Optimization of inlet temperature for deactivating LTWGS reactor performance

Ayastuy, J.L.; Gutiérrez-Ortiz, M.A.; González‐Marcos, José A.; Aranzabal, A.; González‐Velasco, Juan R.

doi:10.1002/aic.10433

Cited by 8 publications

(8 citation statements)

References 28 publications

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“…This approach was used earlier mainly to describe the kinetics over the conventional catalysts. Another approach adopted was finding the power law type kinetics by tracing the effect of each of the chemical species 15, 42–46. Some investigators have used the redox chain mechanism for describing the kinetics 47, 48.…”

Section: Resultsmentioning

confidence: 99%

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

2009

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The water-gas shift (WGS) reaction was carried out in the presence of Pd and Pt substituted nanocrystalline ceria catalysts synthesized by solution combustion technique. The catalysts were characterized by powder XRD and XPS. The noble metals were found to be present in ionic form substituted for the cerium atoms. The catalysts showed high activity for the WGS reaction with high conversions below 250 C. The products of reaction were only carbon dioxide and hydrogen, and no hydrocarbons were observed even in trace quantities. The reactions were carried out with different amounts of noble metal ion substitution and 2% Pt substituted ceria was found to be the best catalyst. The various possible mechanisms for the reaction were proposed and tested for their consistency with experimental data. The dual site mechanism best described the kinetics of the reaction and the corresponding rate parameters were obtained.

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Section: Resultsmentioning

confidence: 99%

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

2009

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“…Rate constants (k) at temperature T = 463 K (standard temperature for the low-temperature WGS reaction, 44 other temperatures were also considered for comparison purposes being the related data reported in the Supporting Information) and the Gibbs free energies (at T = 463 K and pressure P = 1 bar) for the water dissociation on the bimetallic surfaces considered have been estimated by using eqs 1 45 and 2, 26,46 respectively,…”

Section: Catalyst Surface Models Andmentioning

confidence: 99%

Water Dissociation on Bimetallic Surfaces: General Trends

2012

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General trends for the reaction of water dissociation on some selected transition metal (TM) bimetallic surfaces of the type TM 1 @TM 2 (111) or TM 1 @ TM 2 (110), with TM 1 = Ag, Ni, Rh, or Ir and TM 2 = Cu, Au, Ni, or Ir, are interpreted from periodic density functional theory calculations. It was found that the water dissociation on bimetallic surfaces follows relationships that link the activation energy barrier with the reaction energy or with the adsorption energy of the reaction products. Furthermore, it was also found that the doping of metallic surfaces with atoms of other metals leads to a stabilizing cooperative effect of both in the adsorption of water, its dissociation products, and transition state configuration. Importantly, the catalytic activity of the bimetallic systems is found to increase visibly when compared with the reactivity of the pure parent surfaces. In fact, the activation barriers calculated for water dissociation on some bimetallic surfaces are significantly lowered when compared with the activation energies for the reaction of water dissociation on pure surfaces of the parent metals.

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“…The rate constant was calculated at T c = 463 K as this is the standard temperature for the lowtemperature WGS reaction. 60 2.3. Lattice Motion.…”

Section: Methodsmentioning

confidence: 99%

Efficient Water–Gas Shift Catalysts for H₂O and CO Dissociation Using Cu–Ni Step Alloy Surfaces

Roy

Tiwari

2021

J. Phys. Chem. C

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H2O dissociation is the rate-limiting step for the water–gas shift (WGS) reaction. Density functional theory (DFT) was used to study H2O and CO dissociation on a series of step (211) bimetallic alloy surfaces consisting of Cu and Ni metals. The water dissociation process was more facile on (211) step surfaces than on (111) flat surfaces. But CO dissociation on the (211) step surfaces was less reactive than that on its close-packed (111) counterparts. Depending on the initial-state structures, the transition states for H2O dissociation were located at different sites available on a (211) step surface. The introduction of Cu atoms on a bare Ni(211) surface (Ni-based alloy) decreased the reactivity of H2O dissociation, whereas the introduction of Ni atoms on a bare Cu(211) surface (Cu-based alloy) increased the reactivity. At a given molecular temperature, rate constant values were calculated. They showed that bare Ni(211) and Cu-based alloy surfaces exhibited a significantly higher rate constant for H2O dissociation than bare Cu(211) and Ni-based alloy surfaces. Different surface-based properties such as surface energy, work function, d-band center energy, and H adsorption energy were calculated and qualified as descriptors for H2O dissociation on the alloy surfaces. The linear relationship between the activation energy barrier and the reaction energy (Bronsted–Evans–Polanyi (BEP) relationship) held good for H2O and CO dissociation processes on all of the alloy surfaces. The transition state toward a given dissociation pathway is modified by the motion of top-layer lattice atom over which H2O gets adsorbed. The effect of surface temperature on the reactivity, which was calculated using semiclassical methods, showed that the reactivity increased with surface temperature on all of the alloy surfaces. C2 dimer formation, the first step of coke formation on any catalyst surface, was less reactive for Cu-based alloy surfaces. Overall, considering all of the aspects of H2O and CO dissociation and C2 dimer formation, Cu-based (211) step alloy surfaces showed improved performance as the WGS reaction catalyst.

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Optimization of inlet temperature for deactivating LTWGS reactor performance

Cited by 8 publications

References 28 publications

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

Water Dissociation on Bimetallic Surfaces: General Trends

Efficient Water–Gas Shift Catalysts for H₂O and CO Dissociation Using Cu–Ni Step Alloy Surfaces

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Optimization of inlet temperature for deactivating LTWGS reactor performance

Cited by 8 publications

References 28 publications

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

A mechanistic model for the water‐gas shift reaction over noble metal substituted ceria

Water Dissociation on Bimetallic Surfaces: General Trends

Efficient Water–Gas Shift Catalysts for H2O and CO Dissociation Using Cu–Ni Step Alloy Surfaces

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Efficient Water–Gas Shift Catalysts for H₂O and CO Dissociation Using Cu–Ni Step Alloy Surfaces