Enhancement of thermochemical hydrogen production using an iron–silica magnetically stabilized porous structure

Abstract

A synthesis process for creating an iron-based magnetically stabilized porous structure is described in detail. The structure is used as the reactive substrate for a two-step water splitting, hydrogen production process. The stability and reactivity of a 205 g magnetically stabilized structure operating at 873, 973, 1023 and 1073 K over eleven consecutive oxidation and reduction cycles has been investigated. Applying an external magnetic field exploits sintering and controls the geometry of the matrix of particles inside the structure in a favorable manner so that the chemical reactivity of the structure remains intact. The experimental results demonstrate that this structure yields peak hydrogen production rates of approximately 29 cm3/(min gFe) at 1073 K without noticeable degradation over eleven consecutive cycles. The hydrogen production rate is considerably higher than those reported in the open literature for two-step water splitting processes. SEM images, hydrogen production rates, permeability of the bed, and the bed height confirm that the gas–solid contact area and porosity of the magnetically stabilized porous structure is sustained after consecutive cycling at high reaction temperatures.