An iron-containing POM-based hybrid compound as a heterogeneous catalyst for one-step hydroxylation of benzene to phenol

It is a major challenge to perform one-pot hydroxylation of benzene to phenol under mild conditions, which replaces the environmentally harmful cumene method. Thus, finding highly efficient heterogeneous catalysts that can be recycled is extremely significant. Herein, a (POM)-based hybrid compound {[FeII(pyim)2(C2H5O)][FeII(pyim)2(H2O)][PMoV2MoVI9VIV3O42]}·H2O (pyim = 2-(2-pyridyl)benzimidazole) (Fe2-PMo11V3) was successfully prepared by hydrothermal synthesis using typical Keggin POMs, iron ions and pyim ligands. Single-crystal diffraction shows that the Fe-pyim unit in Fe2-PMo11V3 forms a stable double-supported skeleton by Fe-O bonding to the polyacid anion. Remarkably, due to the introduction of vanadium, Fe2-PMo11V3 forms a divanadium-capped conformation. Benzene oxidation experiments indicated that Fe2-PMo11V3 can catalyze the benzene hydroxylation reaction to phenol in a mixed solution of acetonitrile and acetic acid containing H2O2 at 60 °C, affording a phenol yield of about 16.2% and a selectivity of about 94%.

g-C3N4-modified Zr-Fc MOFs as a novel photocatalysis-self-Fenton system toward the direct hydroxylation of benzene to phenol

In order to explore a green, economic, and sustainable phenol production process, a heterojunction semiconductor materials g-C₃N₄/Zr-Fc MOF was synthesized via an in situ synthesis method. With the synergistic effect of photocatalysis and the Fenton effect, the composite could effectively catalyze the direct hydroxylation of benzene to phenol under visible light irradiation. The yield of phenol and the selectivity were 13.84% and 99.38% under the optimal conditions, respectively, and it could still maintain high photocatalytic activity after 5 photocatalytic cycles. Therefore, the designed photocatalysis-self-Fenton system has great potential in the field of the direct hydroxylation of benzene to phenol.

Tailored activity of Cu–Fe bimetallic Beta zeolite with promising C3H6 resistance for NH3-SCR

The introduction of Cu has inhibited the polymerization of C₃H₆ and promoted the oxidation of C₃H₆, which alleviated competitive adsorption between C₃H₆ and NO_x, therefore results in the enhanced NH₃-SCR performance in the presence of C₃H₆.

Bimetallic Fe–Cu/beta zeolite catalysts for direct hydroxylation of benzene to phenol: effect of the sequence of ion exchange for Fe and Cu cations

Recently, bimetallic cation-exchanged zeolite catalysts have received much attention.