MOR zeolite supported Brønsted acidic ionic liquid: an efficient and recyclable heterogeneous catalyst for ketalization

Abstract

In order to widen the application of ionic liquids as efficient and renewable heterogeneous catalysts, supported ionic liquids (SILs) have received considerable attention. A novel heterogeneous catalyst MOR zeolite supported Brønsted acidic ionic liquid (BAIL@MOR) was therefore prepared, characterized and applied in the ketalization reaction. The influences of reaction temperature, time, and catalyst loading have also been investigated in detail. Combined characterization results of XRD, FT-IR, SEM, TG-DTG and N₂ adsorption–desorption suggested that the BAIL [CPES-BSIM][HSO₄] was successfully immobilized on the surface of MOR zeolite by covalent bonds. Moreover, the catalytic performance tests demonstrated that the catalyst BAIL@MOR exhibited excellent catalytic activities in the ketalization of cyclohexanone with glycol, 1,2-propylene glycol and 1,3-butylene glycol under mild reaction conditions, as comparable with the homogeneous catalysis of the precursors [BSmim][HSO₄] and H₂SO₄. In addition, the catalyst BAIL@MOR was also found to be reusable five times without a significant loss of its catalytic activity. Thus, the heterogeneous catalyst BAIL@MOR can act as a promising candidate for the ketalization reaction.