Hydrogen Storage Materials

The Characterisation of Their Storage Properties

verfasst von: Darren P. Broom

Verlag: Springer London

Buchreihe : Green Energy and Technology

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

The problem of storing hydrogen safely and effectively is one of the major technological barriers currently preventing the widespread adoption of hydrogen as an energy carrier and the subsequent transition to a so-called hydrogen economy. Practical issues with the storage of hydrogen in both gas and liquid form appear to make reversible solid state hydrogen storage the most promising potential solution. Hydrogen Storage Materials addresses the characterisation of the hydrogen storage properties of the materials that are currently being considered for this purpose.

The background to the topic is introduced, along with the various types of materials that are currently under investigation, including nanostructured interstitial and complex hydrides, and porous materials, such as metal-organic frameworks and microporous organic polymers. The main features of Hydrogen Storage Materials include:

an overview of the different types of hydrogen storage materials and the properties that are of interest for their practical use;descriptions of the gas sorption measurement methods used to determine these properties, and the complementary techniques that can be used to help corroborate hydrogen uptake data; andextensive coverage of the practical considerations for accurate hydrogen sorption measurement that drive both instrument design and the development of experimental methodology.

Hydrogen Storage Materials provides an up-to-date overview of the topic for experienced researchers, while including enough introductory material to serve as a useful, practical introduction for newcomers to the field.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

A major technological barrier currently preventing the proposed transition to a “hydrogen economy” is the storage of hydrogen for use as an energy carrier. There are various methods available, but none of these can currently achieve the required storage densities. The use of a reversible solid state hydrogen storage material, however, is one of the most promising potential solutions to this problem. In this opening chapter, we will look at some of the background to this topic, including the use of hydrogen as an energy carrier, the barriers to the widespread use of hydrogen energy in transportation technology, the different methods that can be used for the storage of hydrogen and the use of solid state media. We will then introduce the measurement methods for hydrogen uptake determination and some of the complementary characterisation techniques that can be used. We also discuss the reasons why the accurate characterisation of the storage properties of a material is an important and high profile topic. We will close the chapter by defining some of the terminology used throughout the book.

Darren P. Broom

Chapter 2. Potential Storage Materials

Abstract

This chapter presents an overview of the various materials that are currently being considered as potential solid state storage media. We concentrate on the physical and chemical properties of the materials relevant for the characterisation of their hydrogen storage properties and their practical use in storage devices, as opposed to the materials synthesis methods. The chapter looks first at microporous materials, including activated and nanostructured carbons, zeolites, organic microporous polymers and metal-organic frameworks. Secondly, we cover the alloys and intermetallic compounds that form interstitial hydrides at practical storage temperatures and hydrogen pressures. The complex hydrides, including alanates and lithium-based materials, such as LiNH₂ and LiBH₄, are then discussed before concluding with a look at some materials that do not fit readily into the above categories.

Darren P. Broom

Chapter 3. Hydrogen Sorption Properties of Materials

Abstract

In this chapter we examine the hydrogen sorption properties of materials, considering both the parameters that are of prime practical engineering importance, and the thermodynamic and kinetic properties of interest for future materials development. We begin with the practical storage properties, such as the reversible storage capacity, including definitions of the gravimetric and volumetric capacities and the total and excess adsorption for adsorptive hydrogen storage, the long term cycling stability, gaseous impurity resistance, and the ease of activation. The thermodynamic properties, including the enthalpy of molecular hydrogen adsorption and the enthalpy of hydride formation or decomposition are then covered. We then discuss the kinetics of hydrogen adsorption and absorption, including parameters such as the activation energy, hydrogen diffusion coefficient and the apparent rates of absorption or desorption, which can be used to characterise the time-dependent sorption and desorption properties of materials. The latter part of the chapter then considers both equilibrium and kinetic models that can be used to describe experimental data.

Darren P. Broom

Chapter 4. Gas Sorption Measurement Techniques

Abstract

In this chapter we introduce the main gas sorption techniques applied to the characterisation of the hydrogen sorption properties of potential hydrogen storage materials. We begin with volumetric techniques, with a focus on the commonly used manometric (Sieverts’) method, but also cover some of the alternative approaches, such as the flowing and differential volumetric methods. We then describe the gravimetric technique, including a discussion of vacuum microbalances and the requirements for high pressure hydrogen operation. Thermal desorption techniques are then covered, including Thermogravimetric Analysis (TGA) and Thermal Desorption Spectroscopy (TDS), in which the temperature-programmed desorption of hydrogen can be detected in a number of ways, including quadrupole mass spectrometry. The chapter concludes with a practical comparison of the different gas sorption measurement techniques.

Darren P. Broom

Chapter 5. Complementary Characterisation Techniques

Abstract

In this chapter we cover some of the common complementary techniques used for hydrogen storage material characterisation. We begin with thermal analysis and calorimetry, which can be used to determine the thermodynamic properties that can also be measured using hydrogen sorption techniques, as well as activation energies and characteristic temperatures of absorption and desorption. Gas adsorption methods, such as BET (Brunauer–Emmett–Teller) surface area measurement and DFT (Density Functional Theory) based pore size distribution determination, are commonly used to characterise the properties of porous hydrogen adsorbents and so these are then covered, with a focus on the data analysis methods used in each case. We then consider neutron and X-ray powder diffraction and small angle scattering, which can complement hydrogen sorption measurements for both hydrides and porous adsorbents. Different types of spectroscopy are then covered including Inelastic Neutron Scattering (INS), proton (¹H) Nuclear Magnetic Resonance (NMR) and Variable Temperature Infrared (VTIR) spectroscopy. A number of other techniques that do not fit readily into the above categories are also briefly covered.

Darren P. Broom

Chapter 6. Experimental Considerations

Abstract

In this chapter, we discuss many of the practical issues that can affect the accuracy of gas phase hydrogen sorption measurement techniques. We begin with some relevant properties of gaseous hydrogen, such as the description of its compressibility as a function of temperature and pressure, the Joule–Thomson effect, thermal conductivity and the gas purity. We then cover some of the properties of materials that can affect hydrogen sorption measurement, including our knowledge of the sample volume, density and mass, the sensitivity of materials to air and moisture, the history and purity of samples, and gaseous impurity gettering. General instrumentation issues, such as the vacuum and pressure handling capability of apparatus, its thermal stability and homogeneity, and the accuracy of pressure and temperature measurement, are then discussed. Two aspects of experimental measurement methodology, namely sample degassing and activation, and equilibration times, are then covered. The last three sections of the chapter then discuss a series of issues that can affect the volumetric, gravimetric and thermal desorption methods, respectively.

Darren P. Broom

Chapter 7. Concluding Remarks

Abstract

In this concluding chapter we firstly discuss interlaboratory studies, which can be used to demonstrate the reproducibility of a measurement technique, or to compare the results of different techniques, and hence to assess the accuracy of the characterisation process. In particular, we discuss the results of a recent relevant interlaboratory study on hydrogen adsorption. We then discuss reference materials, which can be used to characterise and corroborate both sorption instrument performance and experimental methodology, before describing some provisional measurement guidelines, which provide both a guide to best practice in hydrogen sorption measurement and serve as a useful practical summary of the discussion of the experimental considerations in Chap. 6. We conclude by emphasising the importance of future research into hydrogen sorption measurement accuracy, in order to aid our understanding of the interaction of hydrogen with matter and to help reduce the variation in the reported hydrogen sorption properties of new materials, as the search for a solution to the hydrogen storage problem continues.

Darren P. Broom

Backmatter

Titel: Hydrogen Storage Materials
verfasst von: Darren P. Broom
Verlag: Springer London
Electronic ISBN: 978-0-85729-221-6
Print ISBN: 978-0-85729-220-9
DOI: https://doi.org/10.1007/978-0-85729-221-6