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Artykuły w czasopismach na temat "Thermochemistry - Chemical Hydrogen Storage"
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Ja'o, Aliyu M., Derek A. Wann, Conor D. Rankine, Matthew I. J. Polson i Sarah L. Masters. "Utilizing the Combined Power of Theory and Experiment to Understand Molecular Structure – Solid-State and Gas-Phase Investigation of Morpholine Borane". Australian Journal of Chemistry 73, nr 8 (2020): 794. http://dx.doi.org/10.1071/ch19492.
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The molecular structure of morpholine borane complex has been studied in the solid state and gas phase using single-crystal X-ray diffraction, gas electron diffraction, and computational methods. Despite both the solid-state and gas-phase structures adopting the same conformation, a definite decrease in the B–N bond length of the solid-state structure was observed. Other structural variations in the different phases are presented and discussed. To explore the hydrogen storage potential of morpholine borane, the potential energy surface for the uncatalyzed and BH3-catalyzed pathways, as well as the thermochemistry for the hydrogen release reaction, were investigated using accurate quantum chemical methods. It was observed that both the catalyzed and uncatalyzed dehydrogenation pathways are favourable, with a barrier lower than the B–N bond dissociation energy, thus indicating a strong propensity for the complex to release a hydrogen molecule rather than dissociate along the B–N bond axis. A minimal energy requirement for the dehydrogenation reaction has been shown. The reaction is close to thermoneutral as demonstrated by the calculated dehydrogenation reaction energies, thus implying that this complex could demonstrate potential for future on-board hydrogen generation.
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Chen, Yuzhu, i Meng Lin. "(Digital Presentation) Photo-Thermo-Electrochemical Cells for on-Demand Solar Power and Hydrogen Generation". ECS Meeting Abstracts MA2022-01, nr 36 (7.07.2022): 1560. http://dx.doi.org/10.1149/ma2022-01361560mtgabs.
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Converting solar energy into power and hydrogen provides a promising pathway to fulfilling instantaneous electricity demand (power generation) as well as continuous demand via storing energy in chemical bonds (hydrogen generation). Co-generation of power and hydrogen is of great interest due to its potential to overcome expensive electricity storage in conventional PV plus battery systems. Both solar thermochemistry processes and photo-electrochemical cells (PECs) are extensively explored technologies to produce solar hydrogen. The key challenges for solar thermochemistry processes are extremely high operating temperature (~ 1500 oC) and low demonstrated efficiency (< 1% for hydrogen generation). For PECs, the limited solar absorption together with sluggish electrochemical reactions, especially for OER, leads to limited theoretical solar fuel generation. Operating PECs at high temperature will lead to decreased photovoltage and interface stability. Inspired by the thermally regenerative batteries, we propose a photo-thermo-electrochemical (PTEC) device that uses the solid oxide-based moderate high temperature cell (~1000 ℃) as the photo-absorber for simultaneously converting concentrated solar radiation into heat and generating fuel or power electrochemically driven by the discharging power from the low temperature cell (~700 ℃). PTEC device enables full solar spectrum utilization, highly favorable thermodynamics and kinetics, and cost-effectiveness. A continuous PTEC device has two working modes, which are voltage differential (VD) mode and current differential (CD) mode. The current-voltage characteristics of a PTEC device are shown in Figure 1. It mainly consists of five parts. A high temperature cell (HTC) serves as a solar absorber and a low temperature cell (LTC) serves as heat recovery. Besides, the opposite electrochemical reactions take place in two cells meaning that HTC and LTC can also function as a hydrogen production as well as an electricity generator component, respectively. Heat exchanger(s) is placed between the HTC and LTC and hot fluids pass through a heat exchanger before entering LTC to reduce heat losses to environment as well as reducing input solar energy. The VD mode and CD mode can be realized in PTECs via controlling of DC-DC converter. In order to identify the main parameters, we develop a multi-physics model based on finite element method, including mass, heat and charge transfer, and electrochemical reactions. In addition, heat exchange is modeled by solving energy balance equation, DC-DC convertor is assumed by constant efficiency, and a lumped parameter model is used to describe solar receiver including energy losses of conduction and reradiation. This framework also allows us to provide design guidelines for PTEC devices with high solar-to-electricity (STE) efficiency and solar-to-hydrogen (STH) efficiency. The maximum STE and STH efficiency under reference conditions of PTEC device was found to be 4 % and 2 %. A further improved performance in terms of STE and STH efficiency are about 19 % and 16 %, respectively, via optimizing temperature configuration between HTC and LTC and material properties. It is also interesting to note that STH can reach higher than 80 % of STE at a large temperature difference, which shows a promising energy storage device by storing excessive electrical power in form of hydrogen. The main results show that the temperature of HTC and efficiency of heat exchange are key parameters to optimize PTEC efficiency. The performance of DC-DC convertor dominates STH efficiency. Besides, ionic conductivity of electrolyte can contribute to significantly expanding the operating current density range. The PTEC is a promising technology for solar energy conversion and storage as it is able to produce electricity and hydrogen in a single device. The solar conversion efficiency predicted with our numerical model supports that by optimizing the design and operational conditions, this technology can compete with existing solar fuel pathways. Figure 1
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Verevkin, Sergey P., Maria E. Konnova, Kseniya V. Zherikova i Aleksey A. Pimerzin. "Sustainable hydrogen storage: Thermochemistry of amino-alcohols as seminal liquid organic hydrogen carriers". Journal of Chemical Thermodynamics 163 (grudzień 2021): 106591. http://dx.doi.org/10.1016/j.jct.2021.106591.
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Wong, Bryan M., David Lacina, Ida M. B. Nielsen, Jason Graetz i Mark D. Allendorf. "Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation". Journal of Physical Chemistry C 115, nr 15 (30.03.2011): 7778–86. http://dx.doi.org/10.1021/jp112258s.
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Wong, Hsi-Wu, Juan Carlos Alva Nieto, Mark T. Swihart i Linda J. Broadbelt. "Thermochemistry of Silicon−Hydrogen Compounds Generalized from Quantum Chemical Calculations". Journal of Physical Chemistry A 108, nr 5 (luty 2004): 874–97. http://dx.doi.org/10.1021/jp030727k.
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Miyaoka, Hiroki, Takayuki Ichikawa i Yoshitsugu Kojima. "Chemical Hydrogen Storage of Carbon Material". Journal of the Japan Institute of Metals and Materials 77, nr 12 (2013): 552–58. http://dx.doi.org/10.2320/jinstmet.jc201301.
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Yang, Xinchun, Dmitri A. Bulushev, Jun Yang i Quan Zhang. "New Liquid Chemical Hydrogen Storage Technology". Energies 15, nr 17 (31.08.2022): 6360. http://dx.doi.org/10.3390/en15176360.
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The liquid chemical hydrogen storage technology has great potentials for high-density hydrogen storage and transportation at ambient temperature and pressure. However, its commercial applications highly rely on the high-performance heterogeneous dehydrogenation catalysts, owing to the dehydrogenation difficulty of chemical hydrogen storage materials. In recent years, the chemists and materials scientists found that the supported metal nanoparticles (MNPs) can exhibit high catalytic activity, selectivity, and stability for the dehydrogenation of chemical hydrogen storage materials, which will clear the way for the commercial application of liquid chemical hydrogen storage technology. This review has summarized the recent important research progress in the MNP-catalyzed liquid chemical hydrogen storage technology, including formic acid dehydrogenation, hydrazine hydrate dehydrogenation and ammonia borane dehydrogenation, discussed the urgent challenges in the key field, and pointed out the future research trends.
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Cheng, Gongzhen, Cheng Du, Wei Luo i Xiuze Hei. "formic acid for chemical hydrogen storage". SCIENTIA SINICA Chimica 46, nr 5 (1.05.2016): 487–95. http://dx.doi.org/10.1360/n032015-00232.
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Tan, Yingbin, i Xuebin Yu. "Chemical regeneration of hydrogen storage materials". RSC Advances 3, nr 46 (2013): 23879. http://dx.doi.org/10.1039/c3ra44103b.
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Yadav, Mahendra, i Qiang Xu. "Liquid-phase chemical hydrogen storage materials". Energy & Environmental Science 5, nr 12 (2012): 9698. http://dx.doi.org/10.1039/c2ee22937d.
Pełny tekst źródłaRozprawy doktorskie na temat "Thermochemistry - Chemical Hydrogen Storage"
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McCaldin, Simon Roger. "Hydrogen storage in graphitic nanofibres". Thesis, University of Nottingham, 2007. http://eprints.nottingham.ac.uk/11568/.
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There is huge need to develop an alternative to hydrocarbons fuel, which does not produce CO2 or contribute to global warming - 'the hydrogen economy' is such an alternative, however the storage of hydrogen is the key technical barrier that must be overcome. The potential of graphitic nanofibres (GNFs) to be used as materials to allow the solid-state storage of hydrogen has thus been investigated. This has been conducted with a view to further developing the understanding of the mechanism(s) of hydrogen storage in GNFs and modifying the material structure to maximise the amount of hydrogen that can be reversibly stored in the material. GNFs were synthesised using chemical vapour deposition (CVD) with careful control of temperature and gas mixture to create predominately herringbone GNFs from both Iron and Nickel catalysts. Within this, it was found that once GNF growth has been initiated under certain conditions, alteration of those conditions does not alter the fundamental structure of the GNF synthesised, but can increase the carbon yield, although reorientation of the surfaces was observed. The GNFs synthesised were subsequently chemically (acid washed and CO2 oxidised) and thermally treated to remove the residual CVD catalyst and alter their surface structures in an attempt to allow dihydrogen molecules to penetrate and adsorb onto the internal graphene layers. However, it was found that after initial growth, the surface layers of the GNFs became re-orientated parallel to the fibre axis - representing a large energy barrier to adsorption onto the surfaces of the internal graphene layers. By careful use and control of conditions, this re-orientated layer can be removed to yield GNFs with cleaned surfaces. Once GNFs with cleaned edges had been synthesised, these were modified to remove oxygen species from their surfaces. To further develop the understanding of the potential hydrogen uptake mechanisms, Pd particles were introduced to the GNF surfaces to act as catalyst gateways. By carefully controlling the variables of the incipient wetness process, a variety of morphologies and structures were synthesised. This allowed the precise determination of the hydrogen uptake mechanism occurring in samples by Kubas binding, Dissociation or Spill-over mechanisms. All of the GNFs created have had their hydrogen uptake capacities precisely determined using a Sieverts apparatus designed and constructed by the author. None of the samples were found to adsorb any significant levels of hydrogen (>0.1 wt%), regardless of the treatments applied to them – this result has been discussed in light of the existing claims for high hydrogen uptake in GNFs made within the literature. The conclusion of this thesis is that no hydrogen uptake capacity could be observed in the GNFs synthesised during the project, however, the development of the uptake mechanisms and GNF structures has led to suggested modifications that may yield GNFs suitable for storing large quantities of hydrogen (i.e. in excess of US-DOE targets).
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BARLOCCO, ILARIA. "HYDROGEN PRODUCTION FROM CHEMICAL HYDROGEN STORAGE MATERIALS USING CARBON-BASED CATALYSTS". Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/901855.
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The aim of this thesis is to design new catalytic systems in order to improve the performances of the existing catalysts to convert formic acid (FA) and hydrazine (N2H4 · H2O) into ultra-pure hydrogen in order to be effective in the future hydrogen economy. Different are the issues to solve in order to efficiently employ these chemicals in our energy transition. In particular, efficient carbon-based heterogeneous systems can effectively make enormous difference in the production of hydrogen from liquid carriers. Indeed, metal-based catalysts and especially Pd-based ones offer enhanced activity also at room temperature, but selectivity and stability need to be improved to be industrially applicable. In addition, carbon materials have the advantage of being easily tuned through variation in their structure, for example, changing the surface area and porosity and adding functional groups or generating topological defects. Moreover, their stability in liquid phase reactions makes them auspicious candidates in catalytic processes.
For these reasons, the first part of this thesis is dedicated to the design of new catalytic materials with the aim to improve the catalytic behaviour compared to existing Pd-based catalysts for the selective decomposition of FA at mild reaction conditions. In particular, the effect of the metal-support interaction and the geometrical and electronic effect in alloyed catalysts play a fundamental role to enhance the catalytic performance (Chapter 3-5).
Chapter 3 is devoted to study the metal-support interaction by doping with O and P functionalities the carbonaceous support. In order to establish the presence of functional groups in the support and their effect on Pd nanoparticles, the obtained samples were then, characterised by Transmission Electron Microscopy (HR-TEM, STEM-HAADF and STEM-EDS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) simulations provided further insights in the interaction of Pd15 cluster with different support surfaces, i.e. pristine graphene (PG), carboxyl doped graphene (G_COOH), hydroxyl doped graphene (G_OH), carbonyl doped graphene (G_CO) and phosphate doped graphene (G_PO3H).
The effect of the addition of a second metal to Pd is considered (Rh in Chapter 4 and Au in Chapter 5). In particular, in Chapter 4 the synthesis of PdRh nanoparticles with different Pd:Rh molar ratios was studied. The obtained catalysts were characterised by Transmission Electron Microscopy (TEM) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). For bimetallic catalysts, EDX-STEM analysis of individual nanoparticles was employed to investigate the presence of random-alloyed nanoparticles. Finally, PdRh catalysts were tested in the liquid-phase hydrogenation of muconic acid using formic acid as hydrogen donor.
Chapter 5 combines DFT and experimental data to disclose the role of gold in enhancing activity, selectivity and stability of palladium catalyst during the formic acid decomposition. PdAu bimetallic nanoparticles with different Pd:Au molar ratio were synthesised and the obtained catalysts were characterised by using Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP - OES). Finally, Density functional theory (DFT) calculations on Pd15, Au15 and Pd9Au6 clusters supported on a carbon sheet were then simulated to provide atomic level understanding to the beneficial effect of gold observed in the experimental results.
In addition, in order to decrease the cost and increase the environmental benignity of the catalyst, the application of metal-free carbon materials in the formic acid dehydrogenation is investigated (Chapter 6). Indeed, Commercial graphite (GP), graphite oxide (GO), and two carbon nanofibers (CNF-PR24-PS and CNF-PR24-LHT) were used as catalysts for the metal-free dehydrogenation reaction of formic acid (FA) in liquid phase. Raman and XPS spectroscopies were employed to characterize the materials and Density Functional Theory (DFT) calculations were utilized to study the role of defects in this reaction.
In the final results chapter (Chapter 7), the above reported metal-free carbocatalysts are employed for the hydrazine hydrate dehydrogenation reaction, in order to produce H2 without the presence of CO2. A combination of DFT and experimental studies were used to unravelling the hydrazine hydrate decomposition reaction on metal-free catalysts. The study focuses on commercial graphite and two different carbon nanofibers, Pyrolytically Stripped (CNF-PS) and High Heat-Treated (CNF-HHT), respectively treated at 700 and 3000 °C to increase their intrinsic defects.
Finally, Chapter 8 presents a summary of the main findings of this work and different possibilities to continue this research study.
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Liu, Zhe. "Novel solid state materials for chemical hydrogen storage". Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8324/.
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This work investigates the hydrogen storage potential of a variety of solid state materials. The work has showed their synthesis, structure, morphology and hydrogen storage properties comprehensively. An MgH2 nanocomposite composed of 80% tetragonal α-MgH2 and 18% orthorhombic γ-MgH2 has been prepared for the first time without recourse to high pressure or temperature. By optimizing the ball milling conditions, addition of LiCl and use of THF solvent, the α-/γ-MgH2 nanocomposite so-produced is capable of releasing 6.6 wt% H2 with rapid kinetics, from ca. 260 °C without the use of a catalyst. Moreover, Ti-catalyzed MgH2 offering a capacity of 5.5 wt. % of H2 and superior hydrogen desorption kinetics has been successfully prepared by a novel wet chemical route. The MgH2 material, containing approximately 2~3 wt. % of Ti-additive exhibits hydrogen desorption at a temperature approximately 220 °C lower than pristine MgH2 where pure hydrogen evolution starts at ca. 420 °C via a synergetic effect of mechanochemical treatment and additives. Neutron scattering was employed to study the structure of activated MgD2 and for the first time local disorder in activated MgD2 has been verified using total neutron scattering (PDF fitting). Small angle neutron scattering (SANS) analysis indicates a surface fractal geometry, i.e high degree of surface roughness for activated MgD2 particles, in accordance with SEM analysis suggesting the morphological alteration introduced by mechanochemical treatment. A novel PANI-LiBH4 composite has been successfully fabricated through simple mixing. It is found that PANI-LiBH4 composites dehydrogenates from ca. 200 °C with over 10 wt.% H2 released by 400 °C, significantly outperforming pristine LiBH4. Importantly, rehydrogenation can be achieved under conditions unprecedented for LiBH4 in isolation (200 °C; 100 bar H2 or 330 °C, 20 bar H2 vs. 600 °C, 350 bar H2). Moreover, the PANI-LiBH4 composite can be readily cycled and a new endothermic uptake event at 140 °C, a remarkably low temperature for LiBH4-based systems, suggests that the polymer thermodynamically alters the hydrogenation mechanism. PANI-NaBH4 and PANI-LiH also exhibit vastly improved dehydrogenation properties compared with the respective hydride materials alone. The structures of some first row transition metal halide hydrazinates, TMX2·2N2H4 (TM= Mn, Fe, Co, Ni, Cu and Zn; X= Cl and Br), have been revisited and detailed structural information of three typical complexes, MnCl2·2N2H4, ZnCl2·2N2H4 and MnBr2·2N2H4 have been accurately determined by using a combination techniques of PXD, FTIR and PND. It is also found that TMX2·2N2H4 decomposes at relatively high temperature ( > 250 °C) with massive weight loss due to the dissociation and decomposition of the N2H4 ligand. However the major gas evolution has been determined to be N2 and NH3 with only a minor amount of H2 (and undesired impurity N2H2) released, which makes TMX2·2N2H4 unsuitable for hydrogen storage. Our strategy to combine TMCl2·2N2H4 with LiBH4 to fabricate novel transition metal borohydride hydrazinates has been proven to be successful. Two novel complexes, Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 have been successfully prepared via a facile mechanochemical route with careful manipulation over the milling parameters. The crystal structure of Mn(BH4)2·2N2H4 has been determined using SR-PXD to be isostructural with its parent material MnCl2·2N2H4. The phase evolution behaviour of Zn(BH4)2·2N2H4 has been probed with evidence of various intermediate phases during preparation when various milling conditions were employed. The dehydrogenation properties of both complexes have been studied using DTA-TGA coupled with MS. Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 are very promising materials for off-board hydrogen storage due to their high hydrogen content and useful dehydrogenation properties.
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Davies, Rosalind. "Lithium amide halides for hydrogen storage". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6680/.
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The lithium amide halides are a promising series of materials for hydrogen storage as they release hydrogen at a lower temperature than lithium amide on reaction with lithium hydride. The amide chloride system has been studied in detail, and two phases with reduced chloride content, Li\(_7\)(NH\(_2\))\(_6\)Cl and Li\(_6\)Mg\(_1\)\(_/\)\(_2\)(NH\(_2\))\(_6\)Cl, have been identified by powder X-ray diffraction and Raman spectroscopy. Both were seen to release hydrogen on reaction with LiH at a lower temperature than lithium amide, and ammonia release was suppressed. Rehydrogenation of the imide products of reaction of both new phases occurred more readily under the conditions used than for the known phase Li\(_4\)(NH\(_2\))\(_3\)Cl. The hydrogen cycling properties of Li\(_7\)(NH\(_2\))\(_6\)Cl were investigated alongside Li\(_7\)(NH\(_2\))\(_6\)Br and Li\(_3\)(NH\(_2\))\(_2\)I. The systems successfully cycled hydrogen, and the reversible structural changes that happened during cycling were studied. All three materials, however, showed a capacity loss on cycling under dynamic vacuum. The conductivity of the amide and imide halides was studied using A.C. impedance and found to be higher than for LiNH\(_2\) and Li\(_2\)NH, respectively. This supports kinetic analyses that indicate ion diffusion is not rate-limiting for the hydrogen cycling of these systems.
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Price, Tobias E. C. "Multi-component complex hydrides for hydrogen storage". Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11988/.
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Hydrogen as an energy vector offers great potential for mobile energy generation through fuel cell technology, however this depends on safe, mobile and high density storage of hydrogen. The destabilised multi-component complex hydride system LiBH4 : MgH2 was investigated in order to characterise the destabilisation reactions which enable reduction of operating temperatures for this high capacity system (ca. 9.8 wt.%). In-situ neutron diffraction showed that regardless of stoichiometry similar reaction paths were followed forming LiH and MgB¬2¬ when decomposed under H¬2 and Mg-Li alloys (Mg0.816Li0.184 and Mg0.70Li0.30) when under dynamic vacuum. Hydrogen isotherms of the 0.3LiBH4 : MgH¬2¬ showed a dual plateau behaviour with the lower plateau due to the destabilised LiBH4 reaction. Thermodynamic data calculated from the isotherm results showed a significant reduction in the T(1bar) for LiBH4 to 322 C (cf. 459 C for LiBH4(l)). Cycling behaviour of 0.3LiBH4 : MgH2 system decomposed under both reaction environments showed very fast kinetics on deuteriding at 400C and 100 bar D2, reaching 90 % conversion within 20 minutes. In contrast 2LiBH4 : MgH2 samples had kinetics an order of magnitude slower and after 4 hours conversions <50 %. These results demonstrate the strong influence of stoichiometry in the cycling kinetics compared to decomposition conditions. Investigation of catalysts found dispersion of metal hydrides through long ball-milling times, or dispersion through reaction with metal halide additions provided the greatest degree of kinetic advantage, with pre-milled NbH providing the best kinetic improvement without reducing capacity due to Li-halide formation. Finally, additions of LiAlH4 to the system formed an Al dispersion through the sample during decomposition, which acted both as a catalyst and destabilising agent on the MgH2 component, forming Mg-Al-Li alloys. Decomposition under H2 also showed a destabilisation effect for the LiBH4 component.
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Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure". Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/509.
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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure". University of Sydney. Chemistry, 2003. http://hdl.handle.net/2123/509.
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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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Mostajeran, Mehdi. "Catalyzed Hydrogen Release from BH- and BNH-based Hydrogen Storage Materials". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36875.
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In order to reduce our ties to fossil-based energy and mitigate the undeniable impacts of climate change on the environment, remarkable efforts have been directed over the last 4 decades toward developing renewable energy sources such as solar, wind, geothermal, etc. For transportation applications biofuels, electricity and hydrogen all offer potential solutions although current usage is still largely linked to fossil fuels (bio-based ethanol-gasoline mixtures, power generation for battery recharging, and steam reforming for hydrogen production). While hydrogen offers the greatest potential in terms of energy density, its poor volumetric density (0.01 MJ/L at RT) requires costly compression and pressurized storage. When future technology finally allows for efficient hydrogen release from water splitting, we need to have optimal solutions in place for hydrogen storage. One promising solution is chemical hydrogen storage in which thermolysis of a chemical precursor affords a controlled hydrogen release that can then be reversed in an off-board regeneration step. With a focus on maximum gravimetric hydrogen storage, various BNH compounds have been shown to be promising chemical hydrogen storage precursors. In this Thesis we summarize the state of the art in B-N-H hydrogen storage compounds (Chapter 1) and then investigate several new chemical hydrogen storage solutions with a focus on portable power generation.
In the first project (Chapter 2) we sought to prepare a robust, base-metal borohydride hydrolysis catalyst for use in a custom hydrogen generator designed to use the reaction heat to help separate the borate spent fuel. Active ‘reverse opal’ layered double hydroxide (LDH) catalysts were prepared and tested. While the classical Ni-Mg-Al LDH released 3.4 equiv. of hydrogen at 50 °C in 150 minutes, the polystyrene templated Ni-Mg-Al catalyst released 4 equiv. of hydrogen with a higher initial rate under the same reaction conditions. The long-term objective of this project was to test these catalysts in fuel cells for underground mine forklifts with our industry collaborator (Kingston Process Metallurgy Inc.).
In the next three chapters, the synthesis and hydrogen release properties of ammine metal borohydrides [M(BH4)m(NH3)n, AMBs] were investigated. As promising hydrogen storage materials with high hydrogen content (10-15 wt%), AMBs can access lower hydrogen release temperatures resulting from the combination of protic (N-Hδ+) and hydridic (B-Hδ-) hydrogens. While AMBs also do not suffer from diborane formation that plagues thermolysis of metal borohydrides, hydrogen release is often accompanied by small concentrations of ammonia that deactivate the fuel cell catalyst. Our objective for this work was to identify base metal catalysts that could suppress ammonia formation by further reducing the energy barrier to H2 release.
In Chapter 3 our studies of the solution synthesis of AMB materials (Y, La, Zn, etc.) in coordinating solvents such as tetrahydrofuran (thf) and diethyl ether revealed the unexpected formation of ammonia-borane (H3NBH3, AB). It was shown that while the amounts of produced AB correlate with the Zhang electronegativity for the s- and p-block metals, ionic radius is a stronger determining factor for the transition metals. It was also observed that reducible metals such as Ti and V produce large amounts of AB while Zn produced the least. This knowledge was then used in Chapter 4 to prepare pure samples of the Y and La complexes, M(BH4)3(NH3)4 that were characterized by thermal analysis (TGA-MS), powder X-ray diffraction, FT-IR and 11B and 1H MAS NMR spectroscopy. Furthermore, a series of base-metal nanoparticle catalysts, prepared using a novel route from MCl2 and liquid hexylamine-borane, was shown to suppress ammonia formation from these Y and La AMBs. Immobilizing 5 wt.% of Co NPs on Y(BH4)3(NH3)4 and 5 wt.% of Fe NPs on La(BH4)3(NH3)4 resulted in reduction of ammonia release by three- and fourfold, respectively. In Chapter 5 the attempted solution synthesis of Zn(BH4)2(NH3)2 revealed complications due to preferred formation of MIZn(BH4)3 [instead of Zn(BH4)2] from the reaction of ZnCl2 and MIBH4 (MI= Li, Na, K). As a result, the mixed-metal AMB, KZn(BH4)3(NH3)n was prepared and characterized. Although the effects of both heterogeneous and homogeneous catalysts were not as pronounced as those for Y and La, using 5 wt.% FeNPs resulted in fourfold reduction in the amount of released ammonia which led to a purer hydrogen stream (98.9 mol%) compared to the uncatalyzed thermolysis (97.0 mol%).
Finally, in Chapter 6 our results are considered vs. the current state of the art and suggestions are made for further investigations.
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Peck, Michael S. "Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4860.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Feb. 27, 2008). Vita. Includes bibliographical references.
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Onay, Aytun. "Hydrogen Storage Capacity Of Nanosystems: Molecular". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609636/index.pdf.
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In recent decades, tremendous efforts have been made to obtain high hydrogen storage capacity in a stable configuration. In the literature there are plenty of experimental works investigating different materials for hydrogen storage and their storage values. In the first part of this thesis the available literature data have been collected and tabulated. In addition to the literature survey the hydrogen storage capacity of carbon nanotubes and carbon nanotubes doped with boron nitride (CBN nanotubes) with different chirality have been investigated by performing quantum chemical methods at semiempirical and DFT levels of calculations. It has been found that boron nitrite doping increases the hydrogen storage capacity of carbon nanotubes. Single wall carbon nanotubes (SWNT) can be thought as formed by warping a single graphitic layer into a cylindrical object. SWNTs attract much attention because they have unique electronic properties,
very strong structure and high elastic moduli. The systems under study include the structures C(4,4), H2@C(4,4), C(7,0), C(4,0), and the BN doped C(4,4), H2@C(4,4), 2H2@C(4,4), C(7,0), H2@C(7,0), 2H2@C(7,0). Also, we have investigated adsorption and desorption of hydrogen molecules on BN doped coronene models by means of theoretical calculations.
Książki na temat "Thermochemistry - Chemical Hydrogen Storage"
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Energy production and storage: Inorganic chemical strategies for a warming world. Chichester, West Sussex, U.K: Wiley, 2010.
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D, DiFilippo Frank, i United States. National Aeronautics and Space Administration., red. Energy storage for a lunar base by the reversible chemical reaction, CaO+H₂O[reversal reaction]Ca(OH)₂. [Washington, D.C.]: NASA, 1990.
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Ozkar, Saim. Transition Metal Nanoparticle Catalysts in H2 Release from Hydrogen Storage Materials. Elsevier, 2021.
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Wellnitz, Joerg, Agata Godula-Jopek i Walter Jehle. Hydrogen Storage Technologies: New Materials, Transport, and Infrastructure. Wiley & Sons, Incorporated, John, 2012.
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Wellnitz, Joerg, Agata Godula-Jopek i Walter Jehle. Hydrogen Storage Technologies: New Materials, Transport, and Infrastructure. Wiley & Sons, Incorporated, John, 2012.
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Wellnitz, Joerg, Agata Godula-Jopek i Walter Jehle. Hydrogen Storage Technologies: New Materials, Transport, and Infrastructure. Wiley & Sons, Incorporated, John, 2012.
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Wellnitz, Joerg, Agata Godula-Jopek i Walter Jehle. Hydrogen Storage Technologies: New Materials, Transport, and Infrastructure. Wiley & Sons, Limited, John, 2012.
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Wellnitz, Joerg, Agata Godula-Jopek i Walter Jehle. Hydrogen Storage Technologies: New Materials, Transport, and Infrastructure. Wiley & Sons, Limited, John, 2012.
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Crabtree, Robert H. Energy Production and Storage: Inorganic Chemical Strategies for a Warming World. Wiley & Sons, Incorporated, John, 2013.
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Crabtree, Robert H. Energy Production and Storage: Inorganic Chemical Strategies for a Warming World. Wiley & Sons, Incorporated, John, 2013.
Znajdź pełny tekst źródłaCzęści książek na temat "Thermochemistry - Chemical Hydrogen Storage"
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Jurczyk, M., i M. Nowak. "Introduction to hydrogen based chemical agents for hydrogen technology". W Hydrogen Storage Materials, 486–91. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-54261-3_75.
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Schaub, Georg, Hilko Eilers i Maria Iglesias González. "Chemical Storage of Renewable Electricity via Hydrogen - Principles and Hydrocarbon Fuels as an Example". W Transition to Renewable Energy Systems, 619–28. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527673872.ch30.
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Kusada, Kohei. "Discovery of the Face-Centered Cubic Ruthenium Nanoparticles: Facile Size-Controlled Synthesis Using the Chemical Reduction Method". W Creation of New Metal Nanoparticles and Their Hydrogen-Storage and Catalytic Properties, 59–67. Tokyo: Springer Japan, 2014. http://dx.doi.org/10.1007/978-4-431-55087-7_4.
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Schulte Beerbühl, Simon, Magnus Fröhling i Frank Schultmann. "Comparison of Heuristics Towards Approaching a Scheduling and Capacity Planning MINLP for Hydrogen Storage in Chemical Substances". W Operations Research Proceedings 2013, 413–19. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07001-8_56.
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Lust, Daniel, Marcus Brennenstuhl, Robert Otto, Tobias Erhart, Dietrich Schneider i Dirk Pietruschka. "Case Study of a Hydrogen-Based District Heating in a Rural Area: Modeling and Evaluation of Prediction and Optimization Methodologies". W iCity. Transformative Research for the Livable, Intelligent, and Sustainable City, 145–81. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92096-8_10.
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AbstractBuildings are accountable for about one third of the greenhouse gas emissions in Germany. An important step toward the reduction of greenhouse gases is to decarbonize the power productions and heating systems. However, in an energy system with a high share of renewable energy sources, large shares of energy have to be stored in summer for the winter season. Chemical energy storages, in this case hydrogen, can provide these qualities and offer diverse opportunities for coupling different sectors.In this work, a simulation model is introduced which combines a PEM electrolyzer, a hydrogen compression, a high-pressure storage, and a PEM fuel cell for power and heat production. Applied on a building cluster in a rural area with existing PV modules, this system is optimized for operation as a district heating system based on measured and forecasted data. Evolutionary algorithms were used to determine the optimized system parameters.The investigated system achieves an overall heat demand coverage of 63%. However, the local hydrogen production is not sufficient to meet the fuel cell demand. Several refills of the storage tanks with delivered hydrogen would be necessary within the year studied.
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"Chemical Storage". W Hydrogen Storage Technologies, 171–96. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527649921.ch5.
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"Chemical Hydrogen Storage". W Handbook of Hydrogen Energy, 722–25. CRC Press, 2014. http://dx.doi.org/10.1201/b17226-27.
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Ertas, Ilknur E., Mehmet Yurderi, Ahmet Bulut, Mehmet S. Agirtas i Mehmet Zahmakiran. "Liquid Phase Chemical Hydrogen Storage". W Emerging Materials for Energy Conversion and Storage, 363–92. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-813794-9.00011-9.
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Semelsberger, T. A. "FUELS – HYDROGEN STORAGE | Chemical Carriers". W Encyclopedia of Electrochemical Power Sources, 504–18. Elsevier, 2009. http://dx.doi.org/10.1016/b978-044452745-5.00331-2.
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Chen, P. "Hydrogen Storage: Liquid and Chemical". W Comprehensive Renewable Energy, 144–65. Elsevier, 2012. http://dx.doi.org/10.1016/b978-0-12-819727-1.00193-x.
Pełny tekst źródłaStreszczenia konferencji na temat "Thermochemistry - Chemical Hydrogen Storage"
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Valle-Hernández, Julio, Hernando Romero-Paredes, Camilo A. Arancibia-Bulnes, Heidi I. Villafan-Vidales i Gilberto Espinosa-Paredes. "Modeling of a CeO2 thermochemistry reduction process for hydrogen production by solar concentrated energy". W SOLARPACES 2015: International Conference on Concentrating Solar Power and Chemical Energy Systems. Author(s), 2016. http://dx.doi.org/10.1063/1.4949210.
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Takahashi, Hideyuki, Takashi Mabuchi, Tsugumi Hayashi, Shun Yokoyama i Kazuyuki Tohji. "Effective hydrogen generation and resource circulation based on sulfur cycle system". W SOLAR CHEMICAL ENERGY STORAGE: SolChES. AIP, 2013. http://dx.doi.org/10.1063/1.4848095.
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Nakayama, Takato, Masakazu Matsumoto i Hideki Tanaka. "On the thermodynamic stability of hydrogen hydrates in the presence of promoter molecules". W SOLAR CHEMICAL ENERGY STORAGE: SolChES. AIP, 2013. http://dx.doi.org/10.1063/1.4848090.
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Devarakonda, Maruthi, Kriston Brooks, Ewa Ronnebro, Scot Rassat i Jamie Holladay. "Chemical Hydrides for Hydrogen Storage in Fuel Cell Applications". W SAE 2012 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2012. http://dx.doi.org/10.4271/2012-01-1229.
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Escamilla, Antonio, David Sánchez i Lourdes García-Rodríguez. "Exergy Analysis of Green Power-to-Hydrogen Chemical Energy Storage". W ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-82107.
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Abstract Power-to-Hydrogen-to-Power are chemical energy storage systems that store surplus renewable energy in the form of hydrogen, through water electrolysis, for its later use as power when power demand rises again. Due to the very low energy and mass density of H2 at standard conditions, 0.083 kg/m3, compression of hydrogen to pressures as high as 900 bar is usually performed for storage. This is why variations in the operating conditions of the electrolyzers lead to significantly different operating conditions of the hydrogen compression system. Accordingly, a detailed thermodynamic analysis is required to identify the individual contributions of each component to the total exergy losses: a proton-exchange membrane electrolyser, and a volumetric compressor. As expected, the volumetric compressor shows the largest improvement when switching from single stage compression to multistage intercooled compression; in particular, moving from single adiabatic compression to four compression stages with intercooling enables an exergy efficiency improvement of more than ≈20 %. On the other hand, the study reveals that optimizing the operating temperature and pressure of the electrolyzer can lead to compression exergy efficiency gains of ≈5 % when the operating temperature of the electrolyser is reduced from 352.15 K to 313.15 K and ≈25 % when the corresponding pressure increases from 1bar to 30 bar. On the contrary, reducing the operating temperature of the electrolyzer would lead to an increase in the power requirements to split the water molecule, thereby reducing the overall exergy efficiency of the system by ≈2 %.
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Prawiaswarra, Guta Adi Khrisnayana, Imam Prasetyo i Teguh Ariyanto. "Hydrogen storage using metal oxide loaded in polymer-derived carbon". W THE 11TH REGIONAL CONFERENCE ON CHEMICAL ENGINEERING (RCChE 2018). Author(s), 2019. http://dx.doi.org/10.1063/1.5095021.
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Jorgensen, Scott. "Engineering Hydrogen Storage Systems". W ASME 2007 2nd Energy Nanotechnology International Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/enic2007-45026.
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Increased research into the chemistry, physics and material science of hydrogen cycling compounds has led to the rapid growth of solid-phase hydrogen-storage options. The operating conditions of these new options span a wide range: system temperature can be as low as 70K or over 600K, system pressure varies from less than 100kPa to 35MPa, and heat loads can be moderate or can be measured in megawatts. While the intense focus placed on storage materials has been appropriate, there is also a need for research in engineering, specifically in containment, heat transfer, and controls. The DOE’s recently proposed engineering center of expertise underscores the growing understanding that engineering research will play a role in the success of advanced hydrogen storage systems. Engineering a hydrogen system will minimally require containment of the storage media and control of the hydrogenation and dehydrogenation processes, but an elegant system design will compensate for the storage media’s weaker aspects and capitalize on its strengths. To achieve such a complete solution, the storage tank must be designed to work with the media, the vehicle packaging, the power-plant, and the power-plant’s control system. In some cases there are synergies available that increase the efficiency of both subsystems simultaneously. In addition, system designers will need to make the hard choices needed to convert a technically feasible concept into a commercially successful product. Materials cost, assembly cost, and end of life costs will all shape the final design of a viable hydrogen storage system. Once again there is a critical role for engineering research, in this case into lower cost and higher performance engineering materials. Each form of hydrogen storage has its own, unique, challenges and opportunities for the system designer. These differing requirements stem directly from the properties of the storage media. Aside from physical containment of compressed or liquefied hydrogen, most storage media can be assigned to one of four major categories, chemical storage, metal hydrides, complex hydrides, or physisorption. Specific needs of each technology are discussed below. Physisorption systems currently operate at 77K with very fast kinetics and good gravimetric capacity; and as such, special engineering challenges center on controlling heat transfer. Excellent MLVSI is available, its cost is high and it is not readily applied to complex shape in a mass manufacture setting. Additionally, while the heat of adsorption on most physisorbents is a relatively modest 6–10kJ/mol H2, this heat must be moved up a 200K gradient. Physisorpion systems are also challenged on density. Consequently, methods for reducing the cost of producing and assembling compact, high-quality insulation, tank design to minimize heat transfer while maintaining manufacturability, improved methods of heat transfer to and from the storage media, and controls to optimize filling are areas of profitable research. It may be noted that the first two areas would also contribute to improvement of liquid hydrogen tanks. Metal hydrides are currently nearest application in the form of high pressure metal hydride tanks because of their reduced volume relative to compressed gas tanks of the same capacity and pressure. These systems typically use simple pressure controls, and have enthalpies of roughly 20kJ/mol H2 and plateau pressures of at most a few MPa. During filling, temperatures must be high enough to ensure fast kinetics, but kept low enough that the thermodynamically set plateau pressure is well below the filling pressure. To accomplish this balance the heat transfer system must handle on the order of 300kW during the 5 minute fill of a 10kg tank. These systems are also challenged on mass and the cost of the media. High value areas for research include: heat transfer inside a 35MPa rated pressure vessel, light and strong tank construction materials with reduced cost, and metals or other materials that do not embrittle in the presence of high pressure hydrogen when operated below ∼400K. The latter two topics would also have a beneficial impact on compressed gas hydrogen storage systems, the current “system to beat”. Complex hydrides frequently have high hydrogen capacity but also an enthalpy of adsorption >30kJ/mol H2, a hydrogen release temperature >370K, and in many cases multiple steps of adsorption/desorption with slow kinetics in at least one of the steps. Most complex hydrides are thermal insulators in the hydrided form. From an engineering perspective, improved methods and designs for cost effective heat transfer to the storage media in a 5 to 10MPa vessel is of significant interest, as are materials that resist embrittlement at pressures below 10MPa and temperatures below 500K. Chemical hydrides produce heat when releasing hydrogen; in some systems this can be managed with air cooling of the reactor, but in other systems that may not be possible. In general, chemical hydrides must be removed from the vehicle and regenerated off-board. They are challenged on durability and recycling energy. Engineering research of interest in these systems centers around maintaining the spent fuel in a state suitable for rapid removal while minimizing system mass, and on developing highly efficient recycling plant designs that make the most of heat from exothermic steps. While the designs of each category of storage tank will differ with the material properties, two common engineering research thrusts stand out, heat transfer and structural materials. In addition, control strategies are important to all advanced storage systems, though they will vary significantly from system to system. Chemical systems need controls primarily to match hydrogen supply to power-plant demand, including shut down. High pressure metal hydride systems will need control during filling to maintain an appropriately low plateau pressure. Complex hydrides will need control for optimal filling and release of hydrogen from materials with multi-step reactions. Even the relatively simple compressed-gas tanks require control strategies during refill. Heat transfer systems will modulate performance and directly impact cost. While issues such as thermal conductivity may not be as great as anticipated, the heat transfer system still impacts gravimetric efficiency, volumetric efficiency and cost. These are three key factors to commercial viability, so any research that improves performance or reduces cost is important. Recent work in the DOE FreedomCAR program indicates that some 14% of the system mass may be attributed to heat transfer in complex hydride systems. If this system is made to withstand 100 bar at 450K the material cost will be a meaningful portion of the total tank cost. Improvements to the basic shell and tube structures that can reduce the total mass of heat transfer equipment while maintaining good global and local temperature control are needed. Reducing the mass and cost of the materials of construction would also benefit all systems. Much has been made of the need to reduce the cost of carbon fiber in compressed tanks and new processes are being investigated. Further progress is likely to benefit any composite tank, not just compressed gas tanks. In a like fashion, all tanks have metal parts. Today those parts are made from expensive alloys, such as A286. If other structural materials could be proven suitable for tank construction there would be a direct cost benefit to all tank systems. Finally there is a need to match the system to the storage material and the power-plant. Recent work has shown there are strong effects of material properties on system performance, not only because of the material, but also because the material properties drive the tank design to be more or less efficient. Filling of a hydride tank provides an excellent example. A five minute or less fill time is desirable. Hydrogen will be supplied as a gas, perhaps at a fixed pressure and temperature. The kinetics of the hydride will dictate how fast hydrogen can be absorbed, and the thermodynamics will determine if hydrogen can be absorbed at all; both properties are temperature dependent. The temperature will depend on how fast heat is generated by absorption and how fast heat can be added or removed by the system. If the design system and material properties are not both well suited to this filling scenario the actual amount of hydrogen stored could be significantly less than the capacity of the system. Controls may play an important role as well, by altering the coolant temperature and flow, and the gas temperature and pressure, a better fill is likely. Similar strategies have already been demonstrated for compressed gas systems. Matching system capabilities to power-plant needs is also important. Supplying the demanded fuel in transients and start up are obvious requirements that both the tank system and material must be design to meet. But there are opportunities too. If the power-plant heat can be used to release hydrogen, then the efficiency of vehicle increases greatly. This efficiency comes not only from preventing hydrogen losses from supplying heat to the media, but also from the power-plant cooling that occurs. To reap this benefit, it will be important to have elegant control strategies that avoid unwanted feedback between the power-plant and the fuel system. Hydrogen fueled vehicles are making tremendous strides, as can be seen by the number and increasing market readiness of vehicles in technology validation programs. Research that improves the effectiveness and reduces the costs of heat transfer systems, tank construction materials, and control systems will play a key role in preparing advanced hydrogen storage systems to be a part of this transportation revolution.
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Huo, Qunhai, Qiran Liu, Huawei Deng, Wenyong Wang, Changli Shi i Tongzhen Wei. "Optimal Allocation of Photovoltaic-Storage-Hydrogen Capacity in Coal Chemical Industry Park". W 2023 5th Asia Energy and Electrical Engineering Symposium (AEEES). IEEE, 2023. http://dx.doi.org/10.1109/aeees56888.2023.10114361.
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Pfeiffer, W. T., L. Dedong, B. Wang i S. Bauer. "Porous Media Hydrogen Storage - Dimensioning and Induced Hydraulic, Thermal and Chemical Effects". W The Third Sustainable Earth Sciences Conference and Exhibition. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201414259.
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Keshari, Vikas, i M. P. Maiya. "Numerical Simulation of Metal Hydride Hydrogen Storage Device with Pin Fin Tube Heat Exchanger". W The 3rd World Congress on Mechanical, Chemical, and Material Engineering. Avestia Publishing, 2017. http://dx.doi.org/10.11159/htff17.126.
Pełny tekst źródłaRaporty organizacyjne na temat "Thermochemistry - Chemical Hydrogen Storage"
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Sneddon, Larry G. Amineborane Based Chemical Hydrogen Storage - Final Report. Office of Scientific and Technical Information (OSTI), kwiecień 2011. http://dx.doi.org/10.2172/1011765.
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Kauzlarich, Susan M., Phillip P. Power, Doinita Neiner, Alex Pickering, Eric Rivard, T. M. Bobby Ellis, A. Merrill Atkins, R. Wolf i Julia Wang. LANL Virtual Center for Chemical Hydrogen Storage: Chemical Hydrogen Storage Using Ultra-high Surface Area Main Group Materials. Office of Scientific and Technical Information (OSTI), wrzesień 2010. http://dx.doi.org/10.2172/1053997.
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McClaine, Andrew W. Chemical Hydride Slurry for Hydrogen Production and Storage. Office of Scientific and Technical Information (OSTI), wrzesień 2008. http://dx.doi.org/10.2172/940573.
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Ott, Kevin C. Chemical hydrogen storage: measurements and rapid throughput needs and opportunities. Office of Scientific and Technical Information (OSTI), listopad 2008. http://dx.doi.org/10.2172/1254943.
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Hawthorne, M. Frederick, Satish S. Jalisatgi, Alexander V. Safronov, Han Beak Lee i Jianguo Wu. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes. Office of Scientific and Technical Information (OSTI), październik 2010. http://dx.doi.org/10.2172/990217.
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Ott, Kevin, Sue Linehan, Frank Lipiecki i Christopher L. Aardahl. Down Select Report of Chemical Hydrogen Storage Materials, Catalysts, and Spent Fuel Regeneration Processes. Office of Scientific and Technical Information (OSTI), sierpień 2008. http://dx.doi.org/10.2172/950188.
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Ott, Kevin C., Sue Linehan, Frank Lipiecki i Aardahl L. Christopher. Down Select Report of Chemical Hydrogen Storage Materials, Catalysts, and Spent Fuel Regeneration Processes - May 2008. Office of Scientific and Technical Information (OSTI), maj 2008. http://dx.doi.org/10.2172/1219598.
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Bran Anleu, Gabriela, Michael Kimble i Daniel Carr. Efficient and Safe Hydrogen Refueling of Fuel Cell Vehicles from an Emergency Chemical Hydride Storage Source. Office of Scientific and Technical Information (OSTI), wrzesień 2021. http://dx.doi.org/10.2172/1821784.
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Moreno, Oscar. Final Technical Report for GO15056 Millennium Cell: Development of an Advanced Chemical Hydrogen Storage and Generation System. Office of Scientific and Technical Information (OSTI), luty 2017. http://dx.doi.org/10.2172/1344385.
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Weaver, R., i J. Ogborn. CGX-00-005 Cellulosic-Covered Electrode Storage - Influence on Welding Performance and Weld Properties. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), styczeń 2005. http://dx.doi.org/10.55274/r0011816.
Pełny tekst źródłaStreszczenie:
Cellulosic-covered electrodes have been used for shielded metal arc welding (SMAW) circumferential welding of line pipe over many decades. They are characterized by electrode coverings containing organic matter. Unlike low hydrogen SMAW electrodes that achieve optimum results at low covering moisture levels, cellulosic-covered electrodes require much higher covering moisture levels for proper operation. For example, pipe welders have been known to deliberately expose electrodes to the weather, or even dip them in water prior to use. There are suggestions that high incidents of hydrogen assisted cracking (HAC) might be associated with low moisture levels in the cellulosic-covered electrodes used. This suggests further that storage and handling practices based on conventional wisdom in the field may not be sufficient as the industry transitions to more demanding applications and higher-strength materials. Consequently, this work was undertaken to develop more definitive information on the performance of cellulosic-covered electrodes for three purposes: � determine the influence of various storage and handling practices on electrode covering moisture, � determine the influence of covering moisture on electrode operability, weld metal chemical composition, and weld hardness, and � develop more definitive guidelines for cellulosic-covered electrode storage and handling practice. Three different E8010 type electrodes (one E8018-G and two E8018-P1) were subjected to various storage conditions - temperatures from -40�C (-40�F) to 66�C (150�F), and time periods up to 196 hours. As the temperature increased there was a tendency for lower electrode covering moisture levels with corresponding increases in weld metal alloy content (particularly Mn, Si, and Ti), increased weld hardness, increased weld strength, and higher tendency to HAC. Variations in electrode operation were also noted.