Ethanol electro-oxidation in solid acid fuel cells: effect of the electrocatalyst and operation temperature on the reaction pathways

• Grant number: 14/02032-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: April 15, 2014
• End date: October 14, 2014
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Fabio Henrique Barros de Lima
• Grantee: Adriana Coêlho Queiroz
• Supervisor: Sossina M. Haile
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: California Institute of Technology, United States
• Associated to the scholarship: 12/17581-3 - Electrochemical Oxidation of Ethanol on Polymer Electrolyte Fuel Cell. A Quantitative Study of the Reaction Pathways by On-line Mass Spectrometry, BP.DR

Abstract

Direct Ethanol Fuel Cells (DEFC) are an important type of virtual hydrogen fuel cell. This is mainly because ethanol has a high hydrogen content or high energy density, low toxicity, and possibility to be produced in large amounts through the fermentation of biomass, offering an interesting economic viability. The total electro-oxidation of ethanol to CO2 releases 12 electrons per molecule. Despite the positive aspects of the use of ethanol as a fuel, there are several problems that have to be overcome in order to use it in practical fuel cell devices. The complete electro-oxidation of ethanol ought to follow steps of adsorption, dehydrogenation, C-C bond breaking, and oxygen addition to the resulting adsorbed intermediates (CO and CHx). However, due to the difficulties related to the design and the synthesis of efficient electrocatalysts for such a complex reaction, the ethanol oxidation proceeds following parallel routes, producing acetaldehyde and acetic acid as major products, instead of CO2. Despite several advances in the design and synthesis of electrocatalysts for the EOR, the main parameter considerable affecting the current efficiency for CO2 formation is the temperature. However, the state-of-the-art fuel cells based on polymer electrolyte membrane fuel cells are inoperable above 100 °C, require cumbersome humidification systems, and suffer from fuel permeation. Therefore, the main aim of this project is related to the study of the ethanol electro-oxidation in Solid Acid Fuel Cells (SAFC) with CsH2PO4 as electrolyte, that operates at intermediate temperatures (200 - 300 oC), The electrocatalysts will be formed by Pt/C and W, Ru and Sn-modified Pt/C nanoparticles. The effect of varying the temperature, the electrocatalyst, and the effect of the presence of a reforming catalyst in the anode side, will be investigated on the cell performance and oxidation product distribution. (AU)