Low Temperature Catalytic Ethanol Conversion Over Ceria-Supported Platinum, Rhodium, and Tin-Based Nanoparticle Systems

Due to the feasibility of ethanol production in the United States, ethanol has become more attractive as a fuel source and a possible energy carrier within the hydrogen economy. Ethanol can be stored easily in liquid form, and can be internally pre-formed prior to usage in low temperature (200 o C – 400 o C) solid acid and polymer electrolyte membrane fuel cells. However, complete electrochemical oxidation of ethanol remains a challenge. Prior research of ethanol reforming at high temperatures (> 400 o C) has identified several metallic and oxide-based catalyst systems that improve ethanol conversion, hydrogen production, and catalyst stability. In this study, ceria-supported platinum, rhodium, and tin-based nanoparticle catalyst systems will be developed and analyzed in their performance as low-temperature ethanol reforming catalysts for fuel cell applications. Metallic nanoparticle alloys were synthesized with ceria supports to produce the catalyst systems studied. Gas phase byproducts of catalytic ethanol reforming were analyzed for temperature-dependent trends and chemical reaction kinetic parameters. Results of catalytic data indicate that catalyst composition plays a significant role in low-temperature ethanol conversion. Analysis of byproduct yields demonstrate how ethanol steam reforming over bimetallic catalyst systems (platinum-tin and rhodium-tin) results in higher hydrogen selectivity than was yielded over single-metal catalysts. Additionally, oxidative steam reforming results reveal a correlation between catalyst composition, byproduct yield, and ethanol conversion. By analyzing the role of temperature and reactant composition on byproduct yields from ethanol reforming, this study also proposes how these parameters may contribute to optimal catalytic ethanol reforming.