Hydrogen Production via the Catalytic Partial Oxidation of Ethanol on a Platinum-Rhodium Catalyst: Effect of the Oxygen-to-Ethanol Molar Ratio and the Addition of Steam

摘要

To produce hydrogen for automotive exhaust gas aftertreatment systems, the catalytic partial oxidation of ethanol over a platinum rhodium catalyst supported on alumina is examined via experimental studies as well as thermodynamic analysis. The research focuses on the effects of the ethanol concentration, oxygen-to-ethanol molar ratio, and water content of ethanol on the ethanol conversion and product yield (e.g., H-2, CO, CO2, and CH4). The hot spot temperature and position and the temperature profile along the monolithic catalyst are also analyzed as a function of the inlet gas composition. Different surface chemical reactions (e.g., partial oxidation and steam reforming of ethanol, water-gas shift, and hydrocarbon cracking) are employed to explain the phenomena that take place during ethanol reforming. The process follows the indirect reforming pathway, which involves the exothermic oxidation of ethanol to produce H20, CO2, and heat, followed by endothermic steam reforming to generate CO and H-2. The temperature profile inside the catalyst depends critically on the amount of ethanol supplied and the oxygen-to-ethanol molar ratio. The ethanol conversion, hydrogen production, and selectivity toward hydrogen and methane depend strongly on the operating conditions. The addition of steam has a slightly positive effect on the hydrogen formation and temperature profile.