Investigation of iron oxide reduction by ethanol as a potential route to produce hydrogen

Abstract

In this work, a novel way to indirectly store and produce H2 from ethanol was investigated using a two-step process based on the reduction of iron oxide followed by oxidation with H2O. The reduction of different iron oxides, i.e., Fe2O3, Fe3O4 and FeOOH, with ethanol to produce Feo was investigated. TPRe (Temperature Programmed Reactions) and Mössbauer and XRD analyses showed that ethanol reduces Fe2O3 sequentially to Fe3O4 at 350–500 °C, to Fe3O4/FeO at 500–600 °C and finally to Feo at 700 °C. The formed Feo can then be oxidized by H2O to produce H2 and Fe3O4, as shown by Mössbauer and XRD analyses. Cyclic experiments showed that iron could be consecutively reduced/oxidized at least 5 times without any significant decrease in H2 production after the second cycle. However, reactions of Fe2O3 with ethanol at higher temperatures, i.e., 800 and 900 °C, led to the formation of iron carbide and significant carbon deposition. XPS, SEM, TEM, Raman and TG showed 24–28 wt% carbon content, particularly on the surface as nanofibers and as amorphous and graphitic carbon.