Effect of Si on the hydrogen-based direct reduction of Fe2O3 studied by XPS of sputter-deposited thin-film model systems
Lena Patterer, Eva B. Mayer, Stanislav Mráz, P. Pöllmann, Marcus Hans, Daniel Primetzhofer, Isnaldi Rodrigues de Souza Filho, Hauke Springer, Jochen M. Schneider
Abstract
Understanding the effect of gangue elements is of critical importance to optimize the efficiency of hydrogen-based direct reduction (HyDR) of iron ore, as one of the key steps towards climate-neutral steel production. Here, we demonstrate on the example of Si-doped Fe2O3, how thin films can be effectively utilized as a model system to facilitate systematic investigation of the solid-state reduction behavior. In-vacuo X-ray photoelectron spectroscopy (XPS) is used to probe the reduction kinetics by analyzing the chemical state of iron oxide thin films before and after annealing at 700 °C in an Ar+5%H2 atmosphere. It is demonstrated that even low Si concentrations of 3.7 at.% inhibit the HyDR of Fe2O3 by the formation of a SiOx-enriched reduction barrier in the surface-near region.