Lactic acid synthesis from glucose with sol–gel and USY zeolite catalysts

In this study, sol–gel and zeolite‐based catalysts were prepared for the conversion of glucose to lactic acid under hydrothermal conditions and their activities were investigated. SiO 2 ‐supported catalysts containing different metal structures, such as Al, Fe, Cr, Sn, and Zn representing Lewis acid structures, were synthesized by sol–gel method. Beta H zeolite and USY H zeolite, as well as Sn‐USY and Zn‐USY zeolites, were used as zeolite catalysts. X‐ray diffraction, Brunauer–Emmett–Teller surface analysis, and scanning electron microscopy analyses were performed to characterize the highly active Zn/SiO 2 and USY zeolite catalysts. The highest lactic acid yield of 34.8% was obtained with the Zn/SiO 2 catalyst among the SiO 2 ‐supported sol–gel catalysts at 180 °C for 2 h under 3 MPa N 2 pressure. Among the zeolite catalysts, the highest lactic acid yields of 48.3% and 43.8% were obtained with the USY H zeolite and the Zn‐USY zeolite catalysts, respectively.