Preparation of Fe(II)/MOF-5 Catalyst for Highly Selective Catalytic Hydroxylation of Phenol by Equivalent Loading at Room Temperature

Abstract

The metal-organic framework MOF-5 was synthesized by self-assembling of Zn(NO3)2·7H2O and H2BDC using DMF as solvent by the direct precipitation method and loaded with Fe2+ by the equivalent loading method at room temperature to prepare Fe(II)/MOF-5 catalyst and the microstructure, phases, and pore size of which was characterized by IR, XRD, SEM, TEM, and BET. It was found that Fe(II)/MOF-5 had high specific surface and porosity like MOF-5 and uniform pore distribution, and the pore size is 1.2 nm. In order to study the catalytic activity and reaction conditions of Fe(II)/MOF-5, it was used to catalyze the hydroxylation reaction of phenol with hydrogen peroxide. The results showed that the dihydroxybenzene yield of 53.2% and the catechol selectivity of 98.6% were obtained at the Fe2+ content of 3 wt.%, the mass ratio of Fe(II)/MOF-5 to phenol of 0.053, the reaction temperature of 80°C, and the reaction time of 2 h.

3D-Printed Fe/γ-Al2O3 Monoliths from MOF-Based Boehmite Inks for the Catalytic Hydroxylation of Phenol

“…The performance of other different MOF catalysts, always used in the powder form, does not provide such high selectivity and yields, 22,27,48−50 and the leaching of the metal, typically Fe and Cu, caused by the degradation of the organic linkers was the most critical issue. 22,48,49 3.2.4. Integrity and Stability of the Monoliths.…”

Direct Hydroxylation of Phenol to Dihydroxybenzenes by H2O2 and Fe-based Metal-Organic Framework Catalyst at Room Temperature

“…For As far as we know, this is the best performance reported for the hydroxylation of phenol in water at room conditions. The Fe-BTC activity is clearly superior to that exhibited by other MOF catalysts, based on Fe and Cu, that require higher temperatures for the reaction [25][26][27]. Therefore, the Fe-BTC MOF is a valuable and suitable catalyst for the production of DHBZ, and its use must be accompanied by an adequate process strategy to guarantee the catalyst's stability.…”

“…The prepared Fe-BTC was tested as a catalyst in the hydroxylation of phenol using H 2 O 2 as an oxidant by varying the most affecting operational parameters viz. temperature, H 2 O 2 concentration and catalyst dose [25][26][27][28]33]. Water was the only solvent used.…”

“…Recently, MOFs with different metal active sites have been reported as catalysts for the hydroxylation of phenol [25][26][27][28]. For instance, Cu-MOF [Cu 2 (BPTC)(Im) 4 ] (H 4 BPTC = Bypenyl-3, 3', 4, 4'-tetracarboxylic acid, Im = imidazole) was synthesized by a hydrothermal method and tested for phenol hydroxylation at 30-50 • C using a phenol:H 2 O 2 molar concentration ratio equal to 1.0:1.8, ethanol:water 4:1 and 0.04 g of the catalyst.…”

“…The Fe leached was from 1.8 to 6.0% of initial Fe after 1 h, depending on the operating conditions, and the catalyst synthesis required solvents that increased risks and production cost [26]. A similar material was also synthesized using Fe(II) to decorate MOF-5 [27]; in this case, the catalyst was less stable and 18% of the Fe was leached out after 2 h, using the same conditions as Fe(III)/MOF-5.…”