Steffan, Martin ; Klasovsky, Florian ; Arras, Jürgen ; Roth, Christina ; Radnik, Jörg ; Hofmeister, Herbert ; Claus, Peter (2008)
Carbon-carbon double bond versus carbonyl group hydrogenation: controlling the intramolecular selectivity with polyaniline-supported platinum catalysts.
In: Advanced Synthesis & Catalysis, 350 (9)
doi: 10.1002/adsc.200800035
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI-supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition-precipitation of H₂PtCl₆ onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol-method). The PANI-supported platinum catalysts were applied in the selective hydrogenation of the α,β-unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO₂), alumina (Al₂O₃), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO₂ on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the β-PtO₂ form) which is able to efficiently hydrogenate the conjugated C=C bond of citral (selectivity to citronellal=87%), whereas reduction of the C=O group occurs with polyaniline-supported platinum (selectivity to geraniol/nerol=78%) prepared via the sol-method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated C=C or C=O group is not only particularly useful for the selective hydrogenation of α,β-unsaturated aldehydes but also unveils the great potential of conducting polymer-supported precious metals in the field of hitherto barely investigated chemical catalysis.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2008 |
| Autor(en): | Steffan, Martin ; Klasovsky, Florian ; Arras, Jürgen ; Roth, Christina ; Radnik, Jörg ; Hofmeister, Herbert ; Claus, Peter |
| Art des Eintrags: | Bibliographie |
| Titel: | Carbon-carbon double bond versus carbonyl group hydrogenation: controlling the intramolecular selectivity with polyaniline-supported platinum catalysts. |
| Sprache: | Englisch |
| Publikationsjahr: | 9 Juni 2008 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Advanced Synthesis & Catalysis |
| Jahrgang/Volume einer Zeitschrift: | 350 |
| (Heft-)Nummer: | 9 |
| DOI: | 10.1002/adsc.200800035 |
| Kurzbeschreibung (Abstract): | The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI-supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition-precipitation of H₂PtCl₆ onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol-method). The PANI-supported platinum catalysts were applied in the selective hydrogenation of the α,β-unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO₂), alumina (Al₂O₃), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO₂ on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the β-PtO₂ form) which is able to efficiently hydrogenate the conjugated C=C bond of citral (selectivity to citronellal=87%), whereas reduction of the C=O group occurs with polyaniline-supported platinum (selectivity to geraniol/nerol=78%) prepared via the sol-method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated C=C or C=O group is not only particularly useful for the selective hydrogenation of α,β-unsaturated aldehydes but also unveils the great potential of conducting polymer-supported precious metals in the field of hitherto barely investigated chemical catalysis. |
| Freie Schlagworte: | Adams catalyst • citral hydrogenation • platinum catalyst • polyaniline |
| Zusätzliche Informationen: | Published Online: 9. Mai 2008 |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Erneuerbare Energien 07 Fachbereich Chemie 07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Technische Chemie 07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Technische Chemie > Technische Chemie II 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften |
| Hinterlegungsdatum: | 20 Mär 2009 08:48 |
| Letzte Änderung: | 05 Mär 2013 09:18 |
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