Interactions of water vapor and carbon dioxide with Ca doped ceria surfaces

Mordekovitz, Yuval; Shelly, Lee; Hayun, Shmuel

doi:10.1016/j.ceramint.2020.09.091

Cited by 1 publication

(13 citation statements)

References 62 publications

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“…The CO 2 uptake in this point is very much affected by the addition of dopants. Ti significantly lowered the uptake while co‐doping showed a resemblance to pure CeO 2 , due to the mitigating effects of Ca 27 . Though CO 2 uptake is different between the samples, the measured heats of adsorption are similar in most samples, excluding Ce 0.88 Ti 0.12 O 2 , which showed a much lower value.…”

Section: Resultsmentioning

confidence: 94%

“…The addition of Ca to fluorite CeO 2 was shown to increase both water uptake as well as coverage by forming Ca‐based surface phases 27 . Therefore, the co‐doping with Ca showed a mitigation in the effect of Ti on the coverage, resulting in a larger coverage on the co‐doped samples relative to Ti‐doped ceria samples.…”

Section: Discussionmentioning

confidence: 99%

“…Ca addition to CeO 2 was previously shown to increase both the heat of adsorption as well as the coverage of strongly bonded water. 27 As such, co-doping with Ca showed a mitigation in the effect of Ti on the coverage, resulting in a larger coverage of water on the co-doped samples relative to Ti-doped CeO 2 samples. Furthermore, co-doped samples show an increase in the heat of adsorption relative to pure CeO 2 .…”

Section: H 2 O Interactionsmentioning

confidence: 90%

“…Similar and more pronounced peaks were seen in CeO 2 sample doped solely with Ca. 27 Raman measurements are routinely used to assess the amount of defects in doped as well as undoped CeO 2 -based materials. 51,52 Defect assessment is based on the appearance of normally forbidden modes, around ~570 cm −1 and ~600 cm −1 .…”

Section: Surface Statementioning

confidence: 99%

“…phases. 27 Neodymium (Nd) addition, while increasing water uptake, has a heat of adsorption similar to pure ceria, since both strong and weak adsorption sites were added to the surface. 28 While cations of both Ca and Nd are similar in size to Ce cation, CeO 2 solid solutions containing the Ti (which is smaller than Ce and tetravalent in the fluorite structure) were also studied to better understand the effects of valance and size on the surface defect chemistry and subsequent gas-surface interactions.…”

mentioning

confidence: 99%

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Surface properties of Ca, Ti‐doped CeO₂ and their influence on the reverse water‐gas shift reaction

et al. 2021

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CeO2‐based materials can be found in a variety of catalytic processes, including the reverse water‐gas shift (RWGS) reaction. Nevertheless, the interaction of molecular gases with the surfaces of such materials is still not clear. Recently, some progress was reported on the incorporation of neodymium (Nd) and calcium (Ca) into ceria and their effect on H2O and CO2 adsorption. Titanium (Ti), which has a much smaller ionic radius, has the ability to change the interaction landscape, both as a co‐dopant to Ca and as a sole dopant in the CeO2 system. In this study, the interactions of environmental gases (i.e., water vapor and CO2) on the surface of Ti‐doped CeO2 and Ca,Ti co‐doped CeO2 were investigated. Ti addition to CeO2 was shown to decrease water vapor uptake by up to 25% all while maintaining similar heats of adsorption. In the case of CO2 adsorption, Ti addition to CeO2 had lowered the uptake by more than 50% as well as lowering the heat of adsorption. Co‐doping with Ti and Ca showed small decrease in H2O uptake accompanied with increased heat of adsorption. For CO2, the changes to the uptake and energetics were small and did not indicate a specific trend. The RWGS catalytic performance showed improvement by the addition of Ti in certain levels. The relationship between the doping, surface properties, gas‐surface interactions, and catalytic performance is discussed.

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Section: Resultsmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: H 2 O Interactionsmentioning

confidence: 90%