Water Inhibition in Methane Oxidation over Alumina Supported Palladium Catalysts
(2019) In Journal of Physical Chemistry C 123(42). p.25724-25737- Abstract
In situ diffuse reflectance infrared Fourier transform spectroscopy has been used to distinguish surface hydroxyl groups on Al2O3 and PdO/Al2O3 model catalysts calcined at 500-900 °C. Employing the operando approach, the formation of surface hydroxyl groups has been correlated to the methane oxidation activity for PdO/Al2O3 catalysts using a PdO powder sample as reference. The results show that the alumina support stabilizes active PdO particles leading to enhanced apparent methane turnover frequency (TOF), which decreases slowly in dry conditions due to alumina hydroxylation. Wet conditions cause severe hydroxylation that is detrimental for the methane TOF. The... (More)
In situ diffuse reflectance infrared Fourier transform spectroscopy has been used to distinguish surface hydroxyl groups on Al2O3 and PdO/Al2O3 model catalysts calcined at 500-900 °C. Employing the operando approach, the formation of surface hydroxyl groups has been correlated to the methane oxidation activity for PdO/Al2O3 catalysts using a PdO powder sample as reference. The results show that the alumina support stabilizes active PdO particles leading to enhanced apparent methane turnover frequency (TOF), which decreases slowly in dry conditions due to alumina hydroxylation. Wet conditions cause severe hydroxylation that is detrimental for the methane TOF. The hydroxylation follows two different routes, i.e., spillover of hydrogen-containing species to the PdO-Al2O3 boundary and/or the close proximity of the supported PdO particles and under wet conditions also dissociation of gas phase water on the entire alumina surface. Both hydroxylation routes obey varying kinetics such that near saturation is reached quickly (minutes) followed by a continuous slow growth for prolonged exposure times (hours). At low temperatures, inhibition of palladium active sites on the rim of the PdO particles close to alumina seems to be of particular importance for the observed detrimental effect of water, whereas water induced morphological changes (no sintering observed) of the PdO particles play a minor role.
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- author
- Velin, Peter ; Ek, Martin LU ; Skoglundh, Magnus ; Schaefer, Andreas ; Raj, Agnes ; Thompsett, David ; Smedler, Gudmund and Carlsson, Per Anders
- organization
- publishing date
- 2019
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Physical Chemistry C
- volume
- 123
- issue
- 42
- pages
- 25724 - 25737
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- scopus:85073221729
- ISSN
- 1932-7447
- DOI
- 10.1021/acs.jpcc.9b07606
- project
- Understanding of Catalysts for Climate-Neutral Chemicals by in situ Transmission Electron Microscopy Characterization
- language
- English
- LU publication?
- yes
- id
- 4363bc6b-167b-460a-95e1-4efbc09a16a2
- date added to LUP
- 2019-10-25 12:05:23
- date last changed
- 2022-04-18 18:19:35
@article{4363bc6b-167b-460a-95e1-4efbc09a16a2, abstract = {{<p>In situ diffuse reflectance infrared Fourier transform spectroscopy has been used to distinguish surface hydroxyl groups on Al<sub>2</sub>O<sub>3</sub> and PdO/Al<sub>2</sub>O<sub>3</sub> model catalysts calcined at 500-900 °C. Employing the operando approach, the formation of surface hydroxyl groups has been correlated to the methane oxidation activity for PdO/Al<sub>2</sub>O<sub>3</sub> catalysts using a PdO powder sample as reference. The results show that the alumina support stabilizes active PdO particles leading to enhanced apparent methane turnover frequency (TOF), which decreases slowly in dry conditions due to alumina hydroxylation. Wet conditions cause severe hydroxylation that is detrimental for the methane TOF. The hydroxylation follows two different routes, i.e., spillover of hydrogen-containing species to the PdO-Al<sub>2</sub>O<sub>3</sub> boundary and/or the close proximity of the supported PdO particles and under wet conditions also dissociation of gas phase water on the entire alumina surface. Both hydroxylation routes obey varying kinetics such that near saturation is reached quickly (minutes) followed by a continuous slow growth for prolonged exposure times (hours). At low temperatures, inhibition of palladium active sites on the rim of the PdO particles close to alumina seems to be of particular importance for the observed detrimental effect of water, whereas water induced morphological changes (no sintering observed) of the PdO particles play a minor role.</p>}}, author = {{Velin, Peter and Ek, Martin and Skoglundh, Magnus and Schaefer, Andreas and Raj, Agnes and Thompsett, David and Smedler, Gudmund and Carlsson, Per Anders}}, issn = {{1932-7447}}, language = {{eng}}, number = {{42}}, pages = {{25724--25737}}, publisher = {{The American Chemical Society (ACS)}}, series = {{Journal of Physical Chemistry C}}, title = {{Water Inhibition in Methane Oxidation over Alumina Supported Palladium Catalysts}}, url = {{http://dx.doi.org/10.1021/acs.jpcc.9b07606}}, doi = {{10.1021/acs.jpcc.9b07606}}, volume = {{123}}, year = {{2019}}, }