Arras, Jürgen ; Paki, Elisabeth ; Roth, Christina ; Radnik, Jörg ; Lucas, Martin ; Claus, Peter (2010)
How a Supported Metal Is Influenced by an Ionic Liquid: In-Depth Characterization of SCILL-Type Palladium Catalysts and Their Hydrogen Adsorption.
In: The Journal of Physical Chemistry C, 114 (23)
doi: 10.1021/jp1016196
Article, Bibliographie
Abstract
A novel approach to tremendously influence the gas adsorption behavior of heterogeneous metal catalysts consists of adding a small quantity of an ionic liquid during the catalyst synthesis yielding a supported catalyst with an ionic liquid layer (SCILL). Herein, SCILL-type catalysts derived from silica-supported palladium were characterized by means of ICP-OES, TPR, X-ray absorption spectroscopy (XANES/EXAFS), X-ray photoelectron spectroscopy (XPS), hydrogen pulse chemisorption, and differential scanning hydrogen adsorption calorimetry. EXAFS analysis of SCILL-type palladium catalysts did not indicate significant changes in the bulk properties of Pd compared to untreated Pd/SiO₂, the results are in good agreement with metallic Pd. XPS analysis revealed a more oxidized Pd surface if Pd/SiO₂ was treated with ionic liquids. In the case of [BMIM][N(CN)₂], Pd(II) species were present in part indicating a complexation of palladium by [N(CN)₂]⁻. Hydrogen uptakes determined by pulse chemisorption varied between 38 and 609 μmol gPd⁻¹ depending on the chosen IL, IL content, and temperature and were decreased in comparison to Pd/SiO₂ without IL. The initial heats of hydrogen adsorption were also affected in the presence of ionic liquids and were lowered compared to those of the untreated Pd/SiO₂. Mechanisms showing how the ionic liquids interact with the active palladium site are proposed and might be in summary interpreted as a ligand effect by the ionic liquid similar to the influence of second metals in bimetallic catalysts.
| Item Type: | Article |
|---|---|
| Erschienen: | 2010 |
| Creators: | Arras, Jürgen ; Paki, Elisabeth ; Roth, Christina ; Radnik, Jörg ; Lucas, Martin ; Claus, Peter |
| Type of entry: | Bibliographie |
| Title: | How a Supported Metal Is Influenced by an Ionic Liquid: In-Depth Characterization of SCILL-Type Palladium Catalysts and Their Hydrogen Adsorption |
| Language: | English |
| Date: | 24 May 2010 |
| Journal or Publication Title: | The Journal of Physical Chemistry C |
| Volume of the journal: | 114 |
| Issue Number: | 23 |
| DOI: | 10.1021/jp1016196 |
| Abstract: | A novel approach to tremendously influence the gas adsorption behavior of heterogeneous metal catalysts consists of adding a small quantity of an ionic liquid during the catalyst synthesis yielding a supported catalyst with an ionic liquid layer (SCILL). Herein, SCILL-type catalysts derived from silica-supported palladium were characterized by means of ICP-OES, TPR, X-ray absorption spectroscopy (XANES/EXAFS), X-ray photoelectron spectroscopy (XPS), hydrogen pulse chemisorption, and differential scanning hydrogen adsorption calorimetry. EXAFS analysis of SCILL-type palladium catalysts did not indicate significant changes in the bulk properties of Pd compared to untreated Pd/SiO₂, the results are in good agreement with metallic Pd. XPS analysis revealed a more oxidized Pd surface if Pd/SiO₂ was treated with ionic liquids. In the case of [BMIM][N(CN)₂], Pd(II) species were present in part indicating a complexation of palladium by [N(CN)₂]⁻. Hydrogen uptakes determined by pulse chemisorption varied between 38 and 609 μmol gPd⁻¹ depending on the chosen IL, IL content, and temperature and were decreased in comparison to Pd/SiO₂ without IL. The initial heats of hydrogen adsorption were also affected in the presence of ionic liquids and were lowered compared to those of the untreated Pd/SiO₂. Mechanisms showing how the ionic liquids interact with the active palladium site are proposed and might be in summary interpreted as a ligand effect by the ionic liquid similar to the influence of second metals in bimetallic catalysts. |
| Divisions: | 11 Department of Materials and Earth Sciences > Material Science > Erneuerbare Energien 07 Department of Chemistry 07 Department of Chemistry > Ernst-Berl-Institut > Fachgebiet Technische Chemie 07 Department of Chemistry > Ernst-Berl-Institut > Fachgebiet Technische Chemie > Technische Chemie II 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences |
| Date Deposited: | 12 Sep 2011 05:30 |
| Last Modified: | 05 Mar 2013 09:54 |
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