Gianni Girotti

Alkylation of benzene with isopropanol on β-zeolite: influence of physical state and water concentration on catalyst performances

By using isopropanol as alkylating agent in the direct alkylation of benzene to cumene, under properly selected conditions, performances comparable to those afforded by the current industrial use of propylene have been obtained. The reaction is carried out in the presence of a β-zeolite-based catalyst. Catalytic performances are influenced by temperature and pressure at fixed benzene to isopropanol molar ratio. In particular, catalyst activity and catalyst deactivation rate depend on the water content in the liquid phase fraction of the reaction mixture, as predicted by state equations for LV equilibria in the reacting system. The successful use of isopropanol as alkylating agent has paved the road toward a viable acetone recycle in phenol production, as foreseeable in case of acetone/phenol unbalanced demand.

Stability upon thermal treatment of coked zeolite beta

Abstract Dealumination during thermal treatment of zeolite Beta was examined. Repeated thermal treatments of zeolite impregnated with poly-alkylated tars (coked Beta) were made to simulate prolonged industrial usage. The partial structural collapse caused by each impregnation/calcination was quantified by XRD and the migration of aluminum (from framework to extra-framework sites) was evidenced by 27 Al MAS NMR and IR spectroscopies. Non-impregnated Beta was thermally stable up to 750°C. On the contrary, limited but significant framework dealumination occurred during thermal treatment of impregnated zeolite Beta, due to H 2 O produced by the combustion of the organic species trapped inside the pores. These results allowed the design of an appropriate regeneration procedure for the proprietary zeolite Beta-based catalyst, which is necessary to avoid removal of framework aluminum and zeolite structure collapse.