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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Interfacial Activity of Amine-Functionalized Polyhedral Oligomeric Silsesquioxanes (POSS): A Simple Strategy To Structure Liquids

Amine-functionalized polyhedral oligomeric silsesquioxane (POSS), the smallest, monodisperse cage-shaped silica cubic nanoparticle, is exceptionally interfacially active and can form assemblies that jam the toluene/water interface, locking in non-equilibrium shapes of one liquid phase in another. The packing density of the amine-functionalized POSS assembly at the water/toluene interface can be tuned by varying the concentration, the pH value, and the degree of POSS functionalization. Functionalized POSS gives a higher interface coverage, and hence a lower interfacial tension, than nanoparticle surfactants formed by interactions between functionalized nanoparticles and polymeric ligands. Here, hydrogen-bonded POSS surfactants are more stable at the interface, offering some unique advantages for generating Pickering emulsions over typical micron-sized colloidal particles and ligand-stabilized nanoparticle surfactants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Dual Tunability for Uncatalyzed N‐Alkylation of Primary Amines Enabled by Plasma‐Microdroplet Fusion

Abstract The fusion of non‐thermal plasma with charged microdroplets facilitates catalyst‐free N‐alkylation for a variety of primary amines, without halide salt biproduct generation. Significant reaction enhancement (up to >200×) is observed over microdroplet reactions generated from electrospray. This enhancement for the plasma‐microdroplet system is attributed to the combined effects of energetic collisions and the presence of reactive oxygen species (ROS). The ROS (e.g., O 2 ⋅ − ) act as a proton sink to increase abundance of free neutral amines in the charged microdroplet environment. The effect of ROS on N‐alkylation is confirmed through three unique experiments: (i) utilization of radical scavenging reagent, (ii) characterization of internal energy distribution, and (iii) controls performed without plasma, which lacked reaction acceleration. Establishing plasma discharge in the wake of charged microdroplets as a green synthetic methodology overcomes two major challenges within conventional gas‐phase plasma chemistry, including the lack of selectivity and product scale‐up. Both limitations are overcome here, where dual tunability is achieved by controlling reagent concentration and residence time in the microdroplet environment, affording single or double N‐alkylated products. Products are readily collected yielding milligram quantities in eight hours. These results showcase a novel synthetic strategy that represents a straightforward and sustainable C−N bond‐forming process.

Chemistry↗
DOE OSTI2023

Atomic force microscopy and scanning electron microscopy characterization of the controlling of surface morphology of epoxy‐amine‐cured spin‐coated films

Abstract Atomic force microscopy (AFM) was successfully used to study spin‐coated, amine‐cured epoxy film microstructure and morphology. The air‐epoxy and epoxy‐substrate interfaces were examined using tapping‐mode height and phase imaging AFM. The impact of relative humidity on the morphology and microstructure of the surfaces was determined. AFM was able to elucidate the changes on the surface as relative humidity during processing increased. It was observed that large nodular formations formed on the epoxy surface expose to the air but not epoxy surface formed on the substrate in addition to varying regions of more or less compliant structures, which was attributed to carbamate formation caused by the amine curing agent reaction with atmospheric CO 2 . Scanning electron microscopy (SEM) was used to further elucidate interface and interphase morphology of spin‐coated epoxies. Experimentation also demonstrated that post‐curing above the glass transition did not change the morphology structure, suggesting surface structures are “locked‐in.” SEM was used to further elucidate how the interface and interphase change with changing environmental conditions at both the air‐epoxy and epoxy‐substrate interface/interphases, including the impact of atmospheric CO 2 on Marangoni cell formation.

Shenk, Timothy M.↗
DOE OSTI2022

Efficient Electrochemical Reduction of CO 2 to Formate in Methanol Solutions by Mn‐Functionalized Electrodes in the Presence of Amines**

Carbon cloth electrode modified by covalently attaching a manganese organometallic catalyst is used as cathode for the electrochemical reduction of CO 2 in methanol solutions. Six different industrial amines are employed as co-catalyst in millimolar concentrations to deliver a series of new reactive system. While such absorbents were so far believed to provide a CO 2 reservoir and act as sacrificial proton source, we herein demonstrate that this role can be played by methanol, and that the adduct formed between CO 2 and the amine can act as an effector or inhibitor toward the catalyst, thereby enhancing or reducing the production of formate. Pentamethyldiethylentriamine (PMDETA), identified as the best effector in our series, converts CO 2 in wet methanolic solution into bisammonium bicarbonate. Computational studies revealed that this adduct is responsible for a barrierless transformation of CO 2 to formate by the reduced form of the Mn catalyst covalently bonded to the electrode surface. As a consequence, selectivity can be switched on demand from CO to formate anion, and in the case of (PMDETA) an impressive TON HCOO- of 2.8×10 4 can be reached. This new valuable knowledge on an integrated capture and utilization system paves the way toward more efficient transformation of CO 2 into liquid fuel.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Carbon Capture Beyond Amines: CO 2 Sorption at Nucleophilic Oxygen Sites in Materials

Carbon capture and utilization or sequestration and direct air capture will be needed to reduce atmospheric levels of greenhouse gases over the next century. Current amine-based technologies bind CO 2 with high selectivities but suffer from poor oxidative and thermal stabilities. Herein, we discuss understudied sorbents based on oxygen nucleophiles, including metal oxides and hydroxides, hydroxide-containing polymers, and hydroxide-based metal–organic frameworks. In general, these materials display improved oxidative stabilities compared to traditional amine-based sorbents. Here, we outline the challenges and opportunities offered by these alternative sorbents for carbon capture applications.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Rapid Screening of Immobilized Amine CO 2 Sorbents for Steam Stability by Their Direct Contact with Liquid H 2 O

Abstract Rapid testing of hydrophilic and hydrophobic basic immobilized amine sorbents (BIAS) for CO 2 capture stability under practical conditions was achieved by direct contact of the sorbents with flowing liquid water. Losses in both CO 2 capture capacity and amine content of sorbents after exposure to 0.5 mL min −1 of H 2 O at 25 °C for 40 min followed similar trends as losses observed after exposure to N 2 /steam (105 °C, 7 % H 2 O) for 10 h. We also found that hydrophobic TMPED helped stabilize sorbents to H 2 O, which was confirmed by DRIFTS and combined TGA‐DSC.

Wilfong, Walter Christopher↗
DOE OSTI2017

Diiron Dithiolate Hydrides Complemented with Proton‐Responsive Phosphine–Amine Ligands

The reaction of Fe 2 (pdt)(CO) 6 with two equivalents of Ph 2 PC 6 H 4 NH 2 (PNH 2 ) affords the amido hydride HFe 2 (pdt)(CO) 2 (PNH 2 )(PNH) {[H 1 H] 0 , pdt 2– = CH 2 (CH 2 S – ) 2 }. Isolated intermediates in this conversion include Fe 2 (pdt)(CO) 5 (κ 1 ‐PNH 2 ) and Fe 2 (pdt)(CO) 4 (κ 2 ‐PNH 2 ). X‐ray crystallographic analysis of [H 1 H] 0 shows that the chelating amino/amido–phosphine ligands occupy trans ‐dibasal positions. The 31 P NMR spectrum indicates that [H 1 H] 0 undergoes rapid proton exchange between the amido and amine centers. No exchange was observed for the hydride. Protonation of [H 1 H] 0 gives [HFe 2 (pdt)(CO) 2 (PNH 2 ) 2 ] + ([H 2 1 H] + ), which contains two equivalent amino–phosphine ligands. Single‐crystal X‐ray crystallographic analysis of [H 2 1 H] + also reveals hydrogen bonds between the exo amine protons with a THF molecule and BF 4 . Deprotonation of [H 1 H] 0 with potassium tert ‐butoxide gave [HFe 2 (pdt)(CO) 2 (PNH) 2 ] – ([ 1 H] – ), which was characterized spectroscopically. The complex has time‐averaged C 2 symmetry with two amido–phosphine ligands. FTIR spectroscopic measurements show that υ CO shifts by approximately 20 cm –1 in the series [ 1 H] – , [H 1 H] 0 , and [H 2 1 H] + . These shifts are comparable to those seen for the S‐protonation of the (NC) 2 (CO)Fe(µ‐Scys) 2 Ni(Scys) 2 site in the [NiFe]‐hydrogenases.

Carlson, Michaela R.↗
DOE OSTI2023

Impact of carbamate formation on the surface tension of epoxy‐amine curing systems

Abstract Epoxy‐amine reactive systems, including their surface tension, have been studied due to their use and importance in composites and adhesives in laboratory and industrial applications. Understanding how the system's surface tension changes during curing could help target applications for tailored composites. Using the Wilhelmy plate method, surface tensions for epoxy‐curing agent systems were investigated under different environments. While the epoxy exhibited an expected negative temperature coefficient of −0.096 mN/m/°C, the curing agent exhibited a positive temperature coefficient of 0.073 mN/m/°C, which is due to the curing agent reacting with atmospheric CO 2 to form carbamate through a zwitterion pathway and functional groups accumulating at the surface of the reacting systems. Carbamate formation results in a surface tension below that of the individual constituents in the epoxy‐amine curing agent system. Fourier transform infrared (FTIR) spectroscopy was used to verify in situ formation of carbamate, and by reducing the system's temperature, it was demonstrated that the system surface tension profiles displayed micellar surfactant‐like characteristics. FTIR was used to explore the difference in composition between the surface and the bulk, in particular carbamate formation at the surface, resulting in a lowering of the surface tension of reacting systems.

Shenk, Timothy M.↗
DOE OSTI2017

Pilot testing of a heat integrated 0.7 MWe CO 2 capture system with two-stage air-stripping: Amine degradation and metal accumulation

An advanced 0.7 MWe small pilot coal-fired post-combustion CO 2 capture system with heat integration combined with two-stage stripping was tested here on a slipstream of flue gas by the University of Kentucky Center for Applied Energy Research (UKy-CAER). Evaluation of solvent degradation products was performed to determine the impact of oxygen exposure due to incorporation of the secondary air stripper into the conventional amine absorber/stripper system. The overall degradation rates and products observed during the testing campaign were comparable to previously published reports using 30% monoethanolamine (MEA) as the baseline/commissioning solvent. The rates of heat stable salt accumulation and amine degradation were similar to those from conventional CO 2 capture systems using MEA. Metal accumulation as the result of material corrosion inside the system from an improperly constructed material was observed. Finally, the impact of the secondary air stripper appears negligible relative to other published MEA campaigns tested at similar flue gas conditions and system operating hours.

03 NATURAL GAS↗
DOE OSTI2022

Dehydration of gas-phase benzyl amine alcohols studied at atmospheric pressure

Gas-phase ion chemistry is a useful approach for the investigation of physical organic chemistry and the study of reactivity, structure, and thermochemical properties of ionic and neutral organic substrates. Herein, one-step dehydration of gas-phase benzyl amine alcohols to give benzazetidines was discovered without the use of catalysts. Mechanistic investigations of the gas-phase dehydration reactions were explored to study the possible influence of charged microdroplet acceleration during electrospray ionization (ESI) and collisions occurring during ion transfer through the atmospheric pressure interface (API) of the mass spectrometer. The product ion distribution was observed to be less sensitive to droplet effects (spray distance and voltage), and temperature of transfer capillary in the API. However, the product ion distribution exhibit high sensitivity to different S-lens radio frequency (RF) voltage of the API, providing evidence that the dehydration reaction is driven by collisions during ion transfer in the API. With this insight, we developed atmospheric pressure thermal dissociation platform that allowed thermal-induced collisions outside of the mass spectrometer when the benzyl amine alcohols are carried through a heated coiled tube. Up to 98% dissociation efficiency was achieved with the coiled tube heated to a temperature of 200 °C, yielding only the desired benzazetidine product. Finally, by performing the atmospheric pressure thermal dissociation experiment outside of the mass spectrometer, we believe it will be straightforward to collect the dehydration product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis, crystal structures, and dye removal properties of a series of discrete and polymeric copper, zinc, cobalt, and cadmium complexes containing bis-pyridyl-bis-amine ligands

Two bis-pyridyl-bis-amine ligands, trans-1,2-bis(m-picolyamino)cyclohexane (rac-m-picchxn) and trans-1,2-bis(p-picolyamino)cyclohexane (rac-p-picchxn), derived from trans-1,2-diaminocyclohexane (rac-chxn), were assembled with CuCl{sub 2}, ZnCl{sub 2}, ZnBr{sub 2}, Co(NO{sub 3}){sub 2}, and CdCl{sub 2} through reactants slow diffusion to afford corresponding metal complexes. Complexes [Cu(R,R-m-picchxn)Cl{sub 2}] (1) and [Zn(rac-m-picchxn)Br{sub 2}] (3) are mononuclear coordination structures, complex [Zn{sub 2}(rac-m-picchxn)Cl{sub 4}]{sub n} (2) adopts a one-dimensional (1D) helical chain, complex {[Co(R,R-p-picchxn)(NO_3)_2]·THF·2/3H_2O}{sub n} (4) has a two-dimensional (2D) kgm layer structure, complex [Cd(rac-p-picchxn)Cl{sub 2}]{sub n} (5) suits a 1D double-stranded zigzag chain structure, and compound [Cu(rac-chxn){sub 2}][CuCl{sub 3}] (6) is a Cu(I)-Cu(II) mixed-valence ionic product generated from the hydrolysis of rac-p-picchxn associated with the reduction of Cu(II) ion. The two bis-pyridyl-bis-amine ligands possess a chelating-bridging mode in forming infinite network and a chelating-only mode in forming discrete complexes. These metal–organic architectures show the influence of metal ion combining with organic ligand and anion on the structure variation. Noteworthy, chain polymers 2 and 5 could be utilized in the removal of methyl orange (MO), acid orange 7 (AO7), and malachite green (MG) from water through adsorptive processes. The adsorption dynamics of MO and AO7 on 2 and MG on both 2 and 5 obeyed a pseudo-second-order kinetics while that of MO and AO7 on 5 followed a pseudo-first-order kinetics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Nickel Ligation of the N-Terminal Amine of HypA Is Required for Urease Maturation in Helicobacter pylori

The human pathogen Helicobacter pylori requires nickel for colonization of the acidic environment of the stomach. HypA, a Ni metallochaperone that is typically associated with hydrogenase maturation, is also required for urease maturation and acid survival of H. pylori. There are two proposed Ni site structures for HypA; one is a paramagnetic six-coordinate site characterized by X-ray absorption spectroscopy (XAS) in unmodified HypA, while another is a diamagnetic four-coordinate planar site characterized by solution nuclear magnetic resonance in an N-terminally modified HypA construct. To determine the role of the N-terminal amine in Ni binding of HypA, an N-terminal extension variant, L2*-HypA, in which a leucine residue was inserted into the second position of the amino acid sequence in the proposed Ni-binding motif, was characterized in vitro and in vivo. Structural characterization of the Ni site using XAS showed a coordination change from six-coordinate in wild-type HypA (WT-HypA) to five-coordinate pyramidal in L2*-HypA, which was accompanied by the loss of two N/O donor protein ligands and the addition of an exogenous bromide ligand from the buffer. The magnetic properties of the Ni sites in WT-HypA compared to those of the Ni sites in L2*-HypA confirmed that a spin-state change from high to low spin accompanied this change in structure. The L2*-HypA H. pylori strain was shown to be acid sensitive and deficient in urease activity in vivo. In vitro characterization showed that L2*-HypA did not disrupt the HypA–UreE interaction that is essential for urease maturation but was at least 20-fold weaker in Ni binding than WT-HypA. Characterization of the L2*-HypA variant clearly demonstrates that the N-terminal amine of HypA is involved in proper Ni coordination and is necessary for urease activity and acid survival.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Technoeconomic Analysis of the Electrochemically Mediated Amine Regeneration CO 2 Capture Process

The electrochemically mediated amine regeneration (EMAR) process presents an alternative route to the conventional thermal amine regeneration for carbon capture from a flue gas source. In this study, we conducted an economic analysis on the EMAR system for postcombustion CO2 capture from a 550 MWe power plant capturing 3.1 MtCO2 annually and from a mini steel mill with annual capture close to 170 ktCO2. We followed the recommendation of the National Energy Technology Laboratory (NETL) 2010 report to estimate the cost of CO2 avoided ([$/tCO2]). Detailed cost modeling of the electrochemical separation stage was conducted. This is integrated with the entire process flowsheet (e.g., including absorber, compressor, pumps, and other auxiliary equipment). Here, we identified the membrane cost as the dominant capital cost for the electrochemical separation train. At a membrane unit price of less than 10/m2, the CO2 capture cost can be reduced to below 50/tCO2 with optimized process conditions (e.g., desorption pressure and utilization of waste heat). Improvements in process design, cell construction, and solvent formulation may lead to additional reductions in the CO2 capture cost.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Corrosion Prevention of Additively Manufactured Aluminum Packing Devices Developed for Process Intensification of CO 2 Capture by Aqueous Amines

Corrosion of additively manufactured (i.e., 3D printed) aluminum packing devices, developed to enhance heat and mass transfer in CO 2 absorption columns using amine-CO 2 scrubbing solutions, is investigated in this paper. The aluminum structures printed by selective laser melting with Al-10Si-0.3Mg feed powder are susceptible to corrosion in aqueous monoethanolamine, both fresh and used CO 2 -saturated solutions. The efficacy of corrosion-protective surface layers of aqueous polyether–ketone–ketone (PEKK) dip coating to provide amine corrosion resistance to the 3D printed aluminum structure is also evaluated. PEKK nanothick layers were coated on the corrugated surface of a 3D printed structure, identical to that of the intensified device, yielding 27 times higher corrosion resistance than the uncoated Al alloy surface. Finally, a systematic long-term electrochemical corrosion analysis revealed that a multilayer PEKK dip coating protocol enables protection of the 3D printed Al alloy surface in various CO 2 –monoethanolamine solutions.

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

Performance Degradation of Amine-Infused Fiber Sorbents for Direct Air Capture: Mechanisms and Solutions

Sorbent stability poses significant impacts on longterm performance of direct air capture (DAC) of CO 2 and levelized cost of capture (LCOC). We report the DAC performance degradation of amine-infused fiber sorbents based on poly(ethylenimine) (PEI), mesoporous SiO 2 , and cellulose acetate (CA) over CO 2 cyclic sorption cycles in a nonoxidative environment. Infrared and nuclear magnetic resonance spectra indicate that the aminolysis reactions between CA ester moieties and PEI amine sites lead to the formation of acetamides and hence lower CO 2 affinities of the sorbents. This stability issue can be remedied by hydrolysis treatment of the CA fiber sorbents before PEI impregnation or replacing CA with poly(ether sulfone). This study underscores the importance of selecting proper support or additive materials of DAC contactors that are compatible with active species of CO 2 capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Complexation of NpO 2 + with Amine-Functionalized Diacetamide Ligands in Aqueous Solution: Thermodynamic, Structural, and Computational Studies

Complexation of Np(V) with three structurally related amine-functionalized diacetamide ligands, including 2,2'-azanediylbis( N, N'-dimethylacetamide) (ABDMA), 2,2'-(methylazanediyl)bis( N, N'-dimethylacetamide) (MABDMA), and 2,2'-(benzylazanediyl)bis( N, N'-dimethylacetamide) (BnABDMA), in aqueous solutions was investigated. The stability constants of two successive complexes, namely, NpO 2 L + and NpO 2 L 2 + , where L stands for the ligands, were determined by absorption spectrophotometry. The results suggest that the stability constants of corresponding Np(V) complexes follow the trend: MABDMA > ABDMA ≈ BnABDMA. The data are discussed in terms of the basicity of the ligands and compared with those for the complexation of Np(V) with an ether oxygen-linked diacetamide ligand. Extended X-ray absorption fine structure data indicate that, similar to the complexation with Nd 3+ and UO 2 2+ , the ligands coordinate to NpO 2 + in a tridentate mode through the amine nitrogen and two oxygen atoms of the amide groups. Furthermore, computational results, in conjunction with spectrophotometric data, verify that the 1:2 complexes (NpO 2 (L) 2 + ) in aqueous solutions are highly symmetric with Np at the inversion center, so that the f-f transition of Np(V) is forbidden and NpO 2 (L) 2 + does not display significant absorption in the near-IR region.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Quantum Chemical Calculation of p K a s of Environmentally Relevant Functional Groups: Carboxylic Acids, Amines, and Thiols in Aqueous Solution

Developing accurate quantum chemical approaches for calculating p K a s is of broad interest. Useful accuracy can be obtained by using density functional theory (DFT) in combination with a polarizable continuum solvent model. However, some classes of molecules present problems for this approach, yielding errors greater than 5 p K units. Various methods have been developed to improve the accuracy of the combined strategy. These methods perform well but either do not generalize or introduce additional degrees of freedom, increasing the computational cost. The Solvation Model based on Density (SMD) has emerged as one of the most commonly used continuum solvent models. Nevertheless, for some classes of organic compounds, e.g., thiols, the p K a s calculated with the original SMD model show errors of 6–10 p K units, and we traced these errors to inaccuracies in the solvation free energies of the anions. To improve the accuracy of p K a s calculated with DFT and the SMD model, we developed a scaled solvent-accessible surface approach for constructing the solute–solvent boundary. By using a “direct” approach, in which all quantities are computed in the presence of the continuum solvent, the use of thermodynamic cycles is avoided. Furthermore, no explicit water molecules are required. Three benchmark data sets of experimentally measured p K a values, including 28 carboxylic acids, 10 aliphatic amines, and 45 thiols, were used to assess the optimized SMD model, which we call SMD with a scaled solvent-accessible surface (SMD sSAS ). Of the methods tested, the M06-2X density functional approximation, 6-31+G(d,p) basis set, and SMD sSAS solvent model provided the most accurate p K a s for each set, yielding mean unsigned errors of 0.9, 0.4, and 0.5 p K units, respectively, for carboxylic acids, aliphatic amines, and thiols. As a result, this approach is therefore useful for efficiently calculating the p K a s of environmentally relevant functional groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Elucidating the Mechanism for the Reaction of $o$-Phthalaldehyde with Primary Amines in the Presence of Thiols

The use of o-phthalaldehyde (OPA) in combination with a thiol reagent is a common method for detecting primary amines in amino acids, peptides, and proteins. Despite its widespread use, the exact reaction mechanism has been debated since the 1980s. Here, we measure the kinetics of the reaction between OPA, alanine, and a dithiol (1,4-dithiolthreitol, DTT) as a function of pH and reagent concentration. Using these new measurements and accompanying kinetic models, we find evidence that the pH dependence of the kinetics arises from both the protonation states of alanine and DTT, the hydration state of OPA, and the unproductive equilibrium with DTT, all of which are pH-dependent. Importantly, these results support the mechanism originally proposed by Sternson [Rational design and evaluation of improved o-phthalaldehyde-like fluorogenic reagents. Anal. Biochem. 1985, 144, 233–246] and Wong [Reaction of o-phthalaldehyde with alanine and thiols: kinetics and mechanism. J. Am. Chem. Soc. 1985, 107, 6421–6422], in which the primary amine first reacts with OPA, followed by a reaction with the thiol to form the fluorescent isoindole product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗