Raman Spectroscopy Applied to Monitor Furfural Liquid-PhaseOxidation Catalyzed by Supported Gold Nanoparticles

摘要

Inthis paper, Raman spectroscopy is used as a tool to study themechanism of furfural oxidation using H O asa reagent on gold nanoparticles (NPs) supported on hydrotalcites (HTs).This reaction was repeated, under the same conditions, but with differentreaction times in a parallel multireactor system. The reaction mediawere analyzed using a macro device associated with a multipass cellpermitting us to enhance the Raman signal by reflecting the laserbeam 3 times. The Raman spectra showed the conversion of furfuralto furoic acid without any chemical intermediates, thus privileginga direct pathway. Combining the results of the catalytic tests withthose of the Raman study, the mechanism of furfural oxidation to furoicacid using gold NPs supported on HTs is proposed. The key points ofthis mechanism were found to be as follows: (i) the formation of a base, originating from the Mg leaching from the HTsupport, initiates the oxidation of furfural by deprotonation; (ii)H O used as a reagent in the solution increasesthe catalytic activity by its dissociation to form hydroxide ions;and (iii) the oxidation of furfural occurs on the surface of goldNPs and leads to higher furoic acid yield.