Methane Combustion Mechanism on Supported Pd Catalysts Revisited: In Situ Spectroscopic Approach
- 1Faculty of Chemistry, Jagiellonian University, ul. Gronostajowa 2, 30-387 Kraków, Poland
- 2Małopolska Centre of Biotechnology, Jagiellonian University, ul. Gronostajowa 7A, 30-387 Kraków, Poland
- 3Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2R3, Canada
Abstract
Palladium supported on oxide carriers is among the most active catalyst systems for methane combustion, yet the role of the support in governing Pd speciation and reaction pathways remains incompletely resolved. Here, ultra-low-loading Pd/Al2O3, Pd/SiO2, Pd/TiO2, Pd/ZrO2 and Pd/CeO2 catalysts were investigated by quantitative CO-FTIR site counting, in situ DRIFTS using CH4, CO and HCOOH probe molecules, and fixed-bed kinetic testing. CO-FTIR revealed support-dependent populations of CO-accessible Pd centres, with experimentally determined CO absorption coefficients providing the basis for their quantification. The low apparent activation energies and convergence of the high-temperature rates indicate a substantial contribution from mass transport, limiting the kinetic comparison to apparent catalytic performance. Across CH4, HCOOH and CO sorption experiments, methane oxidation is consistent with a proposed methoxy → formate → carbonate sequence whose extent and thermal stability are support-dependent. CeO2 and ZrO2 enable carbonate formation and removal, Al2O3 favours carbonate retention, and SiO2 shows no reliably detectable chemisorbed intermediates. These findings link quantitative Pd site counting with a support-resolved mechanistic hierarchy, suggesting that efficient methane combustion benefits from both dispersed PdO/Pd+ centres and a redox-active support that promotes oxygenate turnover rather than surface trapping.
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BibTeX
@article{chrzan2026methane,
title = {{Methane Combustion Mechanism on Supported Pd Catalysts Revisited: In Situ Spectroscopic Approach}},
author = {Magdalena Chrzan and Roman Jędrzejczyk and Joanna Profic-Paczkowska and Joseph Mmbaga and Robert E. Hayes},
journal = {Catalysts},
year = {2026},
month = oct,
doi = {10.3390/catal16100893},
url = {https://www.mdpi.com/2073-4344/16/10/893},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Methane Combustion Mechanism on Supported Pd Catalysts Revisited: In Situ Spectroscopic Approach
AU - Magdalena Chrzan
AU - Roman Jędrzejczyk
AU - Joanna Profic-Paczkowska
AU - Joseph Mmbaga
AU - Robert E. Hayes
PY - 2026
DA - 2026/10/08
JO - Catalysts
DO - 10.3390/catal16100893
UR - https://www.mdpi.com/2073-4344/16/10/893
AB - Palladium supported on oxide carriers is among the most active catalyst systems for methane combustion, yet the role of the support in governing Pd speciation and reaction pathways remains incompletely resolved. Here, ultra-low-loading Pd/Al2O3, Pd/SiO2, Pd/TiO2, Pd/ZrO2 and Pd/CeO2 catalysts were investigated by quantitative CO-FTIR site counting, in situ DRIFTS using CH4, CO and HCOOH probe molecules, and fixed-bed kinetic testing. CO-FTIR revealed support-dependent populations of CO-accessible Pd centres, with experimentally determined CO absorption coefficients providing the basis for their quantification. The low apparent activation energies and convergence of the high-temperature rates indicate a substantial contribution from mass transport, limiting the kinetic comparison to apparent catalytic performance. Across CH4, HCOOH and CO sorption experiments, methane oxidation is consistent with a proposed methoxy → formate → carbonate sequence whose extent and thermal stability are support-dependent. CeO2 and ZrO2 enable carbonate formation and removal, Al2O3 favours carbonate retention, and SiO2 shows no reliably detectable chemisorbed intermediates. These findings link quantitative Pd site counting with a support-resolved mechanistic hierarchy, suggesting that efficient methane combustion benefits from both dispersed PdO/Pd+ centres and a redox-active support that promotes oxygenate turnover rather than surface trapping.
SN - 2073-4344
ER -