Efficient Conversion of Glycerol into High Value‐Added Chemicals by Partial Oxidation

Abstract

Glycerol can be effectively converted to glyceric acid, a high value‐added pharmaceutical raw material, through its partial oxidation over an Au/Al2O3 catalyst under strongly basic conditions. The factors important for the highly selective production of glyceric acid were investigated experimentally. It was clarified that NaOH was involved in the glycerol activation step to a glycerol alkoxide intermediate (2, 3‐dihydroxypropoxide) in the liquid phase, then glyceric acid was formed by OOH species derived from O2 on an Au catalyst in the partial oxidation step. We have newly discovered the concerted effect of NaOH and O2 in different reaction steps.

Comprehensive Study on Kinetic Modeling of Liquid-Phase Selective Oxidation Using Au-Supported Catalysts for Efficient Production of Value-Added Chemicals from Glycerol

“…In our previous study, 7 GL oxidation experiments were carried out under conditions in which the alkali concentration was varied across a range of NaOH/GL molar ratio of 0.0−6.0 (solution pH 5.9−13.9), and O 2 partial pressure was varied across a range of 0.38−0.93 MPa. In the current study, additional experiments were conducted under a wider range of O 2 partial pressures and newly varied temperature conditions to investigate the effects of operating factors in more detail.…”

“…The catalyst preparation and experimental methods were the same as given in the previous study. 7 The main points are summarized below and detailed in the Supporting Information.…”

“…In the current study, the alkaline condition was kept constant (solution pH 13.8), the O 2 partial pressure (P Od 2 ) was set at 0.00 or 0.93 MPa, and the temperature was varied across the range of 40−70 °C. In the analysis, as in the previous study, 7 the concentrations of the reactant GL and products in solution samples were determined by high-performance liquid chromatography (CBM-20A; Shimadzu, Kyoto, Japan). In the present study, the pH of the solution samples was also measured by a pH meter (F-71, Horiba, Kyoto, Japan).…”

“…The following reaction steps, as proposed in our previous report, 7 were considered as parts of the reaction mechanism:…”

“…In this study, a new kinetic model was developed based on the reaction mechanism proposed in our previous report 7 and on the assumption that several reactive oxygen species involved in the reaction are generated at several active sites on the catalyst. The model was applied to the experimental results of GL oxidation under various conditions to estimate the model constants.…”