Reactor design, modeling and optimization for the high-temperature methane pyrolysis and the reverse water-gas shift reaction
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Date
2018
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Abstract
In this work, two reactions are studied as a mean to deal with the current CO2 conundrum.
The first reaction is the high-temperature pyrolysis of methane. This reaction serves
as a way to avoid the stoichiometric production of CO2 when producing hydrogen,
which could either be used for energy production or as a base chemical. The second
reaction is the reverse Water-Gas Shift (rWGS) reaction. By means of this reaction,
CO2 that is unavoidably produced and has been captured, can be activated to the
more reactive CO and subsequently mixed with hydrogen to produce syngas.
For the methane pyrolysis, liquid- and solid-based reactors are studied. The former
are reactor concepts based on the use of molten media. Capillary, falling-film and
rotating reactors are introduced as alternatives to carry out the pyrolysis with efficient
heat transfer and to avoid carbon deposition. Solid-based reactors, in the form of
moving-bed, are studied from a theoretical perspective. First the operation stability
of the reactor is investigated by means of bifurcation analysis, and then several heat
input strategies are modeled and optimized to determine solutions in the short, mid
and long-term.
For the rWGS, multifunctional adsorptive reactors are studied as a workaround to
the problem of low equilibrium conversion, as well as heat input for more attractive
low-temperature rWGS, as compared to the industrially common high-temperature
counterpart. Two concepts are investigated; a fixed-bed and a moving-bed reactor.
Their potential for optimization is determined, and a comparison between the concepts
is achieved.
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Keywords
Methane pyrolysis, rWGS, Reaction engineering, Modelling, Optimization, Hydrogen production, C02 utilization