Catalytic HCl oxidation reaction: Stabilizing effect of Zr-doping on CeO2 nano-rods

Li, Chenwei; Sun, Yueming; Heß, Franziska; Djerdj, Igor; Sann, Joachim; Voepel, Pascal; Cop, Pascal; Guo, Yanglong; Smarsly, Bernd M.; Over, Herbert

doi:10.1016/j.apcatb.2018.08.047

Cited by 38 publications

(27 citation statements)

References 33 publications

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“…While only 75 % of the catalyst is chlorinated in the pure CeO 2 samples, the fitted nucleation rate is substantially lower, possibly indicating that the CeO 2 surface contributes less to nucleation. This assumption is consistent with the earlier conclusion that the surface of residual CeO 2 is entirely covered by CeCl 3 after chlorination (and thereby not available as a site for oxide nucleation), thereby suppressing complete chlorination [11] …”

Section: Discussionsupporting

confidence: 92%

“…After Ar purging, the catalyst is exposed to a harsh reaction mixture (Ar : HCl : O 2 =9 : 4.5 : 1.5). During 1.5 h on stream, the STY of CeO 2 declines continuously and saturates finally at a residual activity that is likely due to hydrated CeCl 3 [11,18] . In the next step, the deactivated CeO 2 catalyst is reactivated by the mixed atmosphere of O 2 and Ar (Ar : O 2 =7.5 : 7.5).…”

Section: Resultsmentioning

confidence: 99%

“…How does our approach compare with other methods for quantifying the degree of chlorination? So far, mostly Rietveld analyses of XRD data have been employed to quantify the bulk chlorination of CeO 2 ‐based catalysts [10,11] . This method is only applicable if hydrated CeCl 3 is crystalline.…”

Section: Discussionmentioning

confidence: 99%

“…It has been recognized that CeO 2 ‐based catalysts deactivate in the Deacon reaction through bulk chlorination [8,9,11] . There is also clear evidence that stoichiometric CeOCl is catalytically not active at all [14] .…”

Section: Discussionmentioning

confidence: 99%

“…For the commercialized RuO 2 /rutile‐TiO 2 catalyst these reduction and oxidation steps are not bulk transformations of the catalysts, but rather take place at the surface only [7] . However, for the case of CeO 2 ‐based catalysts, a promising and viable alternative to RuO 2 , it was recognized that they deactivate in the Deacon reaction through bulk chlorination, [8–12] although being partly reactivated with excess oxygen in the reaction feed at reaction temperatures of typically 430 °C [8,13,14] . Improved chemical stability against bulk chlorination is achieved by mixing CeO 2 with ZrO 2 , either in the form of solid solutions [15,16] or as CeO 2 deposited on preformed ZrO 2 particles [17,18] .…”

Section: Introductionmentioning

confidence: 99%

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sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

et al. 2020

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Deactivation of CeO2‐based catalysts in the HCl oxidation reaction proceeds via selective bulk chlorination of the active CeO2 component to form CeCl3×nH2O. We study the reactivation of two bulk‐chlorinated CeO2‐based Deacon catalysts by oxygen treatment at 430 °C, namely pure CeO2 and 20 mol % of CeO2 supported on preformed ZrO2 particles (20CeO2@ZrO2), with a dedicated experiment. In the flow reactor setup we determine in‐situ the degree of chlorination of the catalyst by quantifying down‐stream with in‐situ UV‐Vis spectroscopy the total amount of chlorine in the catalyst that is exchanged by reoxidation at 430 °C. The activity of deactivated 20CeO2@ZrO2 can be fully restored by oxygen exposure at 430 °C, while that of pure CeO2 declines steadily. Since the UV‐Vis analytics is fast and sensitive, we can follow the kinetics of reoxidation. To rationalize the observed kinetics, we develop a modified Johnson‐Mehl‐Avrami‐Kolmogorov (JMAK) model based on a nucleation‐and‐growth approach for the reoxidation of the catalyst starting from the chlorinated phase. The fast reoxidation kinetics of chlorinated 20CeO2@ZrO2 is traced to a fast nucleation rate.

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Section: Discussionsupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

et al. 2020

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Understanding the Promotion Effect of Mn on CuO/Al₂O₃ for Catalyzed HCl Oxidation to Cl₂

Tian

Wang

et al. 2020

ChemCatChem

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HCl oxidation to Cl2 catalyzed by Cu‐based catalysis is an effective way to realize the sustainable development of chlorine‐involved industries. In this work, we investigated the role of promoter Mn on CuO/Al2O3 in HCl oxidation to Cl2. The X‐ray diffraction (XRD), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM) and H2‐temperature programmed reduction (H2‐TPR) characterizations suggested that Cu could be well dispersed in the MnOx lattice and hindered the reduction of CuO due to their strong interaction. The catalyst showed an unprecedentedly stable HCl conversion rate (xHCl) of about 79 % with space time yield (STY) of 2.14 gCl2 gcat−1 h−1 in a 1000 hours test. The results of reaction kinetics suggested that the deep chlorination of catalysts was significantly inhibited under the reaction atmosphere. Density functional theory (DFT) calculations proved that the binding energy of O on CuO−MnOx/Al2O3 ternary system was significantly strengthened that overwhelmed Cl, with ΔGO (−4.12 eV) ≪ ΔGCl (‐1.75 eV), which greatly inhibited the poisoning of reactive sites by Cl*. A good correlation between experimental observations and theoretical calculations was established in this work.

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Effect of Conversion, Temperature and Feed Ratio on In₂O₃/In(OH)₃ Phase Transitions in Methanol Synthesis Catalysts: A Combined Experimental and Computational Study

Kampe,

Wesner,

Schühle

et al. 2023

ChemPlusChem

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Catalytic hydrogenation of CO2 to methanol has attracted lots of attention as it makes CO2 useable as a sustainable carbon source. This study combines theoretical calculations based on the dummy catalytic cycle model with experimental studies on the performance and degradation of Indium‐based methanol synthesis catalysts. In detail, the reversibility of phase transitions in the In2O3/In(OH)3 system under industrial methanol synthesis conditions are investigated depending on conversion, temperature and feed ratio. The dummy catalytic cycle model predicts a peculiar degradation behavior of In(OH)3 at 275°C depending on the water formed either by methanol synthesis or the competing reverse water‐gas‐shift reaction. These results were validated by dedicated experimental studies confirming the predicted trends. Moreover, X‐ray diffraction and thermogravimetric analysis analysis proved the ensuing phase transition between the indium species. Finally, the validated model is used to predict how hydrogen drop out will affect the stability of the catalyst and derive practical strategies to prevent irreversible catalyst degradation.

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Catalytic HCl oxidation reaction: Stabilizing effect of Zr-doping on CeO2 nano-rods

Cited by 38 publications

References 33 publications

sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

Understanding the Promotion Effect of Mn on CuO/Al₂O₃ for Catalyzed HCl Oxidation to Cl₂

Effect of Conversion, Temperature and Feed Ratio on In₂O₃/In(OH)₃ Phase Transitions in Methanol Synthesis Catalysts: A Combined Experimental and Computational Study

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Catalytic HCl oxidation reaction: Stabilizing effect of Zr-doping on CeO2 nano-rods

Cited by 38 publications

References 33 publications

sReactivation of CeO2‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

sReactivation of CeO2‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

Understanding the Promotion Effect of Mn on CuO/Al2O3 for Catalyzed HCl Oxidation to Cl2

Effect of Conversion, Temperature and Feed Ratio on In2O3/In(OH)3 Phase Transitions in Methanol Synthesis Catalysts: A Combined Experimental and Computational Study

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Product

Resources

About

sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

sReactivation of CeO₂‐based Catalysts in the HCl Oxidation Reaction: In situ Quantification of the Degree of Chlorination and Kinetic Modeling

Understanding the Promotion Effect of Mn on CuO/Al₂O₃ for Catalyzed HCl Oxidation to Cl₂

Effect of Conversion, Temperature and Feed Ratio on In₂O₃/In(OH)₃ Phase Transitions in Methanol Synthesis Catalysts: A Combined Experimental and Computational Study