(406f) Design of Robust and Efficient Diesel Autothermal Reforming System Using Bi-Metallic Catalyst for the Mobile Applications

In contrast to the studies dealing with the hydrogen production from the light fossil fuels, the degradation problem of the catalyst for the diesel reforming has not been scrutinized thoroughly. Among the several reasons for the degradation problem, coke formation on the surface of the catalyst is known as the main cause of the catalytic failure and it encourages the production of the un-cracked hydrocarbons such as ethylene (C₂H₄), which may lead the severe poisoning problem on the anode of the fuel cell. In this study, bi-metallic catalyst consisted of platinum and ruthenium was introduced to prevent coke formation and ethylene production during the long-term autothermal reforming (ATR) of commercial diesel fuel. Every catalysts synthesized using a combustion method were demonstrated its long-term stability and catalytic activity over 200 hours. The rate of degradation for each time-on-stream experiment was evaluated by calculating its reforming efficiency containing the amount of hydrogen, carbon monoxide and methane produced from the diesel fuel. Through this study, we have found that the additive ruthenium performed as a great oxidation assistant on the catalytic surface and it could successfully oxidize the carbon species formed on the surface of the catalyst. Consequently, the prepared catalysts containing ruthenium showed great stability and the lowest rate of degradation among the samples. Several fresh and post-mortem characterizations were performed in terms of physical and redox properties using X-ray diffraction (XRD), N₂-isotherms, temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) analyses. Based on the findings from the catalytic experiments and characterization, we could minimize the oxygen to carbon ratio (OCR) and steam to carbon ratio (SCR) for the diesel autothermal reforming reaction to enhance the overall efficiency without sacrificing the long-term stability. The bi-metallic catalyst containing ruthenium showed great performance and negligible degradation under the low OCR and SCR condition than conventional values with minimal production of ethylene species. The overall autothermal reforming efficiency was also dramatically enhanced without significant degradation for over 200 hours operation. Moreover, we suggested the total system design containing diesel reformer consisted of the bi-metallic catalyst and conventional solid oxide fuel cell using the commercial software and thermodynamic calculations. Finally, to demonstrate the possibility to use this new catalyst for the mobile application, we coated the bi-metallic catalyst on the cordierite monolith structure using a dip-coating method. The final structured catalyst containing only 0.4 g of active bi-metallic catalyst layer showed excellent reforming activity and efficiency near the thermodynamic limitation and presented no degradation signal over 1,000 hours under the commercial diesel autothermal reforming condition.