Controlled selectivity for palladium catalysts using self-assembled monolayers

The selective reaction of one part of a bifunctional molecule is a fundamental challenge in heterogeneous catalysis and for many processes including the conversion of biomass-derived intermediates. Selective hydrogenation of unsaturated epoxides to saturated epoxides is particularly difficult given...

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Bibliographic Details
Published in:	Nature materials Vol. 9; no. 10; pp. 853 - 858
Main Authors:	Medlin, J. William, Marshall, Stephen T, O’Brien, Marykate, Oetter, Brittany, Corpuz, April, Richards, Ryan M, Schwartz, Daniel K
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 01-10-2010 Nature Publishing Group
Subjects:	639/301/119/544 639/301/299 639/301/923/966 Biomass Biomaterials Carbon monoxide Catalysis Catalysts Chemical engineering Chemical reactions Chemistry and Materials Science Coatings Condensed Matter Physics Hydrocarbons Hydrogenation Materials Science Nanotechnology Optical and Electronic Materials Palladium Platinum Poisoning Poisons Selectivity Self-assembled monolayers Sulfur Sulphur
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Summary:	The selective reaction of one part of a bifunctional molecule is a fundamental challenge in heterogeneous catalysis and for many processes including the conversion of biomass-derived intermediates. Selective hydrogenation of unsaturated epoxides to saturated epoxides is particularly difficult given the reactivity of the strained epoxide ring, and traditional platinum group catalysts show low selectivities. We describe the preparation of highly selective Pd catalysts involving the deposition of n -alkanethiol self-assembled monolayer (SAM) coatings. These coatings improve the selectivity of 1-epoxybutane formation from 1-epoxy-3-butene on palladium catalysts from 11 to 94% at equivalent reaction conditions and conversions. Although sulphur species are generally considered to be indiscriminate catalyst poisons, the reaction rate to the desired product on a catalyst coated with a thiol was 40% of the rate on an uncoated catalyst. Interestingly the activity decreased for less-ordered SAMs with shorter chains. The behaviour of SAM-coated catalysts was compared with catalysts where surface sites were modified by carbon monoxide, hydrocarbons or sulphur atoms. The results suggest that the SAMs restrict sulphur coverage to enhance selectivity without significantly poisoning the activity of the desired reaction. The selective reaction of one part of a bifunctional molecule is a fundamental challenge in heterogeneous catalysis. Modifying a supported palladium catalyst with alkanethiol self-assembled monolayers is now shown to increase selectivity for the hydrogenation of 1-epoxy-3-butane to 1-epoxybutane.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	1476-1122 1476-4660
DOI:	10.1038/nmat2849