Sol-gel synthesis of alumina, titania and mixed alumina/titania in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulphonyl) amide

In this paper we report on the synthesis of alumina, titania and mixed alumina–titania in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulphonyl) amide [Py_1,4]TFSA via sol-gel methods using aluminium isopropoxide and titanium isopropoxide as precursors. Our results show that the as-synthesized alumina is mainly mesoporous boehmite with an average pore diameter of 3.8 nm. The obtained boehmite is subject to a phase transformation into γ-Al₂O₃ and δ-Al₂O₃ after calcinations at 800 and 1,000 °C, respectively. The as-synthesized TiO₂ shows amorphous behaviour and calcination at 400 °C yields anatase which undergoes a further transformation to rutile at 800 °C. The as-prepared alumina–titania powders are amorphous and transformed to rutile and α-Al₂O₃ after calcination at 1,000 °C TiO₂. The obtained alumina–titania has a higher surface area than those of alumina or titania. The surface area of the as-synthesized alumina–titania was found to exceed 486 m² g⁻¹, whereas the surface areas of the as-synthesized boehmite and titania were around 100 m² g⁻¹, respectively.