Comparison of Catalytic Performances of Lewis Acids, Sulfated Zirconia and Zeolite B Towards Acetylation of Aromatics

Paul Wilson1 Mark L. Kaliya2, Miron. V. Landau2 and Moti Herskowitz2

1Madras Christian College, Tambaram, Chennai 600 059, India

2Blechner Center for Industrial Catalysis and Process Development Department of Chemical Engineering, Ben-Gurion University of the Negev, 84105 Beersheva, Israel

Abstract

Evaluation of catalytic performances of selected metal chlorides such as AlCl3, SnCl4, ZnCl2, FeCl3, InCl3 and GaCl3 with solid acids such as sulfated zirconia, and zeolite beta was accomplished for acetylation of anisole, toluene and naphthalene. Presence of super acidity (Lewis or Bronsted acid) is found to be indispensable for activation of substrates towards acetylation reactions. In addition, presence of redox centers would further complement with the Lewis acid sites rendering catalytic stamina against deactivation. Strength of Lewis acid basically determines the activity of the metal chlorides towards acetylation. Among the Lewis acids investigated, FeCl3, InCl3 and GaCl3 exhibit their catalytic behaviour mostly through redox property as is evident from the conservation of Turn over number even after first cycle. Sulfated zirconia surpasses all the acid catalysts including metal chlorides and exhibits extended catalytic activity in acetylation of anisole. The pre-eminence of sulphated zirconia over other catalytic systems is owing to the synergistic effect of Lewis and Bronsted acidity.