Beta Zeolite Catalytic Isomerization of endo-Dicyclopentadiene
ZHANG Yu1, HAN Hong1,2, ZOU Ji-Jun1
（1.Key laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; 2.Jining University, Qufu 273155, China）
Abstract Hβ-catalytic isomerization of endo-dicyclopentadiene (endo-DCPD) to exo-dicyclopentadiene (exo-DCPD) in liquid phase was studied. With the absence of zeolite, DCPD is converted into oligomers and the formation of exo-DCPD is neglectable. With the presence of Hβ, considerable amount of exo-DCPD is formed. Passivation of the external surface with amorphous silica layer improves the selectivity of isomerization reaction with a little decline in conversion. This means that the isomerization reaction occurs inside the pore of zeolite, meanwhile the external acidity accelerates the undesired oligomerizations. Hβ with low SiO2/Al2O3 ratio contains highest concentration of weak Lewis acid, and exhibits highest activity, confirming that weak L acidity is the active site for the isomerization. The calcination temperature has great influence on the acidity and porous structure of zeolite. The amount of weak L acid is not enough at low temperature, while the framework and pores are destroyed at high temperature. Calcination at 500 ℃ produces enough weak L acid and keeps relatively well crystallinity, thereby providing best catalytic performance.
2014, Vol. 31 
