Victor Stivenson Sandoval-Bohorquez
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Edgar M. Morales-Valencia
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Carlos Omar Castillo-Araiza
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Luz Marina Ballesteros Rueda
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Víctor Gabriel Baldovino Medrano
The dry reforming of
methane is a promising technology for the abatement of CH<sub>4</sub> and CO<sub>2</sub>.
Solid solution Ni–La oxide catalysts are characterized by their long–term
stability (100h) when tested at full conversion. The kinetics of dry reforming
over this type of catalysts has been studied using both power law and Langmuir–Hinshelwood
based approaches. However, these studies typically deal with fitting the net CH<sub>4</sub>
rate hence disregarding competing and parallel surface processes and the different
possible configurations of the active surface. In this work, we synthesized a solid
solution Ni–La oxide catalyst and tested six Langmuir–Hinshelwood mechanisms considering
both single and dual active sites for assessing the kinetics of dry reforming and
the competing reverse water gas shift reaction and investigated the performance
of the derived kinetic models. In doing this, it was found that: (1) all the
net rates were better fitted by a single–site model that considered that the
first C–H bond cleavage
in methane occurred over a <a>metal−oxygen </a>pair
site; (2) this model predicted the existence of a
nearly saturated nickel surface with chemisorbed oxygen adatoms derived from
the dissociation of CO<sub>2</sub>; (3) the dissociation of CO<sub>2</sub> can
either be an inhibitory or an irrelevant step, and it can also modify the apparent
activation energy for CH<sub>4</sub> activation. These findings contribute to a
better understanding of the dry reforming reaction's kinetics and provide a
robust kinetic model for the design and scale–up of the process.
Comment on “Dry reforming of methane by stable Ni–Mo nanocatalysts on single-crystalline MgO”