engleski

Sol-gel Synthesis of Ceria-Zirconia-Based High- Entropy Oxides as High-Promotion Catalysts for the Synthesis of 1,2-Diketones from Aldehyde

Four ceria–zirconia-based high-entropy catalysts were successfully synthesized. The applied synthetic route, the modified sol-gel citrate route, resulted in phase-pure compounds with a cubic structure, with lattice parameters that differ from pure CeO2. This is related to the lattice expansion/contraction due to the incorporation of five cations into a single-cation lattice. The investigation of the physicochemical properties of the newly developed and synthesized catalysts shows that the crystallite size, lattice parameters, surface areas, and pore volumes are similar, while the Lewis acidity differs significantly. The pinacol-type oxidative coupling reaction of the aldehydes was presented, using HEOs as the actual catalysts, which demonstrated the catalytic abilities and chemoselectivity of the catalysts. The reaction conditions were optimized followed by a comparative study of the HEOs under the same conditions. Upon using high-entropy oxides as the catalysts, the desired diketone product was produced with almost the same selectivity, unlike the activity, which followed the trend of increasing acidity. The remarkable activity of the HEOs was proven in comparison with the pure building block oxides and their physically mixed composites, especially in the case of the Ce0.2Zr0.2La0.2Pr0.2Y0.2O2 (CZLPY) compound. CZLPY oxide proved to be a versatile, reusable, and heterogeneous catalyst, taking into account the results of the recycling and hot filtration test, as well as the scope.

high entropy materials ; Pinacol ; ceria-based

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