ef9b04350_si_001.pdf (1.39 MB)
Computational Study of the Evolution of Ni-Based Catalysts during the Dry Reforming of Methane
journal contribution
posted on 2020-03-26, 15:38 authored by Supareak Praserthdam, Siriwimol Somdee, Meena Rittiruam, Perla B. BalbuenaWe
evaluated the Ni-based catalyst surface properties during possible
transformation pathways between its metallic, oxide, and carbide phases,
causing catalytic deactivation. The study uses density functional
theory (DFT) calculations to determine thermodynamics and reaction
mechanisms of elementary reactions, and the ratings concept is introduced
previously as an evaluation tool for the dry reforming reaction of
methane (DRR) catalyst. The results for carbon atom adsorption strength
and activation energy of higher coke formation (2C* ⇄ C–C*
+ *) suggest that on metallic surfaces, coke formation would be easy
on the (111) facet but suppressed on the (100). Likewise, the carbide
surface exposing metal atoms strongly binds to carbon and easily forms
higher coke. In contrast, the oxide of Ni exhibits coke-resistant
properties as it weakly adsorbs carbon. Finally, a ternary contour
plot featuring metallic/oxide/carbide phases of Ni on the (111) facet
was employed for identifying surface compositions, yielding highly
reactive and stable DRR catalysts through a microkinetics model. It
is found that, to become coke-resistant, the surface should contain
less than 10% of carbide, whereas more than 75% of metallic surface
is needed for the catalyst to be out of the coke formation zone, and
to enter the coke removal zone, up to 80% of the metallic surface
is required.
History
Usage metrics
Categories
Keywords
Ni-Based Catalystsreaction mechanismscarbide phasesratings conceptNi exhibits coke-resistant propertiescarbide surfacemetal atomsDry ReformingComputational Studycarbon atom adsorption strengthternary contour plotcoke formationNi-based catalyst surface propertiescoke removal zoneevaluation toolcoke formation zonetransformation pathwaysDRR catalystsmicrokinetics modelDFTsurface compositionsactivation energy
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC