to increase as the sweep gas flow rate
increases. The co-current mode offers higher production rate and more
stability than counter-current mode over the range of feed ratio. On the other
hand, fixed bed reactor shows stable performance and produces more CO
and H2 for both modes.