Production of TiFe Hydrogen-Storage Material by Direct Reduction of Ilmenite Mineral Sand.

Abstract

The transition to a hydrogen-based economy necessitates the development of safe, cost-effective hydrogen storage media at an industrial scale. The equiatomic intermetallic titanium-iron (TiFe) alloy is a prime candidate for stationary hydrogen applications due to its high volumetric storage density, nontoxicity, and safety attributes. However, the conventional synthesis of TiFe alloy relies on high purity titanium and iron metal feedstocks, which must first be extracted from their respective ores before being alloyed in equiatomic ratio. This is a complex, multistep process posing environmental and economic challenges associated with the extraction of metallurgical-grade titanium. Here, we propose an alternate straightforward synthesis pathway for TiFe alloy through the direct calciothermic reduction of ilmenite sand (FeTiO₃). Initial small-scale experiments have achieved a maximum TiFe yield of approximately 52 wt %, with similar yields observed when scaling up to 100 g samples. The TiFe alloy produced via this pathway demonstrated a hydrogen storage capacity of approximately 0.71 wt % after activation at 65 bar, indicating that direct metallothermic reduction of ilmenite sand represents an attractive alternative production route for hydrogen storage alloys, which offers economic and sustainability advantages over the existing industrial pathway.