Titanyl sulfate extracted from the mineral ilmenite as mesoporous catalyst for the oleic acid esterification

Titanyl sulfate (TiOSO4) extracted with sulfuric acid from the mineral ilmenite (FeTiO3), which has a high content of titanium (32.2 wt.%) was study as acid solid catalyst for the oleic acid esterification. The maximum extraction of Ti was 98 wt.%. As reference catalysts sulfated titania ( SO 4 2 - – TiO 2 ) and titania (TiO2) were synthesized by sol–gel route using as starting precursor titanyl sulfate. Characterization by XRD, XRF, FT-IR and nitrogen adsorption was made on calcined samples at 673 and 923 K. The acid strength and number of acid sites of the solids were determinate by potentiometric titration with n-butylamine. The catalytic activity of the characterized solids was evaluated in the esterification of oleic acid (79 wt.%) with ethanol at 353 K using an oleic acid:ethanol molar ratio of 1:10. Titanyl sulfate (673 K) catalyst under such reaction conditions and without additional treatments showed to be more active (86%) than sulfated titania (64%).