On the activity of bimetallic catalysts for ethanol steam reforming

• Pt/Ni/CeO2 and Pt/Co/CeO2 as selective catalysts for ethanol steam reforming.
• Co-based catalysts are very durable, yet at a low water-to-ethanol molar ratio.
• The catalysts stability could be improved by water through gasification reactions.
• A few carbon deposition could occur, but the catalysts activity is not affected.
• A complex surface reaction path is proposed over Pt/Ni sample.

The performance of CeO2-supported Pt–Ni and Pt–Co catalysts in the low temperature-Ethanol Steam Reforming (ESR) reaction has been evaluated studying the effect of the preparation method (impregnation/coprecipitation) and parameters such as dilution ratio, temperature, water-to-ethanol feed ratio and Gas Hourly Space Velocity (GHSV). The results show that impregnated samples perform better. In particular, the Pt/Ni/CeO2 catalyst starting from 350 °C leads to a products distribution very close to the equilibrium calculations, with a low CO content that is ideal for fuel cells devices. In addition, the Co-based catalysts appear attractive in terms of hydrogen yield and coking tendency.For the Pt/Ni sample at 370 °C, the analysis of products distributions vs contact time suggests a surface reaction path involving ethanol dissociative adsorption, dehydrogenation to acetaldehyde at short contact time (5–40 ms), followed by decomposition, reforming and CO-WGS reactions, to obtain H2, CH4, CO2 and CO. The last step is the methanation reaction, occurring at contact times higher than 100 ms, which drives the system to the equilibrium.

For the Pt/Ni sample, the analysis of products distributions at different contact time suggest a surface reaction path involving ethanol dissociative adsorption on catalyst surface, dehydrogenation to form acetaldehyde at short contact time (5–40 ms), immediately followed by decomposition, reforming and CO-WGS reactions, to obtain H2, CH4, CO2 and very low CO amount. The last reaction step is the methanation reaction, which drives the system to the equilibrium, and happens at contact times higher than 100 ms.Figure optionsDownload as PowerPoint slide