Deoxygenation of Furfural On Pd and Pd-Cu Catalysts

Aldehydes are commonly found in bio-oils, but they exhibit low stability which is undesirable for fuel uses. Deoxygenation is needed to make bio-oil more fungible with standard gasolines and diesels. It can be achieved by hydrotreating over standard hydrogenation catalysts at high temperatures and pressures. However, using noble metal catalysts, the reaction conditions can be much less severe. In the present work, supported Pd-Cu bimetallic catalysts have been used for converting fufural. TPR suggests that the addition of Cu to supported Pd catalyst results in formation of Pd-Cu bimetallic alloys. The activity and selectivity of the catalysts are largely influenced by the addition of Cu. The yield of furan from decarboylation was significantly reduced when Cu was incoporated. However, no loss of hydrogenation activity to furfuryl alcohol was observed. This is because the addition of Cu readily reduces the exposed Pd ensembles. Hence, the decabonylation activity that requires a large ensemble of Pd is much more affected. In contrast, hydrogenation remains unchanged as the dilution of ensembles has little effect on structure insensitive reactions. The deoxygenation activity also depends on the molecular structure of the feed. When 5-methyl furfural was used, significantly higher decarbonylation rates to methyl furan were obtained. No hydrogenated products were found, but only small amounts of dimethyl furan, obtained by hydrogenolysis.