Isopropylation of benzene over sulfated ZrO2-TiO2 mixed-oxide catalyst

Zirconia-titania mixed oxide containing 60 mol% of zirconium was synthesized by co-precipitation method with and without sodium dodecyl sulfate (SDS) as surfactant. The 110 degreesC dried mixed oxides were loaded with 10 wt.% sulfate by wetness impregnation method. Each of the sulfated samples was calcined for 3 h at 500, 600 and 800 degreesC, and characterized by surface area and pore size distributions using multipoint BET method. Further, the 600 degreesC calcined sulfated mixed-oxide samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and ammonia temperature programmed desorption (TPD). The results revealed that amorphous, high surface area materials were obtained possessing both Lewis and Bronsted acid sites. However, the sample prepared with surfactant showed higher total pore volume and average pore diameter and was more acidic than that prepared without surfactant. The catalytic activity of these samples was tested for isopropylation of benzene with isopropanol varying different reaction parameters. The results are correlated to the acidity and textural properties, which show that catalyst prepared in presence of SDS, with improved texture and high acidity, is excellent for this reaction with cumene selectivity more than 97 mol%. The deactivation was found to be faster at lower reaction temperature. (C) 2002 Elsevier Science B.V. All rights reserved.