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DOE OSTI2022

p-Block Metal Oxide Noninnocence in the Oxygen Evolution Reaction in Acid: The Case of Bismuth Oxide

The Pourbaix diagrams of p-block Pb, Sb, and Bi establish a robust stability for their oxides in acidic solutions. Such oxides have found utility as stable frameworks to support metals that are active for oxygen evolution reaction (OER) catalysis, but they also possess two-electron redox couples, which can potentially engender OER activity. Thus, the use of p-block oxide supports provides an imperative for understanding the OER activity of the unary oxides. Toward this end, we report BiO x films that are able to perform OER catalysis at moderate overpotentials for extended periods of operation (>110 h) in highly acidic solutions (pH 1.0–2.25) with no sign of decreased OER activity during operation at current densities of 1–5 mA cm –2 . X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and UV-vis spectroelectrochemistry reveal a change in the Bi oxidation state prior to OER catalysis, from predominantly Bi 3+ in the as-deposited films to primarily Bi 5+ in the catalytically active films. Furthermore, this transformation is accompanied by a prominent color change from orange to dark brown. Simulations of the cyclic voltammogram catalytic profiles suggest two OER pathways for BiO x involving Bi IV O x and Bi V O x catalysts with the Bi V O x pathway prevailing after catalyst activation. Together, these results demonstrate the ability of BiO x to facilitate OER in acid with high functional stability and underscore the noninnocent role that p-block metal oxides may play in OER catalysis in acidic media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Conversion of Phenolic Oil from Biomass Pyrolysis into Phenyl Esters

Bio-oil is among the most economical approaches for advanced biofuel production. However, bio-oil faces several challenges including high acidity and viscosity, poor storage, and thermal stability. This study focuses on the upgradation of lignocellulosic (corn stover and yellow pine) bio-oil derived phenolic oil (PO), produced by the autothermal fast pyrolysis, through acid-catalyzed esterification reaction. Our strategy exploits a little recognized chemistry: the Fischer esterification of PO and carboxylic acids into carboxylic acid phenyl esters (CAPE) using Dean Stark distillation. Analyses by the Folin–Ciocalteu method, Karl Fischer titration, gas chromatography flame ionization detector, and the molecular weight determination by gel permeation chromatography suggest the conversion of 50 wt% added phenolics to their corresponding CAPE. The Fourier transform infrared spectroscopy analysis confirmed the formation of new C=O and two C–O stretching bands and decrease in the intensity of phenolic-OH bands in the CAPE. The 13 C NMR analysis supports the formation of CAPE together with some unreacted precursors. A base-catalyzed ester hydrolysis experiment and mass balance calculation show an excellent agreement (within 5% range) of the equivalent weight between the produced ester and the phenyl hexanoate. Brookfield analysis indicates that CAPE has 330-fold lower viscosity than starting PO. Heating values of CAPE were higher than PO, from which they were derived (42.2 and 43.6%, respectively, for PO from pyrolysis of corn stover and yellow pine), while moisture content decreased by 98.3 and 98.7%, respectively. The CAPE, which is a phenolic analogue of methyl esters used in biodiesel, has improved stability compared to PO from which it was derived.

42 ENGINEERING↗

DOE OSTI2023

Elucidation of Structure and Physical Properties of Pyrolytic Sugar Oligomers Derived from Cellulose Depolymerization/Dehydration Reactions: A Density Functional Theory Study

Fast pyrolysis of lignocellulosic materials is a promising research area to produce renewable fuels and chemicals. Dehydration is known to be among the most important reaction families during cellulose pyrolysis; water is the most important product. Together with water, dehydration reactions also form a range of poorly known oligomer species of varying molecular sizes, often collected as part of bio-oil water-soluble (WS) fraction. In this work, we used electronic structure calculations to evaluate the relative thermodynamic stabilities of several oligomer species resulting from up to three consecutive dehydration events from cellulose depolymerization intermediates. A library of the thermodynamically favored candidate molecular structures was compiled. Results revealed that most of the water molecules are eliminated from the non-reducing end, forming thermodynamically more stable conjugated compounds. This is consistent with results reported by other researchers in literature where dehydration reactions occur preferably at the non-reducing ends of oligomers. The physical-chemical properties of the proposed structures were estimated using quantitative structure-property relationships (QSPRs) and quantitative property-property relationships (QPPRs). The anhydro-sugars derived from cellulose are often blamed for coke formation during bio-oil hydrotreatment. Understanding their chemical structure could help to develop rational strategies to mitigate coke formation. Furthermore, the thermo-physical properties reported (boiling point, melting point, Gibb’s free energy of formation, enthalpy of formation, and solubility parameters among others) are also fundamental to conducting first principle engineering calculations to design and analyze new pyrolysis reactors and bio-oil up-grading units.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Chemical Diversity of Oligomers in Biomass Fast Pyrolysis Oils, Part 2: Heavy Lignin-Derived Molecules and Highly Dehydrated Sugars from Dichloromethane-Insoluble Pyrolytic Lignin

Here, this paper, the second in a series, investigates the water-insoluble, dichloromethane (DCM)-insoluble residue of BTG pyrolysis oil, also known in the literature as high-molecular-weight pyrolytic lignin (HMW-PL). HMW-PL accounts for 9.2 wt % of the original bio-oil, which is known to increase upon aging and contribute to coke formation during bio-oil upgrading. Understanding its composition is crucial for managing pyrolysis oil during the processing. The HMW-PL was fractionated using a silica gel column with solvents of increasing polarity: ethyl acetate (EA), acetone (AC), isopropanol (ISO), and methanol (MeOH), yielding 49.2, 19.9, 8.2, and 8.1 wt %, respectively. Each subfraction was characterized by UV-fluorescence, FTIR, HSQC NMR, and (−)APCI-FT-Orbitrap MS. Analysis revealed that the EA subfraction primarily contained aromatic dimers (C 19 –C 20 ) and trimers (C 17 –C 13 ), while the MeOH subfraction was rich in oxygenated aliphatic monomers (C 8 –C 16 ) likely derived from sugar dehydration products. The resulting fractions were further separated via preparatory HPLC. Fifty-five candidate molecular structures were proposed based on the Orbitrap MS data, supported by UV-fluorescence, FTIR, and NMR results. This fractionation strategy defined four distinct subfractions, enabling the proposal of surrogate molecular structures and advancing the molecular-level understanding of the HMW-PL fraction in the pyrolysis bio-oil.

High-Molecular-Weight PL↗

DOE OSTI2025

Techno-Economic Analysis and Life Cycle Assessment of Alternative Fuels for Locomotives in the U.S. Freight Rail Sector

Freight rail is more energy-efficient than truck transport over long-haul distances, offering a low-energy and emissions-intensive option for transporting freight. This study evaluates techno-economic analysis and life cycle assessment of seven alternative unblended fuels for freight locomotive engines─biodiesel, renewable diesel (RD), bio-oils, methanol, dimethyl ether (DME), ethanol, and ammonia─across 16 fuel pathways utilizing soybean, corn, woody biomass, renewable hydrogen, and waste sources, e.g., sludge, manure, and industrial CO 2 , and compares these to conventional diesel. The minimum fuel selling price (MFSP) ranged from $\$2.05$ to $\$8.27$ per diesel gallon equivalent (2020 US dollars), with biocrude and RDs produced from hydrothermal liquefaction (HTL) of sludge having the lowest MFSPs due to coproduct credits and avoided waste treatment cost. Life cycle GHG emissions ranged from −41 to 53 g of CO 2 e/MJ. RD from waste via HTL achieves negative emissions by diverting sludge/manure from GHG-intensive conventional management. Few pathways such as biocrude, methanol, and DME require additional control for SO X emissions in the refinery, while ethanol, FT-diesel, and bio-oil require additional control for particulate matter emissions. Bio-oil and RD from sludge have lower marginal abatement cost or MAC (–$\$38$/tonne CO 2 lowest) while methanol and ammonia with renewable hydrogen have higher MAC ($\$490$/tonne CO 2 maximum).

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2023

A Machine Learning Model for Predicting Composition of Catalytic Coprocessing Products from Molecular Beam Mass Spectra

Demand for the development of an automated and integrated refining process for biofuels has increased in recent years due to the lack of generalized process inspection tools. In bio-oil upgrading processes, all process variables are maintained based on the offline specification of intermediates and products. A lack of real-time product specifications in batch-wise monitoring can cause process failure and wasted resources. Therefore, there is a need for a fast and accurate intermediates/product specification tool that can be used for real-time specification to reduce waste and mitigate the risk of process failure. Here, to address this gap, we developed a machine learning (ML) model for predicting speciated bio-oil composition, including paraffin, iso-paraffins, olefins, naphthene, and aromatics. The model is trained using the mass spectra from upgraded products collected in the vapor phase before condensation and predicts the composition of the condensed product. Training ML models using raw mass spectra is challenging due to numerous overlapped peaks originating from different parent compounds. With this in mind, we propose a protocol that (i) transforms raw mass spectra to chemistry-inspired predefined features and (ii) trains decision tree-based models using these features. Our results show that the random forest model was robust against overfitting and had the highest accuracy compared to other models. Moreover, a stochastic ablation method determined the eight most significant features while maximizing the accuracy. Our protocol facilitates real-time compositional analysis of upgraded bio-oils and thus real-time process monitoring. Additionally, this protocol enables the rational design of efficient catalysts and the determination of optimal process conditions.

09 BIOMASS FUELS↗

DOE OSTI2024

Down-selection of biomolecules to assemble “reverse micelle” with perovskites

Abstract Biological molecule-semiconductor interfacing has triggered numerous opportunities in applied physics such as bio-assisted data storage and computation, brain-computer interface, and advanced distributed bio-sensing. The introduction of electronics into biological embodiment is being quickly developed as it has great potential in providing adaptivity and improving functionality. Reciprocally, introducing biomaterials into semiconductors to manifest bio-mimetic functionality is impactful in triggering new enhanced mechanisms. In this study, we utilize the vulnerable perovskite semiconductors as a platform to understand if certain types of biomolecules can regulate the lattice and endow a unique mechanism for stabilizing the metastable perovskite lattice. Three tiers of biomolecules have been systematically tested and the results reveal a fundamental mechanism for the formation of a “reverse-micelle” structure. Systematic exploration of a large set of biomolecules led to the discovery of guiding principle for down-selection of biomolecules which extends the classic emulsion theory to this hybrid systems. Results demonstrate that by introducing biomaterials into semiconductors, natural phenomena typically observed in biological systems can also be incorporated into semiconducting crystals, providing a new perspective to engineer existing synthetic materials.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

An ontology-based knowledge graph for representing interactions involving RNA molecules

The "RNA world" represents a novel frontier for the study of fundamental biological processes and human diseases and is paving the way for the development of new drugs tailored to each patient's biomolecular characteristics. Although scientific data about coding and non-coding RNA molecules are constantly produced and available from public repositories, they are scattered across different databases and a centralized, uniform, and semantically consistent representation of the "RNA world" is still lacking. We propose RNA-KG, a knowledge graph (KG) encompassing biological knowledge about RNAs gathered from more than 60 public databases, integrating functional relationships with genes, proteins, and chemicals and ontologically grounded biomedical concepts. To develop RNA-KG, we first identified, pre-processed, and characterized each data source; next, we built a meta-graph that provides an ontological description of the KG by representing all the bio-molecular entities and medical concepts of interest in this domain, as well as the types of interactions connecting them. Finally, we leveraged an instance-based semantically abstracted knowledge model to specify the ontological alignment according to which RNA-KG was generated. RNA-KG can be downloaded in different formats and also queried by a SPARQL endpoint. A thorough topological analysis of the resulting heterogeneous graph provides further insights into the characteristics of the "RNA world". RNA-KG can be both directly explored and visualized, and/or analyzed by applying computational methods to infer bio-medical knowledge from its heterogeneous nodes and edges. The resource can be easily updated with new experimental data, and specific views of the overall KG can be extracted according to the bio-medical problem to be studied.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2020

Niche Partitioning of Microbial Communities at an Ancient Vitrified Hillfort: Implications for Vitrified Radioactive Waste Disposal

A pre-Viking era vitrified hillfort, Broborg, provides a habitat analogue for disposed radioactive waste glass and shows strong niche partitioning among the organisms involved in glass alteration. Microbes cannot be eliminated from radioactive waste disposal facilities and the consequences of bio-colonization must be understood. We use Broborg as a model system to inform what microbial processes might influence long-term radioactive waste glass durability by examining anthropogenic glass that has been subjected to bio-colonization for over 1,500 years. Scanning electron microscopy (SEM) images reveal the surficial biofilm structure, and chemical/mineralogy analysis in combination with deoxyribonucleic acid (DNA) sequencing of samples from the vitrified substrate, the adjacent soil, and the general topsoil provide insight into niche partitioning. The ancient glass niche supports a unique microbial community of bacteria, fungi, and protists that manifests the species response to local geochemical and mineralogical conditions. Communities from the geochemical niche associated with the glass are distinct and less diverse than soil communities. The microbiome of the glass and adjacent soil are dominated by lichens, lichen-associated microorganisms, and other epilithic, endolithic, and epigeic organisms. Pseudomonads dominate the prokaryotic communities on the vitrified material, but not the adjacent soil. In contrast, the general topsoil communities are enriched in plant rhizosphere organisms. Taxa associated with vitrification have bio-corrosive properties that could be detrimental to glass durability, including silicate mineral dissolution, extraction of essential elements, secretion of geochemically reactive organic acids, and dissolution induced by improved water retention. However, these stable long-term biofilms also possess a homeostatic function that could limit glass alteration. Overall, this study demonstrates the potential impacts that microbial colonization and niche partitioning can have on glass alteration and subsequent release of radionuclides from a disposal facility for vitrified radioactive waste.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2020

Conversion of poplar biomass into high-energy density tricyclic sesquiterpene jet fuel blendstocks

In an effort to ensure future energy security, reduce greenhouse gas emissions and create domestic jobs, the US has invested in technologies to develop sustainable biofuels and bioproducts from renewable carbon sources such as lignocellulosic biomass. Bio-derived jet fuel is of particular interest as aviation is less amenable to electrification compared to other modes of transportation and synthetic biology provides the ability to tailor fuel properties to enhance performance. Specific energy and energy density are important properties in determining the attractiveness of potential bio-derived jet fuels. For example, increased energy content can give the industry options such as longer range, higher load or reduced takeoff weight. Energy-dense sesquiterpenes have been identified as potential next-generation jet fuels that can be renewably produced from lignocellulosic biomass. We developed a biomass deconstruction and conversion process that enabled the production of two tricyclic sesquiterpenes, epi-isozizaene and prespatane, from the woody biomass poplar using the versatile basidiomycete Rhodosporidium toruloides. We demonstrated terpene production at both bench and bioreactor scales, with prespatane titers reaching 1173.6 mg/L when grown in poplar hydrolysate in a 2 L bioreactor. Additionally, we examined the theoretical fuel properties of prespatane and epi-isozizaene in their hydrogenated states as blending options for jet fuel, and compared them to aviation fuel, Jet A. Our findings indicate that prespatane and epi-isozizaene in their hydrogenated states would be attractive blending options in Jet A or other lower density renewable jet fuels as they would improve viscosity and increase their energy density. Saturated epi-isozizaene and saturated prespatane have energy densities that are 16.6 and 18.8% higher than Jet A, respectively. These results highlight the potential of R. toruloides as a production host for the sustainable and scalable production of bio-derived jet fuel blends, and this is the first report of prespatane as an alternative jet fuel.

09 BIOMASS FUELS↗

DOE OSTI2020

Performance and community structure dynamics of microbial electrolysis cells operated on multiple complex feedstocks

Microbial electrolysis is a promising technology for converting aqueous wastes into hydrogen. However, substrate adaptability is an important feature, seldom documented in microbial electrolysis cells (MECs). In addition, the correlation between substrate composition and community structure has not been well established. This study used an MEC capable of producing over 10 L/L-day of hydrogen from a switchgrass-derived bio-oil aqueous phase and investigated four additional substrates, tested in sequence on a mature biofilm. The additional substrates included a red oak-derived bio-oil aqueous phase, a corn stover fermentation product, a mixture of phenol and acetate, and acetate alone. The MECs fed with the corn stover fermentation product resulted in the highest performance among the complex feedstocks, producing an average current density of 7.3 ± 0.51 A/m 2 , although the acetate fed MECs outperformed complex substrates, producing 12.3 ± 0.01 A/m 2 . 16S rRNA gene sequencing showed that community structure and community diversity were not predictive of performance, and replicate community structures diverged despite identical inoculum and enrichment procedure. The trends in each replicate, however, were indicative of the influence of the substrates. Geobacter was the most dominant genus across most of the samples tested, but its abundance did not correlate strongly to current density. High-performance liquid chromatography (HPLC) showed that acetic acid accumulated during open circuit conditions when MECs were fed with complex feedstocks and was quickly degraded once closed circuit conditions were applied. The largest net acetic acid removal rate occurred when MECs were fed with red oak bio-oil aqueous phase, consuming 2.93 ± 0.00 g/L-day. Principal component analysis found that MEC performance metrics such as current density, hydrogen productivity, and chemical oxygen demand removal were closely correlated. Net acetic acid removal was also found to correlate with performance. However, no bacterial genus appeared to correlated to these performance metrics strongly, and the analysis suggested that less than 70% of the variance was accounted for by the two components. This study demonstrates the robustness of microbial communities to adapt to a range of feedstocks and conditions without relying on specific species, delivering high hydrogen productivities despite differences in community structure. The results indicate that functional adaptation may play a larger role in performance than community composition. Further investigation of the roles each microbe plays in these communities will help MECs to become integral in the 21st-century bioeconomy to produce zero-emission fuels.

09 BIOMASS FUELS↗

DOE OSTI2020

Materials Data on Ba5(Bi2O3)7 by Materials Project

Ba5Bi10O17(BiO)4 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Ba5Bi10O17 sheet oriented in the (0, 0, 1) direction and two BiO sheets oriented in the (0, 0, 1) direction. In the Ba5Bi10O17 sheet, there are five inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.73–3.12 Å. In the second Ba2+ site, Ba2+ is bonded to six O2- atoms to form distorted BaO6 octahedra that share corners with four equivalent BaO6 octahedra, edges with four equivalent BaO6 octahedra, and edges with four equivalent BiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are a spread of Ba–O bond distances ranging from 2.59–2.98 Å. In the third Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.64–3.13 Å. In the fourth Ba2+ site, Ba2+ is bonded to five O2- atoms to form a mixture of distorted edge and corner-sharing BaO5 trigonal bipyramids. There are a spread of Ba–O bond distances ranging from 2.65–2.83 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.61–2.98 Å. There are ten inequivalent Bi+2.29+ sites. In the first Bi+2.29+ site, Bi+2.29+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.05–2.84 Å. In the second Bi+2.29+ site, Bi+2.29+ is bonded to six O2- atoms to form distorted BiO6 octahedra that share corners with four equivalent BiO6 octahedra, edges with four equivalent BaO6 octahedra, and edges with four equivalent BiO6 octahedra. The corner-sharing octahedra tilt angles range from 2–15°. There are a spread of Bi–O bond distances ranging from 2.28–2.98 Å. In the third Bi+2.29+ site, Bi+2.29+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.33–2.97 Å. In the fourth Bi+2.29+ site, Bi+2.29+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.14–2.61 Å. In the fifth Bi+2.29+ site, Bi+2.29+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are a spread of Bi–O bond distances ranging from 2.52–2.94 Å. In the sixth Bi+2.29+ site, Bi+2.29+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There are a spread of Bi–O bond distances ranging from 2.49–2.76 Å. In the seventh Bi+2.29+ site, Bi+2.29+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.20–2.96 Å. In the eighth Bi+2.29+ site, Bi+2.29+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.16–2.59 Å. In the ninth Bi+2.29+ site, Bi+2.29+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing BiO6 octahedra. The corner-sharing octahedra tilt angles range from 2–15°. There are a spread of Bi–O bond distances ranging from 2.30–2.98 Å. In the tenth Bi+2.29+ site, Bi+2.29+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.18–2.98 Å. There are seventeen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four equivalent Ba2+ and one O2- atom. The O–O bond length is 1.50 Å. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, one Bi+2.29+, and one O2- atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four equivalent Ba2+ and one Bi+2.29+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three equivalent Bi+2.29+ atoms. In the fifth O2- site, O2- is bonded to four equivalent Ba2+ and one Bi+2.29+ atom to form a mixture of distorted edge and corner-sharing OBa4Bi trigonal bipyramids. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+ and four equivalent Bi+2.29+ atoms. In the seventh O2- site, O2- is bonded to four equivalent Ba2+ and one Bi+2.29+ atom to form a mixture of distorted edge and corner-sharing OBa4Bi trigonal bipyramids. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to one Ba2+ and four equivalent Bi+2.29+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi+2.29+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to four Bi+2.29+ atoms. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to four Bi+2.29+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to five Bi+2.29+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three equivalent Bi+2.29+ atoms. In the fourteenth O2- site, O2- is bonded to five Ba2+ atoms to form a mixture of distorted edge and corner-sharing OBa5 trigonal bipyramids. In the fifteenth O2- site, O2- is bonded to four equivalent Ba2+ and one Bi+2.29+ atom to form distorted OBa4Bi trigonal bipyramids that share a cornercorner with one OBi4 tetrahedra, corners with eight OBa5 trigonal bipyramids, and edges with four equivalent OBa4Bi trigonal bipyramids. In the sixteenth O2- site, O2- is bonded in a 6-coordinate geometry to one Ba2+ and five Bi+2.29+ atoms. In the seventeenth O2- site, O2- is bonded to four Bi+2.29+ atoms to form distorted OBi4 tetrahedra that share corners with six equivalent OBi4 tetrahedra and a cornercorner with one OBa4Bi trigonal bipyramid. In each BiO sheet, there are two inequivalent Bi+2.29+ sites. In the first Bi+2.29+ site, Bi+2.29+ is bonded in a 2-coordinate geometry to three equivalent O2- atoms. There are a spread of Bi–O bond distances ranging from 2.35–2.98 Å. In the second Bi+2.29+ site, Bi+2.29+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.12–2.85 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to four Bi+2.29+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three equivalent Bi+2.29+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on CaBi2(CO)2 by Materials Project

CaC2(BiO)2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two BiO sheets oriented in the (0, 0, 1) direction and two CaC2 sheets oriented in the (0, 0, 1) direction. In each BiO sheet, Bi3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Bi–O bond lengths are 2.33 Å. O2- is bonded to four equivalent Bi3+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra. In each CaC2 sheet, Ca2+ is bonded to eight equivalent C2- atoms to form a mixture of edge and face-sharing CaC8 hexagonal bipyramids. All Ca–C bond lengths are 2.74 Å. C2- is bonded in a 5-coordinate geometry to four equivalent Ca2+ and one C2- atom. The C–C bond length is 1.29 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Bi3O2 by Materials Project

Bi(BiO)2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two bismuth molecules and two BiO sheets oriented in the (0, 0, 1) direction. In each BiO sheet, Bi+1.33+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Bi–O bond lengths are 2.35 Å. O2- is bonded to four equivalent Bi+1.33+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaBi2(CO)2 by Materials Project

LaC2(BiO)2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two BiO sheets oriented in the (0, 0, 1) direction and two LaC2 sheets oriented in the (0, 0, 1) direction. In each BiO sheet, Bi3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Bi–O bond lengths are 2.34 Å. O2- is bonded to four equivalent Bi3+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra. In each LaC2 sheet, La3+ is bonded to eight equivalent C+2.50- atoms to form a mixture of edge and face-sharing LaC8 hexagonal bipyramids. All La–C bond lengths are 2.83 Å. C+2.50- is bonded in a 5-coordinate geometry to four equivalent La3+ and one C+2.50- atom. The C–C bond length is 1.32 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Economic Extraction, Recovery and Upgrading of Rare Earth Elements from Coal-Based Resources

The overall objective of this project is to produce a rare earth elements product with greater than 8% rare earth elements from coal-based resources using an economically viable and environmentally benign processing methodology. The objective of the coal processing work will be to acquire appropriate coal feed and produce a viable clean coal product, a concentrated REE feed stream, and a pyrite stream (where available) that can be used to enhance leaching. The objective of the bio-oxidation portion of the project is to utilize bacteria to oxidize sulfide minerals and ferrous ions to ferric ions to accelerate leaching and remove the sulfides to prevent future acid mine drainage and related liabilities. The objective of the solution conditioning work is to remove iron and control leaching solution conditions to facilitate extraction of REEs without significant thorium extraction. The objective of the column leaching work is to engineer/model and simulate heap leaching to demonstrate low-cost extraction of REEs from coal-based resources. The objective of the solvent extraction work is to selectively extract and recover through controlled stripping of REEs that are solubilized through leaching. The objective of the precipitation portion of the project is to recover the REEs from the solvent extraction stripping solutions and dry them to achieve the final product of rare earth elements that is > 8 % REEs. The objective of the technical, economic, and environmental analysis is to determine the overall viability of the processing approach that is demonstrated in this project. This project encompasses a range of technologies that are currently in industrial practice that are applied and engineered to produce rare earth element product from coal feed sources. The potential sources include large coal feed resources in active coal mines in addition to coal waste. This technology involves the utilization of advanced coal processing technology that can be used to deliver clean coal for the market as well as rare-earth-element-bearing non-coal rock that is of the correct size for heap leaching applications in addition to providing concentrated sulfide minerals (for mid to high sulfur coals) for cleaner coal and for enhanced bio-oxidation to accelerate leaching of REEs from the non-coal rock. The removal of the sulfide minerals cleans the coal, accelerates subsequent REEs extraction, and it removes the future potential for most acid-rock drainage. (For low sulfur coals some pyrite may be purchased if needed.) The processing method also utilizes bio-oxidation to enhance ferric ion production to enhance leaching, while also consuming the sulfide mineral and its associated environmental liability. The project includes a technical, economic, and environmental analysis to facilitate an appropriate assessment of commercial viability for this processing technology.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2022

Co-processing Part 3: LANL Studies Quicker Method to Identify Renewable Carbon Percentages in Fuel Blends [Success Story]

Upgrading bio-oils with petroleum feedstocks at existing refineries—known as “co-processing”—could offer a fast pathway for lowering the carbon footprint of today’s transportation fuels. With equipment and infrastructure already in place, more than 100 refineries across the country are equipped to integrate bio-oil into their processes. But just where might companies insert sustainable bio-oils into existing refinery systems like fluid catalytic crackers and hydrotreaters? If successful, just how much of that renewable or “green” carbon makes it into final fuel products? In this three-part blog series, the National Renewable Energy Laboratory (NREL), Pacific Northwest National Laboratory (PNNL), and Los Alamos National Laboratory (LANL) offer insights into these pressing coprocessing questions—and others—amid the push to dramatically expand the production of climate-friendly fuels. Read part 1 and part 2.

02 PETROLEUM↗

DOE OSTI2020

Malleable Thermosets (Vitrimers) from CO 2 and Plants

Fiber-reinforced composite materials are increasingly used to replace heavy metal components in transportation applications for lightweighting purposes. Polymer matrix materials used in automotive parts, such as epoxies, nylons, and polypropylenes, are almost all produced from fossil fuels. Higher performance thermoset composites are generally not repairable and lower-cost thermoplastic composites do not have enough performance to replace steel. Vitrimers are a new class of polymer materials with long shelf life, low waste in production, ease of processing, and repairability that have the potential to break through the high-cost thermoset/low-performance thermoplastic barrier to vehicle light-weighting. Vitrimers also exhibit easier chemical recyclability than conventional thermosets with reversible chemical crosslinking that enables reprocessing of scrap from production and end of life components. Vitrimers are a new class of engineered plastics that are weldable, repairable and recyclable like thermoplastics but have high mechanical properties like thermosets. Bio-based vitrimers have only recently been reported in the academic and patent literature. These materials represent an unusual opportunity to meet both VTO light-weighting targets for low-density, high performance materials and BETO sustainability targets for value-added high-volume applications of bio-fuel byproducts. Also, PNNL researchers have previously demonstrated a process to convert CO 2 into potential vitrimer precursors. Washington State University (WSU) success in demonstration of bio-based vitrimers and recent steps toward commercialization of petroleum-based vitrimers support the opportunity for PNNL success in development of sustainable vitrimer materials for recyclable, high-performance fiber-reinforced composites for the transportation sectors.

36 MATERIALS SCIENCE↗