Engineering topics

Autrey, Thomas

Publications and source records attributed to Autrey, Thomas.

At least 19 records

DOE OSTI2024

Achieving gigawatt-scale green hydrogen production and seasonal storage at industrial locations across the U.S

Onsite production of gigawatt-scale wind- and solar-sourced hydrogen (H 2 ) at industrial locations depends on the ability to store and deliver otherwise-curtailed H 2 during times of power shortages. Thousands of tonnes of H 2 will require storage in regions where subsurface storage is scarce, which may only be possible using liquid organic H 2 carriers. We evaluate aboveground system with a focus on providing technical insights into toluene/methylcyclohexane (TOL/MCH) storage systems in locations suitable for gigawatt-scale wind- and solar-powered electrolyzer systems in the United States. Here we show that the levelized cost of storage, at a national median of US dollar $1.84/kg-H 2 is spatially heterogeneous, causing minor impact on the cost of H 2 supply in the Midwest, and significant impact in Central California and the Southeast. While TOL/MCH may be the cheapest aboveground bulk storage solution evaluated, upfront capital costs, modest energy efficiency, reliance on critical materials and pre-sulfided catalysts, and greenhouse gas emissions from heating are opportunities for further development.

14 SOLAR ENERGY↗

DOE OSTI2021

Experimental Studies of the Dynamics of Adsorbed and Condensed Phase Iodine Species Formed in Severe Reactor Accidents (Final Project Report)

We have studied the chemical transformations of semi-volatile organic iodide species (RI) in the condensed phase as well as adsorbed onto the surfaces of environmentally relevant particles, e.g., soot (carbon) and dust (silica) under real-world conditions. The combination of chosen experimental methods provide a molecular-level insight into the chemical dynamics of organic iodides. Throughout this project, we have developed new experimental, quantum chemistry, and data analysis capabilities. All experimental work was performed with 127 I.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2021

Roundtable on Foundational Science for Carbon-Neutral Hydrogen Technologies (Technology Status Document)

This document summarizes the status of carbon-neutral hydrogen production, storage and transport, and utilization. The state of the art in the implementation, limitations, and challenges of these technologies are summarized. Sources of hydrogen are broadly categorized as hydrcoarbons or water and the processes used to convert these sources to hydrogen as catalytic, thermochemical, or electrochemical. Catalytic steam methane reforming of methane is the dominant process today. Other processes have smaller production volumes and the technology is less mature, but are being deployed at increasing rates, most notably water electrolyzers for hydrogen fueling stations. Efficient transport and storage of hydrogen is one of the major challenges facing a hydrogen-based energy economy. This arises in part from its low volumetric energy density necessitating very high pressures or cryogenic temperatures to store sufficient amounts for practical applications. High-pressure compressed hydrogen cylinders are the incumbent hydrogen storage technology for applications such as light-duty fuel cell electric vehicles, for example. The storage of hydrogen in materials or in chemicals is being pursued to address the issues associated with compression, such as parasitic energy loss and weight, size, and cost of storage containers. The complex nature of the chemical and physical processes involved in the uptake, storage, and release of hydrogen has slowed the discovery of suitable hydrogen storage materials. Both small and large-scale storage face the challenge of embrittlement of the storage media by hydrogen. There is a myriad of uses of hydrogen offering the promises of improving the efficiency of various applications and reducing or eliminating CO 2 emissions. These range from direct electrochemical conversion to electricity to power vehicles and grid-level stationary applications to combustion to production of chemicals and commodities. One of the most impactful applications in terms of reduction of CO 2 emissions is fuel cell passenger vehicles and heavy-duty vehicles such as class 8 trucks. The challenges facing widespread deployment of fuel cells, beyond the major hurdle of the lack of a hydrogen distribution infrastructure, are cost and durability, primarily related to the precious metal cathode catalyst and its durability. The other uses of hydrogen from conversion to hydrocarbons, polymer upcycling, and upgrading of bio-oils are at varying stages of maturity and also face fundamental challenges associated with catalytic processes and materials.

08 HYDROGEN↗

DOE OSTI2015

Heterolysis of H 2 Across a Classical Lewis Pair, 2,6-Lutidine∙BCl3: Synthesis, Characterization, and Mechanism

In this study, we report that 2,6-lutidine∙trichloroborane (Lut∙BCl 3 ) reacts with H 2 in toluene, bromobenzene, dichloromethane, and Lut solvents producing the neutral hydride, Lut∙BHCl 2 . The mechanism was modeled with density functional theory, and energies of stationary states were calculated at the G3(MP2)B3 level of theory. Lut∙BCl 3 was calculated to react with H 2 and form the ion pair, [LutH + ][HBCl 3 – ], with a barrier of ΔH ≠ =24.7 kcal mol –1 (ΔG ≠ =29.8 kcal mol –1 ). Metathesis with a second molecule of Lut∙BCl 3 produced Lut∙BHCl 2 and [LutH + ][BCl 4 – ]. The overall reaction is exothermic by 6.0 kcal mol –1 (Δ r G°=–1.1). Alternate pathways were explored involving the borenium cation (LutBCl 2 + ) and the four-membered boracycle [(CH 2 {NC 5 H 3 Me})BCl 2 ]. Barriers for addition of H 2 across the Lut/LutBCl 2 + pair and the boracycle B—C bond are substantially higher (ΔG ≠ =42.1 and 49.4 kcal mol –1 , respectively), such that these pathways are excluded. The barrier for addition of H 2 to the boracycle B—N bond is comparable (ΔH ≠ =28.5 and ΔG ≠ =32 kcal mol –1 ). Conversion of the intermediate 2-(BHCl 2 CH 2 )-6-Me(C 5 H 3 NH) to Lut∙BHCl 2 may occur by intermolecular steps involving proton/hydride transfers to Lut/BCl 3 . Intramolecular protodeboronation, which could form Lut∙BHCl 2 directly, is prohibited by a high barrier (ΔH ≠ =52, ΔG ≠ =51 kcal mol –1 ).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair

The reaction enthalpy and rate of reduction of 1,1-diphenylethylene (DPE) by the Frustrated Lewis pair formed between tris-pentafluorophenylborane (BCF) and diethyl ether (Et₂O) in dichloromethane have been determined by mixing calorimetry. At 50 °C and 13.6 atm hydrogen a 0.08 M solution of DPE is reduced to 1,1-diphenylethane in the presence of 1 equivalent BCF and 0.8 equivalents Et₂O in 40 minutes. NMR spectroscopy showed >99% conversion to the reduced product. The rate of conversion of the olefin to the alkane as monitored by the time dependent heat flow showed a linear dependence on the free Et₂O and BCF concentration. Integration of the heat flux provides a measure of the reaction enthalpy of ΔH ca. -116±4 kJ/mol for the reaction Ph₂C=CH₂+H2→Ph₂CHCH₃. The equilibrium constant for dative adduct formation, Et₂O+BCF↔Et₂O—BCF, was determined as a function of temperature by ¹⁹F NMR spectroscopy and provided an experimental measure of the enthalpy, ΔH = -54.6±3.3 kJ/mol⁻¹ and entropy, ΔS=-154±13 Jmol⁻¹ K⁻¹, for dative bond formation in DCM. Extrapolation of the van’t Hoff plot to 50 ºC provides K eq that is used to estimate the concentration of free BCF and Et₂O available to activate hydrogen. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

Whittemore, Sean M.↗

DOE OSTI2014

Multifunctional Catalysts to Synthesize and Utilize Energy Carriers

The central role and critical importance of catalysis in a future based on sustainability, together with the insight that developments have to be knowledge-based have motivated significant efforts to better understand catalyzed processes and to develop new catalytic routes from this knowledge. Overall, three main energy carriers are used worldwide, carbon (and hydrocarbons), hydrogen, and electrons. Conventionally, the stored energy is accessed by oxidizing carbon and hydrogen, forming O-H and C-O bonds and performing work with the produced heat or electricity. Conversely, to synthesize energy carriers sustainably, it is consequently required to reverse the direction, i.e., to break C-O and O-H bonds and form C-C, C-H and H-H bonds. To address these challenges, PNNL’s BES-sponsored program comprises three thrust areas with subtasks, focusing on the fundamentals of biomass conversion processes, direct and indirect CO2 reduction, and on elementary studies aimed at generating and using H2. Multi-functionality, i.e., the simultaneous interaction of more than one catalytically active site with the substrate is the key to achieving the atom and energy efficiency in individual steps. The combination of several types of these sites with carefully selected energetics and rate constants is used to generate complex catalysts able to enhance the rates of multistep processes. This short report summarizes recent results obtained in this BES-funded program.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2014

Experimental and Theoretical Study of Molecular Response of Amine Bases in Organic Solvents

Reorientational correlation times of various amine bases (viz., pyridine, 2,6-lutidene, 2,2,6,6-tetramethylpiperidine) and organic solvents (dichloromethane, toluene) were determined by solution-state NMR relaxation time measurements and compared with predictions from molecular dynamics (MD) simulations. The bases and solvents are reagents in complex reactions involving Frustrated Lewis Pairs (FLP), which display remarkable catalytic activity in metal-free H2 scission. The comparison of measured and simulated correlation times is a key test of the ability of recent MD and quantum electronic structure calculations to elucidate the mechanism of FLP activity. Correla- tion times were found to be in the range 1.4-3.4 ps (NMR) and 1.23-5.28 ps (MD) for the amines, and 0.9-2.3 ps (NMR) and 0.2-1.7 ps (MD) for the solvent molecules. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacic Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

Frustrated Lewis pairs↗

DOE OSTI2013

Rotational dynamics in ammonia borane: Evidence of strong isotope effects

This work reports anelastic spectroscopy measurements on the partially deuterated (ND3BH3 and NH3BD3) and perdeuterated (ND3BD3) ammonia borane (NH3BH3) compounds. The relaxations previously reported in NH3BH3 are observed in all the samples, and are ascribed to the rotational and torsional dynamics of NH(D)3BH(D)3 complexes. A new thermally activated peak appears at 70 K (for a vibration frequency of 1 kHz) in the spectrum of NH3BD3 and ND3BD3. The peak is practically a single-time Debye process, indicating absence of interaction between the relaxing units, and has a strikingly high intensity. A secondary relaxation process is also detected around 55 K. The anelastic spectrum of the ND3BH3 only displays this less intense process at 55 K. The analysis of the peaks supplies information about the dynamics of the relaxing species, and the obtained results provide indications on the effect of partial and selective deuteration on the hydrogen (deuterium) dynamics.

hydrogen absorbing materials↗

DOE OSTI2013

Methods to Stabilize and Destabilize Ammonium Borohydride

Ammonium borohydride, NH4BH4, has a high hydrogen content of ρm = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may be explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ΔT = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.

ammonium borohydride↗

DOE OSTI2013

3-Methyl-1,2-BN-Cyclopentane: A Promising H2 Storage Material?

We provide detailed characterization of properties for 3-methyl-1,2-BN-cyclopentane 1 that are relevant to H2 storage applications such as viscosity, thermal stability, H2 gas stream purity, and polarity. The viscosity of 1 at room temperature is 25±5 cP, about one fourth the viscosity of olive oil. TGA/MS analysis indicates that liquid carrier 1 is thermally stable at 30 °C but decomposes slowly at 50 °C. RGA data suggest that the H2 desorption from 1 is a clean process, producing relatively pure H2 gas. Compound 1 is a polar zwitterionic type liquid consistent with theoretical predictions and solvatochromic studies. "T.A. acknowledges support from the Fuel Cell Technology Program at U.S. DOE, Office of Energy Efficiency 65 and Renewable Energy. Pacific Northwest National Laboratory is operated by Battelle."

Luo, Wei↗

DOE OSTI2013

A Thermodynamic and Kenetic Study of the Heterolytic Activation of Hydrogen by Frustrated Borane-Amine Lewis Pairs

Calorimetry is used to measure the reaction enthalpies of hydrogen activation by 2,6-lutidine (Lut), 2,2,6,6-tetramethylpiperidine (TMP), N-methyl-2,2,6,6-tetramethylpiperidine (MeTMP) and tri-tert-butylphosphine (TBP) with tris(pentafluorophenyl)borane (BCF). At 6.6 bar H2 the conversion of the Lewis acid Lewis base pair to the corresponding ionic pair in bromobenzene at 294 K was quantitative in under 60 minutes. Integration of the heat release from the reaction of the Frustrated Lewis Pair (FLP) with hydrogen as a function of time yields a relative rate of hydrogenation in addition to the enthalpy of hydrogenation. The half-lives of hydrogenation range from 230 seconds with TMP, ΔHH2 = -31.5(0.2) kcal/mol, to 1400 seconds with Lut, ΔHH2 = -23.4(0.4) kcal/mol. The 11B NMR spectrum of B(C6F5)3 in bromobenzene exhibits three distinct traits depending on the sterics of the Lewis base; (i) in the presence of pyridine, only the dative bond adduct pyridine--B(C6F5)3 is observed, (ii) in the presence of TMP and MeTMP only the free B(C6F5)3 is observed, and (iii) in the presence of Lut both the free B(C6F5)3 and the Lut--B(C6F5)3 adduct appear in equilibrium. A measure of the change in Keq of Lut + B(C6F5)3 <->Lut--B(C6F5)3 as a function of temperature provides thermodynamic properties of the Lewis acid Lewis base adduct, ΔH = -17.9(1.0) kcal/mol and a ΔS = -49.2(2.5) cal/mol K, suggesting the Lut--B(C6F5)3 adduct is more stable in bromobenzene than in toluene. This research was supported by the U.S. Department of Energy’s Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. D.M.C. and A.K. acknowledges support by the Laboratory Directed Research and Development program at the Pacific Northwest National Laboratory (PNNL) to perform kinetic analyses of the calorimetry data. The work was performed in part at EMSL, a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research. EMSL is located at Pacific Northwest National Laboratory (PNNL), which is operated by Battelle for DOE.

calorimetry↗

DOE OSTI2013

Temperature Dependence of the Infrared Spectrum of Ammonia Borane: Librations, Rotations, and Molecular Vibrations

The absorbance of solid ammonia borane (AB) was measured in the energy range between 30 and 5000 cm(-1) and in the temperature range between 10 and 300 K. The intramolecular vibrations and their evolution through the structural phase transition around T-t approximate to 220 K fairly agree with previous measurements performed by means of Raman spectroscopy. In addition, we observed new vibrations centered in the far-infrared range, which can be tentatively ascribed to rotations and librations. The number of such modes does not agree with the calculations based on the group theory for both the tetragonal and the orthorhombic crystal structure of AB. We suggest that such a discrepancy is due to local reduction of the crystal symmetry compared to the one reported by X-ray diffraction and used to compute the number of IR active modes.

CRYSTAL↗

DOE OSTI2012

Role of Solvents on the Thermodynamics and Kinetics of Forming Frustrated Lewis Pairs

To enhance our understanding of the role of solvent on the thermodynamics and kinetics of forming Frustrated Lewis pairs (FLP), we carried out a systematic simulation study on these systems in dichloromethane and toluene solvents. These molecular systems are of particular interest due to their relevance in the catalytic hydrogenation and hydrogen storage processes. While the computed structural observables for both molecules are very similar, the slow molecular reorientation was consistent with the size of the species. The computed free energy profiles for the FLP in both solvents show similar gross characteristics but differ in details. We observe two well-defined contact and a solvent-separated regions with different well depths and barrier heights to dissociation. The kinetics of solute-pair interconversion was studied using transition state theory, comparing Kramers and Grote Hynes treatment of the dynamic response of the solvent. These rate results were used to predict solvent effects on dynamical features of contact solute-pair association. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The calculations were carried out using computer resources provided by BES. Method development benefits M86304. The scientific understanding of the systems studied benefits F63768

Dang, Liem X↗

DOE OSTI2012

Immobilizing Highly Catalytically Active Pt Nanoparticles inside the Pores of Metal-Organic Framework: A Double Solvents Approach

Ultrafine Pt nanoparticles were successfully immobilized inside the pores of a metal-organic framework MIL-101 without deposition of Pt nanoparticles on the external surfaces of framework by using a 'double solvents' method. The resulting Pt@MIL-101 composites with different Pt loadings represent the first highly active MOF-immobilized metal nanocatalysts for catalytic reactions in all three phases: liquid-phase ammonia borane hydrolysis; solid-phase ammonia borane thermal dehy-drogenation and gas-phase CO oxidation. The observed excellent catalytic performances are at-tributed to the small Pt nanoparticles within the pores of MIL-101. 'We are thankful to AIST and METI for financial support. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. PNNL is operated by Battelle.'

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Analysis of the Activation and Heterolytic Dissociation of H2 by Frustrated Lewis Pairs: NH3/BX3 (X = H, F, and Cl)

We present results of our computational study aimed at understanding the mechanism of H2 activation and heterolytic dissociation by 'frustrated' Lewis pairs (FLPs). We studied the pairs of ammonia (NH3) with BH3, BF3, and most extensively, BCl3. While these pairs are capable of forming a strong dative bond, electronic structure theories make it possible to explore the potential surface in regions away from the dative complex relevant to H2 activation by frustrated Lewis pairs. We analyzed in great detail the changes that occur along the minimum energy path between the FLP and the product ion pair complex. For X = Cl, the mechanism involves a precursor complex, H3N-H2-BCl3, with a B-H-H angle of {approx}80{sup o} and nearly linear N-H-H angle. At the transition state (TS), the H2 bond is weakened but not broken, and the BCl3 moiety has undergone significant pyramidal distortion. As such, the FLP is prepared to accept the incipient proton and hydride ion on the product-side. The interaction energy of the H2 with the acid/base pair and the different contributions for the precursor and TS complex from an energy decomposition analysis expose the dominant factors affecting the reactivity. We find that structural reorganization of precursor complex plays a significant role in the 'activation' and that charge-transfer interactions are the dominant stabilizing force in the activated complex. The electric field clearly has a role in polarizing H2, but its contribution to the overall interaction energy seems to be smaller. Our detailed study of the nature of the bonding and the different types of interaction between the prototypical Lewis pair and H2 provides insight into the important components that should be taken into account when designing related systems to activate hydrogen.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate

Possessing high H{sub 2} capacities and interesting dehydrogenation behavior, metal amidoborane ammoniates were prepared by reacting Ca(NH{sub 2}){sub 2}, MgNH, and LiNH{sub 2} with ammonia borane to form Ca(NH{sub 2}BH{sub 3}){sub 2} - 2 NH{sub 3}, Mg(NH{sub 2}BH{sub 3}){sub 2} - NH{sub 3}, and Li(NH{sub 2}BH{sub 3}){sub 2} - NH{sub 3} (LiAB - NH{sub 3}). Insight into the mechanisms of amidoborane ammoniate formation and dehydrogenation was obtained by using isotopic labeling techniques. Selective {sup 15}N and {sup 2}H labeling showed that the formation of the ammoniate occurs via the transfer of one H(N) from ammonia borane to the [NH{sub 2}]{sup -} unit in Ca(NH{sub 2}){sub 2} giving rise to NH{sub 3} and [NH{sub 2}BH{sub 3}]{sup -}. Supported by theoretical calculations, it is suggested that the improved dehydrogenation properties of metal amidoborane ammoniates compared to metal amidoboranes are a result of the participation of a strong dihydrogen bond between the NH{sub 3} molecule and [NH{sub 2}BH{sub 3}]{sup -}. Our study elucidates the reaction pathway involved in the synthesis and dehydrogenation of Ca(NH{sub 2}BH{sub 3}){sub 2}-2NH{sub 3}, and clarifies our understanding of the role of NH{sub 3}, that is, it is not only involved in stabilizing the structure, but also in improving the dehydrogenation properties of metal amidoboranes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Understanding Vibrational Anharmonicity and Phonon Dispersion in Solid Ammonia Borane

We compute the hydrogen vibrational spectra for bulk ammonia borane (NH3BH3) using harmonic and anharmonic methodologies as well as quantifying dispersive effects to determine their influence on the resulting spectra. Even at 10K the accounting of anharmonic effects on the IINS signal are more significant than approximations introduced by sampling and interpolating a finite simulation cell to capture dispersion effects. We compare our computed anharmonic power spectrum with IINS spectral measurements and find excellent agreement. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences and Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

08 HYDROGEN↗

DOE OSTI2011

Kinetic and Thermodynamic Investigation of Hydrogen Release from Ethane 1,2-di-amineborane

The thermodynamics and kinetics of hydrogen (H2) release from ethane 1,2-di-amineborane (EDAB, BH3NH2CH2CH2NH2BH3) were measured using Calvet and differential scanning calorimetry (DSC), pressure-composition isotherms, and volumetric gas-burette experiments. The results presented here indicate that EDAB releases ~ 9 wt.% H2 at temperatures ranging from 100 °C to 200 °C in two moderately exothermic steps, approximately -10±1 kJ/mol H2 and -3.8±1 kJ/mol H2. Isothermal kinetic analysis shows that EDAB is more stable than ammonia borane (AB) at temperatures lower than 100°C; however, the rates of hydrogen release are faster for EDAB than for AB at temperatures higher than 120°C. In addition, no volatile impurities in the H2 released by EDAB were detected by mass spectrometry upon heating with 1°C/min to 200°C in a calorimeter.

08 HYDROGEN↗