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- Singh, Sandip K., et al.
(författare)
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Integrated Two-Stage Alkaline-Oxidative Pretreatment of Hybrid Poplar. Part 1 : Impact of Alkaline Pre-Extraction Conditions on Process Performance and Lignin Properties
- 2019
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 58:35, s. 15989-15999
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Tidskriftsartikel (refereegranskat)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. Finally, the pre-extracted biomass from select conditions was 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.
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- Yuan, Zhaoyang, et al.
(författare)
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Effective Biomass Fractionation through Oxygen-Enhanced Alkaline–Oxidative Pretreatment
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:3, s. 1118-1127
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Tidskriftsartikel (refereegranskat)abstract
- The high recalcitrance of plant cell walls is an obstacle for effective chemical or biological conversion into renewable chemicals and transportation fuels. Here, we investigated the utilization of both oxygen (O2) and hydrogen peroxide (H2O2) as co-oxidants during alkaline–oxidative pretreatment to improve biomass fractionation and increase enzymatic digestibility. The oxidative pretreatment of hybrid poplar was studied over a variety of conditions. Employing O2 in addition to H2O2 as a co-oxidant during the two-stage alkaline pre-extraction/copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment process resulted in a substantial improvement in delignification relative to using H2O2 alone during the second-stage Cu-AHP pretreatment, leading to high overall sugar yields even at H2O2 loadings as low as 2% (w/w of the original biomass). The presence of H2O2, however, was both critical and synergistic. Performing analogous reactions in the absence of H2O2 resulted in approximately 25% less delignification and 30% decrease in sugar yields. The lignin isolated from this dual oxidant second stage had high aliphatic hydroxyl group content and reactivity to isocyanate, indicating that it is a promising substrate for the production of polyurethanes. To test the suitability of the isolated lignin as a source of aromatic monomers, the lignin was subjected to a sequential Bobbitt’s salt oxidation followed by a formic acid-catalyzed depolymerization process. Monomer yields of approximately 17% (w/w) were obtained, and the difference in yields was not significant between lignin isolated from our Cu-AHP process with and without O2 as a co-oxidant. Thus, the addition of O2 did not lead to significant lignin crosslinking, a result consistent with the two-dimensional heteronuclear single-quantum coherence NMR spectra of the isolated lignin.
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- Yuan, Zhaoyang, et al.
(författare)
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Integrated Two-Stage Alkaline–Oxidative Pretreatment of Hybrid Poplar. Part 2 : Impact of Cu-Catalyzed Alkaline Hydrogen Peroxide Pretreatment Conditions on Process Performance and Economics
- 2019
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 58:35, s. 16000-16008
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Tidskriftsartikel (refereegranskat)abstract
- Two-stage alkaline/copper 2,2′-bipyridine-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment is an effective strategy for improving the enzymatic digestibility of hybrid poplar. To reduce the chemical inputs and processing costs associated with this process, we investigated the effect of increasing the temperature for both the alkaline pre-extraction and the Cu-AHP pretreatment stages. The results indicate that increasing the alkaline pre-extraction and the Cu-AHP pretreatment temperatures from 30 to 120 and 80 °C, respectively, allowed us to reduce both the pretreatment time of the Cu-AHP stage and the chemical loadings. Incubating alkaline pre-extracted hybrid poplar for 12 h with 10% NaOH (w/w biomass), 8% hydrogen peroxide (w/w biomass), and a Cu2+ and 2,2′-bipyridine (bpy) concentration of 1 mM yielded monomeric sugar yields of approximately 77% glucose and 66% xylose (based on the initial sugar composition) following enzymatic hydrolysis. Technoeconomic analysis (TEA) indicates that these changes to the two-stage alkaline/Cu-AHP pretreatment process could potentially reduce the minimum fuel selling price (MFSP) by more than $1.00 per gallon of biofuel compared to the reference case where both stages were conducted at 30 °C with higher chemical inputs.
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- Yuan, Zhaoyang, et al.
(författare)
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Technoeconomic evaluation of recent process improvements in production of sugar and high-value lignin co-products via two-stage Cu-catalyzed alkaline-oxidative pretreatment
- 2022
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Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Nature. - 2731-3654. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: A lignocellulose-to-biofuel biorefinery process that enables multiple product streams is recognized as a promising strategy to improve the economics of this biorefinery and to accelerate technology commercialization. We recently identified an innovative pretreatment technology that enables of the production of sugars at high yields while simultaneously generating a high-quality lignin stream that has been demonstrated as both a promising renewable polyol replacement for polyurethane applications and is highly susceptible to depolymerization into monomers. This technology comprises a two-stage pretreatment approach that includes an alkaline pre-extraction followed by a metal-catalyzed alkaline-oxidative pretreatment. Our recent work demonstrated that H2O2 and O2 act synergistically as co-oxidants during the alkaline-oxidative pretreatment and could significantly reduce the pretreatment chemical input while maintaining high sugar yields (~ 95% glucose and ~ 100% xylose of initial sugar composition), high lignin yields (~ 75% of initial lignin), and improvements in lignin usage.Results: This study considers the economic impact of these advances and provides strategies that could lead to additional economic improvements for future commercialization. The results of the technoeconomic analysis (TEA) demonstrated that adding O2 as a co-oxidant at 50 psig for the alkaline-oxidative pretreatment and reducing the raw material input reduced the minimum fuel selling price from $1.08/L to $0.85/L, assuming recoverable lignin is used as a polyol replacement. If additional lignin can be recovered and sold as more valuable monomers, the minimum fuel selling price (MFSP) can be further reduced to $0.73/L.Conclusions: The present work demonstrated that high sugar and lignin yields combined with low raw material inputs and increasing the value of lignin could greatly increase the economic viability of a poplar-based biorefinery. Continued research on integrating sugar production with lignin valorization is thus warranted to confirm this economic potential as the technology matures.
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