Title: Integrated Two-Stage Alkaline-Oxidative Pretreatment of Hybrid Poplar. Part 1: Impact of Alkaline Pre-Extraction Conditions on Process Performance and Lignin Properties

Abstract

We previously demonstrated that a two-stage pretreatment comprising of an alkaline pre-extraction followed by a Cu-catalyzed alkaline–oxidative treatment is effective at pretreating hardwoods under relatively mild reaction conditions. In this work, we focus on characterizing how biomass source and reaction conditions used during the alkaline pre-extraction impact the subsequent processing stages as well as lignin yields and properties. Specifically, three hybrid poplars were subjected to the first stage alkaline pre-extraction under various conditions including differences in time (15–300 min), temperature (95–155 °C), and alkali loadings (50–200 mg NaOH/g biomass), and the impact on total mass solubilization, lignin recovery, and lignin purity was determined. Empirical correlations were developed between reaction conditions and mass solubilization and lignin recovery during the pre-extraction stage. For select conditions, lignin properties were assessed and include β-O-4 content determined by 13C NMR, molecular mass distributions as determined by gel permeation chromatography, and susceptibility to depolymerization to aromatic monomers using thioacidolysis and formic acid catalyzed depolymerization. We found alkaline pre-extraction performed at higher temperatures generated lignins exhibiting lower contamination by polysaccharides, lower aromatic monomer yields from depolymerization, lower molar masses, and lower β-O-4 contents relative to the lower temperature pre-extractions. Lastly, the pre-extracted biomass from select conditions wasmore » assessed for its response to the subsequent Cu-catalyzed alkaline–oxidative treatment and enzymatic hydrolysis. It was demonstrated that minor differences in delignification during pre-extraction have quantifiable impacts on the subsequent efficacy of the second stage of pretreatment and enzymatic hydrolysis with improved lignin removal during the first pre-extraction stage resulting in improved hydrolysis yields.« less

Authors:

Singh, Sandip K.  ^[1];

• Search DOE PAGES for author "Singh, Sandip K."
• Search DOE PAGES for ORCID "0000-0003-0094-6253"

Savoy, Anthony W. ^[1]; Yuan, Zhaoyang  ^[2];

• Search DOE PAGES for author "Yuan, Zhaoyang"
• Search DOE PAGES for ORCID "0000-0003-2445-9505"

Luo, Hao ^[3]; Stahl, Shannon S.  ^[3];

• Search DOE PAGES for author "Stahl, Shannon S."
• Search DOE PAGES for ORCID "0000-0002-9000-7665"

Hegg, Eric L.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-2055-5495"

Hodge, David B.  ^[4]

• Search DOE PAGES for author "Hodge, David B."
• Search DOE PAGES for ORCID "0000-0002-9313-941X"

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1. Montana State Univ., Bozeman, MT (United States)
2. Michigan State Univ., East Lansing, MI (United States)
3. Univ. of Wisconsin, Madison, WI (United States)
4. Montana State Univ., Bozeman, MT (United States); Luleå Univ. (Sweden)

Publication Date:

Wed Jun 05 00:00:00 EDT 2019

Research Org.:

Michigan State Univ., East Lansing, MI (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1877690

Grant/Contract Number:  

EE0008148; SC0018409

Resource Type:

Accepted Manuscript

Journal Name:

Industrial and Engineering Chemistry Research

Additional Journal Information:

Journal Volume: 58; Journal Issue: 35; Journal ID: ISSN 0888-5885

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; Catalysis; Copper; Alkaline hydrogen peroxide (Cu-AHP) pretreatment; Hybrid poplar; Techno-economic analysis (TEA); Biomass; Biopolymers; Hydrolysis; Organic polymers; Pretreatment