Esterification of lactic acid over TiO2–Al2O3 catalysts

N-butyl lactate was synthesized with a good yield (the maximum product yield was 95.7% at 140 °C) by the reaction between lactic acid and n-butanol over TiO2–Al2O3 catalysts. These catalysts had various Ti/Al atomic ratios (ratio = 1/0, 9/1, 3/1, 1/1, 1/3, 1/9, and 0/1) and were prepared by a co-precipitation method. XRD, n-butylamine adsorption, nitrogen adsorption, and SEM were used to characterize the oxides. The maximum activity was found for the catalyst with Ti/Al atomic ratio = 1 (TA11). The superiority of TA11 was ascribed to its largest surface area and its maximum acidity. Under identical reaction conditions, TA11 catalyst exhibited significantly better activity than the TiO2–ZrO2 catalysts reported earlier, which should be due to the larger surface area of the former.

Figure optionsDownload high-quality image (119 K)Download as PowerPoint slideHighlights
► Binary oxide with a Ti/Al atomic ratio of 1/1 (TA11) had the best activity.
► TA11 catalyst had the largest surface area and maximum acidity.
► TA11 catalyst had higher ester yield than cation-exchanged resins and Ti–Zr catalysts.