Submission Title

Calculation of Enthalpy of Desorption for Metal Hydrides used as Candidate Materials for Hydrogen Storage

Session Number

PS1

Location

Graves Gym

Abstract Number

PS1-i

Abstract

Metal hydrides are used in hydrogen storage applications when volumetric efficiency is critical. For example, such as that necessary in the development of hydrogen fuel cell vehicles, where volumetric efficiency in storage is desirable. One of the critical material properties that affects the performance of metal hydride alloys is the enthalpy of desorption (ΔH). If this value is too high, a metal hydride is not a likely choice when hydrogen storage reversibility is critical. If ΔH is too low, such as that found with sorption materials including carbon nanotubes, hydrogen storage is not easily reversible because the hydrogen cannot stay reliably charged.

To measure the enthalpy of desorption for the candidate materials studied, equilibrium pressure measurements were made at two different temperatures for a portable hydrogen storage canister. By graphing the natural log equilibrium pressure data as a function of reciprocal temperature and multiplying the slope by the universal gas constant, the enthalpy of desorption for the candidate material was estimated. The calculated value was compared with published literature data to allow for a ‘reverse engineered’ estimate of the alloy chemistry.

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Apr 23rd, 10:45 AM Apr 23rd, 12:15 PM

Calculation of Enthalpy of Desorption for Metal Hydrides used as Candidate Materials for Hydrogen Storage

Graves Gym

Metal hydrides are used in hydrogen storage applications when volumetric efficiency is critical. For example, such as that necessary in the development of hydrogen fuel cell vehicles, where volumetric efficiency in storage is desirable. One of the critical material properties that affects the performance of metal hydride alloys is the enthalpy of desorption (ΔH). If this value is too high, a metal hydride is not a likely choice when hydrogen storage reversibility is critical. If ΔH is too low, such as that found with sorption materials including carbon nanotubes, hydrogen storage is not easily reversible because the hydrogen cannot stay reliably charged.

To measure the enthalpy of desorption for the candidate materials studied, equilibrium pressure measurements were made at two different temperatures for a portable hydrogen storage canister. By graphing the natural log equilibrium pressure data as a function of reciprocal temperature and multiplying the slope by the universal gas constant, the enthalpy of desorption for the candidate material was estimated. The calculated value was compared with published literature data to allow for a ‘reverse engineered’ estimate of the alloy chemistry.