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Results for “CARBONIC ACID”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Spectroscopic evidence for intact carbonic acid stabilized by halide anions in the gas phase

Here we show elusive carbonic acid being effectively stabilized in the gas phase by interacting with halide anions X – (X = F, Cl, Br, and I). The formed H 2 CO 3 ·X – complexes, characterized by negative ion photoelectron spectroscopy and ab initio calculations, all contain intact trans – trans carbonic acid binding onto the respective halide via two identical strong ionic O–H...X – hydrogen bonds. For X = Cl, Br, and I, the complex spectra exhibit the corresponding X – signature by simply shifting to the higher binding energy side, while an extremely 2 eV wide broader band is observed for X = F. This spectroscopic evidence indicates that an excess electron is removed from each halide in the former case, while a proton is transferred from carbonic acid to fluoride upon electron detachment for the latter. The above H 2 CO 3 ·X – structures as well as those of the previously studied H 2 SO 4 ·X – along the homologous halogen series cannot be explained using the proton affinity (PA) argument. Instead, a qualitative correlation is found between these structural motifs and the constituent acid p K a values, strongly suggesting that p K a is a more suitable factor to predict correct acid–base chemistry between these diprotic oxyacids and halides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Unraveling the structural properties and dynamics of sulfonated solid acid carbon catalysts with neutron vibrational spectroscopy

Last year, nearly 1 billion waste tires were disposed of globally, a number that continues to grow with the deployment of more automobiles. Recycling this hazardous waste to produce useful products is paramount towards sustainability that has a direct impact on society. In an effort to alleviate the impact of this waste, we have shown that scrap tire crumb rubber can be turned into value-added sulfonated carbon catalysts that can be used for a number of applications. Here, we analyze the sulfonated carbon catalysts with several techniques in order to elucidate the structural properties as well as the impact of pre- and post-sulfonation on the surface functionalities. Most notably, we applied neutron vibrational spectroscopy in order to better understand the surface chemistry of carbon material and resolve the role of protons in tire-derived carbon. Our results suggest that tuning the surface chemistry and the content of sulfur and hydrogen will promote Lewis-acid catalysis, which allows for important heterogeneous reactions such as esterification.

esterification reaction↗
DOE OSTI2022

Effects of Carbonic Acid-Rock Interactions on CO2/Brine Multiphase Flow Properties in the Upper Minnelusa Sandstones

Summary Carbon dioxide (CO2) injection into a deep saline aquifer can dissolve into formation brine and generate carbonic acid. The resulting acid can drive fluid-rock geochemical reactions. The impact of these fluid-rock geochemical reactions on porosity, permeability, and multiphase flow responses is relevant to the determination of CO2 storage capacity of deep saline aquifers. In this research, carbonic acid flooding experiments were performed on core samples consisting of poorly sorted, quartz-rich sand with laminated bedding from a possible CO2 storage target in northwest Wyoming. Complementary pre- and post-injection porosity and permeability, thin-section, Brunauer-Emmett-Teller (BET) surface area, mercury intrusion capillary pressure (MICP), and time-domain nuclear magnetic resonance (TD-NMR) measurements were conducted. Overall, both core porosity and permeability increased after a 7-day carbonic acid injection, from 6.2 to 8.4% and 1.6 to 3.7 md, respectively. We attributed these changes to carbonate mineral dissolution, which was evidenced by the effluent brine geochemistry, pore-throat size distribution (PTSD), and BET surface area. To be more specific, within the more-permeable section of core samples containing larger pore size, the permeability increment is apparent due to dolomite mineral grains and cements dissolution. However, for the lower-permeability section corresponding to the smaller pore size, mineral precipitation possibly lessened dissolution effects, leading to insignificant petrophysical properties changes. Consequently, the observed heterogeneous carbonic acid-rock interactions resulted in alterations of CO2/brine relative permeability (i.e., the initial CO2 saturation decreased and the CO2 flow capacity was enhanced). This research provides a fundamental understanding regarding effects of fluid-rock reactions on changes in static and multiphase flow properties of eolian sandstones, which lays the foundation for more accurate prediction/simulation of CO2 injection into deep saline aquifers.

Engineering↗
DOE OSTI2021

CO 2 electrolysis to multicarbon products in strong acid

Carbon dioxide electroreduction (CO 2 R) is being actively studied as a promising route to convert carbon emissions to valuable chemicals and fuels. However, the fraction of input CO 2 that is productively reduced has typically been very low, <2% for multicarbon products; the balance reacts with hydroxide to form carbonate in both alkaline and neutral reactors. Acidic electrolytes would overcome this limitation, but hydrogen evolution has hitherto dominated under those conditions. We report that concentrating potassium cations in the vicinity of electrochemically active sites accelerates CO 2 activation to enable efficient CO 2 R in acid. We achieve CO 2 R on copper at pH <1 with a single-pass CO 2 utilization of 77%, including a conversion efficiency of 50% toward multicarbon products (ethylene, ethanol, and 1-propanol) at a current density of 1.2 amperes per square centimeter and a full-cell voltage of 4.2 volts.

Huang, Jianan Erick↗
DOE OSTI2022

Unconventional aliphatic fluorophores discovered as the luminescence origin in citric acid–urea carbon dots

Carbon dots (CDs) are emerging as the material of choice in a range of applications due to their excellent photoluminescence properties, ease of preparation from inexpensive precursors, and low toxicity. However, the precise nature of the mechanism for the fluorescence is still under debate, and several molecular fluorophores have been reported. In this work, a new blue fluorophore, 5-oxopyrrolidine-3-carboxylic acid, was discovered in carbon dots synthesized from the most commonly used precursors: citric acid and urea. The molecular product alone has demonstrated interesting aggregation-enhanced emission (AEE), making it unique compared to other fluorophores known to be generated in CDs. We propose that this molecular fluorophore is associated with a polymer backbone within the CDs, and its fluorescence behavior is largely dependent on intermolecular interactions with the polymers or other fluorophores. As a result, a new class of non-traditional fluorophores is now relevant to the consideration of the CD fluorescence mechanism, providing both an additional challenge to the community in resolving the mechanism and an opportunity for a greater range of CD design schemes and applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Low Carbon Inducible2/Fatty Acid Desaturase4 locus in C. reinhardtii directs plastid peroxidase location and trans fatty acid production

Light capture and photosynthetic energy conversion depend on photosynthetic complexes that are embedded within lipid membranes. Components of these complexes are vulnerable to damage by reactive oxygen species, byproducts of photosynthesis that accumulate under environmental stress. Here we explore the basis for a lipid-based sensing mechanism allowing plants or algae to assess and respond to damage to the photosynthetic membranes. In Chlamydomonas reinhardtii, Low Carbon Inducible2 (LCI2) and Fatty Acid Desaturase4 (FAD4) are two proteins derived from the same locus by a differential splicing event, sharing an N-terminus encoded by the first two exons. FAD4 produces a 16-carbon, trans double bond-containing fatty acid found exclusively in phosphatidylglycerol of chloroplast membranes, while LCI2 recruits peroxidase activity to the membrane. The unique organization and transcriptional regulation of the LCI2/FAD4 locus represents a regulatory interface that allows cells to initiate the biosynthesis of a fatty acid unique to the photosynthetic membranes while also linking it to the production of an enzyme involved in the mitigation of reactive oxygen species.

Nicodemus, Timothy J [Michigan State University, E↗
DOE OSTI2021

Inside out: Measuring the effect of wood anatomy on the efflux and assimilation of xylem–transported CO 2

Carbon dioxide concentrations (including aqueous CO 2 , carbonic acid, bicarbonate, and carbonate) in woody tissues can be up to 750 times higher than atmospheric CO 2 concentrations, ranging from <1% to >26% vs atmospheric ~0.04% (Fig. 1) (Teskey et al. 2008). CO 2 formed through respiration is generally assumed to diffuse to the atmosphere from tissues adjacent to where it is produced. Here, this CO 2 buildups in the stem due to the diffusional barriers in woody and bark tissues. CO 2 in the stem has three fates: 1) it can be refixed for photosynthesis, 2) it can be used for anaplerotic reactions, or 3) it can exit the plant either adjacent to where it was produced (radial diffusion) or in an area remote from its point of origin (xylem-transported CO 2 ). Not accounting for assimilation of xylem-transported CO 2 may result in underestimating total plant photosynthesis. Alternatively, overlooking the transport of CO 2 away from its point of origin complicates the estimation of respiration in stems, branches, or even leaves. For example, CO 2 efflux from the stem may not solely represent stem respiration, but it may represent CO 2 generated through respiration in areas remote from the point of efflux (Stutz et al., 2017). Additionally, wood anatomy and branching architecture likely influence how much and how far xylem-transported CO 2 travels (Fig. 2). Few studies have combined measurements of both the efflux of xylem-transported CO 2 from trees together and the assimilation of xylem-transported CO 2 . Excitingly in this issue of Plant, Cell & Environment, Salomón et al. (pp. ) demonstrate the importance of xylem-transported CO 2 in plants with different wood anatomies by comparing the amount of xylem-transported CO 2 used for photosynthesis to the amount effluxed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Characterizing Pore-Scale Geochemical Alterations in Eagle Ford and Barnett Shale from Exposure to Hydraulic Fracturing Fluid and CO 2 /H 2 O

As demand increases for an affordable energy source that is tied to an environmental obligation to reduce greenhouse gas emissions and water usage, there is a growing consideration in shale production utilizing processes such as 1) enhancing hydrocarbon recovery via carbon dioxide (CO 2 ) flooding, 2) using CO 2 as a fracturing agent to minimize water use, and 3) storing CO 2 in depleted shale formations to mitigate emissions to the atmosphere. Understanding the geochemical reactions and alterations that occur as shale is exposed to fluids and CO 2 is necessary to develop and optimize each of these processes for field applications. While the majority of shale formations are stimulated using traditional fracturing fluid, some may be fractured using CO 2 or other non-traditional means. We examine the effect fracturing fluid has on shale and how it behaves with secondary exposure to dry CO 2 or CO 2 -saturated water using in situ Fourier Transform infrared spectroscopy (FTIR), feature relocation scanning electron microscopy (SEM), and surface area and pore size analysis using volumetric gas sorption. These techniques were performed on Eagle Ford and Barnett shale samples that were exposed to fracturing fluid and unexposed (as received). Shales that have been exposed to traditional fracturing fluid experienced two reaction fronts. The first reaction front was formed during exposure to the fracturing fluid (pH of ~1.4). A secondary reaction front was formed as a result of CO 2 -saturated fluid exposure in the form of carbonic acid (pH ~5.6). These two different reaction mechanisms drove multiple dissolution and precipitation cycles which altered petrophysical properties of the shale and could lead to a significant impact on flow pathways. FTIR showed that equilibration of carbonate dissolution and precipitation cycles could take as long as 35 days. Samples exposed to fracturing fluid showed significantly less carbonate reactivity compared to those exposed to water. Pore size analysis results indicate exposure to fracturing fluid blocked small nanopores (10-15 nm) reducing BET surface area and total pore volume. SEM results show barite precipitated heavily during exposure to fracturing fluid. It appeared that carbonic acid was able to extract sulfur from organic matter to form gypsum evaporites. The mineralogical (barite precipitation and calcite dissolution/precipitation) and pore-scale alterations observed in these samples may lead to enhancement of flow pathways for injected CO 2 or produced hydrocarbons.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2020

Joining Techniques for Novel Metal Polymer Hybrid Heat Exchangers

In the United States, over 50% of the unrecovered energy from industrial processes is in the form of low-grade heat (< 220°C). Materials and maintenance costs of common heat exchangers are typically too high to justify their usage. Polymers, though more affordable, are usually unsuitable for HX applications due to their low thermal conductivity (~0.2 W/mK). Here, we show that metal-polymer hybrids may be attractive from both performance and cost perspectives. The use of polymers further increases the resistance to corrosion by sulfuric and carbonic acids often present in flue gases. An ongoing work explores different configurations of layered polyimide-copper macroscale hybrids for heat exchanger applications using numerical simulations. This paper explores a manufacturing pathway for producing such layered hybrid tubes that involves directly rolling and bonding tapes made of polymer and copper foil into tubes. A critical problem in the fabrication process is the bonding of metal and polymers. We explore approaches involving adhesives (epoxy, acrylic and silicone) for metal/polymer interfaces and direct welding (ultrasonic) for metal/metal interfaces that can be integrated into the manufacturing process. We report characterizations of the thermomechanical properties of these joining processes. This work paves the way for realizing cost-effective manufacturing of heat exchangers for low grade waste heat recovery.

Kuntumalla, Gowtham↗
DOE OSTI2019

Quantitative Analysis of Micro-structural Changes in a Bituminous Coal After Exposure to Supercritical CO{sub 2} and Water

High-volatile bituminous coal samples were reacted in deionized water with supercritical CO{sub 2} (ScCO{sub 2}–water) under simulated in situ pressure and temperature conditions (8 MPa and 40 °C) in unconfined stress state for 14 days, in order to characterize potential CO{sub 2}–water–coal reactions. Micro-structural changes were identified pre- and post-experiment using X-ray powder diffraction (XRD) analysis for powdered coal (mineralogical changes), optical microscopy and scanning electron microscopy (SEM) for polished thin sections (surface feature changes) and micro-CT scanning for a small core (porosity and permeability changes). XRD analysis revealed that carbonic acid leaches out mineral matters in coal, including carbonates (calcite) and silicate minerals (albite, illite and kaolinite). Optical microscopy, SEM and CT images confirmed that the interaction of coal with ScCO{sub 2}–water causes an abundance of micro-cracks to open or propagate in unconfined coal samples. Most micro-cracks preferably propagated along maceral–mineral and maceral–maceral interfaces, which demonstrates that the micro-cracking was caused by differential swelling of different coal lithotypes. Wormhole formation was observed in coal caused by mineral dissolution and hydrocarbon mobilization, which significantly increases coal porosity compared with swelling-induced cracking. 3-D pore network models extracted from CT images show that ScCO{sub 2}–water treatment enlarges the pore and throat size, increases the numbers of pores and throats and improves pore network connectivity. Overall, CO{sub 2}–water–coal interactions under unconfined conditions enhance coal porosity, connectivity and permeability, which can be attributed to the combined effect of micro-cracking, mineral dissolution and hydrocarbon mobilization.

58 GEOSCIENCES↗
DOE OSTI2020

Acid Erosion of Carbonate Fractures and Accessibility of Arsenic-Bearing Minerals: In Operando Synchrotron-Based Microfluidic Experiment

Underground flows of acidic fluids through fractured rock can create new porosity and increase accessibility to hazardous trace elements such as arsenic. In this study, we developed a custom microfluidic cell for an in operando synchrotron experiment using X-ray attenuation. The experiment mimics reactive fracture flow by passing an acidic fluid over a surface of mineralogically heterogeneous rock from the Eagle Ford shale. Over 48 h, calcite was preferentially dissolved, forming an altered layer 200–500 μm thick with a porosity of 63–68% and surface area >10$\times$ higher than that in the unreacted shale as shown by xCT analyses. Calcite dissolution rate quantified from the attenuation data was 3 $\times$ 10 –4 mol/m 2 s and decreased to 3 $\times$ 10 –5 mol/m 2 s after 24 h because of increasing diffusion limitations. Erosion of the fracture surface increased access to iron-rich minerals, thereby increasing access to toxic metals such as arsenic. Quantification using XRF and XANES microspectroscopy indicated up to 0.5 wt % of As(-I) in arsenopyrite and 1.2 wt % of As(V) associated with ferrihydrite. This study provides valuable contributions for understanding and predicting fracture alteration and changes to the mobilization potential of hazardous metals and metalloids.

58 GEOSCIENCES↗
DOE OSTI2021

Reactivity of CO 2 with Utica, Marcellus, Barnett, and Eagle Ford Shales and Impact on Permeability

We report that in order to reduce greenhouse gas emissions while recovering hydrocarbons from unconventional shale formations, processes that make use of carbon dioxide to enhance oil recovery while storing carbon dioxide (CO 2 ) should be considered. Here, we examine samples from three shale basins across the United States (Utica and Marcellus Shales in the Appalachian Basin, Barnett Shale in the Bend Arch-Ft. Worth Basin, and Eagle Ford in the Western Gulf Basin) to address the following questions: (1) do changes from reaction with CO 2 and fluids at the micrometer and nanometer scale alter flow pathways and, in turn, impact hydrocarbon production, CO 2 storage, and seal integrity and (2) can CO 2 or fluid reactivity be predicted based on physical or chemical properties of shale formations? Experiments were conducted at 40 °C and 10.3 MPa to characterize the interaction between CO 2 and shale using X-ray diffraction (XRD), carbon and sulfur analysis, in situ Fourier transform infrared spectroscopy (FT-IR), feature relocation scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), mercury (Hg) intrusion porosimetry, and Brunauer-Emmett-Teller (BET) surface area and pore size analysis coupled with density functional theory (DFT) methods. Changes in mechanical, physical, and flow properties of shale cores due to CO 2 exposure were addressed using a New England Research Autolab 1500 and Xenon X-ray computed tomography (CT) scanning. Results showed that CO 2 did not promote significant reactivity with the shale if water was not present; only shales with swelling clays or residual interstitial pore water reacted with dry CO 2 to promote reactivity in shale. When water was added as a reactant, CO 2 formed carbonic acid and reacted with the shale to dissolve carbonate pockets, etched and pitted the shale matrix surfaces, and increased the microporosity and decreased nanoporosity. Porosity and permeability increased appreciably in core shale samples after exposure to CO 2 saturated fluid due to dissolution of carbonate. Shale mechanical properties were not altered. Trends were not observed that could tie CO 2 or fluid reactivity to physical or chemical properties of the shale formations at the basin scale from the samples we examined. However, if the shale contained significant amounts of carbonate and water was available to react with the CO 2 , pore sizes were altered in the matrix and permeability and porosity increased.

04 OIL SHALES AND TAR SANDS↗