Biodiesel reforming with a NiAl2O4/Al2O3-YSZ catalyst for the production of renewable SOFC fuel

Biodiesel’s contribution as a renewable energy carrier is increasing continuously. Fuel cell market penetration, although slow, is now an irreversible reality. The combination of solid oxide fuel cells (SOFC) with biodiesel offers considerable advantages because it entails both high energy conversion efficiency and nearzero atmospheric carbon emissions. This work is aimed at proving the efficiency of a newly-developed (patent pending), Al2O3/YSZ-supported NiAl2O4 spinel catalyst to steam reform biodiesel. Reforming converts biodiesel into a gaseous mixture, mainly composed of H2 and CO, used directly as SOFC fuel. The work is performed in a test rig comprising a lab-scale, fixed-bed isothermal reactor and a product-conditioning train. The biodiesel/water mixtures are emulsified prior to their spray injection in the reactor preheating zone, where they are instantaneously vaporized and rapidly brought to the desired reaction temperature to avoid thermal cracking. Reforming takes place at gas hourly space velocities equal to or higher than those in industrial reforming units. The products are analysed by at-line gas chromatography. The results show that biodiesel conversion is complete at steady state. Thermodynamic calculations reveal that the fast reforming reaction reaches chemical equilibrium. The catalyst’s performance is very efficient and prevents carbon formation and deactivation.