Preparation of CuO-CoO-MnO/SiO₂ nanocomposite aerogels as catalyst carriers and their application in the synthesis of diphenyl carbonate

Abstract

CuO-CoO-MnO/SiO₂ nanocomposite aerogels were prepared by using tetraethyl orthosilicate (TEOS) as Si source, and aqueous solution of Cu, Co and Mn acetates as transition metal sources via solgel process and supercritical drying (SCD) technique. The effect of synthesis conditions on gelation was investigated. Moreover, the composition of the CuO-CoO-MnO/SiO₂ nanocomposite aerogels was characterized by electron dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and the specific surface area of the nanocomposite aerogels was determined by the Brunauer-Emmett-Teller (BET) method. Diphenyl carbonate (DPC) as the product was analyzed by gas chromatography (GC). The experimental results show that the range of optimal temperature for gelation is 30–45 °C, and the pH is 3.0–4.5. CuO-CoO-MnO/SiO₂ nanocomposite aerogels are porous with a specific surface area of 384.9–700.6 m²/g. Compared to CO₂ SCD, ethanol SCD is even favorable to the formation of aerogel with high specific surface area. The transition metals content in the nanocomposite aerogels can be controlled to be 0.71at%–13.77at%. With CuO-CoO-MnO/SiO₂ nanocomposite aerogels as catalyst carrier, the yield of DPC is in direct proportion to the atomic fraction of transition metals in the nanocomposite aerogels, and it is up to 26.31 mass%, which is much higher than that via other porous carriers.

Keywords

composite aerogel / preparation / catalyst carrier / diphenyl carbonate

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