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Lehrstuhl für Makromolekulare Stoffe und Faserchemie |
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Prof. Dr. Michael R. Buchmeiser |
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| Nowadays, the immobilization of metal nanoparticles on micro- and mesoporous polymeric monoliths is an attractive
topic. Originally developed for applications in separation science polymeric monoliths now entered the field of
heterogeneous catalysis. So far, ROMP-derived supports have been employed in catalysis as continuous-flow devices and
disk-shaped supports for the immobilization of well-defined transition metal complexes such as Pd-based Heck catalysts
as well as Schrock and Grubbs catalysts. Pt(0) and Pd(0) metal nanoparticles were selectively immobilized inside the open pores of electron-beam (EB) and ROMP-derived monoliths. The epoxy groups in pores of >7 nm were hydrolyzed by using poly(styrenesulfonic acid) (Mw= 69 400 gmol-1, PDI=2.4). The remaining epoxy groups inside pores of <7 nm were used for a grafting of N,N-di-2-pyridyl based ligands for the stabilization of metal nanoparticles. Finally, these selectively functionalized pores were used for the immobilization of Pd2+and Pt4+, respectively. After reduction, metal nanoparticles 2 nm in diameter was formed (Figure 1). The palladium-nanoparticle-loaded monoliths were used in both Heck- and Suzuki-type coupling reactions achieving high turnover numbers up to 167 000. .jpg) .jpg) Figure 1. TEM micrographs of (a) Pd and (b) Pt nanoparticles formed within the small pores of a monolith. Alternatively, Pt (0) and Pd (0) nanoparticles were immobilized within the pores of ROMP-derived monoliths in which particularly the unsaturated backbone provides stabilization, thereby completely avoiding the use of any other organic ligand. The Pt-nanoparticle-loaded monoliths were used in the hydrosilylation of olefins under continuous flow conditions (Figure 2) resulting in constant product formation in 98% yield for 8 h.  Figure 2. Hydrosilylation of 1-octene on a Pt-nanoparticles loaded monolith under continuous conditions. Current work focuses on the reduction of CO2 under continuous conditions employing polymeric monolith supported transition metal nanoparticles. Selected Publications [1] J. O. Krause, K. Wurst, O. Nuyken, M. R. Buchmeiser, Chem. Eur. J. 2004, 10, 777-784. [2] L. Yang, M. Mayr, K. Wurst, M. R. Buchmeiser, Chem. Eur. J. 2004, 10, 5761-5770. [3] M. Mayr, D. Wang, R. Kröll, N. Schuler, S. Prühs, A. Fürstner, M. R. Buchmeiser, Adv. Synth. Catal. 2005, 347, 484-492. [4] D. Wang, R. Kröll, M. Mayr, K. Wurst, M. R. Buchmeiser, Adv. Synth. Catal. 2006, 348, 1567-1579. [5] M. R. Buchmeiser, Chem. Rev. 2009, 109, 303-321. [6] R. Bandari, Th. Höche, A. Prager, K. Dirnberger, M. R. Buchmeiser, Chem. Eur. J., 2010, 16, 4650-4658. [7] R. Bandari, A. Prager, T. Höche, M. R. Buchmeiser, Arkivoc 2011, 2011, 71. [8] R. Bandari, M. R. Buchmeiser, Catal. Sci. Tech. 2012, 2, 220. 
All research topics |
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Letzte Änderung 12.04.2012
( JP) | © Universität Stuttgart |
Impressum |