Direct conversion of 5-hydroxymethylfurfural to fuel components on silicalite-1 with tuned acidity

5-hydroxymethylfurfural (HMF) is one of the renewable building blocks with a high potential for further chemical modifications. Its conversion to valuable derivatives, such as fuels, monomers for polymers and valuable fine chemicals has recently attracted considerable attention. We have previously demonstrated that the reaction between HMF and ethanol on acidic solid catalysts produces valuable components for biofuels, such as 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP), and that the selectivity to these products can be correlated to the presence of Lewis or Brönsted acidic sites on the catalyst [2]. In this work we have studied the performances of Silicalite-1 materials in this reaction in order to understand the role of the zeolitic defective sites on the catalytic behavior. In order to tune the hydroxyl population of the Silicalite-1 surface, different post-synthesis treatments have been carried out on the as-made catalysts. As function of the thermal treatment, the pH value of the ionic-exchange and the silylation procedure, the study on the catalytic activity of the Silicalite-1 materials, in the above mentioned reaction, has been carried out. 29Si-NMR, NH3-TPD and IR analyses have been used as usual techniques in order to characterize the activated catalysts. The Amberlyst®15 catalyst has been used as referring solid acid catalyst, with strong Brönsted acidity.