Shape control of CeO2 nano-particles and synthesis of nano-metric solid acid SO42−/CeO2

Nano-particles of CeO2 with the smallest average particle size (18.7 nm) and spherical morphology were obtained from a mixture solution of Ce(NO3)3·6H2O, citric acid, polyvinyl alcohol by an auto-combustion process exploiting sol–gel as precursors. The course of size control and shape control by polyvinyl alcohol was examined in detail. A transmission electron microscopy (TEM) and an atomic force microscopy (AFM) were employed to characterize the particle-size and morphology of CeO2 particles. In addition, a sort of nano-metric solid acid SO42−/CeO2 based on CeO2 nano-particles was prepared by macerating, filtering, drying and calcining processes. The particle-size of SO42−/CeO2 was also assessed by TEM. The composition of SO42−/CeO2 was analyzed by X-ray diffraction (XRD) and infrared spectra (IR). The influencing factors in the formation of SO42−/CeO2 were examined in the reaction of isobutyl alcohol and acetic acid. The relationship between the catalytic activity and the adsorption amount of SO42− groups was examined by precipitation titration.