(95d) Modeling Catalyst Deactivation in a Packed Bed Reactor for Thermo-Catalytic Hydrogenation of CO2

Modeling
catalyst deactivation in a packed bed reactor for thermo-catalytic
hydrogenation of CO₂

Duo Sun and David Simakov

Department of Chemical
Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada

Converting CO₂
into synthetic fuels and chemicals is an attractive route to reduce CO₂
emissions and, at the same time, fossil fuels consumption. There are several
pathways, including thermocatalytic conversion via Sabatier reaction (CO₂
+ 4H₂ = CH₄ + 2H₂O) to produce synthetic
natural gas [1-4]. Some technological issues are yet to be resolved in order to
make this process truly viable economically, including catalyst deactivation by
sintering and carbon formation. Sabatier reaction is highly exothermic which
can lead to reactor overheating, catalyst sintering and accelerated methane
cracking producing large amounts of coke. We developed a transient numerical model
to study the effects of catalyst deactivation on the performance of the heat-exchanger
type packed bed CO₂ hydrogenation reactor. Our results show that
catalyst deactivation can significantly limit CO₂ conversion under
certain operating conditions, changing also products distribution. On the other
hand, the presence of H₂ in the reaction mixture and the generation
of H₂O lead to in situ catalyst reactivation. Our model
predicts that, with a proper design, it is possible to operate the reactor at
reasonably high CO₂ conversions (e.g. 80% CO₂ conversion
after 1,000 h on stream) even using Ni-based catalysts which are prone to
coking.

References

[1] Rönsch, S. et al. Review on methanation – From
fundamentals to current projects. Fuel 2016, 166, 276-296.

[2] Schaaf, T. et al. Methanation of CO₂ –
storage of renewable energy in a gas distribution system. Energy Sustain.
Soc. 2014, 4, 29.

[3] Götz, M et al. Renewable Power-to-Gas: A
technological and economic review. Renew. Energ. 2016, 85, 1371-1390.

[4] Gahleitner, G. Hydrogen from renewable
electricity: An international review of power-to-gas pilot plants for
stationary applications. Int. J. Hydrogen Energ. 2013, 38, 2039-2061.