Gary S. Groenewold

Pine needles are an industrial feedstock for extracts used in a variety of applications, but conventional extraction methods often result in a degradation of the terpenoid compounds that naturally occur in loblolly pine (Pinus taeda). Separation of these compounds from pine biomass is an energy-intensive operation, typically requiring a significant input of thermal energy. An alternative separation approach with potential energy savings is extraction with a condensable gas, namely, dimethyl ether. Biomass materials are exposed to liquid dimethyl ether under pressure, which mobilizes the organics. The extract is then separated from the insoluble pine matter, and dimethyl ether is volatilized away from the separated organic species. A variety of terpene derivatives were extracted from pine needle biomass using this approach, including monoterpenes, sesquiterpenes, and related oxygenates, which were identified using two-dimensional gas chromatography/mass spectrometry. Additionally, the dimethyl ether-treated needles resemble needles subjected to low-temperature drying, whereas needles treated with a high-temperature drying method appear to have shrunken structures. The results suggest that dimethyl ether extraction has significant potential for separating valuable organics from complex matrices without the application of thermal energy during treatment.

This report documents the outcomes of the Tri-Laboratory Materials Workshop that was held July 31 and August 1, 2019 to begin addressing the needs, opportunities, and challenges associated with the development, fabrication, and testing of the needed materials and components for integrated hybrid energy systems (i.e., incorporating nuclear, fossil, and renewables for electric and thermal applications). This was accomplished by assembling the research program leads and principal investigators at Idaho National Laboratory (INL), National Energy Technology Laboratory (NETL), and National Renewable Energy Laboratory (NREL), who support the research and development of new technology and system integration. The team then identified and prioritized key materials development needs. This effort was intended to enhance communications and synergy among the Tri-Lab partners. Advanced functional and structural materials are central to transformative energy technologies for energy generation, conversion, delivery, and storage. With that in mind, the workshop focused on identifying and assessing the foundational materials research needs at both the basic and applied levels. Materials challenges include the ability to withstand harsh environments, such as high temperatures and pressures, corrosion, oxidation, or irradiation while maintaining flexible mission profiles and long service lifespans. Advanced energy system material challenges and needs range from materials for themore » capture, upgrading/concentration, storage, and delivery of low-grade heat to materials for high temperature environments that involve liquid metals, molten salt, and very high temperature gas heat delivery and storage systems. Material improvements are needed for hybrid energy systems due to accelerated corrosion and stress-fatigue failure of materials and equipment, which results from increased frequency and amplitude of thermal, mechanical, and electrical cycling of systems components. Multifunctional materials are needed for high temperature solid-oxide fuel cells, advanced electrochemical reactors, and in-process separation. Relative to materials manufacturing, application of advanced additive and subtractive methods need to be understood to develop both thin-layer homogenous materials and materials of graded composition. Materials modeling and machine learning will be critical to accelerate the design and production of power electronics, and nuclear reactor materials and fuel, as well as to gain an understanding of beneficial materials phenomena or deleterious microstructure evolution. There is also a need for standardized models, computational structures, data reporting protocols and modeling tools across the three laboratories. This would allow consistent results, analysis, and data sharing. Combining computational capabilities between the three laboratories (e.g., hardware, software) would greatly increase computational capabilities and throughput. The workshop identified the need for laboratories to anticipate and address problems that will occur during scale-up. Laboratory work must connect with industry to ensure that research focuses on processes that are scalable and marketable. Industry input and perspective are essential to guide laboratory research to meet these requirements and deploy new technology in industrial demonstrations. Another aspect of scale-up is the integration of multiple systems since new challenges often arise at the subsystem interfaces. Establishing a scale-up manufacturing demonstration/pilot plant, potentially as an industrial user facility, would be beneficial to the laboratories and industry. That modular scale-up manufacturing demonstration/pilot plant would allow researchers to find and resolve interface problems that cannot be identified by focusing only on individual parts. Communication exchanges among the organizers, attendees, and workshop survey responses indicate that the workshop was successful in achieving its goal to identify key technology gaps and research needs. Strong positive feedback was received on the sharing of ideas, capabilities, talent, and passion to move forward on the materials-related action items. « less

Metal fluoroanions are of significant interest for fundamental structure and reactivity studies and for making isotope ratio measurements that are free from isobaric overlap. Iron fluoroanions [FeF₄]^– and [FeF₃]^– were generated by electrospray ionization of solutions of Fe(III) and Fe(II) with the fluorinating ionic liquid 1-ethyl-3-methylimidazolium fluorohydrogenate [EMIm]⁺[F(HF)_2.3]^-. Solutions containing Fe(III) salts produce predominately uncomplexed [FeF₄]^– in the negative ion spectrum, as do solutions containing salts of Fe(II). This behavior contrasts with that of solutions of FeCl₃ and FeCl₂ (without [EMIm]⁺[F(HF)_2.3]^–) that preserve the solution-phase oxidation state by producing the gas-phase halide complexes [FeCl₄]^– and [FeCl₃]^–, respectively. Thus, the electrospray-[EMIm]⁺[F(HF)_2.3]^– process is oxidative with respect to Fe(II). The positive ion spectra of Fe with [EMIm]⁺[F(HF)_2.3]^– displays cluster ions having the general formula [EMIm]⁺ _(n+1)[FeF₄]^– _n, and DFT calculations predict stable complexes, both of which substantiate the conclusion that [FeF₄]^– is present in solution stabilized by the imidazolium cation. The negative ion ESI mass spectrum of the Fe-ionic liquid solution has a very low background in the region of the [FeF₄]^– complex, and isotope ratios measured for both [FeF₄]^– and adventitious [SiF₅]^– produced values in close agreement with theoretical values; this suggests that very wide isotope ratio measurements should be attainable with good accuracy and precision when the ion formation scheme is implemented on a dedicated isotope ratio mass spectrometer. Graphical Abstract

RATIONALE: New approaches for forming anions are sought that have strong abundance and no isobaric overlap, attributes that are compatible with the measurement of isotope ratios. Fluoroanions are particularly attractive because fluorine is monoisotopic, and thus will not have overlapping isobars with the isotope of interest. Since many elements do not have positive electron affinity values, they do not form stable negative atomic ions, and hence are not compatible with isotope ratio measurement using high sensitivity isotope ratio mass spectrometers such as accelerator mass spectrometers. METHODS: Zirconium fluoroanions were prepared using the fluorinating ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium fluorohydrogenate, which was used to generate abundant [ZrF ₅ ] ⁻ ions using electrospray ionization. The IL was dissolved in acetonitrile, combined with a dilute solution of either Zr ⁴⁺ or ZrO ²⁺ , and then electrosprayed. Mass analysis and collision‐induced dissociation experiments were conducted using a time‐of‐flight mass spectrometer. Cluster structures were predicted using density functional theory calculations. RESULTS: The fluorohydrogenate IL solutions generated abundant [ZrF ₅ ] ⁻ ions starting from solutions of both Zr ⁴⁺ and ZrO ²⁺ . The mass spectra also contained IL‐bearing cluster ions, whose compositions indicated the presence of [ZrF ₆ ] ²⁻ in solution, a conclusion supported by the structural calculations. Rinsing out the zirconium‐IL solution with acetonitrile decreased the IL clusters, but enhanced [ZrF ₅ ] ⁻ , which was sorbed by the polymeric electrospray supply capillary, and then released upon rinsing. This reduced the ion background in the mass spectrum. CONCLUSIONS: The fluorohydrogenate‐IL solutions are a facile way to form zirconium fluoroanions in the gas phase using electrospray. The approach has potential as a source of fluoroanions for isotope ratio measurements, which would enable high‐sensitivity measurement of minor zirconium isotopes without overlapping isobars caused by the charge carrier (i.e., the monoisotopic fluorine atoms). Copyright © 2014 John Wiley & Sons, Ltd.

Electrospray ionization of the fluorohydrogenate ionic liquid [1-ethyl-3-methylimidazolium][F(HF)_2.3] ionic liquid was conducted to understand the nature of the anionic species as they exist in the gas phase. Abundant fluorohydrogenate clusters were produced; however, the dominant anion in the clusters was [FHF^–], and not the fluoride-bound HF dimers or trimers that are seen in solution. Density functional theory (DFT) calculations suggest that HF molecules are bound to the clusters by about 30 kcal/mol. The DFT-calculated structures of the [FHF^–]-bearing clusters show that the favored interactions of the anions are with the methynic and acetylenic hydrogen atoms on the imidazolium cation, forming planar structures similar to those observed in the solid state. A second series of abundant negative ions was also formed that contained [SiF₅^–] together with the imidazolium cation and the fluorohydrogenate anions that originate from reaction of the spray solution with silicate surfaces.

Electrospray ionization mass spectra of lanthanide coordination complexes were measured by launching nanoliter-sized droplets directly into the aperture of an electrospray ionization mass spectrometer. Droplets ranged in size from 102 nL to 17 nL, while metal concentrations were 293 μM. The sample solution was delivered to a source capillary by a nanoliter dispenser at a rate of 21 nL/s, and droplets were ejected from the capillary by pulsing a potential onto the capillary. The end of the capillary was situated in front of the mass spectrometer and aimed directly at the aperture. The period and power of the electrical pulse was controlled by a digital energy source. The intensity of the extracted ion time profiles from the experiment showed reproducible production of lanthanide nitrato-anion complexes (Ce, Tb, and Lu). The integrated ion intensities of the complexes were reproducible, having relative standard deviations on the order 10% for anions, and 10-30% for cations. The integrated ion intensities were proportional to the droplet size, and the response was linear from about 100 to 650 pmol. However, the intercept is not zero, indicating a nonlinear response at lower analyte quantities or droplet sizes. Cation complexes were generated in separate experiments that corresponded to lanthanide nitrate ion pairs coordinated with the separations ligand octyl,phenyl,(N,N-diisobutylcarbamoyl)methylphosphine oxide (CMPO). Experiments showed a preference for formation of CMPO complexes with Ln(3+) having larger ionic radii. The relative standard deviation values of the cation abundance measurements were somewhat higher for the more highly coordinated complexes, which are also less stable. The mass spectral quality was high enough to measure the ratios of the minor isotopic ions to a high degree of accuracy. The approach suggests that the methodology has utility for analysis of solutions where the sample quantity is limited, or where the sampling efficiency of a normal ESI source is limiting on account of hazards derived from the sample solution.