Characterization and Catalytic Upgrading of Aqueous Stream Carbon from Catalytic Fast Pyrolysis of Biomass

Calvin Mukarakate, Anne Starace, Brenna Pleitner, Kellene Orton, William Michener, Gregg Beckham, Kimberly Magrini, Elizabeth Palmiotti, Michael Watson, Jeroen Dam, David Lee

Research output: Contribution to journalArticlepeer-review

28 Scopus Citations


Catalytic fast pyrolysis (CFP) of biomass produces a liquid product consisting of organic and aqueous streams. The organic stream is typically slated for hydrotreating to produce hydrocarbon biofuels, while the aqueous stream is considered a waste stream, resulting in the loss of residual biogenic carbon. Here, we report the detailed characterization and catalytic conversion of a CFP wastewater stream with the ultimate aim to improve overall biomass utilization within a thermochemical biorefinery. An aqueous stream derived from CFP of beech wood was comprehensively characterized, quantifying 53 organic compounds to a total of 17 wt % organics. The most abundant classes of compounds were acids, aldehydes, and alcohols. The most abundant components identified in the aqueous stream were C1-C2 organics, comprising 6.40% acetic acid, 2.16% methanol, and 1.84% formaldehyde on wet basis. The CFP aqueous stream was catalytically upgraded to olefins and aromatic hydrocarbons using a Ga/HZSM-5 catalyst at 500 °C. When the conversion yield of the upgraded products was measured with fresh, active catalyst, 33% of the carbon in the aqueous stream was recovered as aromatic hydrocarbons and 29% as olefins. The majority of the experiments were conducted using a molecular beam mass spectrometer, and separate GC-MS/FID experiments were used to confirm the assignments and quantification of products with fresh excess catalyst. The recovered 62% carbon in the form of olefins and aromatics can be used to make coproducts and/or fuels potentially improving biorefinery economics and sustainability. Spent catalysts were collected after exposure to varying amounts of the feed, and were characterized using multipoint-Brunauer-Emmett-Teller (BET) adsorption, ammonia temperature-programmed desorption (TPD), and thermogravimetric analysis (TGA) to monitor deactivation of Ga/HZSM-5. These characterization data revealed that deactivation was caused by coke deposits, which blocked access to active sites of the catalyst, and spent catalysts regained total activity after regeneration.

Original languageAmerican English
Pages (from-to)11761-11769
Number of pages9
JournalACS Sustainable Chemistry and Engineering
Issue number12
StatePublished - 4 Dec 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-5100-70293


  • BTX
  • CFP aqueous stream
  • Coke formation
  • HZSM-5
  • Wastewater treatment


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