tert-Butylation of naphthalene by tertiary butanol over HY zeolite and cerium-modified HY catalysts

Abstract

tert-Butylation of naphthalene is a promising process for the production of 2,6-DANs, which are fundamental starting materials for PEN. Herein, the tert-butylation of naphthalene with tertiary butanol was carried out in the liquid phase over a series of Ce-modified HY zeolites. XRD, SEM, TEM, XPS, NH₃-TPD and FT-IR characterization studies proved that the Ce species dispersed uniformly on the HY zeolite in the form of small cerium oxide clusters/nanoparticles. The formed Ce₂O₃ and CeO₂ interacted with the hydroxyl groups in the zeolite, which caused the passivation of silicon–aluminium bridge hydroxyl groups in supercages and sodalite cages, resulting in the decrease of acid concentration and acid strength. Due to the weakened acid strength, the selectivity for 2,6-DTBN in the pores was greatly enhanced. Moreover, the non-selective acid sites on the external surface were reduced by Ce modification, which effectively inhibited dealkylation and isomerization reactions and thus helped to maintain the high selectivity for 2,6-DTBN.