Magnetically recyclable Ag-ferrite catalysts: general synthesis and support effects in the epoxidation of styrene

Abstract

A series of new magnetically recyclable catalysts (MRCs), Ag-M(1-x)Fe(2+x)O(4) (M = Co, Ni, Mn, Zn) nanocomposites, have been synthesized via a generalized one-pot route, and these materials prove to be efficient MRCs in the catalytic epoxidation of styrene. Characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) and X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and magnetic measurement reveal that the nanocomposites are assembled from well crystallized Ag and corresponding ferrite primary particles with the assistance of polyvinylpyrrolidone (PVP). The nanocomposite samples are comparable in Brunauer-Emmett-Teller (BET) specific surface areas and are superparamagnetic at room temperature. The as-prepared MRCs exhibit high activities in the epoxidation of styrene in toluene with tert-butylhydroperoxide (TBHP) as the oxidant and very high yields of styrene oxide can be achieved within 5 h of reaction. All the MRCs can be easily recovered by using a magnet and no decrease in the yield of styrene oxide has been observed after several consecutive rounds of reaction. It has been demonstrated that the ferrite supports affect the structure of Ag and the efficiency in oxygen supply and thus the catalytic performance.

Synthesis of confined Ag nanowires within mesoporous silica via double solvent technique and their catalytic properties

“…Ag supported on ferrite can be used as catalysts in the oxidation of styrene [43]. This study evaluated the catalytic efficiency of the Ag/mesoporous silica composites to oxidize styrene.…”

A facile synthesis methodology for preparation of Ag–Ni-reduced graphene oxide: a magnetically separable versatile nanocatalyst for multiple organic reactions and density functional study of its electronic structures

“…suffer from some disadvantages, such as the production of the large amount of undesirable by-products, harsh reaction conditions, cost-effectiveness, separation problem associated with homogeneous catalysts, etc. 10,26,27 Therefore, till date, several researchers are engaged in developing novel catalysts for chlorine-free epoxidation reaction. [27][28][29][30] (iv) Click reaction: synthesis of triazoles by 'Click reaction' has gained immense attention due to the use of triazoles as biologically active chemicals, agrochemicals, pharmaceuticals, drug molecules with signicant anti-HIV activity, antimicrobial activity against Gram-positive bacteria, etc.…”

Magnetically recyclable nanocatalysts (MRNCs): a versatile integration of high catalytic activity and facile recovery

“…12b). 123 Similar routes have recently been reported by Gusevskaya et al 141 in the fabrication of cobaltiron magnetic composites, and their catalytic activity, stability and recyclability were studied in aerobic oxidation of thiols. Very recently Ni-Fe 3 O 4 , 143 Pd-Fe, 144 and Ag-Fe 3 O 4 142 MRNCs were also obtained through one-pot synthesis.…”