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Facile Synthesis of CuMgFe Layered Double Hydroxides for Efficient Catalytic Phenol Hydroxylation under Mild Conditions
Author(s) -
Shen Jiecan,
Liang Jinhua,
Fu Xiaomin,
Jiang Yong,
Yan Shichang,
He Haiming,
Ren Xiaoqian
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201904242
Subject(s) - layered double hydroxides , catalysis , thermogravimetric analysis , temperature programmed reduction , x ray photoelectron spectroscopy , fourier transform infrared spectroscopy , hydroxylation , chemistry , scanning electron microscope , inorganic chemistry , desorption , copper , phenol , differential scanning calorimetry , thermal desorption spectroscopy , nuclear chemistry , materials science , adsorption , chemical engineering , organic chemistry , physics , engineering , composite material , thermodynamics , enzyme
A series of CuMgFe layered double hydroxides (denoted as X/CuMgFe–LDHs) with different Cu contents were synthesized by co‐precipitation as catalysts for phenol hydroxylation under mild conditions. The as‐prepared samples were analyzed by X‐ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP‐ES), N 2 adsorption–desorption, Fourier transform infrared (FT‐IR), thermogravimetric differential scanning calorimetry (TG‐DSC), X‐ray photoelectron spectroscopy (XPS) and hydrogen temperature‐programmed reduction (H 2 ‐TPR) to investigate the morphologies and physicochemical properties. As presented by the characterization results, introducing a certain amount of copper not only increased the amount of active metal centers but also formed more oxygen vacancies and lattice oxygen to promote electron transport between the double layers in LDHs. However, the excess copper would significantly disrupt the X/CuMgFe–LDH framework, declining the activity. Therefore, the 20/CuMgFe–LDH sample presented the best catalytic performance among all the catalysts in terms of activity, which was correlated with the layered structure, low‐temperature reducibility, oxygen species and low Cu + /Cu 2+ and Fe 2+ /Fe 3+ ratios. The catalyst could maintain good stability even after recycling for five times. Finally, a possible mechanism for phenol hydroxylation via Cu + –O V –Fe 2+ and Cu 2+ –O–Fe 3+ redox cycles on CuMgFe–LDHs was proposed.