ELETROCATÁLISE DA OXIDAÇÃO DE ETANOL SOBRE CATALISADORES À BASE DE PtSnO₂: UM ESTUDO DE DEMS

Detalhes bibliográficos
Ano de defesa: 2013
Autor(a) principal: Silva, Wanderson Oliveira da lattes
Orientador(a): RODRIGUES, Isaide de Araújo
Banca de defesa: Tanaka, Auro Atsushi
Tipo de documento: Dissertação
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal do Maranhão
Programa de Pós-Graduação: PROGRAMA DE PÓS-GRADUAÇÃO EM QUÍMICA/CCET
Departamento: QUIMICA
País: BR
Palavras-chave em Português:
Palavras-chave em Inglês:
/C
Área do conhecimento CNPq:
Link de acesso: http://tedebc.ufma.br:8080/jspui/handle/tede/964
Resumo: The ethanol oxidation reaction was investigated using on line differential electrochemical mass spectrometry (DEMS) on carbon-supported Pt-SnO2 electrocatalysts at atomic ratio 1:1, 2:1 and 3:1 as a function of ethanol concentration and combined analysis of the reaction products and electrochemical measurements. The materials were prepared by two methods: impregnation/thermal decomposition with and without chemical reduction via sodium borohydride. They were characterized by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. A comparative study showed that the second method was more efficient to synthesize of these materials, which were chosen for DEMS and electrochemistry studies. Electrochemical measurements showed better faradaic current in lower potentials, indicating better activity to ethanol oxidation on PtSnO₂/C, Pt₂SnO₂/C and Pt₃SnO₂/C catalysts compared to Pt/C E-TEK. Pt/C E-TEK presented the best ratio between the CO₂ and acetaldehyde production in 0.01 mol Lˉ¹ ethanol, showing that this electrode favors the reaction via CO₂ production. When the ethanol concentration is increased, the ratio CO₂ /acetaldehyde decreases for all catalysts studied, mainly for Pt/C E-TEK. This increasing formation of acetaldehyde was largely responsible for the profile of faradaic currents in view of the onset for the formation of acetaldehyde to coincide with the beginning of the ethanol oxidation reaction. In general, the catalysts based on Pt-SnO₂ showed better performances for the ethanol reaction compared to Pt/C E-TEK, thus confirming the ability of SnO₂ to provide oxygen species for oxidize adsorbed intermediates such as CHx and OHads, at lower potentials.