Active and recyclable sulphated zirconia catalysts for the acylation of aromatic compounds

Mesoporous sulphated zirconia catalysts have been prepared by precipitation of Zr(OH)4 at constant basic pH and tested for the acylation of anisole with benzoic anhydride. All samples have been characterized by N-2 physisorption, ion chromatography and thermal analysis coupled with MS analysis of evolved gases (EGA). The samples possessed high specific surface areas and mean pore size in the mesopore range. TG/DSC/EGA analysis allowed us to observe all phenomena related to the calcination process and to better understand the catalyst behavior. Observed phenomena are physisorbed water elimination, dehydroxylation, sulphating agent decomposition, phase transitions and sulphate species removal. Catalytic tests were carried out at different temperatures (30-50 degrees C) after a thermal treatment. The effects of the precipitation pH, calcination temperature and activation temperature on the catalytic performances were studied. Reuse of the catalyst was also appraised. (c) 2005 Elsevier B.V. All rights reserved.