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Doctoral Thesis
DOI
https://doi.org/10.11606/T.85.2022.tde-09092022-152218
Document
Author
Full name
Conrado de Vasconcelos Pereira
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2022
Supervisor
Committee
Oliveira Neto, Almir (President)
Nandenha, Júlio
Ottoni, Cristiane Angelica
Venancio, Everaldo Carlos
Title in Portuguese
Síntese e caracterização de eletrocatalizadores de PtSb/C pelo método de redução via borohidreto de sódio para oxidação direta de etanol e glicerol em meio alcalino
Keywords in Portuguese
etanol
glicerol
meio alcalino
platina (Pt) antimônio (Sb)
Abstract in Portuguese
Foram preparados eletrocatalisadores de PtSb/C em diferentes proporções pelo método de redução via borohidreto de sódio com uma carga metálica de 20% em massa suportados em carbono Vulcan XC 72. Os eletrocatalisadores foram submetidos às análises de caracterização por difração de raios-x (DRX), microscopia eletrônica de transmissão (MET), espectroscopia de energia dispersiva de raios x (EDX), espectroscopia de infravermelho com transformada de Fourier (FTIR) espectroscopia de fotoelétrons excitados por raios X (XPS) e espectroscopia Raman (RS). Ensaios eletroquímicos pelas técnicas de voltametria cíclica e de cronoamperometria também foram realizados. Para as técnicas eletroquímicas foi utilizado o eletrodo de camada fina porosa, no qual os eletrocatalisadores foram testados em meio alcalino para os combustíveis etanol e glicerol. As análises eletroquímicas e de caracterização físico-química permitiram comparar o desempenho e a estabilidade dos eletrocatalisadores estudados e também demonstraram a eficácia da adição do antimônio e sua proporção ótima. Ensaios em célula unitária foram realizados simulando condições reais de operação. Composições nas razões de PtSb/C 90:10, 80:20 e 70:30 se destacaram para a oxidação do etanol. Para o glicerol, composições nas razões de PtSb/C 80:20 e 70:30 foram melhores. Na oxidação do glicerol destacou-se o o produto dihidroxiacetona (DHT) que possui alto valor agregado.
Title in English
Synthesis and characterization of PtSb/C electrocatalysts by sodium borohydride reduction method for direct ethanol and glycerol oxidation in alkaline medium
Keywords in English
alkaline medium
ethanol
glycerol
platinum (Pt) antimony (Sb)
Abstract in English
PtSb/C electrocatalysts were prepared in different proportions by the sodium borohydride reduction method with a metallic charge of 20% by mass supported on Vulcan XC 72 carbon. The electrocatalysts were subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), infrared Fourier transform spectroscopy (FTIR), X-ray excited photoelectron spectroscopy (XPS) and Raman spectroscopy (RS), characterization analyses. Electrochemical assays using cyclic voltammetry and chronoamperometry techniques were also performed. For the electrochemical techniques, a porous thin layer electrode was used, on which the electrocatalysts were tested both in alkaline medium for ethanol and glycerol fuels. The electrochemical and physico-chemical characterization analyses made it possible to compare the performance and stabilities of the studied electrocatalysts and also demonstrated the effectiveness of the antimony addition and its optimal proportion. Unit cell tests were performed simulating real operating conditions. PtSb/C Compositions at ratios 90:10, 80:20 and 70:30 stood out for ethanol oxidation. For glycerol, PtSb/C compositions at 80:20 and 70:30 ratios were better. In the oxidation of glycerol, the product dihydroxyacetone (DHT) was highlighted, which has a high added value.
 
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Publishing Date
2022-09-20
 
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