The isopropylation of naphthalene over ordered mesoporous aluminosilicate AlSBA-1: The formation of diisopropylnaphthalene and triisopropylnaphthalene isomers

• Published in: Molecular catalysis Vol. 547; p. 113322
• Main Authors: Tabish, Ahmad, Ruban, Sujanya Maria, Joseph, Stalin, Indirathankam, Sathish Clastinrusselraj, Bezingar, Mercy, Ramadass, Kavitha, Yang, Jae-Hun, Nimisha, Naroth P., Ayyamperumal, Sakthivel, Sugi, Yoshihiro, Vinu, Ajayan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2023
• Subjects: AlSBA-I; Diisopropylnaphthalene; Isopropylation; Mesoporous aluminosilicate; Triisopropylnaphthalene; Mesoporous aluminosilicate; AlSBA-I; NP; Diisopropylnaphthalene; Isopropylation; Triisopropylnaphthalene
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2023.113322

•The high selectivities for TriIPN isomers in the isopropylation of naphthalene over AlSBA-1.•The high yields of TriIPN isomers started from low temperature, 225 °C by multi-step isopropylation during one stay on catalytic site with the co-operation of neighbor propylene adsorbed sites.•The isopropylation of NP was controlled by kinetic properties of NP derivatives and/or thermodynamical properties of TriIPN isomers, not by steric restriction of AlSBA-1.•Big differences of the cooperation of neighbor acid sites between AlSBA-1 and FAU zeolite: possible for AlSBA-1, but not for FAU zeolite, resulting in high yield of TriIPN isomers for AlSBA-1. We report on the catalytic activity of ordered mesoporous aluminosilicate, AlSBA-1 with 3D cage type porous structure, in the isopropylation of naphthalene (NP). The higher isopropylates: triisopropylnaphthalene (TriIPN) and tetraisopropylnaphthalene (TetIPN) isomers were formed over AlSBA-1 in addition to isopropylnaphthalene (IPN) and diisoprpylnaphthalene (DIPN) isomers. The higher isopropylates were started to form at 225 °C as primary products, which were produced by multi-step isopropylation from NP occurred during one stay on the catalytic site cooperated with the propene adsorbed neighbor acid sites. TriIPN isomers were composed of four isomers (1,3,7-. 1,3,5-, 1,3,6-, and 1,4,6-) formed from DIPN isomers. These formations of TriIPN isomers are controlled by the distribution of DIPN isomers. β,β-DIPN isomers lead to α,β,β-TriIPN isomers, and α,α-DIPN to α,α,β-TriIPN, respectively. However, α,β-DIPN isomers give both of α,α,β- and α,β,β-TriIPN isomers depending on the reaction conditions. The distribution of TriIPN isomers is operated by their kinetic and thermodynamic properties. Bulky and unstable α,α,β-TriIPN isomers (1,3,5- and 1,4,6-) were predominant at low temperatures, 175–250 °C, and at low NP/Cat ratio at 250 °C, where the catalysis mainly proceeded under kinetic control. However, the formation of slim and stable α,β,β-TriIPN isomers (1,3,7- and 1,3,6-) increased with raising the temperatures, and was primary at 300 °C, where the catalysis occurred under thermodynamic control. From these results, it is concluded that the isopropylation of NP over AlSBA-1 occurs under kinetic and/or thermodynamically controls based on the reactivity of the reactants and the stability of the products, and no steric control concerns by mesopores. [Display omitted]