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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Expression of a bacterial 3-dehydroshikimate dehydratase (QsuB) reduces lignin and improves biomass saccharification efficiency in switchgrass (Panicum virgatum L.)

Abstract Background Lignin deposited in plant cell walls negatively affects biomass conversion into advanced bioproducts. There is therefore a strong interest in developing bioenergy crops with reduced lignin content or altered lignin structures. Another desired trait for bioenergy crops is the ability to accumulate novel bioproducts, which would enhance the development of economically sustainable biorefineries. As previously demonstrated in the model plant Arabidopsis, expression of a 3-dehydroshikimate dehydratase in plants offers the potential for decreasing lignin content and overproducing a value-added metabolic coproduct (i.e., protocatechuate) suitable for biological upgrading. Results The 3-dehydroshikimate dehydratase QsuB from Corynebacterium glutamicum was expressed in the bioenergy crop switchgrass ( Panicum virgatum L.) using the stem-specific promoter of an O-methyltransferase gene ( pShOMT ) from sugarcane. The activity of pShOMT was validated in switchgrass after observation in-situ of beta-glucuronidase (GUS) activity in stem nodes of plants carrying a pShOMT::GUS fusion construct. Under controlled growth conditions, engineered switchgrass lines containing a pShOMT::QsuB construct showed reductions of lignin content, improvements of biomass saccharification efficiency, and accumulated higher amount of protocatechuate compared to control plants. Attempts to generate transgenic switchgrass lines carrying the QsuB gene under the control of the constitutive promoter pZmUbi-1 were unsuccessful, suggesting possible toxicity issues associated with ectopic QsuB expression during the plant regeneration process. Conclusion This study validates the transfer of the QsuB engineering approach from a model plant to switchgrass. We have demonstrated altered expression of two important traits: lignin content and accumulation of a co-product. We found that the choice of promoter to drive QsuB expression should be carefully considered when deploying this strategy to other bioenergy crops. Field-testing of engineered QsuB switchgrass are in progress to assess the performance of the introduced traits and agronomic performances of the transgenic plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Enhanced Catalyst Durability and Sulfur Tolerance by Atomic Layer Deposition (CRADA Final Report)

This CRADA advanced the use of atomic layer deposition (ALD) catalyst coatings to improve sulfur tolerance and demonstrate improved catalyst durability for biomass conversion chemistries. This project leveraged National Laboratory and industry expertise for ALD catalyst coating development between NREL, ALD NanoSolutions, Inc. ("ALD NanoSolutions"), and Johnson Matthey PLC ("Johnson Matthey"). To better understand the role of ALD coatings on catalyst activity and durability, a joint experimental and computational effort combined bench-scale ALD catalyst synthesis, material characterization, catalyst testing, and modeling of catalyst surface energetics. In addition, to demonstrate the commercial relevance of this technology, scaled ALD coated catalysts were subjected to continuous testing and accelerated aging to validate performance gains. Results were used to inform ALD catalyst coating manufacturing cost models, as well as biobased chemical process cost models.

09 BIOMASS FUELS↗
DOE OSTI2021

The Development of Catalysts for Upgrading of Pyrolysis Vapor for Refinery Feedstocks and Intermediates: Cooperative Research and Development, CRADA Number CRD-12-00497 (Final Report)

Fast pyrolysis of biomass with vapor phase upgrading (VPU) can produce refinery feedstocks or intermediates that can meet the Department of Energy’s goal of cost-competitive hydrocarbon fuels by 2017. A key technical barrier for this technology is the lack of selective, cost effective catalysts that can produce high yields of fuel-appropriate hydrocarbons from the pyrolysis vapors. In overcoming this barrier, it will be important to engage leading catalyst development companies to devote their resources and expertise to the development of these materials. Thus, we propose a Cooperative Research and Development Agreement (CRADA) between the National Renewable Energy Laboratory (NREL), a world leader in biomass pyrolysis research and Johnson Matthey (JM), a world leader in the production of advanced catalyst materials to develop and test novel catalysts for efficient VPU. Through its Intercat Inc. subsidiary in Savannah, Ga., Johnson Matthey is internationally recognized as a leader in zeolite-based vapor phase upgrading in refinery duties and an emerging developer of biomass conversion technologies. The research and development efforts described in the proposed work will build upon existing collaborations between NREL and JM and play to the strengths of both institutions. NREL will analyze the composition of pyrolysis vapors as an input to catalyst design, screen and test catalysts, characterize the resulting oil and conduct techno-economic analysis. Catalyst samples will be produced and funded by JM. JM will design and synthesize catalysts, characterize fresh and used catalysts and develop catalyst supports needed to achieve commercially meaningful lifetimes. The project will span catalyst development and testing from the fundamental stage using quantum mechanical modeling and chemical reaction analysis to catalyst screening to integrated pilot studies.

09 BIOMASS FUELS↗
DOE OSTI2026

Understanding Electrochemical Alcohol Hydrogenolysis Enabled by Carbonyl Reduction in Lignocellulosic Biomass-Derived Aromatic Oxygenates

Molecules derived from lignocellulosic biomass are oxygenates with multiple oxygen-containing functional groups, such as hydroxyl and carbonyl groups. Therefore, the ability to selectively reduce a specific oxygenate group is essential for the reductive upgrading of such molecules. Previous studies on electrochemical biomass conversion have shown that alcohol hydrogenolysis, which involves cleavage of the σ(C–O alcohol ) bond, is extremely challenging for furfural and 5-hydroxymethylfurfural (HMF) derivatives, including furfuryl alcohol, 5-methylfurfuryl alcohol (MFA), and 2,5-bis(hydroxymethyl)furan (BHMF). In contrast, HMF itself undergoes alcohol hydrogenolysis relatively easily in acidic aqueous media. Considering that the only structural difference between HMF and BHMF or MFA is the presence of a carbonyl group, this observation raises the question of whether the carbonyl group in HMF facilitates alcohol hydrogenolysis. In this study, we designed systematic experiments to provide a coherent explanation of when and how a carbonyl group enables hydrogenolysis of a copresent alcohol group. Specifically, we show that alcohol hydrogenolysis in HMF proceeds via reduction of the carbonyl group to a ketyl radical, followed by a spin-center shift (SCS) through extended π conjugation. We also elucidate the effect of pH on the selectivity between carbonyl hydrogenation and alcohol hydrogenolysis, both of which share the ketyl radical intermediate. This mechanistic understanding enhances our ability to predict and control alcohol hydrogenolysis in the reductive upgrading of biomass-derived oxygenates.

alcohols↗
DOE OSTI2022

Screening and evaluation of biomass upgrading strategies for sustainable transportation fuel production with biomass-derived volatile fatty acids

Biomass conversion to fuels and chemicals is crucial to decarbonization, but choosing an advantageous upgrading pathway out of many options is challenging. Rigorously evaluating all candidate pathways (process simulation, product property testing) requires a prohibitive amount of research effort; even simple upgrading schemes have hundreds of possible permutations. We present a method enabling high-throughput screening by approximating upgrading unit operations and drop-in compatibility of products (e.g., fuel properties) and apply it to volatile fatty acid (VFA) conversion to liquid transportation fuels via a MATLAB script, VFA Upgrading to Liquid Transportation fUels Refinery Estimation (VULTURE). VULTURE selects upgrading configurations that maximize fuel blend bio-derived content. We validate VULTURE's approximations through surrogate fuel property testing and process simulation. Techno-economic and life cycle analyses suggest that VFA upgrading processes down-selected by VULTURE are profitable and have low carbon intensities, demonstrating the potential for the strategy to accelerate process development timelines at decreased costs.

09 BIOMASS FUELS↗
DOE OSTI2022

Techno-Economic Analysis for Co-Processing Fast Pyrolysis Liquid in Fossil Refineries

Recent work at the National Renewable Energy Laboratory (NREL) and throughout the bioenergy community has highlighted incentives associated with co-processing bio-intermediates in existing refineries to reduce capital costs associated with renewable fuels and chemicals production and reduce overall risk for emerging biomass conversion technologies. This presentation summarizes the techno-economic analysis results from the NREL-Petrobras collaboration that focused on refinery integration of fast pyrolysis oil through co-processing in the fluid catalytic cracking (FCC) process. The NREL-Petrobras work highlights the economic opportunity for refiners to engage in co-processing for low-carbon products and introduces the risks for refiners based on variability in crude and fossil-product markets. The NREL-Petrobras results also serve as a basis to inform policy design that reduces economic risk for refinery co-processing and repurposing opportunities. The final topics in the presentation highlight experimental capabilities and emerging analysis approaches at NREL and partner laboratories that support the development and commercial deployment of refinery utilization strategies.

bio-fuels↗
DOE OSTI2020

Production of levulinic acid and biocarbon electrode material from corn stover through an integrated biorefinery process

To overcome the inefficient biomass conversion, waste generation, and lack of co-production in biorefineries, an integrated process was proposed for the conversion of corn stover into levulinic acid and biocarbon electrode material. Corn stover was pretreated through hydrothermal process using 0.45 wt% K 2 CO 3 which removed 76 wt% lignin and 85 wt% xylan while preserving 83 wt% glucan. This was followed by acid hydrolysis to produce levulinic acid at varying H 2 SO 4 concentrations and reaction time in a batch reactor at 190 °C. At a reaction time of 5 min in 2 wt% H 2 SO 4 , 35.8 wt% and 30 wt% glucan in raw and pretreated corn stover was converted to levulinic acid, respectively. The residue from acid hydrolysis was converted into biocarbon for supercapacitor electrodes via a two-step thermal activation process which showed a specific capacitance of 120 F g -1 . The proposed integrated biorefinery concept provides multiple value-added products for a greater financial and environmental sustainability.

09 BIOMASS FUELS↗
DOE OSTI2025

A “Sweet” Biorefinery: Sugar-derived ionic liquids for the pretreatment of lignocellulosic biomass

Sugar-based ionic liquids (ILs) derived from biomass-based cations (choline, betaine) and sugar-derived anions were developed as sustainable pretreatment solvents to advance the concept of self-reliant biorefinery. Cholinium gluconate ([Ch][GlcA]) enabled streamlined one-pot sorghum pretreatment without the need for pH adjustment or washing, while betainium gluconate ([Bet][GlcA]) achieved higher sugar yields, improving overall process efficiency and economics. Both ILs produced hydrolysates fully compatible with microbial fermentation, demonstrating their potential for efficient, simplified biomass conversion. This work positions sugar-based ILs as powerful platforms that unite sustainable chemistry with integrated bioprocessing, marking a pivotal step toward realizing the self-reliant biorefinery.

Biomass-based ions↗
DOE OSTI2023

Catalytic Upgrading of Carbohydrates in Waste Streams to Hydrocarbons: Paper Sludge to Fuel Project (PStF)

This research, funded by the Department of Energy Bioenergy Technologies Office (DOE BETO), aims to understand the barriers and assess opportunities for transforming carbohydrates in paper sludge, a solid lignocellulosic residue from the pulp and paper industry. The goal is to turn the paper sludge into a liquid hydrocarbon product that can be blended into jet fuel, both economically and sustainably. Research groups at North Carolina State University, National Renewable Energy Laboratory, and Yale University collaborated synergistically, leveraging their expertise in pulp and paper operations, biomass deconstruction, and catalytic upgrading to propose a pathway that efficiently captures the energy in paper sludge. Findings from this study could potentially contribute to advancing biomass conversion technologies, aligning with the efforts of the U.S. DOE BETO. This report documents the experimental and simulation results of a biochemical and catalytic pathway designed to transform paper sludge into a liquid hydrocarbon product. The process involves a sequence of seven steps, including ash removal, carbohydrate enzymatic hydrolysis, sugar dehydration, solvent recovery, aldol-condensation between furans and ketone, hydrogenation, and hydrodeoxygenation to obtain a hydrocarbon blend in the ~C10 range. The experimental efforts from the initiation of the project were guided by techno-economic analysis (TEA) and sensitivity analysis results including around seventy-eight operational parameters. This methodology facilitated the efficient use of resources over time. This study relies on detailed process simulations and TEA to determine the minimum fuel selling price (MFSP) for the hydrocarbon fuel product. Preliminary TEA results led to the evaluation of eight case studies considering alternative dehydration co-solvents, operational settings, and biorefinery layouts. Finally, the life cycle assessment of twenty-eight scenarios, comparing various dehydration co-solvents, fuel sources, chemical feedstock sources, side product utilization, and other process settings, was conducted. Landfilling scenarios with and without landfill gas recovery were also estimated, analyzed, and compared.

09 BIOMASS FUELS↗
DOE OSTI2023

Diffusion in intact secondary cell wall models of plants at different equilibrium moisture content

Secondary plant cell walls are composed of carbohydrate and lignin polymers, and collectively represent a significant renewable resource. Leveraging these resources depends in part on a mechanistic understanding for diffusive processes within plant cell walls. Common wood protection treatments and biomass conversion processes to create biorefinery feedstocks feature ion or solvent diffusion within the cell wall. X-ray fluorescence microscopy experiments have determined that ionic diffusion rates are dependent on cell wall hydration as well as the ionic species through non-linear relationships. In this work, we use classical molecular dynamics simulations to map the diffusion behavior of different plant cell wall components (cellulose, hemicellulose, lignin), ions (Na + , K + , Cu2 + , Cl - ) and water within a model for an intact plant cell wall at various hydration states (3-30 wt% water). From these simulations, we analyze the contacts between different plant cell wall components with each other and their interaction with the ions. Generally, diffusion increases with increasing hydration, with lignin and hemicellulose components increasing diffusion by an order of magnitude over the tested hydration range. Ion diffusion depends on charge. Positively charged cations preferentially interact with hemicellulose components, which include negatively charged carboxylates. As a result, positive ions diffuse more slowly than negatively charged ions. Measured diffusion coefficients are largely observed to best fit piecewise linear trends, with an inflection point between 10 and 15% hydration. These observations shed light onto the molecular mechanisms for diffusive processes within secondary plant cell walls at atomic resolution.

09 BIOMASS FUELS↗
DOE OSTI2022

Triacetic Acid Lactone and 4-Hydroxycoumarin as Bioprivileged Molecules for the Development of Performance-Advantaged Organic Corrosion Inhibitors

Biomass conversion, especially the development of bioprivileged molecules utilizing integration of biological and chemical processes, has shown potential to produce novel chemicals with enhanced properties. Here, organic corrosion inhibitors based on triacetic acid lactone and 4-hydroxycoumarin have been synthesized in good yield and tested for corrosion inhibition on mild steel in both sulfuric acid and hydrochloric acid. Sixteen novel corrosion inhibitors derived from triacetic acid lactone and 4-hydroxycoumarin were efficiently synthesized and twelve of them showed high corrosion inhibition efficiency as confirmed by electrochemical impedance spectroscopy (giving values greater than 78%) and polarization analysis. While triacetic acid lactone-based compounds showed good corrosion inhibition performance, the 4-hydroxycoumarin-based compounds showed further improvement in corrosion inhibition performance. Scanning electron microscopy (SEM) analysis of the mild steel coupon in the presence of selected inhibitors showed that corrosion was significantly diminished, with complementary X-ray photoelectron spectroscopy (XPS) analysis suggesting the inhibitor molecules strongly adsorbed on the steel surface. Quantum chemical calculations showed poor correlation between calculated parameters and the performance of these molecules. This large set of corrosion inhibitors containing a dozen promising corrosion inhibitors is useful for future rational design of corrosion inhibitors. In conclusion, the results demonstrate a new direction for the development of bioprivileged molecules.

09 BIOMASS FUELS↗
DOE OSTI2020

Atomic Layer Deposition (ALD) to Extend Catalyst Lifetime for Biobased Adipic Acid Production

Robust heterogeneous catalysts are essential for enabling biomass conversion; however, harsh reaction environments introduce durability challenges for many conventional catalyst materials [1]. The hydrogenation of biobased muconic acid to adipic acid is one such emerging chemistry that faces PGM catalyst stability challenges [2]. Muconic acid is a heavily-investigated biobased platform chemical that can be converted into an array of large-market commodity chemicals [2]. PGM catalysts are exceptionally effective for muconic acid hydrogenation to adipic acid, with Pd the most active to date. [2] However, Pd leaches in an acidic environment and this chemistry has a high propensity for fouling. Atomic layer deposition (ALD) is one such material design strategy that has emerged to stabilize supported metal catalysts [3]. ALD coatings are theorized to stabilize supported metal active sites by i) covering high-energy facets most susceptible to degradation, ii) disrupting the physical mobility of active sites, and iii) reinforcing the structure of the underlying catalyst support [3]. However, ALD coatings for catalyst durability with carboxylic acids remains an underdeveloped area of research and literature reports have yet to consider the techno-economic tradeoffs between the ALD manufacturing cost and catalyst lifetime productivity. This study examines low-cycle Al2O3 ALD coatings to stabilize Pd/TiO2 against deactivation during muconic acid hydrogenation. The unique harshness of muconic acid for Pd leaching was evaluated by both experiment and computation. Based on batch reactor screening results, uncoated and ALD coated catalysts were evaluated in a continuous flow reactor for their productivity, stability, and post-reaction regenerability at 700 degrees C. Characterization was performed to assess the impact of ALD coatings on catalyst morphology, as well as following regeneration. Finally, techno-economic analysis models evaluated the value proposition for ALD-coated catalysts within an nth-generation adipic acid biorefinery.

09 BIOMASS FUELS↗
DOE OSTI2021

Layer‐by‐Layer Engineered All‐Liquid Microfluidic Chips for Enzyme Immobilization

Abstract Enzyme immobilization in the confines of microfluidic chips, that promote enzyme activity and stability, has become a powerful strategy to enhance biocatalysis and biomass conversion. Here, based on a newly developed all‐liquid microfluidic chip, fabricated by the interfacial assembly of nanoparticle surfactants (NPSs) in a biphasic system, a layer‐by‐layer assembly strategy to generate polysaccharide multilayers on the surface of a microchannel, greatly enhancing the mechanical properties of the microchannel and offering a biocompatible microenvironment for enzyme immobilization, is presented. Using horseradish peroxidase and glucose oxidase as model enzymes, all‐liquid microfluidic enzymatic and cascade reactors have been constructed and the crucial role of polysaccharide multilayers on enhancing the enzyme loading and catalytic efficiency is demonstrated.

Liu, Tan↗
DOE OSTI2020

Phosphonate‐Modified UiO‐66 Brønsted Acid Catalyst and Its Use in Dehydra‐Decyclization of 2‐Methyltetrahydrofuran to Pentadienes

Abstract Phosphorus‐modified all‐silica zeolites exhibit activity and selectivity in certain Brønsted acid catalyzed reactions for biomass conversion. In an effort to achieve similar performance with catalysts having well‐defined sites, we report the incorporation of Brønsted acidity to metal–organic frameworks with the UiO‐66 topology, achieved by attaching phosphonic acid to the 1,4‐benzenedicarboxylate ligand and using it to form UiO‐66‐PO 3 H 2 by post‐synthesis modification. Characterization reveals that UiO‐66‐PO 3 H 2 retains stability similar to UiO‐66, and exhibits weak Brønsted acidity, as demonstrated by titrations, alcohol dehydration, and dehydra‐decyclization of 2‐methyltetrahydrofuran (2‐MTHF). For the later reaction, the reported catalyst exhibits site‐time yields and selectivity approaching that of phosphoric acid on all‐silica zeolites. Using solid‐state NMR and deprotonation energy calculations, the chemical environments of P and the corresponding acidities are determined.

Dorneles de Mello, Matheus↗
DOE OSTI2020

Reduced type-A carbohydrate-binding module interactions to cellulose I leads to improved endocellulase activity

Dissociation of nonproductively bound cellulolytic enzymes from cellulose is hypothesized to be a key rate-limiting factor impeding cost-effective biomass conversion to fermentable sugars. However, the role of carbohydrate-binding modules (CBMs) in enabling nonproductive enzyme binding is not well understood. Here, we examine the subtle interplay of CBM binding and cellulose hydrolysis activity for three models type-A CBMs (Families 1, 3a, and 64) tethered to multifunctional endoglucanase (CelE) on two distinct cellulose allomorphs (i.e., cellulose I and III). We generated a small library of mutant CBMs with varying cellulose affinity, as determined by equilibrium binding assays, followed by monitoring cellulose hydrolysis activity of CelE–CBM fusion constructs. Finally, kinetic binding assays using quartz crystal microbalance with dissipation were employed to measure CBM adsorption and desorption rate constants kon and koff, respectively, towards nanocrystalline cellulose derived from both allomorphs. Overall, our results indicate that reduced CBM equilibrium binding affinity towards cellulose I alone, resulting from increased desorption rates (koff) and reduced effective adsorption rates (nkon), is correlated to overall improved endocellulase activity. Future studies could employ similar approaches to unravel the role of CBMs in nonproductive enzyme binding and develop improved cellulolytic enzymes for industrial applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Mechanistic Insights into the Demethylation of Lignin‐Derived Structures Using Protic Ionic Liquids: A Density Functional Theory Study

Lignin valorization is restricted by the stability of its methoxy groups, creating a critical need for efficient demethylation strategies. Here, in this study, density functional theory (DFT) is employed to dissect the mechanistic pathways of demethylation in lignin model compounds, guaiacol and syringol, using protic ionic liquids (PILs) that act as both solvent and catalyst. Conductor‐like Screening Model for Real Solvents (COSMO‐RS) analysis identifies monoethanolammonium acetate ([MEOA][Ace]) as the most promising medium, attributed to its strong hydrogen bonding network and solvation ability. By integrating implicit and explicit solvation models, it is revealed that an acid‐catalyzed hydrolytic mechanism governs demethylation, with PILs stabilizing crucial transition states and intermediates. Complementary electronic structure evaluations, including highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) gap analysis, charge distribution, and electrostatic potential mapping, demonstrate how PILs lower energetic barriers and enhance reactivity. To simulate realistic environments, this study is extended to lignin dimer complexes with varying water content, uncovering how water‐bridged solvation reverses demethylation preference from guaiacyl to syringyl units. This mechanistic shift aligns with experimental observations showing faster S‐unit reactivity in hydrated systems. Together, these findings provide atomic‐level insight into lignin demethylation dynamics and highlight how tuning acid concentration in PILs can accelerate kinetics, enabling a rational pathway toward next‐generation biomass conversion technologies.

COSMO-RS↗
DOE OSTI2021

Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water

Catalytic wet oxidation (CWO) of aqueous effluents rich in organic compounds is a very promising technology for the treatment of liquid wastes from biomass conversion processes. CWO reactions occur through the formation of free radical species, produced in the presence of an oxidant, which act on organic contaminates in the effluent. Although the reaction is well known, there exists a lack of affordable catalysts to conduct this process at the lower temperatures and pressures in novel bioenergy processes. Here, this study assessed the catalytic effect of nitrogen-doped chars as such an option. Phenol in aqueous solution was used as a model waste effluent. Treatment was conducted at moderate temperatures (190 to 260 °C), oxygen partial pressure of 1 MPa, and reaction times of 15, 30, and 45 min in stainless steel and glass-lined tube reactors. High pressure liquid chromatography (HPLC) analyses of the products quantified phenol and by-product concentrations used in the calculation of reaction activation energy. The char catalyst was studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) in order to gain insight into its structure and surface composition. The results indicate that nitrogen-doped char catalysts accelerate the oxidation of phenol by decreasing its reaction activation energy from 82.2 kJ/mol (non-catalyzed) to 40.4 kJ/mol (catalyzed). An analysis from first principles using density functional theory (DFT) was conducted to ascertain which N functional group has the most significant impact on free radical formation in the presence of oxygen. Among all the N functional groups studied, the dipyridinic functional groups showed the most promising characteristics to facilitate the formation of hydroxyl free radicals.

Advanced Oxidation Processes for Organic Pollutant↗