The Isopropylation of Naphthalene over USY Zeolite with FAU Topology. The Selectivities of the Products

The isopropylation of naphthalene (NP) over USY zeolite (FAU06, SiO2/Al2O3 = 6) gave all eight possible diisopropylnaphthalene (DIPN) isomers: beta,beta- (2,6- and 2,7-), alpha,beta- (1,3-, 1,6-, and 1,7-), and alpha,alpha- (1,4- and 1,5-). The catalyses are operated under kinetic and/or thermodynamic controls depending on the reaction temperatures because the cavities of FAU topology are wide enough to form all DIPN isomers. Enhanced selectivities for beta,beta-DIPN were observed at the early stages at 200, 250, and 300 degrees C although the selectivities decreased with the increasing periods, accompanying the increase in alpha,alpha- and alpha,beta-DIPN. The enhancement occurs under new types of thermodynamic controls through thermodynamically preferred transition states to beta,beta-DIPN. Triisopropylnaphthalene (TriIPN) isomers are also formed in the isopropylation. Unstable alpha,alpha,beta-TriIPN (1,4,6- and 1,3,5-) is predominantly formed at lower temperatures; however, decreased with the increase of stable alpha,beta,beta-TriIPN (1,3,6- and 1,3,7-) at higher temperatures. The predominant formation of 1,4,6-TriIPN was also observed in the initial stages in the range of 200, 250 and 300 degrees C, as reaction period was increased, while the selectivity for the isomer was decreased with concomitant increase in the selectivities for the other isomers. These changes of the selectivities operated under kinetic and/or thermodynamic controls. Large cavities of the zeolite allow the formation of all TriIPN isomers without steric restriction.

Automated summary

The isopropylation of naphthalene over USY zeolite resulted in the formation of all eight possible DIPN isomers, operated under kinetic and/or thermodynamic controls at different reaction temperatures. Triisopropylnaphthalene isomers were also formed, with the predominance of certain isomers depending on temperature and reaction period, indicating a combination of kinetic and thermodynamic controls in the selectivities. Large cavities of the zeolite allowed the formation of all TriIPN isomers without steric restriction.