Surface and catalytic properties of Al2O3–ZrO2 solid solutions prepared by sol–gel methods Original Research Article

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 peformed by X-ray diffraction, BET-N2 adsorption, electron microscopy, potentiometry (butylamine) and NH3-TPD. The as synthesized ZrO2 included monoclinic, tetragonal and cubic phases, i.e. XRD peaks at (2Θ)=28.2° and 31.5° for the m-phase, (2Θ)=30.2° and 35.0° for the t-phase and (2Θ)=50.5° and 59.5° 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-N2 isotherms from X=0.2–1.0 showed a Type IV (BDDT) profile, typical of mesopores in the interval between 20