Preparation and Characterization of NiO/CeO₂-ZrO₂/WO₃ Catalyst for Acid Catalysis

다국어 초록 (Multilingual Abstract)

A series of catalysts, NiO/CeO₂-ZrO₂/WO₃, for acid catalysis was prepared by precipitation and impregnation methods. The characterization of the prepared catalysts was performed by using X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and surface area measurements. For the NiO/CeO₂-ZrO₂/WO₃ samples, no diffraction lines of nickel oxide were observed up to 40 wt%, indicating good dispersion of nickel oxide on the catalyst surface. The hexagonal and monoclinic phases of WO₃ were observed when using calcination temperatures up to 500℃. whereas the hexagonal phase of WO₃ was transformed completely into a monoclinic phase of WO₃ at 600℃ and above. The role of CeO, in the catalyst was to form a thermally stable solid solution with zirconia and, consequently, to give high surface area and acidity. The catalytic activities for 2-propanol dehydration and cumene dealkylation correlated with the acidity of the catalysts measured by the ammonia chemisorption method. 20~25- NiO/5-CeO₂-ZrO₂/15-WO₃, containing 20~25 wt% NiO, 15 wt% WO₃, and 5 ㏖% CeO₂and calcined at 400℃, exhibited the maximum catalytic activity because of the effects of WO₃ modifying and CeO₂doping.