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

Wenjie Xue,Zenglong Wang,Jinxiang Dong,Yu Liang,Lei Liu,Hong Xu

doi:10.3390/catal8010020

Wenjie Xue, Zenglong Wang + Show 4 more

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https://doi.org/10.3390/catal8010020

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Abstract

Bismuth plays important roles in promoting the oxidation of alcohols towards high-value-added chemicals over a noble metal loading catalyst. Herein, Mg–Al hydrotalcite-supported platinum–bismuth nanoparticles (Pt–Bi/HT) were prepared by the co-impregnation method and used in the selective oxidation of glycerol towards dihydroxyacetone (DHA). The incorporation of Bi species into Pt/HT significantly enhances the conversion of glycerol and the selectivity of DHA. The high selectivity of DHA with 80.6% could be achieved at 25.1% conversion of glycerol. The Bi species of the Pt–Bi/HT catalyst mainly exist in the form of BiOCl and Bi metal, which is different from the previous Pt–Bi based catalyst, confirmed by a combination of powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM). A plausible mechanism is proposed to elucidate the promoting role of Bi species on the Pt/HT catalyst in the selective oxidation of glycerol towards DHA.

Highlights

Biodiesel, a well-known renewable biomass energy, can be produced by the transesterification of vegetable oils, waste oils, and animal fats with short chain alcohols; glycerol (GLY), as an inevitable byproduct, is abundantly obtained during the production of biodiesel [1]
The successful preparation of Mg–Al hydrotalcite was confirmed by the powder X-ray diffraction (XRD) pattern comparison between the as-synthesized one and the standard Mg–Al HT, Mg4 Al2 (OH)12 CO3 ·3H2 O
The SEM image of the as-synthesized Mg–Al HT sample (Figure S1) shows aggregates of small secondary uniform platelets of about 4 μm in diameter, and some secondary platelets could dissociate from the aggregates after loading the Pt–Bi species

Summary

Introduction

A well-known renewable biomass energy, can be produced by the transesterification of vegetable oils, waste oils, and animal fats with short chain alcohols; glycerol (GLY), as an inevitable byproduct, is abundantly obtained during the production of biodiesel [1]. The biodiesel-derived glycerol, as a potential platform molecule, could be converted into value-added chemicals by employing different chemical reactions [2,3,4,5], such as oxidation, hydrogenolysis, dehydration, and esterification. Glycerol oxidation could produce various high-value fine chemicals [6,7], such as dihydroxyacetone (DHA), glyceric acid, glyceraldehyde, and hydroxypyruvic acid. 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; the main product was generally glyceric acid on mono-Pt and Au supported catalysts

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