Applied Catalysis A: General, Vol.197, No.1, 119-130, 2000
Surface and catalytic properties of Al2O3-ZrO2 solid solutions prepared by sol-gel methods
A series of ZrO2-Al2O3 solid solutions was prepared by co-hydrolysis of Al-tri-sec-butoxide and Zr-propoxide, having molar ratios X=Zr/(Zr+Al)=0.0.29, 0.53, 0.63, 0.71, 0.81, 1.0. A systematic study was performed by X-ray diffraction, BET-N-2 adsorption, electron microscopy, potentiometry (butylamine) and NH3-TPD. The as synthesized ZrO2 included monoclinic, tetragonal and cubic phases, i.e. XRD peaks at (2 Theta)=28.2 degrees and 31.5 degrees for the m-phase, (2 Theta)=30.2 degrees and 35.0 degrees for the t-phase and (2 Theta)=50.5 degrees and 59.5 degrees for the c-phase. The progressive formation of a solid solution occurs, between Al2O3 and ZrO2 along the composition axis, with poorly crystallized mixed phases. The BET-N-2 isotherms from X=0.2-1.0 showed a Type IV (BDDT) profile, typical of mesopores in the interval between 20