Hydroxylation of benzene and phenol in presence of vanadium grafted Beta and ZSM-5 zeolites

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.

Selective catalytic oxidation of benzene to phenol by a vanadium oxide nanorod (Vnr) catalyst in CH3CN using H2O2(aq) and pyrazine-2-carboxylic acid (PCA)

A vanadium oxide nanorod (V_nr) catalyst has been synthesized without using surfactants through crystallization, which is highly active for benzene to phenol oxidation.

Direct synthesis of V-containing all-silica beta-zeolite for efficient one-pot, one-step conversion of carbohydrates into 2,5-diformylfuran

V-containing all silica beta-zeolite exhibited high atom-efficiency in the direct synthesis of 2,5-diformylfuran from carbohydrates.

Paramagnetic dioxovanadium(IV) molecules inside the channels of zeolite BEA--EPR screening of VO2 reactivity toward small gas-phase molecules

Interaction of small gas-phase molecules (NO, N2O, O2, CO) with VO2 radicals inside the channels of a dealuminated SiBEA zeolite was investigated by means of electron paramagnetic resonance (EPR), infrared (IR), and mass (QMS) spectroscopies to provide direct insights into the chemistry of a unique paramagnetic state of vanadium - VO2 molecules. A facile way of forming VO2 inside the channels of SiBEA via thermal reduction of VO2(+) precursor cations was shown. Dioxovanadium(IV) was identified based on its unusual EPR signal which, as compared with the typical monooxovanadium(IV) (VO(2+) cation), is featured by rhombic symmetry and a positive Aiso value leading to a hyperfine splitting as large as 32 mT. VO2 molecules exhibit reducing properties transforming N2O and O2 into vanadium intrachannel cage adducts comprising of reactive oxygen species (O(-) and O2(-), respectively). Interaction with CO led to its oxidation to CO2, while paramagnetic NO acted as a scavenger for VO2 radicals producing diamagnetic adducts. The observed reactivity was rationalized in terms of spin-pairing, electron transfer, and oxygen transfer processes. As a result new chemical pathways of vanadium reactivity were demonstrated which were not observed so far either in the homogeneous molecular systems or supported vanadium materials.

The preparation of Fe/wood-based activated carbon catalyst for phenol hydroxylation from Fe2+ and Fe3+ precursors

Loading of Fe³⁺ and Fe²⁺ on wood-based activated carbon obtained Fe-based catalyst with good catalytic performance for phenol hydroxylation.

Facile synthesis of Fe(3)O(4)/MWCNTs by spontaneous redox and their catalytic performance

Fe(3)O(4) nanoparticles with a size range of 4-8 nm were formed by the spontaneous redox reaction between Fe(3 + ) and multi-walled carbon nanotubes (MWCNTs). Cyclic voltammetry, Raman spectroscopy and x-ray photoelectron spectroscopy were employed to study the thermodynamic and dynamic conditions for the Fe(3)O(4)/MWCNTs formation. It is found that the high defect density of MWCNTs was thermodynamically favorable for the spontaneous reduction of Fe(3 + ) ions and a reaction time of above 2.5 h should be guaranteed. As the catalysts for benzene hydroxylation to phenol, the as-obtained Fe(3)O(4)/MWCNTs exhibit superior catalytic performance to those prepared by the hydrothermal method. Therefore, the spontaneous redox between the Fe(3 + ) and MWCNTs supplies an attractive facile route for the preparation of Fe(3)O(4) nanoscale catalysts.