Ionic Liquid Templated Ordered Hexagonal Mesoporous Iron Phosphate Molecular Sieves: A Highly Effective Heterogeneous Catalysts with Remarkable Selectivity for Phenol Hydroxylation Reaction

Chem Asian J. 2023 Jul 17;18(14):e202300389. doi: 10.1002/asia.202300389. Epub 2023 Jun 16.

Abstract

A highly organized hexagonal mesoporous iron phosphate framework structure with the designation HMI-41 was successfully synthesized for the first-time in a reproducible way using imidazolium-based ionic liquid as structure directing agent. The unique templating properties of ionic liquid generated a highly ordered well-crystallized mesoporous matrix having high surface area (445 m2 g-1 ), thicker pore wall (2.1 nm) and narrow pore size distribution (3.1 nm). The presence of active sites within a tetrahedral framework structure made the novel HMI-41 catalyst highly effective for phenol hydroxylation in an acidic medium with hydrogen peroxide as the oxidant. The catalyst exhibited outstanding performance, achieving an impressive 80% hydroquinone selectivity and 21% phenol conversion with a hydroquinone-to-catechol ratio of seven, which is the highest value ever reported.

Keywords: Hydroxylation; Ionic Liquid; Iron phosphate; Mesoporous; Phenol; Quinones.