Utilization of al2o3 and mgo as structural promoters of fe into 2 and 3 steps chemical looping hydrogen process: pure and green h2 production

The use of H2 as alternative fuel in the transportation sector is one of the most promising solutions to reduce global warming. Chemical looping hydrogen processes (CLH) allow the production of high purity H2, suitable for powering PEM fuel cells. This work focuses on the production of pure and renewable H2 by CLH process using iron as redox material and ethanol as renewable reductant. To scale up the technology, the thermal stability of Fe for repeated redox cycles is a key point and still needs improvement. The addition of structural promoters can be an effective solution. Experiments at 3 different reaction temperatures (675°C-750°C) are conducted to evaluate the effect of the addition of Al2O3 and MgO on FexOy redox performances. The particles' thermal stability is evaluated for 10 redox cycles. The results show that the presence of Al2O3 led to a completely deactivation of iron oxides after few cycles at all the conditions due to the formation of Hercynite (FeAl2O4), which cannot be oxidized by water. However, introducing an air oxidation step in the system (3 steps CLH) makes this material suitable for this application. The addition of MgO guarantees stable H2 yields at the lowest temperature tested (675°C, E=35%).