Optimization of modified sol-gel method for the formation of tetragonal phase zirconia in Zr(IV)/Ce(IV) catalyst

Abstract

Zirconium-cerium mixed metal oxides is widely used as promoters in automobile emissions control catalyst systems (Three-Way Catalyst, TWC). In order to improve the performance of zirconia-ceria catalysts, a research has been done to develop a zirconia-based catalyst doped with ceria by modified sol-gel method with zirconium oxychloride and cerium (III) nitrate hexahydrate as the precursors. This research investigated the optimum conditions on the formation of single phase tetragonal Zr02. A series of Zrl_xCex02 catalyst by varying the atomic percentage ratios were prepared in different amount of water and calcinations temperature. The properties of catalysts were characterized with X-Ray Diffraction (XRD), surface area analysis, and Fourier-Transform Infrared Spectroscopy (FTIR). The catalyst showed the best result is selected to test for CO conversion. The ZrO.70CeO.3002 catalyst prepared in 5 mL of water dried for two days at 70 DC and calcined at 400 DC for 17 hours gives the optimum condition on the highest formation of single phase tetragonal Zr02. The XRD analysis showed that this catalyst has crystallinity property, consists oftetragonal Zr02 as the main phase and average crystallite size of approximately 12.98 urn serve as the active phases for the catalyst. Surface area analysis showed that this catalyst has 35.36 m2/g of surface area. The FTIR analysis showed the existence of surface hydroxyl group on the surface of catalyst. The bands that were assigned to the water deformation mode and hydroxyl deformation mode of surface hydroxyl groups have been eliminated as the calcination temperature increased. The ZrO.70CeO.3002 catalyst prepared in 5 mL of water was reported to exhibit the best catalytic activity towards CO conversion, it showed the lowest Tw at room temperature while 100 % CO conversion was achieved at T100 ~ 320 DC.