Abstract
In the present study, we report the synthesis and catalytic activity of tungsten- and molybdenum-promoted mesoporous metal oxides in the aminolysis of epoxides. The as-synthesized catalysts were fully characterized by a variety of techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), temperature-programmed reduction (TPR) and desorption (TPD), nitrogen sorption measurements, powder X-ray diffraction (p-XRD), and thermogravimetric analysis (TGA). Amongst the two supports utilized, ZrO2 is a better support compared to SiO2. Furthermore, MoO3 proved to be a better dopant compared to its counterpart. Several parameters such as the variation of solvents, substrates, catalyst amounts, and stirring speed were investigated. It was observed that 450 rpm was the optimum stirring speed, with toluene as the best solvent and styrene oxide as the best substrate. Moreover, the optimum parameters afforded 98% conversion with 95% selectivity towards 2-phenyl-2-(phenylamino) ethanol and 5% towards 1-phenyl-2-(phenylamino) ethanol. Furthermore, 5%MoO3-ZrO2 catalyst demonstrated optimal performance and it exhibited excellent activity as well as great stability after being recycled 6 times.
Highlights
An increasing interest in the solid Lewis acids has attracted researchers from both industrial and academical fields
Most investigations have been conducted in such a way that they focus on the expansion of the pore sizes into the mesopore range, permitting larger molecules to enter the pore system to be refined and exit at a later stage [2]
The experiment was performed under the following conditions: 94.10 mmol of toluene, 0.23 mmol of decane, 4.20 mmol of aniline, and 3.50 mmol of the substrate were stirred in the round bottom flask, which was embedded inside the temperature-controlled silicone oil bath
Summary
An increasing interest in the solid Lewis acids has attracted researchers from both industrial and academical fields. It was reported that ZrO2 has higher thermal stability and due to this, it was found to be excellent catalytic support [10] This led researchers to have a significant interest in examining MoOx /ZrO2 and WOx /ZrO2 catalysts, since the pure ZrO2 becomes more active upon interaction with the dopant [11]. The acidic sites of the catalyst can be by addition of a second metal [13]. This is entirely in line with the ‘hard-soft acid-base’ theory, ory,harder but harder willout turn out tothe retard rate of reaction [15,24].
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