Stabilization of Softwood-Derived Pyrolysis Oils for Continuous Bio-oil Hydroprocessing
- 633 Downloads
The use of fast pyrolysis oil as a potential renewable liquid transportation fuel alternative to crude oil depends on successful catalytic upgrading to produce a refinery-ready product with oxygen content and qualities (i.e., specific functional group or compound content) compatible with the product’s proposed refinery insertion point. Similar to crude oil hydrotreating, catalytic upgrading of bio-oil requires high temperature and pressure. However, processing thermally unstable pyrolysis oil is not straightforward. For years, a two-temperature, downflow trickle bed reactor using sulfided catalysts was the state-of-the art for continuous operation. However, pressure excursion due to plug formation still occurred, typically at the high-temperature transition zone, and led to a process shutdown within 140 h. A plug typically consists of polymerized bio-oil and inorganic constituents that bind catalysts at specific portions preventing liquid and gas flow through the bed, resulting to a potential pressure incursion. Recently, two factors were found to enable continuous operation by preventing reactor shutdown due to plug formation: (1) a bio-oil pretreatment process prior to the two-temperature reactor, and (2) a robust commercial catalyst for the high temperature zone reactor. Here, we report the use and characterization of bio-oil that was pre-treated at 413 K and 8.4 MPa under flowing H2 (500 L H2/L bio-oil, 0.5 L bio-oil/L catalyst bed) to enable the long-term (cumulative 1440-h) bio-oil hydroprocessing.
KeywordsFast pyrolysis oil Hydroprocessing Pretreatment Catalyst fouling
The authors gratefully acknowledge the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office for funding for this work. Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle under Contract DE-AC06-76RLO 1830. The authors also thank Shari X. Li (PNNL) for surface area/pore volume measurement and Todd Hart (PNNL) for aging study on the feed oil.
- 2.Diebold JP (2000) A review of the chemical and physical mechanisms of the storage stability of fast pyrolysis bio-oils. National Renewable Energy Laboratory, GoldenGoogle Scholar
- 4.Baker, E.G. and D.C. Elliott, Catalytic upgrading of biomass pyrolysis oils. Research in Thermochemical Biomass Conversion, ed. A.V. Bridgwater and J.L. Kuester. 1988, Barking Essex: Elsevier Appl Sci Publ Ltd. 883-895Google Scholar
- 11.Olarte MV et al (2013) Towards long-term fast pyrolysis oil catalytic upgrading. Abstr Pap Am Chem Soc 246:1Google Scholar
- 12.Jones S et al (2014) Fast pyrolysis and hydrotreating: 2013 State of Technology R&D and Projections to 2017. Pacific Northwest National Laboratory, RichlandGoogle Scholar
- 13.Zacher, A., M. Olarte, and D. Elliott. Enabling extended catalyst lifetime in fixed bed hydrotreating of bio-oil. in tcbiomass 2013. 2013. Chicago, IllinoisGoogle Scholar
- 15.Nicolaides GM (1984) The chemical characterization of pyrolytic oils, in Department of Chemical Engineering. University of Waterloo, WaterlooGoogle Scholar
- 16.Speight JG (2002) Handbook of petroleum product analysis. Wiley, New YorkGoogle Scholar
- 20.Silverstein R, Webster F, Kiemle D (2005) Spectrometric identification of organic compounds. Wiley, New YorkGoogle Scholar
- 23.Christensen, E., T. Alleman, and R. McCormick, Totalacid value titration of hydrotreated biomass fast pyrolysis oil: Determination of carboxylic acids and phenolics with multiple end point detection. Abstracts of Papers of the American Chemical Society, 2013. 245 Google Scholar