Mg–Zn and Mn–Zn Ferrites Derived from Coil Core Materials as New Phenol Methylation Catalysts

Abstract

A catalytic phenol methylation study on two ferrospinel materials (Mg 0.63 Zn 0.37 )(Mn 0.1 Fe 1.8 )O 3.85 (hereafter Mg− Zn) and (Mn 0.55 Zn 0.35 Fe 0.1 )Fe 2 O 4 (hereafter Mn−Zn) was performed. The reaction was carried out in the gas phase in a continuous manner with the feed composition of phenol, methanol, and water in molar ratio 1:5:1. Both ferrites are active in the studied reaction. The alkylation of phenol with methanol led to the selective production of o-methylated phenol derivatives, i.e., o-cresol and 2,6-xylenol. However, both catalysts markedly differ in terms of activity. Different synergy effects on both catalysts cannot be a sufficient explanation. These materials do not differ significantly either in their susceptibility to reduction or in their Lewis type acidity. Because their microstructure differs significantly, a size effect may therefore be responsible for the differences in activity.

Construction of Acid–Base Synergetic Sites on Mg‐bearing BEA Zeolites Triggers the Unexpected Low‐Temperature Alkylation of Phenol

“…All the samples have similar SiO 2 /Al 2 O 3 molar ratios of approximately 31. Characterizations by SEM, TEM, thermogravimetric analysis( TGA), nitrogen sorptionm easurements, and 29 Si and 27 Al NMR spectroscopic analyses confirmt he crystal structure has the morphology of ellipsoid-globoseo f1 -2 mm, has ah omo-dispersion of Mg ions, high thermal stability,a nd abundant open microporosity (Table 1, Figure 1, and FiguresS2-S4 and Table S1 in the SupportingI nformation). Further,t he unit-cellv olumeo fM g b(n)i sa pparently enlarged ( Table S2 in the Supporting Information);a lso, the samples exhibit an IR band shift to approximately 1072 cm À1 for the tetrahedral TO 4 units and new UV/Vis absorbance at approximately 245 nm.…”

“…Inorganic chemical compositions were analyzed with aJ arrell-Ash 1100 inductively coupling plasma (ICP) spectrometer.T he surface chemical composition was analyzed by X-ray photoelectron spectra (XPS) with aP HI 5000 Versa Probe X-ray photoelectron spectrometer equipped with AlK a radiation (1486.6 eV). 29 Si and 27 Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra were recorded with aB ruker AVANCE III 600 spectrometer.T hermogravimetric (TG) curves were determined by using aS TA409 instrument in dry air at ah eating rate of 10 8Cmin À1 .A mmonia (NH 3 )a nd carbon dioxide (CO 2 )t emperature-programmed desorption (TPD) curves were detected by using aC atalyst Analyzer BELCAT-B. Samples were pretreated at 550 8Cf or 2h,a nd then cooled to 50 8C under helium (He) gas.…”

“…Among the variousa lkylation reactions, methylation of phenol with methanoli so ne industrially available pathway to produce cresols, important intermediates for manufacturing functional polymers, antioxidants, pharmaceuticals, and agrochemicals. Various catalystsh ave been developed, such as metal oxides, [20][21][22] zeolites, [23][24][25] sulfates, [26] mixed metal oxides, [27][28][29][30] andh ydrotalcites. [31] MCM-22 with different Si/Al has only approximately 20 %s electivityf or the C-alkylation of phenol at low pressure.…”

Microwave-dried α-Fe2O3 as a highly efficient catalyst for ortho-methylation of phenol with methanol

“…Although MgO has high ortho-selectivity for o-cresol nearly 100%, phenol conversion is only 8.2% at the reaction temperature as high as 673 K, and lacks the test of stability [5][6][7][8]. TiO 2 has phenol conversion about 40%, however the selectivity of o-cresol is only 60% [9][10][11][12].…”

Manganese–Zinc Ferrite Synthesis by the Sol–Gel Autocombustion Method. Effect of the Precursor on the Ferrite’s Catalytic Properties

“…Such processes were studied also on magnesium−zinc and manganese−zinc ferrites, which had originally been synthesized for the microelectronic industry. 28,29 The synthesis method has a significant effect on the properties (crystallite size and specific surface area) of the obtained material and determines its target application. This research was undertaken to synthesize and characterize ultrafine manganese−zinc ferrites and to explore the possibilities of using the obtained products as catalysts in the ketonization of primary alcohols.…”