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

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 m2g-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% of phenol conversion with a hydroquinone-to-catechol ratio of seven, which is the highest value ever reported.