Reuseable Monolithic Nanoporous Graphite-supported Nanocatalysts (Fe, Au, Pt, Pd, Ni, and Rh) from Pyrolysis and Galvanic Transmetalation of Ferrocene-based Polyamide Aerogels


Polyamide aerogels with ferrocene as a monomer repeat unit were prepared in one step from ferrocene dicarboxylic acid and tris(4-isocyanatophenyl)methane. Pyrolysis at ≥800 °C yielded nanoporous carbons doped throughout with crystallites of α-Fe (about 50 nm in diameter), which in turn were shrouded in graphitic ribbons (<30 graphene layers thick). Transmetalation was carried out with aqueous solutions of Au, Pt, Pd, Rh, and Ni salts, via a path akin to galvanic corrosion, whereas graphitic ribbons separated anodes (α-Fe particles) from cathodes (defects along the ribbons). The new metallic phases formed clusters of smaller crystallites (10-20 nm in diameter) on the graphitic ribbons, leaving behind empty cage-like formations previously occupied by the Fe(0) nanoparticles. All metal-doped carbons were monolithic and over 85% porous. Catalytic activity was demonstrated with the oxidation of benzyl alcohol to benzaldehyde catalyzed with carbon-supported Au or Pt, the reduction of nitrobenzene by hydrazine to aniline catalyzed with carbon-supported Fe, and two Heck coupling reactions of iodobenzene with styrene or butyl acrylate, catalyzed with carbon-supported Pd. The distinguishing feature of those catalysts was that they could be just picked up, for example, with a pair of tweezers, and redeployed in a new reaction mixture immediately, thus bypassing less efficient recovery processes like filtration.



Keywords and Phrases

Aerogels; Catalysis; Catalyst Activity; Catalytic Oxidation; Chemical Reactions; Crystallites; Electrodes; Nickel; Organometallics; Platinum; Pyrolysis; Rhodium; Solutions; Styrene; Carbon-supported Pd; Dicarboxylic Acid; Galvanic Corrosion; Heck Coupling Reaction; Metallic Phasis; Nanoporous Carbons; Reaction Mixture; Recovery Process; Palladium

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Article - Journal

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© 2016 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jul 2016