Isomerization of p-diisopropylbenzene (p-DIPB) to m-diisopropylbenzene (m-DIPB) was carried out using
metal modified Hβ zeolites at high temperature and in the absence of a solvent. The metal cations used for the modification
of Hβ were typical Lewis acidic cations Fe3+, Al3+, Ti4+, Sn4+ and Sb3+. The modified zeolite catalysts were heated at
120oC, and calcined at 280oC, and 550oC. They were characterized by XRD, FE-SEM, HR-TEM, FT-IR, N2-desorption
(BET), NH3-TPD, Pyridine-IR and TGA techniques for structural, morphological, acidity and stability investigation. Particle
size of the crystallites was determined by HR-TEM analysis and the size was in the range of 15-35 nm. At 250oC, Al-
Hβ, Fe-Hβ and Ti-Hβ showed 68-75% conversion of p-DIPB and 42-54% selectivity towards m-DIPB. The calcination
temperature had no effect on the activity. Isomerization increases with increased acidity. Thus, metal modified Hβ catalysts
are excellent, efficient, and alternative heterogeneous catalysts for the isomerization of p-diisopropylbenzene (p-
DIPB) to m-diisopropylbenzene (m-DIPB). This process is a greener alternative for the classical AlCl3 process as discussed
in the article along with the relevant patents.
Diisopropylbenzene, heterogeneous catalysis, isomerization, metal modified zeolite Hβ, rearrangement of dialkylbenzenes.
Organic Chemistry Research Laboratory, Department of Chemistry, Institute of Chemical Technology, N.M. Parekh Road, Matunga, Mumbai 400 019, India.