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 PtÀSn). 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 PtÀSn catalysts showed higher activity and stability than monometallic Pt and Sn catalysts. These tests indicate that monoliths of PtÀSn/CNF/Inconel are potentially effective catalysts for the vapor-phase upgrading of lignin fractions present in bio-oil.

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Alkylation is a promising reaction for the upgrading of bio-oil because it maximizes the retention of carbon in the liquid product. The alkylation of m-cresol with isopropanol and HY zeolite was studied in a liquid phase system. The experimental results were fitted with two conventional surface kinetic models, Langmuir-Hinshelwood and Eley-Rideal, from which adsorption and rate constants were estimated. Two types of alkylation reactions were observed: C-alkylation with formation of a CAC bond with the ring and O-alkylation with formation of an ether bond with the hydroxyl group. It was concluded that O-alkylation products do not undergo intramolecular rearrangement but first decompose into the corresponding phenolic. Alkylation occurs from both isopropanol and propylene, both of them yielding O-and C-alkylation to different extents. Isopropanol favors O-alkylation while propylene favors C-alkylation. Rate constants for multiple alkylation steps were progressively lower, suggesting the presence of steric hindrance during incorporation of additional isopropyl groups.

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