The role of Al2O3, MgO and CeO2 addition on steam iron process stability to produce pure and renewable hydrogen.

Steam iron process represents a technology for H 2 production based on iron redox cycles. Fe x O y are reduced by syngas/carbon to iron, which is subsequently oxidized by steam to produce pure H 2. However, the system shows low stability. In this work, the effect of promoters (Al 2 O 3 , MgO and CeO 2) on Fe x O y stability is investigated (10 consecutive redox cycles). Bioethanol is used as a reducing agent. The particles are synthesized by coprecipitation method, analysed by BET, XRD, SEM and tested in a fixed bed reactor (675 °C, 1 bar). Pure H 2 is obtained controlling the Fe x O y reduction degree feeding different amounts of ethanol (4.56–1.14 mmol) until no CO is detected in oxidation. The results show that the promoters not only improve the thermal stability of Fe x O y but also affect its redox activity and react with iron forming spinel structures. MgO led to the highest activity and cyclability (H 2 = 0.15 NL; E = 35%). • Steam iron process is a promising alternative to obtain pure H 2 ideal for PEMFC. • Pure and renewable H 2 is achieved using bioethanol in the reduction step. • The promoters Al 2 O 3 , CeO 2 and MgO aim to improve the Fe redox cyclability. • Al 2 O 3 and MgO play an active role reacting with Fe and forming spinel structures. • MgO gives the highest pure H 2 yields (H2(NL)/EtOH(g) = 3.422) stable for 10 cycles. [ABSTRACT FROM AUTHOR]