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Au/Pt/TiO2 catalysts prepared by redox method for the chemoselective 1,2-propanediol oxidation to lactic acid and an NMR spectroscopy approach for analyzing the product mixture

Paper ID Volume ID Publish Year Pages File Format Full-Text
39339 45818 2015 14 PDF Available
Title
Au/Pt/TiO2 catalysts prepared by redox method for the chemoselective 1,2-propanediol oxidation to lactic acid and an NMR spectroscopy approach for analyzing the product mixture
Abstract

•Au NPs were selectively deposited on TiO2 supported Pt by facile redox method.•Au/Pt/TiO2 catalysts are active in liquid phase 1,2-propanediol oxidation to lactic acid by O2/air.•The addition of as low as 0.025 wt.% of Au to Pt leads to the most efficient catalyst.•NMR approach was used to precise identification of the reaction products.•An up-to-date scheme of 1,2-propanediol oxidation was proposed.

1,2-propanediol obtained from the waste glycerol is the most prominent substrate to produce lactic acid (LA) through the sustainable “green” catalytic oxidative route. We showed that bimetallic Au/Pt/TiO2 catalysts that could be easily prepared by the redox reaction with preadsorbed hydrogen possessed a high activity in the formation of lactic acid from 1,2-propanediol through selective primary hydroxyl group oxidation by an oxygen–air mixture or an air. The most efficient catalyst with the highest TON value was the sample with the lowest Au content. Even the addition of 0.025 wt.% of gold to the 1%Pt/TiO2 catalyst by the redox method resulted in the enhanced 1,2-propanediol conversion up to 96% with the 91% selectivity to LA. The high oxidation activity of the Au/Pt/TiO2 catalysts was ascribed to the strong interaction between the two metals in Au/Pt bimetallic particles and between the bimetallic particles and the support, which was proved by X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared spectroscopy of adsorbed CO (DRIFTS) technique, and temperature programmed reduction method (TPR-H2). The reaction products were identified and analyzed with the use of 1D and 2D nuclear magnetic resonance spectroscopy (NMR) methods, which also allowed suggesting a plausible up-to-date scheme of 1,2-propanediol catalytic oxidation.

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Keywords
Gold–platinum catalyst; Redox method; Bimetallic catalyst preparation; Lactic acid; 1,2-propanediol oxidation; NMR; DRIFTS
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Au/Pt/TiO2 catalysts prepared by redox method for the chemoselective 1,2-propanediol oxidation to lactic acid and an NMR spectroscopy approach for analyzing the product mixture
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 491, 5 February 2015, Pages 170–183
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us