Dynamic Disproportionation Shapes Ga Sites in Silica-Supported Propane Dehydrogenation Catalysts
13 affiliations
- 1Department of Mechanical and Process Engineering
- 2ETH Zürich
- 3RAS
- 4Department of Chemical Sciences
- 5University of Padova
- 6Centre de RMN à hauts champs de Lyon
- 7UMR 5082 (CNRS, ENS Lyon, Université Lyon
- 8Department of Chemistry and Applied Biosciences
- 9Cochin University of Science and Technology
- 10Departament de Química
- 11Universitat Autònoma de Barcelona
- 12CEMHTI UPR3079
- 13Université d’Orléans
Abstract
Ga is a key component of commercial propane dehydrogenation (PDH) catalysts. The regeneration of those catalysts involves oxidation and reduction cycles, the latter typically under H2 at about 550–650 °C. However, the structural evolution of Ga3+ sites under those strongly reducing conditions is underexplored. Here, we monitored the transformations of Ga3+ sites dispersed on a SiO2 support under H2 at 650 °C. The results show that this treatment generates metastable ºSiOGa1+ sites that disproportionate to Ga0 and Ga3+ sites. The formed Ga0 species react with surface silanols, regenerating ºSiOGa1+ sites, and with water formed during the reduction of Ga3+ to Ga1+, ultimately yielding large crystalline particles of k-Ga2O3. In addition, an overall loss of Ga from the catalyst is observed and attributed to the formation of Ga0 and volatile Ga2O. The Lewis acidity of dispersed Ga3+ decreases when it interacts with weakly Lewis-basic ºSiOGa1+ motifs. All of these processes associated with ºSiOGa1+ sites decrease the number of dispersed Ga3+ sites and are therefore detrimental for PDH activity, except that dispersed Ga3+ sites formed from disproportionation of ºSiOGa1+ sites likely have increased strain, beneficial for PDH activity. While H2 treatment alone has a negative impact on the catalyst’s PDH activity and propene selectivity, an oxidative air treatment of the reduced catalyst terminates disproportionation dynamics by oxidizing Ga0 and increases the Ga-based activity relative to both the reduced and fresh catalysts. These findings suggest that the disproportionation of Ga1+ species under an H2 atmosphere appreciably affects gallium speciation, loading, and catalytic performance.
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BibTeX
@misc{chen2026dynamic,
title = {{Dynamic Disproportionation Shapes Ga Sites in Silica-Supported Propane Dehydrogenation Catalysts}},
author = {Zixuan Chen and Melis Yarar and Nora K. Zimmerli and Alexander I. Serykh and Mattia Cattelan and Stefano Agnoli and Agnieszka Kierzkowska and Yi-Hsuan Wu and David Gajan and Alexander V. Yakimov and Marcel Janák and Praveen Chandramathy Surendran and Aleix Comas-Vives and Christophe Copéret and Pierre Florian and Paula M. Abdala and Christoph R. Müller and Alexey Fedorov},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15011003/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011003/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Dynamic Disproportionation Shapes Ga Sites in Silica-Supported Propane Dehydrogenation Catalysts
AU - Zixuan Chen
AU - Melis Yarar
AU - Nora K. Zimmerli
AU - Alexander I. Serykh
AU - Mattia Cattelan
AU - Stefano Agnoli
AU - Agnieszka Kierzkowska
AU - Yi-Hsuan Wu
AU - David Gajan
AU - Alexander V. Yakimov
AU - Marcel Janák
AU - Praveen Chandramathy Surendran
AU - Aleix Comas-Vives
AU - Christophe Copéret
AU - Pierre Florian
AU - Paula M. Abdala
AU - Christoph R. Müller
AU - Alexey Fedorov
PY - 2026
DA - 2026/10/25
PB - ChemRxiv
DO - 10.26434/chemrxiv.15011003/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011003/v1
AB - Ga is a key component of commercial propane dehydrogenation (PDH) catalysts. The regeneration of those catalysts involves oxidation and reduction cycles, the latter typically under H2 at about 550–650 °C. However, the structural evolution of Ga3+ sites under those strongly reducing conditions is underexplored. Here, we monitored the transformations of Ga3+ sites dispersed on a SiO2 support under H2 at 650 °C. The results show that this treatment generates metastable ºSiOGa1+ sites that disproportionate to Ga0 and Ga3+ sites. The formed Ga0 species react with surface silanols, regenerating ºSiOGa1+ sites, and with water formed during the reduction of Ga3+ to Ga1+, ultimately yielding large crystalline particles of k-Ga2O3. In addition, an overall loss of Ga from the catalyst is observed and attributed to the formation of Ga0 and volatile Ga2O. The Lewis acidity of dispersed Ga3+ decreases when it interacts with weakly Lewis-basic ºSiOGa1+ motifs. All of these processes associated with ºSiOGa1+ sites decrease the number of dispersed Ga3+ sites and are therefore detrimental for PDH activity, except that dispersed Ga3+ sites formed from disproportionation of ºSiOGa1+ sites likely have increased strain, beneficial for PDH activity. While H2 treatment alone has a negative impact on the catalyst’s PDH activity and propene selectivity, an oxidative air treatment of the reduced catalyst terminates disproportionation dynamics by oxidizing Ga0 and increases the Ga-based activity relative to both the reduced and fresh catalysts. These findings suggest that the disproportionation of Ga1+ species under an H2 atmosphere appreciably affects gallium speciation, loading, and catalytic performance.
ER -