Esterification of lactic acid over TiO2–ZrO2 catalysts Original Research Article

n-Butyl lactate was synthesized with a good yield by the reaction between lactic acid and n-butanol over TiO2–ZrO2 catalysts. These catalysts had various Ti/(Ti + Zr) atomic ratios and were prepared by a co-precipitation method. XRD, n-butylamine/acetic acid adsorption, nitrogen adsorption, and SEM/EDS were used to characterize the oxides. The maximum activity was found for the catalyst with Ti/(Ti + Zr) ratio = 0.75 (TZ31), which had smaller surface area and acid amount than the catalyst with Ti/(Ti + Zr) ratio = 0.5. In general, turnover frequency (TOF) increased with increasing areal concentration of acid sites. The superiority performance of TZ31 (with a maximum product yield of 94.2%) was ascribed to the cooperation of TOF, acid site density, and specific surface area.