Anisole and Guaiacol Hydrodeoxygenation over Monolithic Pt–Sn Catalysts

Direct vapor-phase upgrading of biomass pyrolysis products requires a catalytic reactor able to treat high reactant flow rates without generating a large pressure drop, because conventional pyrolysis reactors operate near atmospheric pressure. Monolithic catalysts exhibit important advantages that make them good candidates for this purpose. In this paper, low-surface-area Inconel monoliths were coated with in-situ-grown carbon nanofibers (CNFs), which were subsequently impregnated with catalytic species (Pt, Sn, and bimetallic Pt–Sn). These monoliths were tested for the deoxygenation of guaiacol and anisole (products of lignin pyrolysis), two of the most deactivating compounds present in pyrolysis oil. The main products obtained from these feeds on the monolithic catalysts were phenol and benzene. Coating with CNFs provides increased surface area and anchoring sites for the active species (Pt and Sn), thus increasing the yield of desired products. The bimetallic Pt–Sn catalysts showed higher activity and stability than monometallic Pt and Sn catalysts. These tests indicate that monoliths of Pt–Sn/CNF/Inconel are potentially effective catalysts for the vapor-phase upgrading of lignin fractions present in bio-oil.