Esterification and transesterification on Fe2O3-doped sulfated tin oxide catalysts

A series of Fe2O3-doped (0.2–3.0%) sulfated tin oxides have been prepared by a co-precipitation method, followed by sulfation and calcination. The addition of small amounts of Fe2O3 to sulfated tin oxide results in an enhanced number of very strong and strong acid sites, which makes the Fe2O3-doped catalysts more active than the undoped one for esterification of lauric acid with methanol and transesterification of triacetin with methanol. The catalyst containing 1.0% Fe2O3 exhibits the highest activity for both biodiesel-forming type reactions.