Synthesis of 2,6-diisopropylnaphthalene over zeolite Hβ catalyst

Isopropylation of naphthalene with isopropyl alcohol to 2,6-diisopropylna-phthalene(2,6-DIPN) over Hβ zeolite was studied.Effects of solvent dosage,n(isopropyl alcohol) : n(naphthalene),catalyst dosage,reaction temperature and reaction time were investigated.Hβ zeolite exhibited higher conversion and selectivity for isopropylation of naphthalene under mild reaction condition.Optimal reaction condition was obtained as follows: solvent dosage 25 mL,n(naphthalene)=0.05 mol,n(isopropyl alcohol)∶n(naphthalene)=2.5∶1,catalyst dosage 15%,reaction temperature 270 ℃,reaction time 6 h.Naphthalene conversion of 66.41%,diisopropylnaphthalene(DIPN) yield of 18.72% and 2, 6-diisopropylnaphthalene(2,6-DIPN)yield of 3.41% were obtained under the optimal reaction condition,with the ratio between 2,6-DIPN and 2,7-DIPN of as high as 1.56.Framework structure of Hβ zeolite after silicon-modification was basically unchanged,but surface area and number of acid sites decreased, which enhanced its properties for isopropylation of naphthalene.Under dosage of silicon oil 0.4 mL·g-1 Hβ,naphthalene conversion of 81.21%,2, 6-DIPN yield 7.60%,and 2,6-DIPN to 2,7-DIPN ratio of as high as 1.52 were attained.