Local structures of metals dispersed on coal. 5. Effect of coal, catalyst precursor, and catalyst preparation method on the structure of iron species during heat treatment and steam gasification

Abstract

The effect of types of coal and catalyst precursor on the local structure of iron catalyst during the devolatilization and steam gasification of iron-loaded coals have been studied by transmission Moessbauer spectroscopy and extended X-ray absorption fine structure spectroscopy. The effect of catalyst preparation method was also examined in the case of FeCl[sub 3]-loaded Yallourn coal. After the devolatilization, iron species exist as a mixture of atomically dispersed iron species, ultrafine FeOOH, [gamma]-Fe, and crystalline species like [alpha]-Fe, Fe[sub 3]C, FeO, and Fe[sub 3]O[sub 4]. In the initial stage of steam gasification, atomically dispersed Fe species, ultrafine FeOOH, and [gamma]-Fe transform to ultrafine FeOOH, and other crystalline species transform to Fe[sub 3]O[sub 4]. The ultrafine FeOOH is likely to be the active species in steam gasification since the reactivity is closely related to the content of this species. The conditions suitable to produce these active species were identified in detail.