DOCSLIB.ORG

Mechanical Synthesis of Magnesium Alloys for Hydrogen Storage

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mechanical Synthesis of Magnesium Alloys for Hydrogen Storage MECHANICAL SYNTHESIS OF MAGNESIUM ALLOYS FOR HYDROGEN STORAGE by Luis Felipe Contreras Vásquez A thesis submitted to The University of Birmingham For the degree of DOCTOR OF PHILOSOPHY School of Metallurgy and Materials College of Engineering and Physical Sciences University of Birmingham September 2017 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. SYNOPSIS Synthesis, characterisation and hydrogen sorption properties of a variety of magnesium based hydrides were investigated in this work. The structure of these composites was studied using X-ray diffraction (XRD) and Raman spectroscopy. The thermal stability and decomposition reactions of the Mg-based hydrides was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), coupled with a mass spectrometer (MS) to determine the gaseous products released during heating. Compositional changes and reversibility were investigated in detail using in-situ XRD under Ar and H2. Mechanical milling of magnesium hydride (MgH2) under Ar and H2 resulted in a reduction of the crystallite size from 207 nm for the as received to 18 nm for 10 h milled MgH2. For the first time was reported the effect of Raman spectroscopy on milled MgH2 demonstrating that milled samples were Raman active. Hydrogen desorption temperatures were decreased ~120 °C (DSC) with increasing milling time (10 h), however, hydrogen capacity was decreased ~6.55 wt. % (TGA). Hydrogenation of Li-Mg alloy was investigated via reactive milling in 100 bar H2, after 1 h milling Li-Mg phase was hydrogenated forming LiH and MgH2. Hydrogen desorption was observed at 250 °C (DSC), releasing 0.19 wt. % (TGA). Although, the desorption temperature was decreased, the amount of hydrogen released is insignificant and is hard to consider for on- board applications. Mechanical milling of sodium hydride (NaH) and magnesium hydride (MgH2) under Ar and H2 lead to the formation of sodium magnesium ternary hydride (NaMgH3). Thermal decomposition occurred at ~ 325 °C with a mass change of 5 wt. %, associated with the evolution of hydrogen. Hydrogen desorption occurred in two-step reactions. Rehydrogenation of the NaMgH3 hydride was observed at 250 °C and 10 bar H2. Mechanical milling of lithium hydride (LiH) substituted into NaMgH3 hydride resulted in the formation of a quaternary LixNa1-xMgH3 hydride with molar compositions (x=0, 0.2, 0.5, 0.8). Thermal decomposition started at 250 °C, releasing a total amount of 5 wt% of H2. Decomposition reactions occurred in two and three steps. Furthermore, reversibility of the main phase was achieved at 250 °C and 10 bar H2. Milling calcium hydride (CaH2) and MgH2 lead to the formation of calcium magnesium (Ca- Mg-H) ternary hydride. Hydrogen sorption characteristics showed a dehydrogenation temperature of 325 °C (DSC) with a total amount of 2.24 wt.% H2 evolution up to 500 °C. However, dehydrogenation of CaH2 was not completed even at 500 °C. Thermal decomposition suggested two steps reactions. Reversibility was successfully achieved at 365 °C and 10 bar H2. LiH and NaH were substituted into the Ca-Mg-H to form quaternary hydrides with composition MxCa1-xMgH4. Hydrogen sorption properties showed desorption temperatures between 300 °C and 385°C with a maximum of 3.5 wt.% H2 released. Thermal decomposition proceeded in three-step reaction. Nonetheless, complete dehydrogenation was not achieved. Overall, this investigation has demonstrated for a variety of Mg-based hydrides that reducing crystallite size has a positive effect in the sorption properties, unfortunately, none of the materials and composites investigated in this work meet the targets for light-duty vehicles set out by the Department of Energy (DoE). However, other applications such as heat storage might be of interest. ACKNOWLEDGEMENTS First of all, I would like to thank Almighty GOD for the opportunity to be at this stage of my life, successfully accomplishing one more goal, embarking into a new dream. Thank you for the wisdom, perseverance, love and faith given through Jesus Christ and the Holy Spirit to walk firmly and not tumble. All the Glory Must be to The Lord. Special thanks dedicated to you my beloved wife, for your patience, love, support, and sacrifices. For leaving everything and everyone behind, to help me to accomplish this degree. I can certainly say that without you by my side, I would not be able to be where I am now. Thank you for giving me the best gift one can dream of, a beautiful angel that completely changed my perception of what life is. I love you both, and I am grateful for the time, love and laughs shared with me during these years. I am blessed to have you. Thank you to my family for the love, support, and prayers. You encouraged me to keep going forward no matter what, backed me up as a family and showed me the importance of having GOD in my life. Thank you to my supervisor Professor David Book for his guidance and support on every stage of this work and for the opportunity to be part of the Hydrogen group at the University of Birmingham. Thank you to Dr. Reed, Mr. Simon Cannon, Dr. Joshua Vines, Dr. Luke Hughes, Dr. Sheng Guo and all my fellows at hydrogen group, for their help and share knowledge of the equipment. Thank you for all the food shared during our social hours. I also would like to extend my thanks to the Government of Ecuador through the SENESCYT for the grant awarded to study my postgraduate degree at the University of Birmingham. CONTENTS 1. INTRODUCTION ................................................................................................................ 1 1.1 Introduction ..................................................................................................................... 1 1.2 Hydrogen as Energy vector ............................................................................................. 3 1.3 Hydrogen Storage ............................................................................................................ 8 1.3.1 Physical-based storage ................................................................................................. 13 1.3.1.1 Compressed Gas Hydrogen Storage ...................................................................... 13 1.3.2 Material-based Storage ................................................................................................ 15 1.3.2.1 Physisorption ......................................................................................................... 15 1.3.2.3 Complex Hydrides................................................................................................. 16 1.3.2.4 Metal hydrides ....................................................................................................... 17 1.4 Summary ............................................................................................................................. 21 2. Mg-BASED HYDRIDES ..................................................................................................... 24 2.1 Introduction ........................................................................................................................ 24 2.2 Mg/MgH2 Structures ........................................................................................................... 25 2.3 Hydrogen Storage Properties .............................................................................................. 27 2.3.1 Kinetics ........................................................................................................................ 27 2.3.1.1 Effect of Microstructural Modification ................................................................. 27 2.3.1.2 Catalysis and additives .......................................................................................... 28 2.3.2 Thermodynamic behaviour .......................................................................................... 30 2.3.3 Ternary Hydrides ......................................................................................................... 34 2.3.3.1 Na-Mg-H (Sodium Magnesium Hydride) ............................................................. 35 2.3.3.2 Ca-Mg-H (Calcium Magnesium Hydrides)........................................................... 37 2.3.3.3 Li-Mg-H (Lithium Magnesium Hydrides) ............................................................ 38 2.3.4 Destabilisation of ternary hydrides by light-weight metals substitution. .................... 40 2.3.4.1 Li substitution into Na-Mg-H hydride .................................................................. 40 2.3.4.2 Li and Na substitution into Ca-Mg-H hydrides ..................................................... 42 2.4 Magnesium-based hydrides applications. ........................................................................... 42 2.5 Summary ............................................................................................................................. 44 2.6 Aims and Objectives ..........................................................................................................
Load more

Recommended publications
  • Hydrogen Generation from Magnesium Hydride by Using Organic Acid Yen-Hsi Ho University of Wisconsin-Milwaukee
    University of Wisconsin Milwaukee UWM Digital Commons Theses and Dissertations August 2013 Hydrogen Generation from Magnesium Hydride By Using Organic Acid Yen-Hsi Ho University of Wisconsin-Milwaukee Follow this and additional works at: https://dc.uwm.edu/etd Part of the Mechanical Engineering Commons, and the Oil, Gas, and Energy Commons Recommended Citation Ho, Yen-Hsi, "Hydrogen Generation from Magnesium Hydride By Using Organic Acid" (2013). Theses and Dissertations. 286. https://dc.uwm.edu/etd/286 This Thesis is brought to you for free and open access by UWM Digital Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UWM Digital Commons. For more information, please contact [email protected]. HYDROGEN GENERATION FROM MAGNESIUM HYDRIDE BY USING ORGANIC ACID by Yen-Hsi Ho A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering at The University of Wisconsin-Milwaukee August 2013 ABSTRACT HYDROGEN GENERATION FROM MAGNESIUM HYDRIDE BY USING ORGANIC ACID by Yen-Hsi Ho The University of Wisconsin-Milwaukee, 2013 Under the Supervision of Professor Tien-Chien Jen In this paper, the hydrolysis of solid magnesium hydride has been studied with the high concentration of catalyst at the varying temperature. An organic acid (acetic acid, CH3COOH) has been chosen as the catalyst. The study has three objectives: first, using three different weights of MgH2 react with aqueous solution of acid for the hydrogen generation experiments. Secondly, utilizing acetic acid as the catalyst accelerates hydrogen generation. Third, emphasizing the combination of the three operating conditions (the weight of MgH2, the concentration of acetic acid, and the varying temperature) influence the amount of hydrogen generation.
    [Show full text]
  • Mechanochemical Synthesis of Hydrogen-Storage Materials Based on Aluminum, Magnesium and Their Compounds Ihor Z
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Mechanochemical synthesis of hydrogen-storage materials based on aluminum, magnesium and their compounds Ihor Z. Hlova Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Materials Science and Engineering Commons, Mechanics of Materials Commons, and the Oil, Gas, and Energy Commons Recommended Citation Hlova, Ihor Z., "Mechanochemical synthesis of hydrogen-storage materials based on aluminum, magnesium and their compounds" (2015). Graduate Theses and Dissertations. 14573. https://lib.dr.iastate.edu/etd/14573 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Mechanochemical synthesis of hydrogen-storage materials based on aluminum, magnesium and their compounds by Ihor Z. Hlova A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Materials Science and Engineering Program of Study committee: Vitalij K. Pecharsky, Major Professor Karl A. Gschneidner, Jr. Marek Pruski Duane Johnson Scott Chumbley Iowa State University Ames, Iowa 2015 Copyright © Ihor Z. Hlova, 2015. All rights reserved. ii
    [Show full text]
  • Hydrogen Embrittlement of Magnesium and Magnesium Alloys: a Review Mariano Kappes,A,B,∗ Mariano Iannuzzi,A,Z and Ricardo M
    C168 Journal of The Electrochemical Society, 160 (4) C168-C178 (2013) 0013-4651/2013/160(4)/C168/11/$31.00 © The Electrochemical Society Hydrogen Embrittlement of Magnesium and Magnesium Alloys: A Review Mariano Kappes,a,b,∗ Mariano Iannuzzi,a,z and Ricardo M. Carranzab aNational Center for Education and Research on Corrosion and Materials Performance (NCERCAMP), The University of Akron, Akron, Ohio 44325, USA bComision´ Nacional de Energ´ıa Atomica,´ Instituto Sabato (UNSAM/CNEA), Buenos Aires 1650, Argentina Magnesium and magnesium alloys are susceptible to stress corrosion cracking in various environments, including distilled water. There is compelling evidence to conclude that SCC is assisted, at least in part, by hydrogen embrittlement. This paper reviews the thermodynamics of the Mg-H system and the kinetics of hydrogen transport. Aspects of magnesium corrosion relevant to hydrogen absorption are also discussed. Crack growth mechanisms based on delayed hydride cracking, hydrogen adsorption dislocation emission, hydrogen enhanced decohesion, and hydrogen enhanced localized plasticity have been proposed and evidence for each of them is reviewed herein. © 2013 The Electrochemical Society. [DOI: 10.1149/2.023304jes] All rights reserved. Manuscript submitted October 22, 2012; revised manuscript received January 16, 2013. Published February 26, 2013. Pure magnesium is inherently susceptible to stress corrosion crack- The nucleation and growth of MgH2 during exposure of magne- 1–3 ing (SCC) and many of its alloys suffer SCC in environments con- sium to gaseous H2 at high pressure and temperature (∼5MPaand sidered innocuous for most other engineering alloys, e.g. distilled ∼300–400◦C) has been extensively studied29–32 due to its application water.4,5 In order to prevent SCC, some authors suggest that the ap- as a solid state hydrogen storage medium.
    [Show full text]
  • Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed
    Crystals 2012, 2, 1410-1433; doi:10.3390/cryst2041410 OPEN ACCESS crystals ISSN 2073-4352 www.mdpi.com/journal/crystals Review Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed Thirugnasambandam G. Manivasagam 1,*, Kamil Kiraz 1 and Peter H. L. Notten 1,2 1 Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, MB Eindhoven 5600, The Netherlands; E-Mails: [email protected] (K.K.); [email protected] (P.H.L.N.) 2 Department of Electrical Engineering, Eindhoven University of Technology, MB Eindhoven 5600, The Netherlands * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +31-40-247-2369; Fax: +31-40-247-3481. Received: 18 April 2012; in revised form: 30 July 2012 / Accepted: 10 August 2012 / Published: 15 October 2012 Abstract: As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal- hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g) of reversibly stored hydrogen in MgyTM(1-y)Hx (TM: Sc, Ti) has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content.
    [Show full text]
  • 2020 Emergency Response Guidebook
    2020 A guidebook intended for use by first responders A guidebook intended for use by first responders during the initial phase of a transportation incident during the initial phase of a transportation incident involving hazardous materials/dangerous goods involving hazardous materials/dangerous goods EMERGENCY RESPONSE GUIDEBOOK THIS DOCUMENT SHOULD NOT BE USED TO DETERMINE COMPLIANCE WITH THE HAZARDOUS MATERIALS/ DANGEROUS GOODS REGULATIONS OR 2020 TO CREATE WORKER SAFETY DOCUMENTS EMERGENCY RESPONSE FOR SPECIFIC CHEMICALS GUIDEBOOK NOT FOR SALE This document is intended for distribution free of charge to Public Safety Organizations by the US Department of Transportation and Transport Canada. This copy may not be resold by commercial distributors. https://www.phmsa.dot.gov/hazmat https://www.tc.gc.ca/TDG http://www.sct.gob.mx SHIPPING PAPERS (DOCUMENTS) 24-HOUR EMERGENCY RESPONSE TELEPHONE NUMBERS For the purpose of this guidebook, shipping documents and shipping papers are synonymous. CANADA Shipping papers provide vital information regarding the hazardous materials/dangerous goods to 1. CANUTEC initiate protective actions. A consolidated version of the information found on shipping papers may 1-888-CANUTEC (226-8832) or 613-996-6666 * be found as follows: *666 (STAR 666) cellular (in Canada only) • Road – kept in the cab of a motor vehicle • Rail – kept in possession of a crew member UNITED STATES • Aviation – kept in possession of the pilot or aircraft employees • Marine – kept in a holder on the bridge of a vessel 1. CHEMTREC 1-800-424-9300 Information provided: (in the U.S., Canada and the U.S. Virgin Islands) • 4-digit identification number, UN or NA (go to yellow pages) For calls originating elsewhere: 703-527-3887 * • Proper shipping name (go to blue pages) • Hazard class or division number of material 2.
    [Show full text]
  • Magnesium Hydride for Energy Storage Applications: the Kinetics of Dehydrogenation Under Different Working Conditions
    Magnesium hydride for energy storage applications: The kinetics of dehydrogenation under different working conditions Antonio Perejóna,b,*, Pedro E. Sánchez-Jiméneza, José M. Criadoa, Luis A. Pérez- Maquedaa,* aInstituto de Ciencia de Materiales de Sevilla, (C.S.I.C.-Univ. Sevilla). C. Américo Vespucio 49, Sevilla 41092. Spain bDepartamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla 41071, Spain *Corresponding authors: [email protected] Instituto de Ciencia de Materiales de Sevilla (C.S.I.C.-Univ. Sevilla). C. Américo Vespucio 49, Sevilla 41092. Spain Tel. (+34) 95 448 95 00 Fax (+34) 95 446 01 65 [email protected] Instituto de Ciencia de Materiales de Sevilla (C.S.I.C.-Univ. Sevilla). C. Américo Vespucio 49, Sevilla 41092. Spain Tel. (+34) 95 448 95 48 Fax (+34) 95 446 01 65 1 Magnesium hydride for energy storage applications: The kinetics of dehydrogenation under different working conditions Antonio Perejóna,b,*, Pedro E. Sánchez-Jiméneza, José M. Criadoa, Luis A. Pérez- Maquedaa,* aInstituto de Ciencia de Materiales de Sevilla (C.S.I.C.-Univ. Sevilla). C. Américo Vespucio 49, Sevilla 41092. Spain bDepartamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla 41071, Spain Abstract A new approach to the kinetics of magnesium hydride dehydrogenation is considered. A model able to predict the dehydrogenation under different experimental conditions has been proposed. A new combined kinetic analysis method, which considers the thermodynamic of the process according to the microreversibility principle, has been used for performing the kinetic analysis of data obtained under different thermal schedules at hydrogen pressures ranging from high vacuum up to 20 bar.
    [Show full text]
  • Metal Hydride Materials for Solid Hydrogen Storage: a Reviewଁ
    International Journal of Hydrogen Energy 32 (2007) 1121–1140 www.elsevier.com/locate/ijhydene Review Metal hydride materials for solid hydrogen storage: A reviewଁ Billur Sakintunaa,∗, Farida Lamari-Darkrimb, Michael Hirscherc aGKSS Research Centre, Institute for Materials Research, Max-Planck-Str. 1, Geesthacht D-21502, Germany bLIMHP-CNRS (UPR 1311), Université Paris 13, Avenue J. B. Clément, 93430 Villetaneuse, France cMax-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany Received 31 July 2006; received in revised form 21 November 2006; accepted 21 November 2006 Available online 16 January 2007 Abstract Hydrogen is an ideal energy carrier which is considered for future transport, such as automotive applications. In this context storage of hydrogen is one of the key challenges in developing hydrogen economy. The relatively advanced storage methods such as high-pressure gas or liquid cannot fulfill future storage goals. Chemical or physically combined storage of hydrogen in other materials has potential advantages over other storage methods. Intensive research has been done on metal hydrides recently for improvement of hydrogenation properties. The present review reports recent developments of metal hydrides on properties including hydrogen-storage capacity, kinetics, cyclic behavior, toxicity, pressure and thermal response. A group of Mg-based hydrides stand as promising candidate for competitive hydrogen storage with reversible hydrogen capacity up to 7.6 wt% for on-board applications. Efforts have been devoted to these materials to decrease their desorption temperature, enhance the kinetics and cycle life. The kinetics has been improved by adding an appropriate catalyst into the system and as well as by ball-milling that introduces defects with improved surface properties.
    [Show full text]
  • Lithium, Sodium and Potassium Magnesiate Chemistry: a Structural
    Lithium, Sodium and Potassium Magnesiate Chemistry: A Structural Overview Antonio J. Martínez-Martínez and Charles T. O’Hara WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK Until recently, deprotonative metalation reactions have been performed using organometallic compounds that contain only a single metal (e.g., organolithium reagents). Since the turn of the millennium, bimetallic compounds such as alkali metal magnesiates have begun to emerge as a new class of complementary metalating reagents. These have many benefits over traditional lithium compounds, including their enhanced stability at ambient temperatures, their tolerance of reactive functional groups and their stability in common reaction solvents. In recent years lots of attention has been focused on understanding the structure of alkali metal magnesiates in an effort to maximize synthetic efficiency and thus shed insight into approaches for future rational design. In this chapter, the diverse structural chemistry of alkali metal magnesiate compounds reported since 2007 will be summarized. KEY WORDS: Lithium, Sodium, Potassium, Magnesium, Magnesiate, X-ray Crystallography, Inverse Crowns 1.1 Introduction 1.2 Lithium magnesiate complexes 1.2.1 Alkyl/Aryl lithium magnesiate complexes 1.2.2 Amido lithium magnesiate complexes 1.2.3 Heteroleptic lithium magnesiate complexes 1.3 Sodium magnesiate complexes 1.3.1 Donor-free homo- and heteroleptic sodium magnesiate complexes 1.3.2 Introducing donors to sodium magnesiate
    [Show full text]
  • Reactivity of a Ruthenium Bis(Dinitrogen) Complex
    Reactivity of a Ruthenium Bis(Dinitrogen) Complex By Samantha Lau July 2018 Department of Chemistry Imperial College London A thesis submitted for Doctorate of Philosophy Declaration of Originality The work discussed in this thesis was conducted in the Department of Chemistry, Imperial College London, between October 2014 and April 2018. Unless stated otherwise, all the work is entirely my own and has not been submitted for a previous degree at this, or any other university. Copyright Declaration The copyright of this thesis rests with the author and is made available under a Creative Commons Attribution Non-Commercial No Derivatives licence. Researchers are free to copy, distribute or transmit the thesis on the condition that they attribute it, that they do not use it for commercial purposes and that they do not alter, transform or build upon it. For any reuse or redistribution, researchers must make clear to others the licence terms of this work. [1] Abstract This thesis investigated the reactivity of the ruthenium bis(dinitrogen) complex [Ru(H)2(N2)2(PCy3)2] 2 (1), an analogue of the ruthenium bis(dihydrogen) complex [Ru(H)2(η -H2)2(PCy3)2]. It was demonstrated that 1 was able to effect the sp2C–X (X= H, O) bond cleavage of acetophenone substrates to generate 5-membered organometallic intermediates. The by-products from the C–O cleavage reactions were identified as alcohols which also react with 1 at a faster or equal rate to the substrates. The mechanism of these C–X cleavage reactions were probed experimentally and computationally to show that the C–H bond cleavage pathway was operating through a σ-complex assisted metathesis pathway whereas the C–O cleavage pathway was operating through a Ru(II)/Ru(IV) redox mechanism.
    [Show full text]
  • Magnesium Hydride for Energy Storage Applications: the Kinetics of Dehydrogenation Under Different Working Conditions
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by idUS. Depósito de Investigación Universidad de Sevilla Magnesium hydride for energy storage applications: The kinetics of dehydrogenation under different working conditions Antonio Perejóna,b,*, Pedro E. Sánchez-Jiméneza, José M. Criadoa, Luis A. Pérez- Maquedaa,* aInstituto de Ciencia de Materiales de Sevilla (C.S.I.C.-Univ. Sevilla). C. Américo Vespucio 49, Sevilla 41092. Spain bDepartamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla 41071, Spain Abstract A new approach to the kinetics of magnesium hydride dehydrogenation is considered. A model able to predict the dehydrogenation under different experimental conditions has been proposed. A new combined kinetic analysis method, which considers the thermodynamic of the process according to the microreversibility principle, has been used for performing the kinetic analysis of data obtained under different thermal schedules at hydrogen pressures ranging from high vacuum up to 20 bar. The kinetic analysis shows that the dehydrogenation mechanism of magnesium hydride depends on the experimental conditions. Thus, the reaction follows a first order kinetics, equivalent to an Avarmi-Erofeev kinetic model with an Avrami coefficient equal to 1, when carried out under high vacuum, while a mechanism of tridimensional growth of nuclei previously formed (A3) is followed under hydrogen pressure. An explanation of the change of mechanism is given. It has been shown that the activation energy is closed to the Mg-H bond breaking energy independently of the hydrogen pressure surrounding the sample, which suggests that the breaking of this bond would be the rate limiting step of the process.
    [Show full text]
  • Soluble Magnesium Hydrides, Method of Preparing Them, and Use Thereof
    Europaisches Patentamt 0 299 352 European Patent Office 00 Publication number: A2 Office europeen des brevets EUROPEAN PATENT APPLICATION © Application number: 88110824.5 © intCl/hCOIB 6/04 © Date of filing: 07.07.88 © Priority: 11.07.87 DE 3722993 © Applicant: Studiengesellschaft Kohle mbH Kaiser-Wilhelm-Platz 1 @ Date of publication of application: D-4330 MUIheim/Ruhr(DE) 18.01.89 Bulletin 89/03 © Inventor: Bogdanovic, Borislav ® Designated Contracting States: Kaiser-Wilhelm-Platz 1 AT BE CH DE ES FR GB IT LI LU NL D-4330 Mu!heim/Ruhr(DE) Inventor: Schwickardi, Manfred Kaiser-Wilhelm-Platz 1 D-4330 Mulheim/Ruhr(DE) © Representative: von Kreisler, Alek, Dipl.-Chem. et al Patentanwaite Von Kreisler-Selting-Werner Deichmannhaus am Hauptbahnhof D-5000K6ln 1(DE) © Soluble magnesium hydrides, method of preparing them, and use thereof. © Organic-solvent soluble magnesium hydrides of the formulas M < CM W CO O> O) CM LU Xerox Copy Centre EP 0 299 352 A2 ' (MgH2)n MgQ (ID ' (MgH2)n RM9* (III) ' (MgH2)n Mg/Qj (IV) ^.ngx (MgH-)_ • ( (V) • (MgH2)n /Tn^*R <vi> • (MgH2)n MQnX3_. (VII) • and (MgH2)n ^jj^ ■*,_. (VIID are prepared by catalytically hydrogenating finely powdered magnesium, optionally in the presence of a magnesium halide, in an organic solvent in the presence of their MgH2-free counterparts in which Q is an alkyl, alkenyl, alkoxy, dialkylamide, aralkyl, aryl or diarylamide group, each with up to 18 carbon atoms. R is an alkenyl, aralkyl or aryl group, each with up to 18 carbon atoms, X is chlorine, bromine, or iodine, E~*b -* is a chelating ligand, E is -CH2, -N(R)- or -O-, ^ is an alkylene radical of the formula -(CH2)P, D is a dialkylamide, diarylamide or alkoxy group, each with up to 18 carbon atoms, M is aluminum or boron, m is 1 , 2, or 3, and 1 < n £ 50.
    [Show full text]
  • Magnesium and Zinc Hydride Complexes Intemann, Julia
    University of Groningen Magnesium and zinc hydride complexes Intemann, Julia IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2014 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Intemann, J. (2014). Magnesium and zinc hydride complexes: From fundamental investigations to potential applications in hydrogen storage and catalysis. [S.n.]. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license. More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne- amendment. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 07-10-2021 Magnesium and Zinc Hydride Complexes From Fundamental Investigations to Potential Applications in Hydrogen Storage and Catalysis Julia Intemann The work described in this thesis was performed at the Faculty for Chemistry at the University of Duisburg-Essen, Germany, the Stratingh Institute for Chemistry at the University of Groningen, The Netherlands and at the Department of Chemistry and Pharmacy at the Friedrich-Alexander University Erlangen-Nürnberg, Germany.
    [Show full text]