Theoretical study on the reaction mechanism of carbon dioxide reforming of methane on La and La2O3 modified Ni(1 1 1) surface

Li, Kai; He, Feng; Yu, Gino; Wang, Ying; Wu, Zhijian

doi:10.1016/j.jcat.2018.05.026

Cited by 34 publications

(34 citation statements)

References 63 publications

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“…84 In general, the estimated pre-exponential factors (eq S50) were identical to those reported by Dumesic et al 85 and estimated with the methodology proposed by Campbell et al 86 , Table 3. Similarly, the activation energies, as well as the standard reaction and adsorption enthalpies in this model, matched those reported in microkinetic modelling studies, 41,74,80 molecular simulations over Ni surfaces, 36,73,76,77,87,88 and experimental data. 11,71 For example, the activation energy for the oxygen-assisted C-H bond cleavage (step 1, Table 2) was in close agreement with the experimental value of 95kJ.mol -1 for Ni-Co catalyst 11 and microkinetic studies of 88−93kJ.mol -1 for Ni-based catalysts.…”

Section: Analysis Of the Solution Of The Kinetic Modelssupporting

confidence: 79%

“…74,80 Likewise, the reaction enthalpy for this step matched with the value of -8.0kJ mol -1 reported elsewhere. 87 The values of the activation energy and reaction enthalpy for the sequential H-abstraction reactions (step 2-4) were in the range of 65-130kJ.mol -1 , 36,41,73,74,80 and even their trend, i.e., a decrease in the activation energy upon the first H-abstraction and increase again for the last H-scission was similar to those predicted with molecular simulations. 36,73,76,88 Moreover, the steps involved in H2O production (steps 7 and 8) displayed activation energies of 89 ± 3 and 48 ± 3kJ.mol -1 , respectively, which were close to the values of 104 and 41kJ.mol -1 reported in microkinetic models.…”

Section: Analysis Of the Solution Of The Kinetic Modelssupporting

confidence: 74%

“…These mechanisms were based on both the data collected herein and on the extensive literature on this topic. 4,5,10,11,17,19,25,35,36,71,73,74,[76][77][78][79][80] In this section, the kinetics of the process is analyzed under the light of the model that best fitted the experimental data and fulfilled the thermodynamic consistency criteria, Table 2. The competing models are comprehensively explained in the Supplementary Information, section E, and summarized in Table S8.…”

Section: Six Different Langmuir-hinshelwood Reaction Mechanisms and Smentioning

confidence: 99%

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Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Sandoval-Bohorquez

Morales-Valencia²,

Castillo‐Araiza³

et al. 2021

Preprint

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The dry reforming of methane is a promising technology for the abatement of CH4 and CO2. 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 CH4 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 CO2; (3) the dissociation of CO2 can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH4 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.

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Section: Analysis Of the Solution Of The Kinetic Modelssupporting

confidence: 79%

Section: Analysis Of the Solution Of The Kinetic Modelssupporting

confidence: 74%

Section: Six Different Langmuir-hinshelwood Reaction Mechanisms and Smentioning

confidence: 99%

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Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Sandoval-Bohorquez

Morales-Valencia²,

Castillo‐Araiza³

et al. 2021

Preprint

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“…The basic character of La 2 O 3 could attract CO 2 adsorption to yield lanthanum dioxycarbonate, La 2 O 2 CO 3 (see Equation ), further reacting with adjacent surface carbon (see Equation ), thereby prolonging the lifecycle of 3%La‐10%Co/Al 2 O 3. Based on theoretical calculation using density functional theory in recent study, Li et al also concluded that the strong CO 2 adsorption on La 2 O 3 provoked complex CO 2 (La 2 O 2 ‐O) formation and the partly dissociated oxygen atom of this intermediate could oxidize surface C x H y species to preserve active metal sites

{La}_{2} O_{3} + {CO}_{2} \to {La}_{2} O_{2} {CO}_{3}

{La}_{2} O_{2} {CO}_{3} + C \to {La}_{2} O_{3} + 2 italicCO

…”

Section: Resultsmentioning

confidence: 99%

Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

et al. 2018

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Summary Catalytic stability with time‐on‐stream is an important aspect in ethanol dry reforming (EDR) since catalysts could encounter undesirable deterioration arising from deposited carbon. This work examined the promotional effect of La on 10%Co/Al2O3 in terms of activity, stability, and characteristics. Catalysts were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, and X‐ray photoelectron spectroscopy (XPS) measurements whilst catalytic EDR performance of La‐promoted and unpromoted 10%Co/Al2O3 prepared via wet impregnation technique was investigated at 973 K for 72 h using a stoichiometric feed ratio (C2H5OH/CO2 = 1/1). La promoter substantially enhanced both metal dispersion and metal surface area from 0.11% to 0.64% and 0.08 to 0.43 m2 g−1, respectively. Ethanol and CO2 conversions appeared to be stable within 50 to 72 h after experiencing an initial activity drop. The conversion of C2H5OH and CO2 for La‐promoted catalyst was about 1.65 and 1.34 times greater than unpromoted counterpart in this order. The carbonaceous deposition was considerably decreased from 55.6% to 36.8% with La promotion due to La2O2CO3 intermediate formation. Additionally, 3%La‐10%Co/Al2O3 possessed greater oxygen vacancies acting as active sites for CO2 adsorption and hence increasing carbon gasification. Even though graphitic and filamentous carbons were formed on used catalyst surface, La‐addition diminished graphite formation and increased the reactiveness of amorphous carbon.

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“…As La 2 O 3 can promote CO 2 adsorption and activation [33]; Ni/La 2 O 3 [34,35] and La 2 O 3 promoted Ni-based catalysts [36][37][38][39] have shown excellent activity in the DRM reaction. However, due to the low specific surface area of La 2 O 3 , the main problem with Ni/La 2 O 3 catalysts is the poor dispersion of Ni [40,41], leading to carbon deposition on Ni/La 2 O 3 catalysts [40,41].…”

Section: Introductionmentioning

confidence: 99%

Encapsulated Ni@La2O3/SiO2 Catalyst with a One-Pot Method for the Dry Reforming of Methane

Wang

Liu

et al. 2019

Catalysts

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Ni nanoparticles encapsulated within La 2 O 3 porous system (Ni@La 2 O 3 ), the latter supported on SiO 2 (Ni@La 2 O 3 )/SiO 2 ), effectively inhibit carbon deposition for the dry reforming of methane. In this study, Ni@La 2 O 3 /SiO 2 catalyst was prepared using a one-pot colloidal solution combustion method. Catalyst characterization demonstrates that the amorphous La 2 O 3 layer was coated on SiO 2 , and small Ni nanoparticles were encapsulated within the layer of amorphous La 2 O 3 . During 50 h of dry reforming of methane at 700 • C and using a weight hourly space velocity (WHSV) of 120,000 mL g cat −1 h −1 , the CH 4 conversion obtained was maintained at 80%, which is near the equilibrium value, while that of impregnated Ni-La 2 O 3 /SiO 2 catalyst decreased from 63% to 49%. The Ni@La 2 O 3 /SiO 2 catalyst exhibited very good resistance to carbon deposition, and only 1.6 wt% carbon was formed on the Ni@La 2 O 3 /SiO 2 catalyst after 50 h of reaction, far lower than that of 11.5 wt% deposited on the Ni-La 2 O 3 /SiO 2 catalyst. This was mainly attributed to the encapsulated Ni nanoparticles in the amorphous La 2 O 3 layer. In addition, after reaction at 700 • C for 80 h with a high WHSV of 600,000 mL g cat −1 h −1 , the Ni@La 2 O 3 /SiO 2 catalyst exhibited high CH 4 conversion rate, ca. 10.10 mmol g Ni −1 s −1 . These findings outline a simple synthesis method to prepare supported encapsulated Ni within a metal oxide porous structure catalyst for the dry reforming of methane reaction.

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Theoretical study on the reaction mechanism of carbon dioxide reforming of methane on La and La2O3 modified Ni(1 1 1) surface

Cited by 34 publications

References 63 publications

Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

Encapsulated Ni@La2O3/SiO2 Catalyst with a One-Pot Method for the Dry Reforming of Methane

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Theoretical study on the reaction mechanism of carbon dioxide reforming of methane on La and La2O3 modified Ni(1 1 1) surface

Cited by 34 publications

References 63 publications

Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Kinetic Assessment of the Dry Reforming of Methane over a Solid Solution Ni–La Oxide Catalyst

Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

Encapsulated Ni@La2O3/SiO2 Catalyst with a One-Pot Method for the Dry Reforming of Methane

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Theoretical study on the reaction mechanism of carbon dioxide reforming of methane on La and La2O3 modified Ni(1 1 1) surface