Selective chlorination of iron from synthetic pseudobrookite

The chlorination of synthetic pseudobrookite was studied by thermogravimetr y in the temperature range 700-950 degrees C; both isothermal and non-isoth ermal measurements were made. The effect of reaction temperature on the chl orination rate was correlated with the morphological evolution and elementa l composition of the reacting solids by means of scanning-electron microsco py, energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. It was found that chlorination took place as a topochemical process in which the-ir;on was chlorinated selectively, forming FeCl3(g) and leaving TiO2 as a solid residue. During the chlorination, however, some TiCl4(g) was forme d and this was subsequently converted to TiO2 by its reaction with iron oxi de.