Hydrogen Storage for Mobility Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which substance is mentioned as a key organic compound for hydrogen storage in mobility?

Carbon Dioxide

Methanol (correct)

Covalent

Ammonia

What does the DOI reference indicate about the source?

It is an online article with a permanent URL. (correct)

It is a website about hydrogen storage technologies.

It is a book chapter that is not peer-reviewed.

It was published in a limited print edition.

In what volume and issue was the review published?

Volume 12, Issue 6

Volume 10, Issue 5

Volume 12, Issue 12 (correct)

Volume 11, Issue 8

What year was the article on hydrogen storage published?

2018 Signup and view all the answers

Which of the following is NOT mentioned as a focus in the field of hydrogen storage for mobility?

Inorganic salts Signup and view all the answers

What are the two methods mentioned for calculating the storage capacity of metal hydrides?

Gravimetric and volumetric Signup and view all the answers

Which of the following is the focus when discussing the storage capacity of metal hydrides?

The method of hydrogen storage Signup and view all the answers

In which context are gravimetric and volumetric storage capacities relevant?

Calculating the storage capacity of metal hydrides Signup and view all the answers

Why might gravimetric storage capacity be important for metal hydrides?

It expresses storage capacity per unit of weight. Signup and view all the answers

What could be a possible application of knowing the volumetric storage capacity of metal hydrides?

To optimize fuel cell design Signup and view all the answers

What is a method of hydrogen storage that involves the absorption of hydrogen molecules onto the surface of solids?

Adsorption Signup and view all the answers

Which of the following is NOT a form of hydrogen storage mentioned in the content?

Physical storage in gases Signup and view all the answers

In the context of hydrogen storage, what can be classified under physical storage?

Compression of hydrogen gas Signup and view all the answers

Which category includes storing hydrogen in materials that undergo a chemical reaction to release it?

Chemical storage in solids Signup and view all the answers

What is one advantage of using underground storage for hydrogen?

It offers high pressure storage Signup and view all the answers

What is the result of increasing hydrogen pressure on metals in terms of hydrogen absorption?

Metals form metal-hydrogen solutions. Signup and view all the answers

What does the P-C-T curve represent in the context of metal hydride hydrogenation?

The variation of pressure, composition, and temperature during hydrogenation. Signup and view all the answers

Which phase is formed when metals start to absorb hydrogen under increased pressure?

α-phase Signup and view all the answers

Which of the following statements about metal hydrogenation is inaccurate?

Hydrogen pressure has no effect on metal absorption. Signup and view all the answers

During the hydrogenation of metal hydrides, which property of the metal primarily changes as hydrogen pressure increases?

Hydrogen absorption capacity Signup and view all the answers

What is the primary focus of the studies conducted by Broom et al. and Yang et al.?

The chemistry and applications of hydrogen energy Signup and view all the answers

In which journal did Yang et al. publish their findings?

Chemistry of Materials Signup and view all the answers

Which year did the publication of Broom et al. appear in the International Journal of Hydrogen Energy?

2019 Signup and view all the answers

What range of pages covers the article by Yang et al. in the Chemistry of Materials?

464–470 Signup and view all the answers

What is the volume number for the 2012 article by Yang et al. in the Chemistry of Materials?

24 Signup and view all the answers

What aspect of hydrogen storage is primarily examined in this lecture?

Chemical and physical methods Signup and view all the answers

Which of the following challenges is likely addressed in the context of hydrogen storage?

Capacity and density of storage materials Signup and view all the answers

Which property is crucial for materials used in hydrogen storage?

Mechanical strength Signup and view all the answers

What type of materials are primarily discussed for hydrogen storage solutions?

A combination of metals, organics, and composites Signup and view all the answers

Why is research on hydrogen storage for mobility particularly significant?

It contributes to decreasing fossil fuel usage Signup and view all the answers

Study Notes

Introduction to Hydrogen Technologies and Applications (CHEG 360) - FALL 2024

Course: Introduction to Hydrogen Technologies and Applications (CHEG 360)
Semester: Fall 2024
Instructor: Dr. Lourdes F. Vega
Date of Lecture: October 17, 2024
Chapter: 6 - Hydrogen Storage
Lecture: 15 - Chemical and Physical Storage of Hydrogen (Ch6-2)

Hydrogen Storage Content

Focus: Chemical and physical hydrogen storage
Chapter 6: Hydrogen generation, storage, and utilization, Zhang et al. (pages 6.1-6.3)
Hydrogen supply chain
Physical and material-based storage of hydrogen
Underground hydrogen storage
Metal hydrides for chemical hydrogen storage
- Types of metal hydrides
- Practical application challenges of metal hydrides
Physical storage using nanostructured and porous materials
- Adsorption basics
- Physical storage using metal-organic frameworks
- Physical storage using carbon nanostructures
- Other nanostructures (Clathrate Hydrates)
- Current status of hydrogen storage technology

Physical Storage of Hydrogen

Hydrogen storage in cylinders/tanks by changing its physical state to compressed or liquid hydrogen.
Issues:
- Low volumetric energy content
- Stringent operating conditions for state change
- High cost for cylinder storage
Storage of 1 kg of H2:
- Compressed gas: 11,000 liters
- Cold/Cryo compressed: 24 liters
- Liquid H2: 14 liters
Atmospheric pressure for compressed gas, 700 bar for compressed, and liquefied for liquid.

Material-based Storage of Hydrogen

Alternative option to store hydrogen in solids, either physically or chemically bonded.
Examples include Ammonia or LOHC (liquids), both chemically store hydrogen.
Solid materials have smaller volume than liquids for the same mass.
Chemical storage in liquids:
- Ex. MOF-5, BN-methyl cyclopentane
Chemical storage in solids:
- Ex. LaNisH6, NaAlH4, NH3BH3

Metal Hydrides for Hydrogen Storage

Solid materials formed by chemically reacting hydrogen with transition metals, intermetallics or alloys as a form of storage.
Higher volumetric storage capacity than liquid hydrogen, making it ideal for onboard storage applications.
Stable at low pressure, making it safer and easier for hydrogen storage.
Types
- Metal hydride powder

Calculating Metal Hydride Storage Capacity

Gravimetric calculation: [ρ_m = \frac{x M_H}{M_H + M_M} \times 100]
Volumetric calculation: [ρ_v = \frac{V_m M_M}{ρ_M}]
Real capacity deviates from ideal due to impurities, defects, hydrogen physical adsorption.

Measuring Metal Hydride Storage Capacity

Metal hydrides have higher volumetric than liquid hydrogen, but lower gravimetric density.
Safer and easier to store than liquid hydrogen given its lower pressure and high temperatures,

Metal Hydrides for Hydrogen Storage: Process

Two Main Processes
- Hydrogenation: Formation of metal-hydrogen bonds
- Dehydrogenation: Breaking of chemical bonds to release hydrogen.
- Q: Calculated Heat of hydride formation
Hydrogenation is exothermic and high pressure, while Dehydrogenation is endothermic and low pressure.

Hydrogenation of Metal Hydrides: Thermodynamics

Increasing hydrogen pressure results in metal adsorbing hydrogen to form metal-hydrogen solution.
When pressure reaches a point, hydrides formation initiates (β-phase), and hydrogen pressure remains stable.
Hydrogenation process is completed once the hydrogen concentration and pressure are stable at a certain point.

Dehydrogenation of Metal Hydrides: Thermodynamics

Desorption plateaus show lower near-constant hydrogen pressure.
Hysteresis loops indicate efficiency loss due to material degradation during adsorption and desorption processes.
Plateau width (∆(H/M)) represents reversible storage capacity, which is smaller than the maximum ideal value.

Hydrogenation Process - Microscopic

Physisorption of H2 on metal surfaces through weak interactions.
Chemisorption via H atom dissociation from H2 and electron transfer.
H atoms diffuse to subsurface sites becoming H solution in metal (a-phase).
Transition to stable hydride (β-phase) with increasing hydrogen concentration.

Hydrogenation Process - Macroscopic

Hydrogen adsorption at metal surfaces and diffusion through metal.
Reaction forms metal hydride on the surface, where hydride patches form a shell around the metal.
Reaction propagation forms a hydride shell that prevents further hydrogen diffusion from the atmosphere into the metal core.

Binary Metal Hydrides

Even if called "binary," only one metal element is bonded with hydrogen.
Examples include magnesium hydride (MgH₂) and aluminum hydride (AlH₃); both have high gravimetric density but high desorption temperatures at 603 K.

Metal Alloy Hydrides

Ternary systems (ABxH₄) formed when multiple metallic elements react with hydrogen.
Transition metal (B) forms an unstable hydride with X = 0.5, 1, 2, or 5 resulting in intermediate stable hydrides.
Example: LaNi5H7, known for low gravimetric density (1.25 wt%) and high sorption temperatures

Complex Metal Hydrides

Chemical formula AxByH2, where A is a group 1 or 2 element and B is aluminum, nitrogen, or boron.
Examples of Alanates, Nitrides, and Borohydrides.
Forms ionic or covalent bonds with hydrogen.
Highest storage density; example is sodium alanate (NaAlH₄)

Challenges with Practical Application of Metal Hydrides

High adsorption/desorption temperatures
Slow kinetics
Strong chemical bonds (50 kJ/mol) necessitate high temperatures to break bonds and release hydrogen.
Thermodynamic destabilization is essential for lower binding energy while keeping storage capacity high.
Nanometer size hydride crystals and nano-sized catalysts are used to potentially increase capacity.

Current Status and US DOE Targets for Hydrogen Storage

DOE targets for gravimetric and volumetric hydrogen density given varying conditions.
Shows that current methods have limitations reaching necessary standards.

Physical Storage using Metal-Organic Frameworks (MOFs)

Crystalline inorganic-organic hybrids with metal clusters or ions acting as nodes and organic ligands as linkers.
Higher pore count and surface area than zeolites and porous carbon allows for higher hydrogen uptake.

Physical Storage using Carbon Nanostructures

Carbon nanostructures (CNTs, fullerenes, nanofibers, graphene) are carbon-based materials with nanoscale structure and good adsorption ability, high surface area, and low mass density.
Physisorption and chemisorption are mechanisms for H2 uptake.

H2 Storage in Carbon Nanotubes

Loading CNTs with Pd or Pt nanoparticles promotes chemisorption through spillover mechanisms.

H2 Storage in Graphene

High hydrogen storage capacity (surface area = 2,629 m²/g)
Converting graphene to graphane with heating can release stored hydrogen.
Metal doping or composite structures enhance storage capacity at moderate pressure and temperature.

Physical Storage using Clathrate Hydrates

Solids formed from guest molecules occupying cages formed from H-bonded water networks.
Empty cages are usually unstable and stabilize with appropriately sized molecules.
Hydrogen-based clathrates form two different sized cages (512 and 51264) with 136 H2O molecules.
Very high pressure (2000 bar) to maintain stability makes this an impractical method

Absorption vs. Adsorption

Absorption: Fluid accumulates within a solid.
Adsorption: Fluid accumulates on a solid surface, forming a film.

Types of Adsorption

Physisorption: Weak van der Waals forces (5-50 kJ/mol) and multilayer. Reversible
Chemisorption: Strong chemical bonds with orbital overlap (40-800 kJ/mol) and monolayer. Mostly irreversible

Adsorption Isotherm and Equilibria

Relationship between the amount adsorbed and the amount dissolved in a solution.
Initial slope describes adsorbent-adsorbate interactions; the saturation zone describes additional interactions; finally the transition zone describes additional adsorbate interactions.
Adsorption-desorption cycles show pressure and temperature ranges used for reversible uptake.

Compressed Hydrogen vs Adsorption in Materials

Comparison of compressed hydrogen storage methods (normal, lab cylinders, Gen 1, and Gen 2 vehicles) and adsorption techniques in materials by different methods of storage.
High surface area materials are needed for effective hydrogen storage through adsorption methods.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on key organic compounds used for hydrogen storage in mobility applications. This quiz covers essential concepts, methods of calculating storage capacities, and the significance of gravimetric and volumetric capacities. Dive into the various forms of hydrogen storage and their implications in the field.