Abstract
Sulfated tin oxide and sulfated zirconia containing different amounts of sulfate and Al
2
O
3
-sulfated zirconia catalysts were prepared. The materials were characterized by DTA/TGA/DTG, XRD, FT-IR, and BET surface-area techniques. Surface acidity was determined using TGA of pyridine-pretreated samples, and acid strength was determined by potentiometric titration of the solid catalysts with
n
-butylamine in non-aqueous media. The catalytic activity of prepared samples was tested by Friedel–Crafts acylation of toluene with acetic acid anhydride. Incorporation of sulfate into SnO
2
impedes sintering and is associated with a decrease of surface area. Sulfated tin oxide has greater acidity and higher acid strength than Al
3+
-impregnated sulfated zirconia, giving, therefore, a higher yield of acylation products. Sulfated tin oxide was found to pass through maxima of higher acidity and higher efficiency for the acylation reaction when sulfate loading is 10 wt%. A good relationship between structural characteristics, acidity, and catalytic activity is observed.
Graphical abstract