Lithium doped TiO2 as catalysts for the transesterification of bisphenol-A with dimethyl carbonate

Lithium doped TiO2 were prepared by simple impregnation, which was used as heterogeneous catalysts for the transesterification of DMC with BPA. The characterized results of FTIR, XRD, XPS, SEM, TEM and temperature programmed desorption of CO2 (CO2-TPD) showed that the structure and performance of the catalysts were obviously influenced by the doping amount of Li+ and calcining temperature. The optimum catalytic activity was obtained when the molar ratio of Ti/Li reached 6 and the calcination temperature came up to 400 degrees C, which was due to Li+ reaction with TiO2 to form surface Ti-O-Li at 400 degrees C (Ti/Li-6-400). When the transesterification of DMC with BPA was carried out at 160-180 degrees C over Ti/Li-6-400, BPA conversion reached 46.67%, and the yields of one-methylcarbonate-ended-BPA (MmC(1)) and two-methylcarbonate-ended-BPA (DmC(1)) achieved 36.36% and 5.97%, respectively, and only 9.3% methylation selectivity was detected. In addition, the possible transesterification mechanism was provided.