Microreactor Coated with Mesoporous Organosilica Thin Film as a Support for Metal Complex Catalysts

Abstract

In this study, periodic mesoporous organosilica (PMO) thin films containing 2,2'‐bipyridine ligands (BPy‐PMO) were formed on the inner wall of a microreactor by evaporation‐induced self‐assembly approach. The obtained BPy‐PMO thin films had open mesopores ranging from 8 to 12 nm on the outermost surfaces with the thickness of approximately 50 nm. Since BPy‐PMO has a strong chelating ability to metals, the microreactor coated with BPy‐PMO film can be used as a unique support for continuous flow reactions using various metal complex catalysts. Dichlorodioxomolybdenum(VI) (MoO2Cl2) complex was immobilized in the BPy‐PMO layer; the epoxidation of cis‐cyclooctene with tert‐butyl hydroperoxide (TBHP) was evaluated in a continuous flow manner. The immobilized catalysts showed the turnover frequency higher than 3000 h–1 and the turnover number higher than 66000 at 80 °C with maintaining their catalytic activity over 26‐h experiments. These numbers are considerably high compared to Mo catalysts immobilized via conventional methods.

Recent advanced development of metal-loaded mesoporous organosilicas as catalytic nanoreactors

“…More recently, a BPy-PMO thin lm was fabricated on the inner wall of a microreactor by an evaporation-induced selfassembly approach. 100 The obtained BPy-PMO thin lms exhibited open mesopores with a diameter of 8-12 nm on the outermost surfaces and a thickness of approximately 50 nm. MoO 2 Cl 2 could be immobilized into BPy-PMO thin lm layers to form Mo-BPy-PMO inside the microreactor for the epoxidation of cis-cyclooctene with TBHP in a continuous ow manner.…”

Porous organic–inorganic hybrid materials for catalysis, energy and environmental applications

“…Recently, Kataoka and Inagaki employed the evaporation-induced self-assembly (EISA) approach to fabricate a 2,2 0 -bipyridine-PMO thin film, which later served as framework to affix MoO 2 Cl 2 complexes. 67 This new approach to obtain metal complex-grafted PMO thin films can serve as a microreactor for the synthesis of fine chemicals in continuous flow reactors. The versatility in chemical composition offers heterogeneity and idiosyncrasy in the application of PMOs, which is not surprising, given that they were first developed by materials chemists.…”