Hydrodeoxygenation of Guaiacol as a Model Compound for Pyrolysis Oil

UMaine's Forest Bioproducts Research Initiative is active in both biological and thermal conversion of biomass to fuels and chemicals. Thermal conversion routes are attractive because they are potentially less dependent on feedstock composition and process conditions. Of the thermal conversion routes such as fast pyrolysis and Fischer-Tropsch (FT) synthesis, pyrolysis is more practical on a small scale and is also potentially more energy efficient.[1] However, the high oxygen content of fast pyrolysis oils results in a low heating value, and organic acids catalyze polymerization reactions in the mixture which makes long-term storage of the bio-oil problematic. One method for improving the properties of pyrolysis oils is hydrodeoxygenation (HDO). Development of catalysts for HDO began in the 1970's, demonstrating that gasoline-quality fractions can be produced.[2,3] We have constructed a fast pyrolysis reactor for research purposes and are producing bio-oils from mixed softwood flour. The products of this process are a complex mixture of carboxylic acids, aldehydes, ketones, alcohols, and phenols. We are using guaiacol as a model compound to study the efficacy of select catalysts for HDO. Because, guaiacol has two oxygen-containing functional groups, selectivity can be probed. Typical HDO products include phenol, catechol, benzene, cyclohexane, and hexane. Reactions are conducted in a 300 mL batch hydrogenation reactor, and product distribution and extent of reaction are characterized using NMR, GC and GC/MS. Catalysts are characterized using XRD, BET, and XPS. Results of reactions carried out over sulfided and reduced carbon supported catalysts will be presented.

1. Elliott, D. C., Energy & Fuels 2007, 21, 1792-1815. 2. Furimsky, E., Catal. Rev. -Sci. Eng. 1983, 25 (3), 421-458. 3. Huber, G. W.; Iborra, S.; Corma, A., Chemical Reviews 2006.