Influence of Lewis and Br?nsted acid catalysts in the transformation of hexoses into 5-ethoxymethylfurfural

Several sulfonated polymers, which are typical Bronsted acid catalysts, have been employed in the production of two biofuels: 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) as main byproduct, and the catalytic results have been attributed to their different chemical and morphological properties. The Purolite CT275DR attained the best results from 5-hydroxymethylfurfural (HMF) with a 63% EMF yield after 16 h at 100 degrees C thanks to their more abundant superficial acid sites. Moreover, Purolite CT275DR was able to efficiently dehydrate and etherify fructose, with a total EMF plus EL yield of 65% after 24 h at 100 degrees C. When glucose or galactose were used as feedstock, alumina was utilized to provide Lewis acid sites, necessary for the transformation of aldoses in so-lution enabling a combined biofuel yield (EMF plus EL) of 40% from glucose after 24 h at 140 degrees C. With the study of the role of each catalyst, both Bronsted and Lewis acid catalysts (resin and alumina, respectively) were required to obtain considerable EMF yields from aldoses. The reutilization of the catalysts employed for 5 cat-alytic runs demonstrated that Purolite CT275DR suffers no appreciable loss of activity, but alumina showed progressive losses in activity in each cycle due to carbonaceous deposits and catalyst loss.