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

Abstract

Zirconia–titania mixed oxide containing 60mol% of zirconium was synthesized by co-precipitation method with and without sodium dodecyl sulfate (SDS) as surfactant. The 110°C dried mixed oxides were loaded with 10wt.% sulfate by wetness impregnation method. Each of the sulfated samples was calcined for 3h at 500, 600 and 800°C, and characterized by surface area and pore size distributions using multipoint BET method. Further, the 600°C 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 97mol%. The deactivation was found to be faster at lower reaction temperature.