Sponge iron reaction
# Sponge iron reaction

The sponge iron reaction (SIR) is a chemical process based on redox cycling of an iron-based contact mass, the first cycle is a conversion step between iron metal (Fe) and wuestite (FeO), the second cycle is a conversion step between wuestite (FeO) and magnetite $(Fe_3O_4).$ In application, the SIT is used in the reformer sponge iron cycle (RESC) in combination with a steam reforming unit.

## Process description

The process has two modes, a reduction mode and an oxidation mode.

### Iron-wuestite

FeO + H $_2$ ↔ Fe + H $_2O$

### Magnetite-wuestite

Fe $_3O$ $_4$ + H $_2$ ↔ 3FeO + H $_2O$

## Application

The reformer sponge iron cycle is a two step cycle to produce hydrogen from hydrocarbon fuels based SIR and steam.

### Reformer sponge iron cycle

In the first step the hydrocarbon fuel is reformed to syngas in the reformer which is then used to reduce the iron oxide $(magnetite—Fe_3O_4)$ to iron (wüstite—FeO), in the second step steam is utilized to re-oxidise the iron into magnetite and hydrogen. The iron oxide pellets are placed in a pelletbed and have a service life of several thousand redox cycles.

