Recent Advances in Thermo-, Photo-, and Electrocatalytic Glycerol Oxidation

Abstract

Glycerol is a highly versatile molecule because of its three hydroxyl groups and can be transformed to a plethora of different value-added fine chemicals and products. It is an important byproduct in biodiesel production and, hence, produced in high amounts, which resulted in a high surplus flooding the market over the last decades. Thus, glycerol is regarded as a potential platform chemical, and many research efforts were devoted to find active catalysts to transform glycerol to various products via different catalytic processes. The selective oxidation reaction is one of the most promising reaction pathways to produce valuable fine chemicals used in the chemical and pharmaceutical industry. This Review describes the recent developments in selective glycerol oxidation to value-added products over heterogeneous catalysts. Particular emphasis is placed not only on newly developed catalysts based on supported noble-metal nanoparticles but also on catalysts containing nonprecious metals. The idea of using cost-efficient non-noble metals for glycerol oxidation is appealing from an economic point of view. Numerous parameters can influence the catalytic performance of the materials, which can be tuned by various synthetic approaches. The reasons for enhancements in activity are critically examined and put into perspective among the various studies. Moreover, during the past decade, many research groups also reported photocatalytic and, more scarcely, electrocatalytic pathways for glycerol oxidation, which are also described in detail herein and have otherwise found little attention in other reviews.

Bi-modified Pt Electrodes toward Glycerol Electrooxidation in Alkaline Solution: Effects on Activity and Selectivity

“…1 Thus, the need for new application of GlOH motivated scientists from many fields to work in this direction. [2][3][4][5] In this context, the electrooxidation of GlOH (EOG) aroused as a possibility to use this molecule in anodes of: i) Fuel Cells: with the main aim of generating electric energy and ii) Electrolyzers: for the concomitant generation of oxidation products of GlOH with high value (in the anode) 1 and high purity hydrogen (in the cathode). 3,4 Many papers have been published about EOG in noble metalbased electrodes, 6 mainly in acidic media and using carbon (or oxide) supported nanoparticles (NPs).…”

Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

“…More than 90% of the glycerol used today is refined to give purities of higher than 97%, and the process can take purity up to from 99.5 to 99.7%. Intensive research is conducted to find ways to valorise glycerol and many fields of interest focus on its transformation into chemicals and hydrocarbon fuels (Dodekatos et al, 2018). Furthermore, its use as a convenient green reaction medium has been widely documented (Wolfson et al, 2009;Díaz-Álvarez and Cadierno, 2013;Díaz-Álvarez et al, 2014;Tagliapietra et al, 2015;Santoro et al, 2017).…”

Enhancing the understanding of the glycerol to lactic acid reaction mechanism over AuPt/TiO2 under alkaline conditions

“…Since Rossi and Prati 2 first established that supported Au catalysts were highly active for the aerobic oxidation of alcohols, much research has been published on the oxidation of glycerol. 3,4 The complexity of the product distribution, formed from various parallel and sequential processes, makes this reaction an interesting model system for the study of heterogeneous catalysis; a deeper understanding of the influence of different metals, support properties and particle size effects has been established. 3,[5][6][7] The current understanding is that the reaction, as shown in Scheme 1, involves an initial oxidation of an alcohol function to carbonyl producing a mixture of reaction intermediates dihydroxyacetone (DHA) or glyceraldehyde (GLD).…”