Glycerol Oxidation Using Gold-Containing Catalysts

Abstract

Glycerol is an important byproduct of biodiesel production, and it is produced in significant amounts by transesterification of triglycerides with methanol. Due to the highly functionalized nature of glycerol, it is an important biochemical that can be utilized as a platform chemical for the production of high-added-value products. At present, research groups in academia and industry are exploring potential direct processes for the synthesis of useful potential chemicals using catalytic processes. Over the last 10 years, there has been huge development of potential catalytic processes using glycerol as the platform chemical. One of the most common processes investigated so far is the catalytic oxidation of glycerol at mild conditions for the formation of valuable oxygenated compounds used in the chemical and pharmaceutical industry. The major challenges associated with the selective oxidation of glycerol are (i) the control of selectivity to the desired products, (ii) high activity and resistance to poisoning, and (iii) minimizing the usage of alkaline conditions. To address these challenges, the most common catalysts used for the oxidation of glycerol are based on supported metal nanoparticles. The first significant breakthrough was the successful utilization of supported gold nanoparticles for improving the selectivity to specific products, and the second was the utilization of supported bimetallic nanoparticles based on gold, palladium, and platinum for improving activity and controlling the selectivity to the desired products. Moreover, the utilization of base-free reaction conditions for the catalytic oxidation of glycerol has unlocked new pathways for the production of free-base products, which facilitates potential industrial application. The advantages of using gold-based catalysts are the improvement of the catalyst lifetime, stability, and reusability, which are key factors for potential commercialization. In this Account, we discuss the advantages of the using supported gold-based nanoparticles, preparation methods for achieving highly active gold-based catalysts, and parameters such as particle size, morphology of the bimetallic particle, and metal-support interactions, which can influence activity and selectivity to the desired products.

Water-assisted oxygen activation during selective oxidation reactions

“…aldehydes, ketones or carboxylic acids) over solid catalysts is an industrially desired process and was reviewed by Mallat and Baiker in 2004 [55]. Since then numerous studies have appeared discussing the mechanistic implications of water on the product selectivity using Au-based catalysts [56][57][58][59][60]. The theme of this review, combining selective noble metal catalysts with O 2 activation by water-mediated proton transfer chemistry, was successfully followed by Davis and co-workers, who developed methods for the aqueous aerobic oxidation of glycerol to glyceric acid and other partial oxidation products over Au and Au-Pd alloy catalysts [61,62].…”

The Role of Mg(OH)2 in the So‐Called “Base‐Free” Oxidation of Glycerol with AuPd Catalysts

“…The gradually increasing production of biodiesel has generated a huge amount of by‐products, the major part of which is glycerol 1. It is reported that glycerol is comprised of approximately 10 wt % of the total product yield for biodiesel production2 and as such, it is projected that the demand for the consumption of glycerol will increase from 2000 kt in 2011 to 3070 kt by 2018 3. Therefore, transforming glycerol into valuable derivatives could be an effective method to increase the economic efficiency of biodiesel production.…”

Promoting Role of Bismuth on Hydrotalcite-Supported Platinum Catalysts in Aqueous Phase Oxidation of Glycerol to Dihydroxyacetone

“…Glycerol oxidation could produce various high-value fine chemicals [6,7], such as dihydroxyacetone (DHA), glyceric acid, glyceraldehyde, and hydroxypyruvic acid. Platinum and gold catalysts are found to be the most active among the investigated catalysts for glycerol oxidation, and carbons (active carbon and carbon nanotubes, etc.)…”

“…Platinum and gold catalysts are found to be the most active among the investigated catalysts for glycerol oxidation, and carbons (active carbon and carbon nanotubes, etc.) [7][8][9] and metallic oxides (TiO 2 , Al 2 O 3 , CeO 2 , CuO, MgO, MgAl 2 O 4 , etc.) [7,[10][11][12][13][14][15][16] have been widely investigated as supports in previous studies.…”

“…[7][8][9] and metallic oxides (TiO 2 , Al 2 O 3 , CeO 2 , CuO, MgO, MgAl 2 O 4 , etc.) [7,[10][11][12][13][14][15][16] have been widely investigated as supports in previous studies. It has been found that the activity and product distribution are closely related to the support, especially the textural and chemical properties, and the acid-base property of the reaction medium; however, the main product was generally glyceric acid on mono-Pt and Au supported catalysts.…”