Solid base catalysed 5-HMF oxidation to 2,5-FDCA over Au/hydrotalcites:fact or fiction?

Abstract

Nanoparticulate gold has emerged as a promising catalyst for diverse mild and efficient selective aerobic oxidations. However, the mechanism of such atom-economical transformations, and synergy with functional supports, remains poorly understood. Alkali-free Mg-Al hydrotalcites are excellent solid base catalysts for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furan dicarboxylic acid (FDCA), but only in concert with high concentrations of metallic gold nanoparticles. In the absence of soluble base, competitive adsorption between strongly-bound HMF and reactively-formed oxidation intermediates site-blocks gold. Aqueous NaOH dramatically promotes solution phase HMF activation, liberating free gold sites able to activate the alcohol function within the metastable 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) reactive intermediate. Synergistic effects between moderate strength base sites within alkali-free hydrotalcites and high gold surface concentrations can afford highly selective and entirely heterogeneous catalysts for aqueous phase aldehyde and alcohol cascade oxidations pertinent to biomass transformation.

Publication DOI: https://doi.org/10.1039/c5sc00854a
Divisions: College of Engineering & Physical Sciences > Energy and Bioproducts Research Institute (EBRI)
College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences
Additional Information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Funding: EPSRC (EP/G0075944); Leadership Fellowship; Studentship support; Royal Society for an Industry Fellowship; Diamond Light Source for a beam time award (SP8688).
Uncontrolled Keywords: Chemistry(all)
Full Text Link: http://pubs.rsc ... 4A#!divAbstract
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015-08
Published Online Date: 2015-06-08
Authors: Ardemani, Leandro
Cibin, Giannantonio
Dent, Andrew J.
Isaacs, Mark A.
Kyriakou, Georgios
Lee, Adam F. (ORCID Profile 0000-0002-2153-1391)
Parlett, Christopher M.A. (ORCID Profile 0000-0002-3651-7314)
Parry, Stephen A.
Wilson, Karen (ORCID Profile 0000-0003-4873-708X)

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