Abstract:

Nanometer hybrid rare earth solid superacid was prepared by sol-gel method. Tetrabutyl titanate was hydrolyzed and condensation polymerized, then doped with rare earth elements of Ce and La, respectively, by immersion process, and activated under certain temperatures to give a nanometer hybrid rare earth solid superacid catalyst. The structure and morphology of samples were characterized by FT-IR, SEM, and XRD. The results show that the SO2-4 is bonded to the metal oxide by bridged bidentate coordination mode. XRD shows the crystal form is anatase, and SEM reveals the catalyst is globular shape. It also proves that the rare earth solid superacid catalysts exhibit high catalytic activity for the esterification of stearic acid. The precursor soaked in the solution c(Ce4+)=0.12 mol/L, c(H2SO4)=1.0 mol/L and the solution c(La3+)=0.07 mol/L, c(H2SO4)=1.25 mol/L for 10~14 h, then calcinated at 500~550 ℃ for 3 h to obtain the solid superacid catalysts. Under the optimum conditions, the yields of esterification can reach 97.8% and 96.7%, respectively, by using these catalysts.

Key words: sol-gel method, anatase, nanometer titanium dioxide, rare earth solid superacid, stearic acid, esterification reaction, catalysis