Quasi-homogeneous oxidation of glycerol by unsupported gold nanoparticles in the liquid phase.
A quasi-homogeneous solution of gold nanoparticles prepared by the Turkevich method was used as an unconventional catalyst in the oxidation of glycerol (GLY) in the liquid phase. The highest obtained conversion was 100 % after 3 h of reaction at 100 °C under an oxygen atmosphere (5 bar). The main products were glyceric, glycolic, formic, tartronic, and oxalic acid with selectivities of 28, 36, 25, 9, and 2 %, respectively. Traces of hydroxypyruvic and acetic acid were also detected (combined selectivities below 1 %). To elucidate the reaction mechanism and specify the role of gold nanoparticles in the oxidation process, a series of experiments under various reaction conditions were carried out. The effect of reaction temperature, oxygen pressure, gold concentration, and GLY/base molar ratio was investigated. All catalytic results were systematically compared to the corresponding noncatalytic base-induced transformations (blank tests). Such an approach allowed us to separate and clarify the respective driving parameters for the transformation of GLY (presence of a base and activity of the gold catalyst). The reaction mechanism comprised a series of oxidation and C-C cleavage reactions, whereas additional oxidation-reduction reactions (of the Cannizzaro type) could also occur in the presence of the base.
Faculty of Chemical Engineering and Technology, Cracow University of Technology, Ul. Warszawska 24, 31-155 Cracow, Poland. eskrzynska@pk.edu.pl
Elżbieta
E
Skrzyńska
Jamal
J
Ftouni
Jean-Sébastien
JS
Girardon
Mickaël
M
Capron
Louise
L
Jalowiecki-Duhamel
Jean-François
JF
Paul
Franck
F
Dumeignil
D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D005990:Glycerol / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011312:Pressure; D013193:Stainless Steel / Q000737:chemistry; D013696:Temperature
D000447:Aldehydes; D013193:Stainless Steel; D006046:Gold; D005990:Glycerol; D010100:Oxygen