Beyond CO₂ dissociation: The pivotal role of O* surface species in reverse water-gas shift kinetics over nickel
Abstract
This work provides a mechanistic perspective on the role of surface oxygen intermediates in the reaction kinetics of the high-temperature reverse water-gas shift (rWGS) reaction. Above 500 °C, the redox mechanism is generally accepted, typically assuming CO 2 dissociation as the rate-determining step on Ni supported catalysts. However, our microkinetic analysis, with experiments the varying CO 2 /H 2 ratios within a range of 500–800 °C, reveals that the hydrogenation of surface oxygen intermediates is as important as CO 2 dissociation. Data were collected using two different nickel catalysts (0.5 wt% and 5 wt% Ni/CeZrO 4 ), although only the intrinsic kinetic data over the 0.5 wt% Ni/CeZrO 4 were used for model development and regression analysis. Degree of Rate Control (DRC) analysis demonstrates that the relative importance of these two steps shifts as a function of the CO 2 /H 2 feed ratios and temperature. Based on this insight, we developed a Langmuir-Hinshelwood-Hougen-Watson (LHHW) model, incorporating both rate-determining steps. This model captures how the surface oxygen coverage controls overall reaction rate by affecting the apparent reaction orders and activation energy.
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BibTeX
@article{han2026beyond,
title = {{Beyond CO₂ dissociation: The pivotal role of O* surface species in reverse water-gas shift kinetics over nickel}},
author = {Y. Han and N. Guilhaume and Y. Schuurman},
journal = {Chemical Engineering Journal},
year = {2026},
month = sep,
doi = {10.1016/j.cej.2026.181945},
url = {https://hal.science/hal-05770746v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Beyond CO₂ dissociation: The pivotal role of O* surface species in reverse water-gas shift kinetics over nickel
AU - Y. Han
AU - N. Guilhaume
AU - Y. Schuurman
PY - 2026
DA - 2026/09/30
JO - Chemical Engineering Journal
DO - 10.1016/j.cej.2026.181945
UR - https://hal.science/hal-05770746v1
AB - This work provides a mechanistic perspective on the role of surface oxygen intermediates in the reaction kinetics of the high-temperature reverse water-gas shift (rWGS) reaction. Above 500 °C, the redox mechanism is generally accepted, typically assuming CO 2 dissociation as the rate-determining step on Ni supported catalysts. However, our microkinetic analysis, with experiments the varying CO 2 /H 2 ratios within a range of 500–800 °C, reveals that the hydrogenation of surface oxygen intermediates is as important as CO 2 dissociation. Data were collected using two different nickel catalysts (0.5 wt% and 5 wt% Ni/CeZrO 4 ), although only the intrinsic kinetic data over the 0.5 wt% Ni/CeZrO 4 were used for model development and regression analysis. Degree of Rate Control (DRC) analysis demonstrates that the relative importance of these two steps shifts as a function of the CO 2 /H 2 feed ratios and temperature. Based on this insight, we developed a Langmuir-Hinshelwood-Hougen-Watson (LHHW) model, incorporating both rate-determining steps. This model captures how the surface oxygen coverage controls overall reaction rate by affecting the apparent reaction orders and activation energy.
SN - 1385-8947
ER -