Calculation of Enthalpy of Desorption for Metal Hydrides used as Candidate Materials for Hydrogen Storage
Faculty Sponsor
Patrick Ferro, Gonzaga University
Research Project 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.
Session Number
PS1
Location
Graves Gym
Abstract Number
PS1-i
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.
