resumo
Niobium pentoxides are promising acid catalysts for the conversion of biomass into fuels and chemicals. Developing new synthesis routes is essential for designing niobium pentoxide catalysts with improved activity for specific practical processes. Here we show a synthesis approach in acetophenone, which produces nanostructured niobium pentoxides with varying structure and acidity that act as efficient acid catalysts. The oxides have orthorhombic structures with different extents of distortions and coordinatively unsaturated metal atoms. A strong dependence is observed between the type and strength of the acid sites and specific structural motifs. Ultrasmall niobium pentoxide nanoparticles, which have strong Bronsted acidity, as well as Lewis acidity, give product yields of 96% (3 h, 140 degrees C, 100% conversion), 85% (3 h, 140 degrees C, 86% conversion), and 100% (3 h, 110 degrees C, 100% conversion) in the reactions of furfuryl alcohol, 5-(hydroxymethyl)furfural, and a-angelica lactone with ethanol, respectively.
palavras-chave
USEFUL BIO-PRODUCTS; REDUCTIVE ETHERIFICATION; BRONSTED ACIDITY; ETHYL LEVULINATE; HYDROXYL-GROUPS; OXIDE; CONVERSION; RAMAN; NANOSHEETS; LEWIS
categoria
Chemistry
autores
Skrodczky, K; Antunes, MM; Han, XY; Santangelo, S; Scholz, G; Valente, AA; Pinna, N; Russo, PA
nossos autores
Anabela Tavares Aguiar Valente
Investigador Principal
Maria Margarida Feitor Pintão Moreno Antunes
Investigador Júnior
Nicola Pinna
Investigadoragradecimentos
The authors are grateful to the German Research Foundation (DFG, Grant no. RU2012/2-1) for financial support. We thank Dr. M. Feist for the help with the TG-MS measurements and C. Erdmann for the TEM measurements. This work was partially developed in the scope of the project CICECO-Aveiro Institute of Materials, FCT (Fundacao para a Ciencia e Tecnologia) Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. M.M.A. thanks the costs resulting from the FCT hirings which are funded by national funds (OE), through FCT, in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.