Conversion of steel mill waste into nanoscale zerovalent iron (nZVI) particles for hydrogen generation via metal-steam reforming

Abstract

The proton exchange membrane fuel cells (PEMFCs) are the most preferred and efficient energy conversion devices for automotive applications but demand high purity hydrogen which comes at a premium price. The currently pursued hydrogen generation methods suffer from issues such as, low efficiency, high cost, environmental non-benignity, and, in some cases, commercial non-viability. Many of these drawbacks can be overcome by resorting to metal-steam reforming using iron from steel industry's mill-scale waste. A novel solution-based room temperature technique using sodium borohydride (NaBH4) as the reducing agent has been developed that produces highly active nanoscale (30–40nm) iron particles. A slightly modified version of this technique using a surfactant and water–oil microemulsion resulted in the formation of 5nm spherical Fe particles. By using hydrazine as an inexpensive and more stable (compared to NaBH4) reductant, body centered cubic iron particles with edge dimensions ∼5nm were obtained under mild solvothermal conditions in ethanol. The nanoscale zerovalent iron (nZVI) powder showed improved kinetics and greater propensity for hydrogen generation.