The Effect of Al2O3 Addition on Catalytic Activities of NiSO4/Al2O3-ZrO2 for Acid Catalysis

Abstract

A series of catalysts, NiSO 4 /Al 2 O 3 -ZrO 2 , for acid catalysis were prepared by the impregnation method, where support, Al 2 O 3 -ZrO 2 was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and aluminum nitrate solution followed by adding an aqueous ammonia solution. Characterization of prepared catalysts was performed by using Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry and by measuring surface area. No diffraction line of nickel sulfate was observed up to 20 wt%, indicating good dispersion of nickel sulfate on the surface of Al 2 O 3 -ZrO 2 . The addition of nickel sulfate (or Al 2 O 3 ) to ZrO 2 shifted the phase transition of ZrO 2 from amorphous to tetragonal to higher temperature because of the interaction between nickel sulfate (or Al 2 O 3 ) and ZrO 2 . 10-NiSO 4 /Al 2 O 3 -ZrO 2 containing 10 wt% NiSO 4 and 5 mol% Al 2 O 3 was calcined at 973 K and exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of Al 2 O 3 up to 5 mol% gradually enhanced the acidity, thermal property, and catalytic activities of NiSO 4 /Al 2 O 3 -ZrO 2 due to the interaction between Al 2 O 3 and ZrO 2 .