Acid-Modified Clays for the Catalytic Obtention of 5-Hydroxymethylfurfural from Glucose

Identifier:  imarina:9280942

Handle: https://hdl.handle.net/20.500.11797/imarina9280942

Authors:  Sanchez, Vladimir; Gonzalez, Maria Dolores; Salagre, Pilar; Cesteros, Yolanda

Abstract:
5-hydroxymethylfurfural (5-HMF) is an important platform molecule for the synthesis of high-added value products. Several synthesized clay materials, such as mesoporous hectorite and fluorohectorite, in addition to commercial montmorillonite K-10, have been acid modified by different methodologies to be applied as catalysts for the obtention of 5-HMF from glucose. The effects of the Bronsted and/or Lewis acidity, the reaction temperature and time, and the catalyst/glucose ratio on the conversion but especially on the selectivity to 5-HMF have been studied. By comparing the synthesized clays, the best selectivity to 5-HMF (36%) was obtained at 140 degrees C for 4 h with H-fluorohectorite because of the presence of strong Bronsted acid sites, although its conversion was the lowest (33%) due to its low amounts of Lewis acid sites. Different strategies, such as physical mixtures of montmorillonite K10, which contains high amounts of Lewis acid centers, with Amberlyst-15, which has high amounts of Bronsted acid sites, or the incorporation of rhenium compounds, were carried out. The best selectivity to 5-HMF (62%) was achieved with a mixture of 44 wt % Amberlyst-15 and 56 wt % of montmorillonite K10 for a 56% of conversion at 140 degrees C for 4 h. This proportion optimized the amount of Bronsted and Lewis acid sites in the catalyst under these reaction conditions.