Synthesis of sulfated zirconia solid acids and their activities for hydrolysis of ethyl lactate

A kind of solid acid (sulfated zirconia) was proposed to be used as the catalyst for the hydrolysis of ethyl lactate because esterification-hydrolysis was usually applied to produce lactic acid of high purity. The sulfated zirconia was prepared via a simple chemical precipitation and impregnation approach. The prepared catalysts were characterized by means of XRD, TG-DSC, FT-IR, and NH₃-TPD. Catalytic activity of the prepared catalysts was evaluated by the hydrolysis reaction of ethyl lactate. The characterization results showed that the prepared sulfated zirconia was of tetragonal phase at the optimum calcination temperature of 650°C and had strong acidity. The conversion of hydrolysis of ethyl lactate using the prepared catalyst was 82.62%. Although the conversion was lower than that of liquid acid (p-toluenesulfonicacid), the solid acid catalyst was easier to be separated from the products. It resolved the problems of pollution and catalyst reuse. This work might provide a new green process for producing lactic acid of high purity.