Recovery of Low Molecular Weight Compounds from Alkaline Pretreatment Liquor via Membrane Separations

Patrick Saboe, Emily Tomashek, Hanna Monroe, Stefan Haugen, Ryan Prestangen, Nick Cleveland, Renee Happs, Joel Miscall, Kelsey Ramirez, Rui Katahira, Eric Tan, Jipeng Yan, Ning Sun, Gregg Beckham, Eric Karp

Research output: Contribution to journalArticlepeer-review

8 Scopus Citations


Lignin is an abundant renewable resource that is a promising substrate for upgrading to fuels and chemicals. However, lignin-rich biorefinery streams are often physically and chemically complex, and could benefit substantially from fractionation. In this work, a membrane process was developed to fractionate low molecular weight (LMW) lignin-related compounds (molecular weight (MW) < 1000 Da) from a lignin-rich, alkaline pretreated liquor (APL) prepared from pretreatment of corn stover with NaOH. The developed membrane process exhibits up to 98.5% rejection of high molecular weight (HMW) (MW > 1000 Da) species and generates a permeate stream with >80% recovery of LMW lignin-related compounds including aromatic species such as p-coumarate and ferulate, resulting in a 6-fold enrichment in LMW organic compounds relative to the crude APL. Experimental batch data were used to develop a detailed process model of an industrial scale, continuous membrane filtration system. The open-source model has several independent process inputs, such as the concentration of target compounds, feed flow rate, volume recovery, and membrane selectivity. This process model was used to show that the system has a low estimated energy demand (0.75 kW h m−3 permeate) and was used to identify primary cost drivers, including the membrane material cost. These results offer a key step towards a scalable, low energy, and cost-effective lignin MW fractionation method with implications for both improving product isolation from lignin and improving carbon yields across the biorefinery.

Original languageAmerican English
Pages (from-to)3152-3166
Number of pages15
JournalGreen Chemistry
Issue number8
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Royal Society of Chemistry

NREL Publication Number

  • NREL/JA-2800-81294


  • bioseparations
  • lignin fractionation
  • lignin valorization
  • membrane separations
  • process development


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