Size-controlled synthesis of ZrO 2–TiO 2 nanoparticles prepared via reverse micelle method : Investigation of particle size effect on the catalytic performance in vapor phase Beckmann rearrangement

Abstract

Zirconium–titanium mixed oxide nanoparticles have been synthesized using microreactors made of bis-(2-ethylhexyl) sulfosuccinate (AOT)/water/ n-hexane microemulsions. The control of particle size was achieved by varying the process variables, such as water-to-surfactant molar ratio and reagent concentration. Their sizes, appearances, crystal structures, pore diameter and surface area were characterized by TEM, XRD, N 2 adsorption/desorption methods. The results revealed that samples prepared in reverse micelles had no crystalline phase. The Beckmann rearrangement of cyclohexanone oxime on ZrO 2–TiO 2 nanoparticles was carried out in a fixed-bed down flow reactor to investigate the effect of particle size on catalytic activity and selectivity. Samples synthesized in reverse micelles had better reaction performance than samples prepared via sol–gel method. A parallel relationship could be drawn between the catalytic activity and the particle size as well as the selectivity of the catalyst.