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Cerium oxide (ceria, CeO 2−x ) has been traditionally used as a catalyst support functionalized with metal nanoparticles or synthesized with metal dopants for a variety of applications ranging from catalytic converters to solid oxide fuel cells. In a departure from these typical heterogeneous motifs, we explore the interactions of nano-CeO 2−x systems with organometallic oxidation catalysts in organic solvents. Ceria is used here both as an organically-capped colloid and as an uncapped insoluble nanopowder. Both the colloid and nanopowder act as terminal oxidants by accepting hydrogen atoms from a ruthenium Noyori–Ikariya hydride complex. To our knowledge, this is the first demonstration that CeO 2−x can oxidize an organometallic hydride. Building on this concept, we show the uncapped CeO 2−x powder also acts as the terminal acceptor in catalytic alcohol dehydrogenation reactions, utilizing iridium pyridine sulfonamide catalysts under anaerobic and aerobic conditions. The coupling of homogeneous oxidation catalysts with cerium oxide demonstrates the versatility of CeO 2−x and a bridging of concepts in homogeneous and heterogeneous catalysis.
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Ultralow Loading Ruthenium on Alumina Monoliths for Facile, Highly Recyclable Reduction of p-Nitrophenol
The pervasive use of toxic nitroaromatics in industrial processes and their prevalence in industrial effluent has motivated the development of remediation strategies, among which is their catalytic reduction to the less toxic and synthetically useful aniline derivatives. While this area of research has a rich history with innumerable examples of active catalysts, the majority of systems rely on expensive precious metals and are submicron- or even a few-nanometer-sized colloidal particles. Such systems provide invaluable academic insight but are unsuitable for practical application. Herein, we report the fabrication of catalysts based on ultralow loading of the semiprecious metal ruthenium on 2–4 mm diameter spherical alumina monoliths. Ruthenium loading is achieved by atomic layer deposition (ALD) and catalytic activity is benchmarked using the ubiquitous para-nitrophenol, NaBH4 aqueous reduction protocol. Recyclability testing points to a very robust catalyst system with intrinsic ease of handling.
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- Award ID(s):
- 1808625
- PAR ID:
- 10283489
- Date Published:
- Journal Name:
- Catalysts
- Volume:
- 11
- Issue:
- 2
- ISSN:
- 2073-4344
- Page Range / eLocation ID:
- 165
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/catal11020165
