Selective oxidation of glycerol in a base-free aqueous solution: A short review

Abstract

Catalytic transformation of glycerol to value-added products has attracted the attention of scientists all over the world. Among various transformations, selective oxidation of glycerol with molecular oxygen to dihydroxyacetone, glyceric acid, glyceraldehydes, and tartronic acid is challenging both from the viewpoint of academic research and industrial application. Herein, we review the recent progresses in the selective oxidation of glycerol under base-free conditions. Those catalysts widely reported for the selective oxidation of the terminal hydroxyl and secondary hydroxyl groups in glycerol, such as monometallic Au, Pt, and Pd NPs, and bimetallic Au-Pt, Au-Pd, Pt-Bi, Pt-Sb, and Pt-Cu, were compared and discussed in detail. The reaction mechanism over Pt-based catalysts, possible catalyst deactivation, and the corresponding improvements are presented. Further, the recent progresses in the continuous oxidation of glycerol in fixed bed reactors and its excellent selectivity in the formation of dihydroxyacetone are highlighted.

Au‐Promoted Pt nanoparticles supported on MgO/SBA‐15 as an efficient catalyst for selective oxidation of glycerol

“…[1][2][3][4][5] Up to date, selective oxidation of GLY on heterogeneous catalysts without the addition of liquid alkali attracted much attention due to the production of various valuable fine chemicals such as glyceric acid (GLYA), glycollic acid (GLYOA) and dihydroxyacetone (DHA). 6 Moreover, it offers an efficiently, environmentally and economically alternative to traditional time-consuming, polluting base (or heavy metal oxidant)promoted and costly methods as well as biological oxidation processes. 7 To achieve superior catalytic performance for the selective oxidation of GLY in the absence of liquid alkali more excellently, numerous supports (such as metal oxide, carbon materials and mesoporous zeolite) and metal active components (mainly Pt, Au and Pd) have been investigated under mild reaction conditions (20-120 C and 0.1-1.0 MPa O 2 ).…”

“…Developing profitable applications of glycerol (GLY), the main cheap by product in biodiesel production process, is of great importance for the sustainable extension of biodiesel industry chain 1‐5 . Up to date, selective oxidation of GLY on heterogeneous catalysts without the addition of liquid alkali attracted much attention due to the production of various valuable fine chemicals such as glyceric acid (GLYA), glycollic acid (GLYOA) and dihydroxyacetone (DHA) 6 . Moreover, it offers an efficiently, environmentally and economically alternative to traditional time‐consuming, polluting base (or heavy metal oxidant)‐promoted and costly methods as well as biological oxidation processes 7 .…”

On the Mechanistic Origins of the pH-Dependency in Au-Catalyzed Glycerol Electro-Oxidation: Insight from First Principles Calculations

“…This hypothesis can possibly be experimentally tested by doping Au with more basic metals or by decorating Au with basic oxides. 2,[84][85][86][87][88] In addition to the direct influence on reaction thermodynamics and kinetics, solution pH was found to affect EOG selectivity via keto-enol tautomerism between DHA and GLD. The computed reaction free energy demonstrates that DHA-GLD tautomerism is thermoneutral under alkaline conditions and offers an alternative pathway to form GLD from DHA.…”

Selective oxidation of glycerol to dihydroxyacetone using CeO2-ZrO2-Bi2O3-SnO2-supported platinum catalysts

“…The recent increase in biodiesel production has contributed to a glycerol oversupply, making utilization of the excess glycerol an important issue. One effective approach is transformation of glycerol into valuable chemical compounds such as dihydroxyacetone (DHA), glycolic acid, lactic acid, and acrolein [1][2][3]. Of these, DHA is especially important to our lives because of its skin tanning effect without UV irradiation; that is to say, its sunless tanning effect.…”