The Efficient Recyclable Molybdenum- and Tungsten-Promoted Mesoporous ZrO₂ Catalysts for Aminolysis of Epoxides

• Main Authors: Xolani Sibusiso Hlatshwayo, Morena S. Xaba, Matumuene Joe Ndolomingo, Ndzondelelo Bingwa, Reinout Meijboom
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Catalysts
• Subjects: mesoporous zirconium oxide; molybdenum; tungsten; selectivity; heterogeneous catalysis; inverse micelle
• Online Access: https://www.mdpi.com/2073-4344/11/6/673

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.