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At least 109 records · Page 6

Evaluating the industrial potential of emerging biomass pretreatment technologies in bioethanol production and lipid recovery from transgenic sugarcane

The selection of pretreatment methods is critical to achieving high product yields during bioconversion of lignocellulosic biomass. Hydrothermal, soaking-in-aqueous ammonia, and ionic liquid pretreatment methods are viable candidates for minimizing sugar decomposition, permitting the effective hydrolysis of structural carbohydrates, and producing a fermentable substrate suitable for achieving industrial ethanol titers and yields. In this study, the effect of these three pretreatment methods on non-modified sugarcane cultivar CP88-1762 and two transgenic lipid-accumulating sugarcane lines, oilcane 1565 and oilcane 1566, were investigated and compared in terms of lipid recovery, sugar yield, and ethanol yields within the lignocellulosic biomass conversion pipeline. Fed-batch enzymatic hydrolysis at high solid loading yielded hydrolysates capable of supporting industrial bioethanol titers across all conditions. The highest sugar yields were obtained on ammonia-pretreated biomass hydrolysate (253.73 g L −1 ), followed by hydrothermally pretreated hydrolysate (213.10 g L −1 ) and ionic liquid-pretreated hydrolysate (154.20 g L −1 ). Commercially viable ethanol titers of 100.62 g L −1 , 64.47 g L −1 , and 52.95 g L −1 were achieved from ammonia, hydrothermal, and ionic liquid pretreated hydrolysate with the corresponding ethanol productivities of 2.08 g L −1 h −1 , 0.53 g L −1 h −1 , and 0.36 g L −1 h −1 . The lower acetic acid concentration in ammonia-pretreated hydrolysate may have enhanced its fermentability relative to the hydrothermal pretreatment condition, as indicated by the differences in ethanol titer and productivity. Lower sugar yields and ethanol productivities under the ionic liquid conditions likely resulted from the inhibitory effect of cholinium lysinate. Oilcane 1565 and oilcane 1566 bagasse accumulated over 16- and 3 times higher lipids than the non-modified sugarcane CP88-1762. The total fatty acid content in the oilcane samples was reduced in ammonia and ionic liquid-pretreated bagasse relative to the hydrothermal pretreatment condition. While all pretreatment techniques tested are industrially viable, the observed differences in titer, productivity, and lipid content indicate that careful selection and validation of upstream processing methods can contribute to improved economic and environmental outcomes.

09 BIOMASS FUELS↗

Data for "Evaluating the industrial potential of emerging biomass pretreatment technologies in bioethanol production and lipid recovery from transgenic sugarcane"

The selection of pretreatment methods is critical to achieving high product yields during bioconversion of lignocellulosic biomass. Hydrothermal, soaking-in-aqueous ammonia, and ionic liquid pretreatment methods are viable candidates for minimizing sugar decomposition, permitting the effective hydrolysis of structural carbohydrates, and producing a fermentable substrate suitable for achieving industrial ethanol titers and yields. In this study, the effect of these three pretreatment methods on non-modified sugarcane cultivar CP88-1762 and two transgenic lipid-accumulating sugarcane lines, oilcane 1565 and oilcane 1566, were investigated and compared in terms of lipid recovery, sugar yield, and ethanol yields within the lignocellulosic biomass conversion pipeline. Fed-batch enzymatic hydrolysis at high solid loading yielded hydrolysates capable of supporting industrial bioethanol titers across all conditions. The highest sugar yields were obtained on ammonia-pretreated biomass hydrolysate (253.73 g L−1), followed by hydrothermally pretreated hydrolysate (213.10 g L−1) and ionic liquid-pretreated hydrolysate (154.20 g L−1). Commercially viable ethanol titers of 100.62 g L−1, 64.47 g L−1, and 52.95 g L−1 were achieved from ammonia, hydrothermal, and ionic liquid pretreated hydrolysate with the corresponding ethanol productivities of 2.08 g L−1 h−1, 0.53 g L−1 h−1, and 0.36 g L−1 h−1. The lower acetic acid concentration in ammonia-pretreated hydrolysate may have enhanced its fermentability relative to the hydrothermal pretreatment condition, as indicated by the differences in ethanol titer and productivity. Lower sugar yields and ethanol productivities under the ionic liquid conditions likely resulted from the inhibitory effect of cholinium lysinate. Oilcane 1565 and oilcane 1566 bagasse accumulated over 16- and 3 times higher lipids than the non-modified sugarcane CP88-1762. The total fatty acid content in the oilcane samples was reduced in ammonia and ionic liquid-pretreated bagasse relative to the hydrothermal pretreatment condition. While all pretreatment techniques tested are industrially viable, the observed differences in titer, productivity, and lipid content indicate that careful selection and validation of upstream processing methods can contribute to improved economic and environmental outcomes.

biomass analytics↗

Solid–liquid separation of lignocellulosic sugars from biomass by rotating ceramic disc filtration

In many biomass conversion processes, the separation of cellulosic sugars from residual, lignin-rich solids is a critical step, and achieving high recovery yields of sugars by conventional tangential crossflow and vacuum filtration is challenged by the presence of biomass solids, which rapidly foul filters, resulting in decreased throughput. Considering the performance limitations of traditional filtration methods, dynamic filtration, which generates high shear at the membrane surface to decrease fouling, is emerging as a viable alternative for demanding solid–liquid separations. For high solids separations, there is little available information regarding the performance, limitations, and energy consumption of dynamic filtration. To that end, here we characterized the performance of a dynamic filtration module, specifically a rotating ceramic disc (RCD) filter, for the aseptic recovery of cellulosic sugars from biomass solids following pretreatment and enzymatic hydrolysis. We show how RCD rotational velocity and percent biomass solids impact the filter throughput. Additionally, we used computational fluid dynamics (CFD) simulations to estimate the shear rate at the membrane surface and to visualize hydrodynamic profiles within the module. With the combined CFD simulations and experimental results, we estimated the energy demand and operating expenses for a viable dynamic filtration system operating with a lignocellulosic feed slurry. Our results indicate that an RCD filter can achieve ≥95% recovery of sugars and produce a retentate slurry containing 12 wt% insoluble solids with low energy consumption (a 2.2-fold improvement over cross-flow filtration) and low operating costs ($\$$0.06 per kg sugars). These results show a viable path towards operationally reliable, energy efficient, and cost-effective separations of sterilized cellulosic sugars from biomass solids and highlight the potential of dynamic filtration systems for challenging solid–liquid separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Chapter 4 - Pretreatment Technologies for Lignocellulosic Biomass Refineries

Pretreatment is a critical step in processing lignocellulosic biomass into biofuel and bioproducts and is considered the energy and cost center of the biomass conversion process. Although a large number of pretreatment technologies have been developed, not all the techniques are viable on a commercial scale at this stage. Moreover, the technology choice and process conditions depend highly on the type of biomass and the overall biorefinery scheme. This chapter provides an overview of different pretreatment methods, including their mechanism, important process parameters, current status, and challenges. The opportunities associated with new technologies and approaches are presented. Emphasis is placed on low-severity thermal pretreatment technologies. The chapter also provides a brief discussion of the challenges to achieving the economic viability of the technologies on a commercial scale.

BIOMASS FUELS↗

Development of Biofuel and Bioenergy Processes for Photosynthetic CO 2 Assimilation (CRADA Final Report)

In order to fully exploit algae carbon assimilation for fuels, a preqrequisite is high photosynthetic efficiency and carbon conversion to fuel precursors. In the context of this collaborative project between NLR and EMRE we aim to address aspects of both the biological constraints around photosynthesis-driven carbon assimilation flux as well as elements that bridge the gap between laboratory cultivation and meaningful outdoor deployment, building on the unique capabilities of NLR and EMRE’s algae bioengineering teams. The goal of this work is to improve our understanding of key cellular biochemistry, mass cultivation, and biomass conversion constraints that presently limit the potential bio-oil yield. The proposed first phase of this work will focus on biomass growth improvements by testing hypotheses for alleviating identified metabolic and photophysiological bottlenecks. The results of this work could inform decisions by stakeholders (e.g., industry, community, investors) on the design and deployment of a sustainable biofuel supply chain from algae.

09 BIOMASS FUELS↗

State of the Art in Thermal Catalytic Upgrading of Biomass and Biomass-Derived Intermediates

Biomass-derived energy sources represent a promising domestic route for fuel and chemical production, taking advantage of largely underutilized biological and waste resources. Heterogeneous catalysis plays a key role in these biomass conversion processes, as reflected by all American Society for Testing and Materials–approved pathways for producing sustainable aviation fuel proceeding through a catalytic step. This concise review seeks to establish the state of the art in thermal catalytic process development for various biomass-derived feedstocks and the current enabling capabilities that aid this development. Research needs are identified and described throughout the article, as further advancements in heterogeneous catalysis are required to improve the affordability and realize the full potential of biomass-derived products.

09 BIOMASS FUELS↗

Importance of suberin biopolymer in plant function, contributions to soil organic carbon and in the production of bio-derived energy and materials

Abstract Suberin is a hydrophobic biopolymer of significance in the production of biomass-derived materials and in biogeochemical cycling in terrestrial ecosystems. Here, we describe suberin structure and biosynthesis, and its importance in biological (i.e., plant bark and roots), ecological (soil organic carbon) and economic (biomass conversion to bioproducts) contexts. Furthermore, we highlight the genomics and analytical approaches currently available and explore opportunities for future technologies to study suberin in quantitative and/or high-throughput platforms in bioenergy crops. A greater understanding of suberin structure and production in lignocellulosic biomass can be leveraged to improve representation in life cycle analysis and techno-economic analysis models and enable performance improvements in plant biosystems as well as informed crop system management to achieve economic and environmental co-benefits.

09 BIOMASS FUELS↗

NREL's Capabilities in Biorefinery Analysis

NREL remains at the forefront of expertise in conducting process, techno-economic, and life cycle analyses to connect research with future commercial process integration, a critical step in the scale-up of biomass conversion technologies. Technology areas covered include lignocellulosic biorefineries, algae, CO2 utilization, waste-to-energy, aviation and marine fuels, refinery modeling and analysis, and the circular economy.

BIOMASS FUELS,INORGANIC, ORGANIC, PHYSICAL, AND AN↗

Potential Integration Between Residual Biogenic Process Resources and Greener Hydrogen Production from Steam Reformers

Biomass conversion processes have varying efficiencies towards specific products like liquid fuels; process inefficiencies result in byproducts such as off-gases, heat, and solid residues such as char. The efficient use of these byproducts is key towards getting the maximum sustainability benefits from valuable biomass resources. For example, there are various utility product options that can utilize heat and off-gases from biomass pyrolysis processes; they include process heat and steam, hydrogen, fuel gas, and electricity. Further, there is potential for the use of the off-gases to supplement natural gas feed into steam reformers for hydrogen production. This presentation highlights results from previous analyses on tradeoffs based on utility byproduct choices (https://doi.org/10.1039/D3SE00745F); maximizing hydrogen production from off-gases is one potential winning strategy. This leads to the question regarding the utilization of these off-gases in existing steam reformers and the process impacts from feeding off-gases. Process modeling of a steam reformer system (https://doi.org/10.1002/adsu.20230021) quantifies those impacts and shows how much off-gas substitution is possible within the limits of an existing design with such an integration strategy.

biogenic gases↗

Anaerobic Storage and Conversion of Microalgal Biomass to Manage Seasonal Variation in Cultivation

Seasonal variation in microalgal biomass production is a well-known challenge when optimizing economics for algal fuel conversion, especially given the fluctuation in biomass production between winter and summer. Wet storage offers significant potential for cost and energy savings compared to dewatering and dry storage. This study demonstrates the feasibility of preserving harvested Scenedesmus acutus biomass through wet anaerobic storage for use in biochemical conversion. Anaerobic storage effectively preserved biomass with minimal degradation of carbohydrates and preservation of lipids and proteins. Screening experiments identified optimal pretreatment conditions for stored biomass. Scale-up of pretreatment enabled fermentation of the hydrolysate to butyric acid and indicated no observable difference in conversion between unstored and stored biomass. Lipid extraction improved by a relative 12% for stored biomass. These results suggest that wet anaerobic storage can effectively manage seasonal variation in biomass production and is compatible with biochemical approaches for biofuel production.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Hemicellulose Modulates Nanoscale Lignin Architecture in Synthetic Plant Cell Walls

Cellulose, hemicellulose, and lignin─the most abundant biopolymers on Earth─compose the structural matrix of plant biomass, providing renewable resources critical to bioenergy and sustainable materials. Despite their importance, the nanoscale mechanochemical processes underlying lignocellulose assembly during plant secondary cell wall formation remain poorly understood, hindering advancements in biomass conversion technologies. Here, in this study, we synthesize a biomimetic model system comprising cellulose–hemicellulose nanofibrils (CHN) to examine guaiacyl lignin polymerization in a physiologically relevant context. Using advanced nanocharacterization─scattering-type scanning near-field optical microscopy (s-SNOM) with infrared nanospectroscopy coupled to solid-state nuclear magnetic resonance (NMR)─we reveal that hemicellulose presence considerably modulates lignin deposition and alters its interunit bond distribution. Specifically, hemicellulose-rich environments dramatically reduce lignin deposition by approximately 50% and yield highly condensed lignin structures characterized by severely reduced β–O–4′ linkages (<2%) and suppressed β–β′ linkages. Conversely, cellulose-alone scaffolds support notably higher β–O–4′ content (∼10%), resulting in a more uniform nanoscale lignin coating. Our work helps explain how accessible hemicellulose sites, both sterically and chemically, direct radical coupling during lignification, fundamentally reshaping lignin’s nanoscale architecture. These findings deepen our mechanistic understanding of plant cell wall biosynthesis and inform strategies aimed at enhancing biomass deconstruction efficiency for sustainable bioenergy applications.

NMR↗

Process Intensification for Direct Conversion of Biomass-Based Syngas to High Octane Gasoline

The conversion of lignocellulosic-derived carbon sources via the creation of a CO2 rich syngas stream provides means to produce liquid hydrocarbon fuels, with advancements intended to create a cost-competitive method of sequential conversion via methanol and dimethyl ether intermediates. Previously developed methods with Cu/Beta zeolites enabled the conversion of dimethyl ether to linear and branched hydrocarbons, with high selectivities towards products with high-octane fuel properties. Through process intensification, use of a single reactor to convert syngas to methanol and DME, then further to hydrocarbons, allows for reduced capitol and operation cost for the same chemistries that typically use 3 reactors instead of one. Utilization of commercially available methanol synthesis catalyst (Megamax 800, Clariant, CZA) and methanol dehydration catalyst with the Cu/Beta catalyst allowed for conversion into hydrocarbon products in this single reactor set up. Reactor configuration with CZA and alumina catalysts mixed with or stacked in a bed physically above the Cu/Beta catalyst provided a system for the direct conversion of the syngas to hydrocarbons with improved yields and selectivities with higher net C1 conversions for stacked bed configurations. Through control of the process conditions, greater conversion of C1 oxygenate intermediates (i.e., methanol and dimethyl ether) was achieved with concomitant increase in selectivities towards gasoline and jet fuel range olefin and paraffin products. Lower hydrocarbon number products and less naphthenes were observed for the conversion of syngas compared to DME conversion on only the Cu/Beta system with prominent selectivities observed for C4, C5, and C7 hydrocarbons. The DME and methanol formation rates, with understanding of the equilibria for both processes, were determined as important factors to allow for improved performance of the Cu/Beta. Determination of the factors which allow for tuning of selectivities and yields created an intensified process which allows for a "market-responsive" biorefinery design, which can produce high octane gasoline or jet fuel range hydrocarbons to meet demands for a more sustainable route to liquid fuels.

BIOMASS FUELS↗

Pd/C promotes C–H bond activation and oxidation of p -hydroxybenzoate during hydrogenolysis of poplar

Hydrogenolysis of lignin generates a portfolio of products, the yields of which are generally calculated using a subset of phenolic monomers that are dependent on the lignin composition, product distribution, and analytical technique. Some lignins are naturally γ-acylated; poplar lignins, for example, have p-hydroxybenzoate groups on 1–15% of their syringyl subunits. Upon hydrogenolysis, it is generally assumed that the p-hydroxybenzoate is cleaved before the deacylated lignin is depolymerized. Hydrogenolysis of model γ-p-hydroxybenzoylated β-aryl ethers do not, however, produce the deacylated β-aryl ether intermediates, as was previously conjectured; products instead derive from palladium-assisted reactions on the cinnamyl p-hydroxybenzoates resulting in initial β-ether cleavage. The p-hydroxybenzoate moiety itself also undergoes carboxylate-assisted palladium-catalyzed C–H bond activation to form the 2,4-dihydroxybenzoate, that subsequently converts to the 2,4-dihydroxycyclohex-1-enoate. Furthermore, these details underscore previously unrecognized pathways and products that are key to understanding the different hydrogenolysis product distributions from naturally acylated lignins that are prevalent biomass-conversion feedstocks.

09 BIOMASS FUELS↗

Probing Condensed-Phase Structure and Dynamics in Hierarchical Zeolites and Nanosheets for Catalytic Upgradation of Biomass (Final Report)

Understanding complex reaction pathways in systems governed by multi-scale collective interactions across time and length scales remains a central scientific challenge. This project was guided by the hypothesis that the interplay among oligomers, solvents, and active sites can be tuned by a suitable choice of solvation environment and pore architecture in solid-acid catalysts to direct chemical transformations relevant to biomass conversion. Zeolites and zeolite nanosheets were used as model platforms, allowing for the interaction of macromolecules with the surface of the zeolite nanosheets and with smaller pores that host catalytically active sites. To investigate these coupled phenomena, we employ a multi-scale computational framework that integrates molecular-level descriptions with advanced sampling approaches to capture key physical and chemical interactions. Our work through this project improved fundamental understanding of how reactants and solid-acid catalysts interact in solvent-rich environments, thereby enabling the rational design of catalytic systems that upgrade biomass with enhanced selectivity and energy efficiency. In addition, the project developed advanced sampling methodologies critical for disentangling complex, reactive processes in multi-component catalytic environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

The Development of Catalysts for Upgrading of Pyrolysis Vapor for Refinery Feedstocks and Intermediates (CRADA Final Report)

Catalytic fast pyrolysis (CFP) is a versatile technology platform to convert biomass into fungible hydrocarbon transportation fuels and chemical co-products. Key technical barriers to reaching this goal include increasing the product yields and achieving the desired fuel properties for gasoline, diesel, and jet range fuels or blendstocks that would be suitable for introduction into existing refinery unit operations. Overcoming these barriers will require durable catalysts that are effective at upgrading and stabilizing biomass pyrolysis vapors. Towards these goals, this CRADA leveraged NREL experience as a leader in biomass pyrolysis research and Johnson Matthey's (JM) experience as a leader in the production of advanced catalytic materials. The scope spanned CFP catalyst development, characterization, multi-scale reaction testing, and computational modeling. CRADA benefits to DOE, Participant, and U.S. Taxpayer: Assists laboratory in achieving programmatic scope, Uses the laboratory’s core competencies. The purpose of this CRADA was to develop and deploy catalysts for biomass CFP to help achieve cost-competitive biofuels and bio-based products. This was accomplished through a close collaboration between biomass conversion researchers at NREL and catalyst development researchers at JM. Summary of Research Results: Focus Area 1. Foundational research on catalytic conversion and deactivation: Key interactions between pyrolysis vapors and heterogeneous catalysts were probed through catalyst characterization, model compound reaction testing, and atomistic-scale computational modeling. Catalyst development focused on multifunctional materials, which include zeolites, oxides, carbides, and nitrides. Computational modeling identified reaction mechanisms and elucidated surface chemistry to test hypotheses regarding mechanisms of deoxygenation, coupling, cracking, dehydration, coke formation, hydrogen transfer, and aromatic ring reactions. This information was used to design multifunctional catalysts to increase product yields, control product selectivity, and reduce deactivation during CFP and downstream processing steps. The results served to increase fundamental understanding of key catalyst attributes and durability features for the upgrading of biomass pyrolysis vapors. Model compound experiments confirmed the importance of metal-acid bifunctionality for the deoxygenation of lignin-derived phenolic species under hydrodeoxygenation conditions. This insight led to the development of catalysts such as Pt/TiO2 and Mo2C, which were confirmed as high-performing materials during subsequent bench-scale experiments using biomass-derived pyrolysis vapors. This focus area also led to the identification of important catalyst deactivation mechanisms associated with the deposition of inorganic contaminants such as potassium. The molecular-level insight from model compound experiments and computational modeling, shown in Figure 1, informed the development of regeneration procedures that have been shown to be effective for restoration of > 90% of initial catalyst activity. This understanding has subsequently been translated to other catalyst systems, including zeolite materials that can be operated without requirements for co-fed hydrogen.

09 BIOMASS FUELS↗

Structure-guided utilization of lignocellulose for catalysis, energy, and biomaterials

As a complex composite of cellulose, hemicellulose, and lignin, plant lignocellulose has long served as a major resource for biomass conversion, materials engineering, and bio-based product development. High-resolution structural insights enabled by solid-state nuclear magnetic resonance (ssNMR) now allow the mapping of polymer interfaces, identification of functional group accessibility, and tracking of molecular organization during processing, all of which are critical factors for optimizing catalytic strategies. These insights could drive transformative progress in lignocellulose-based applications, including selective depolymerization, improved pretreatment design, and efficient upcycling of lignin into resins, plastics, and biomedical materials. In industry-relevant contexts, such as biofuel generation and renewable material manufacturing, understanding the hydration dynamics, cross-linking patterns, and structural heterogeneity is also essential. The ability to visualize these features in native biomass presents a unique opportunity to develop new strategies for sustainability and performance. As the structural toolbox continues to expand, it is becoming a central enabler for innovations in renewable energy, green chemistry, and advanced bioproducts.

bioproduct↗

Unlocking the distinctive enzymatic functions of the early plant biomass deconstructive genes in a brown rot fungus by cell-free protein expression

ABSTRACT Saprotrophic fungi that cause brown rot of woody biomass evolved a distinctive mechanism that relies on reactive oxygen species (ROS) to kick-start lignocellulosic polymers’ deconstruction. These ROS agents are generated at incipient decay stages through a series of redox relays that shuttle electrons from fungus’s central metabolism to extracellular Fenton chemistry. A list of genes has been suggested encoding the enzyme catalysts of the redox processes involved in ROS’s function. However, navigating the functions of the encoded enzymes has been challenging due to the lack of a rapid method for protein synthesis. Here, we employed cell-free expression system to synthesize four redox or degradative enzymes, which were identified, by transcriptomic data, as conserved players of the ROS oxidation phase across brown rot fungal species. All four enzymes were successfully expressed and showed activities that enable confident assignment of function, namely, benzoquinone reductase (BQR), ferric reductase, α-L-arabinofuranosidase (ABF), and heme-thiolate peroxidase (HTP). Detailed analysis of their catalytic features within the context of brown rot environments allowed us to interpret their roles during ROS-driven wood decomposition. Specifically, we validated the functions of BQR as the driver redox enzyme of Fenton cycles and reconstructed its interactions with the co-occurring HTP or laccase and ABF. Taken together, this research demonstrated that the cell-free expression platform is adequate for synthesizing functional fungal enzymes and provided an alternative route for the rapid characterization of fungal proteins, escalating our understanding of the distinctive biocatalyst system for plant biomass conversion. IMPORTANCE Brown rot fungi are efficient wood decomposers in nature, and their unique degradative systems harbor untapped catalysts pursued by the biorefinery and bioremediation industries. While the use of “omics” platforms has recently uncovered the key “oxidative-hydrolytic” mechanisms that allow these fungi to attack lignocellulose, individual protein characterization is lagging behind due to the lack of a robust method for rapid synthesis of crucial fungal enzymes. This work delves into the studies of biochemical functions of brown rot enzymes using a rapid, cell-free expression platform, which allowed the successful depictions of enzymes’ catalytic features, their interactions with Fenton chemistry, and their roles played during the incipient stage of brown rot when fungus sets off the reactive oxygen species for oxidative degradation. We expect this research could illuminate cell-free protein expression system’s use to fulfill the increasing need for functional studies of fungal enzymes, advancing the discoveries of novel biomass-converting catalysts.

60 APPLIED LIFE SCIENCES↗