Title : Gas phase hydrotreatment reactions of 2,5 Dimethylfuran using bifunctional metal acid catalysts
I n the last few decades, there has been a growing interest in green chemistry. As fossil fuel reserves become depleted,considerable attention is being given to the use of biomass as a sustainable feedstock. Wide range of chemicals and fuels can be synthesised using furanic compounds which are a family of cellulosic and hemicellulosic platform compounds. These compounds, however, require upgrading (deoxygenation) to produce chemicals and fuels. Bifunctional catalysis is widely used in upgrade strategies to achieve high activity and selectivity. Recently, several groups have focused on the direct ring opening of the aromatic furans. The use of noble metal-based bifunctional catalytic systems can enhance ring opening. The aim of this work is to study the hydrogenation and hydrogenolysis of furan derivatives over bifunctional metal-HPA catalysts containing Pt and Pd together with acidic Keggin heteropoly salt Cs2.5H0.5PW12O40 (CsPW). The reactions were studied using a fixed-bed continuous flow reactor with on-line gas chromatographic (GC) analysis in the temperature range of 60–100 °C and ambient pressure. The catalysts were characterized by BET, ICP, XRD, TEM and H2 chemisorption. It is demonstrated that the bifunctional hydrotreatment pathway is more efficient than the monofunctional metal-catalysed pathway. The Pt/C + CsPW physical mixture, as compared to the impregnated catalyst 1% Pt/CsPW, was found to be a very efficient catalyst for the selective one-step hydrodeoxygenation of 2,5-DMF under mild conditions via the metal-acid bifunctional catalysis, providing almost 100% yield of n-hexane at 90 °C. The reaction did not proceed at all in the absence of Pt or in the presence of CsPW alone. The higher activity of the mixed Pt/C + CsPW catalyst, having Pt and H+ sites far apart, compared to the impregnated Pt/ CsPW catalyst with Pt and H+ in close proximity may be explained by catalyst coking, which would affect stronger the Pt/CsPW catalyst.