(308f) Reaction of C2H4 Under Lower Temperature Fischer-Tropsch Conditions on a TiO2 Supported Cobalt Catalyst with Co-Feeding of H2 and Syngas
AIChE Annual Meeting
2017
2017 Annual Meeting
Catalysis and Reaction Engineering Division
Reaction Chemistry and Engineering I
Tuesday, October 31, 2017 - 9:50am to 10:12am
Reaction of C2H4 under
Lower Temperature Fischer-Tropsch Conditions on a TiO2
Supported Cobalt Catalyst with Co-feeding of H2 and Syngas
Xiaojun Lu*, Diane
Hildebrandt, Yusheng Zhang, and Xinying Liu
Material and
Process Synthesis; College of Science, Engineering, and Technology, University
of South Africa
Co-feeding of C2H4 to the
Fischer-Tropsch reaction system has been studied some
years back to investigate the effect of secondary reactions of the olefins in
the Fischer-Tropsch reaction. Some important
phenomena were observed and the conclusions were not consistent due to the
complexity of the Fischer-Tropsch reaction.
Researchers often found that it is very difficult to investigate certain
aspects independently in such complex reaction system. This work tries to investigate
one aspect at a time in the complex system. Three groups of experiments were
designed. The first group of experiments was designed to investigate the reaction
of C2H4 only on the supported Co catalyst. The purpose was
to investigate the possible secondary reactions of C2H4
without other reactants. The second experimental design was to add H2
into the reaction system when keeping the feed of C2H4.
This was to investigate the reactions of C2H4 with the
presence of H2. The C2H4 to H2
ratio was adjusted in a wide range so that excessive amount of both of these
two reactants could be achieved. The third experimental design was to co-feed
synthesis gas (H2/CO/N2) when keeping the feed of C2H4.
The amount of syngas fed into the reaction system was controlled to ensure that
the main feed was still C2H4. This is different from the
feed ratio chose by other researcher in the past as the amounts of C2H4
co-fed by them was always far less than the syngas feed.
The results we have obtained in these
experiments are of big interests. C2H4 was found not to
react under the conditions applied when no other feed was introduced into the
reactor; while it reacts quickly when H2 was co-fed. The reaction temperature, when H2
was co-fed, could be as low as 100oC and only products of C1
to C5 were found. These results suggest that C2H4
can undertake several reaction pathways to form different products. Fischer-Tropsch synthesis reaction was found to occur, with the
presence of C2H4, when the operating temperature was at
140oC, which is much lower than the temperature (higher than 180oC
with Co as the catalyst) required for normal Fischer-Tropsch
synthesis. The reaction temperature required for reactions to happen changed to
around 190oC when the feed of C2H4 was
stopped. The presence of C2H4 can promote the Fischer-Tropsch synthesis by lowering the reaction temperature.
This has not been reported in any existing literature. The products
distribution is quite different when both C2H4 and syngas
were fed and this leads to the understanding of the reaction mechanisms for the
Fischer-Tropsch Synthesis.
Keywords: Fischer-Tropsch Synthesis, C2H4 reaction, Reaction
Mechanism