Improvements in acidity for TiO2 and SnO2 via impregnation with MoO3 for the esterification of fatty acids

The impregnation of TiO2 or SnO2 with MoO3 forms solid materials exhibiting high acidity (MoO3/TiO2 and MoO3/SnO2) that might be applied as catalysts for the esterification of fatty acids. TiO2 and SnO2 oxide matrixes were prepared using a metal-chitosan complex method, and the acidity of these materials was modified via impregnation with MoO3. These catalytic systems were characterized by FTIR, N-2 adsorption/desorption isotherms, thermogravimetric analysis, and NH3 temperature programmed desorption (NH3-TPD) and tested in the esterification of fatty acids in the presence of methanol. The esterification reactions were carried out at three different temperatures (120 degrees C, 140 degrees C and 160 degrees C) with a 400:100 molar ratio of alcohol:fatty acid and 1% (mass) catalyst loading. Both TiO2 and SnO2 only exhibited catalytic activity after their acidity was improved via impregnation with MoO3, and yields of 80% and 90%, respectively, were achieved at 6 h and 160 degrees C. (C) 2013 Elsevier B.V. All rights reserved.