Mechanochemical Synthesis of CuO/MgAl2O4 and MgFe2O4 Spinels for Vanillin Production from Isoeugenol and Vanillyl Alcohol

Abstract

CuO/MgAl2O4 and CuO/MgFe2O4 catalysts were successfully synthesized with the use of spinel supports by a very simple and low-cost mechanochemical method. High-speed ball-milling was used to synthesize these catalyst supports for the first time. Materials were subsequently characterized by using XRD, FESEM, TEM, EDS-Dot mapping, XPS, BET-BJH, and Magnetic Susceptibility to investigate the physical-chemical characteristics of the catalysts. Acidity evaluation results indicated that the catalyst with the Mg-Al spinel support had more acid sites. XRD results showed a successful synthesis of the catalysts with large crystal sizes. Both catalysts were used in isoeugenol oxidation and vanillyl alcohol to vanillin reactions, with the CuO/MgAl2O4 showing optimum results. This catalyst provided 67% conversion (74% selectivity) after 2 h and this value improved to 81% (selectivity 100%) with the second reaction after 8 h. The CuO/MgFe2O4 catalyst in the first reaction after five hours revealed 53% conversion (47% selectivity) and after eight hours with the second reaction, the conversion value improved to 64% (100% selectivity). In terms of reusability, CuO/MgAl2O4 showed better results than the CuO/MgFe2O4 catalyst, for both reactions.

Multifunctional MgFe2O4/GNPs nanocomposite: Graphene-promoted visible light driven photocatalytic activity and electrochemical performance of MgFe2O4 nanoparticles

“…Fig. 4: High resolution XPS spectra of (MFO)1-x(GNPs)x samples.The peak at 50.18 eV (Fig.4 (a)) is attributed to Mg 2+ state in MFO nanoparticles[48]. The Fe 2p binding energy peak consists of two components Fe 2p1/2 and Fe 2p3/2 with maxima at 725.3 eV and 711.4 eV respectively as given in Fig.4(b).…”

Mechanochemical Synthesis of Catalytic Materials

“…From a catalysis viewpoint, the possibilities of controlling composition, structure, valence, and morphology have made spinel systems suitable as catalysts in many different reactions, including NO x reduction, [102, 103] CO oxidation, [104] CO 2 reduction, [105] hydrogen evolution reaction (HER), [106] oxygen reduction reaction (ORR), [107] oxygen evolution reaction (OER), [108] and alcohol oxidation [109–110] . Spinel oxides based on Mg‐Al, Fe‐Co, Mg‐Fe, Ni‐Fe, Zn‐Fe, and Zn‐Al systems are the most important ones among the ternary oxides—together with the perovskite family—and can be fabricated by ball milling [111–119] . In general, the mechanochemical synthesis of spinel oxides is based on a bottom‐up approach, involving the ball milling of the oxide, oxyhydroxide, or hydroxide metal precursors at room temperature in air.…”

Recent advances in mechanochemical synthesis of mesoporous metal oxides

“…15 Mechanochemical concepts seem to be very promising for a large scale production and/or modification of porous metal oxides for catalysis, battery technology, adsorption, medicine, and so on. [16][17][18][19][20][21][22][23][24] Especially, new catalysts have been intensively studied for application in water splitting, organic syntheses, removal of pesticides and dyes from wastewater, and removal of diverse harmful gases and vapors, among others. [25][26][27][28] Recently, a facile mechanochemical process, which relied on dehydration of boehmite in a vibration mill afforded a valuable catalyst -corundum with nanoparticle size of ~13 nm and specific surface area (SSA) 6 of ~140 m 2 /g.…”