abstracts - Институт катализа им. Г.К. Борескова

OP-III-2with formation of diketene (intermediate) and acetone. Such species are also detected on thesurface of the catalyst during toluene acylation and are responsible for the weak activity andstrong deactivation observed with this reactant. The weak basicity of toluene favors a highanhydride coverage, which probably increases bimolecular condensation reactions of theacylating agent.ConclusionOperando IR of Friedel-Crafts acylation of anisole by acetic anhydride on beta zeolites allowsone to describe the deactivation mechanism. It depends on reactants relative concentrationsand on the size of crystallites. A high anisole/anhydride ratio, deactivation is due to a ß-diketone (a secondary product). For a large crystallite zeolite, deactivation is due to thereaction products accumulation and aldolic condensation. At higher gas phase anhydrideproportion, the deactivation is similar to that observed for toluene acylation and is caused bycondensation of the acylating agent.References:[1] Corma, A., Garcia, H., Catal. Today.38 (1997) 257.[2] Spagnol, M.; Gibert, L. ; Benazzi, E. ; Marcilly, C., Patent WO9635656 (1996).[3] Thibault-Starzyk, F. Saussey, J., in In Situ Characterization of Catalysts, B.M.Weckhuysen, Ed., American Scientific Publishers, San Diego (2004), 15.311