Catalytic conversion of alcohols over alumina–zirconia mixed oxides: Reactivity and selectivity

The amorphous and crystalline mixed 25, 50 and 75 wt.% Al2O3–ZrO2 composites were prepared by means of sol–gel method using aluminum iso-propoxide and zirconyl nitrate precursors. Physicochemical properties were determined using XRD, BET, NH3-TPD, TGA, SEM, and FT-IR spectroscopy. Catalytic activity and selectivity were investigated for the dehydration of 2-octanol and 1,2-diphenyl-2-propanol (DPP). Al75Zr25 composite is more selective than other forms for the conversion of 2-octanol. The selectivity of DPP for 1-alkene formation was increased over Al25Zr75 catalyst. The crystalline 50 wt.% catalyst dehydrated tertiary alcohol (DPP) selectively in the presence of 2-octanol. The amorphous 50 wt.% catalyst dehydrated DPP predominately to 1-alkene isomer. The crystalline catalyst favored the formation of E-2-alkene.

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► Mixed 25, 50 and 75 wt.% Al2O3–ZrO2 composites were prepared by means of sol–gel method.
► Doping ZrO2 with alumina eliminates m-ZrO2 but stabilizes the tetragonal phase.
► Crystalline composite selectively dehydrates DPP over 2-octanol to give E-alkene.
► The amorphous composite produced the least stable kinetically controlled 1-alkene.
► BET surface area at 600 (amorphous) and 1000 °C (crystalline) are 104.2 and 0.3 m2/g.