Jamelyn D. Holladay

Kinetic and thermodynamic investigation of hydrogen release from ethane 1,2-di-amineborane

The thermodynamics and kinetics of hydrogen (H2) release from ethane 1,2-di-amineborane (EDAB, BH3NH2CH2CH2NH2BH3) were measured using Calvet and differential scanning calorimetry (DSC), pressure-composition isotherms, and volumetric gas-burette experiments. The results presented here indicate that EDAB releases ∼ 10 wt.% H2 at temperatures ranging from 100 °C to 200 °C in two moderately exothermic steps, approximately −10 ± 1 kJ mol−1 H2 and −3.8 ± 1 kJ mol−1 H2. Isothermal kinetic analysis shows that EDAB is more stable than ammonia borane (AB) at temperatures lower than 100 °C; however, the rates of hydrogen release are faster for EDAB than for AB at temperatures higher than 120 °C. In addition, no volatile impurities in the H2 released by EDAB were detected by mass spectrometry upon heating with 1 °C min−1 to 200 °C in a calorimeter.

High-Efficiency Microscale Power Using a Fuel Processor and Fuel Cell

A microscale power device, composed of a fuel processor and a fuel cell, is described, and results of testing conducted with the fuel reformer are presented. The microscale fuel reformer strips hydrogen from a hydrocarbon fuel, such as methanol, and the hydrogen-rich stream can then be fed to a fuel cell to generate electrical power. In the tests discussed here, the fuel reformer, utilizing methanol, was able to provide up to 100 mWe of hydrogen at an efficiency of up to 4.8%. The device was able to operate independent of any additional external heating, even during start-up.

Systems Modeling of Chemical Hydride Hydrogen Storage Materials for Fuel Cell Applications

A fixed bed reactor was designed, modeled and simulated for hydrogen storage on-board the vehicle for PEM fuel cell applications. Ammonia Borane (AB) was selected by DOEs Hydrogen Storage Engineering Center of Excellence (HSECoE) as the initial chemical hydride of study because of its high hydrogen storage capacity (up to {approx}16% by weight for the release of {approx}2.5 molar equivalents of hydrogen gas) and its stability under typical ambient conditions. The design evaluated consisted of a tank with 8 thermally isolated sections in which H2 flows freely between sections to provide ballast. Heating elements are used to initiate reactions in each section when pressure drops below a specified level in the tank. Reactor models in Excel and COMSOL were developed to demonstrate the proof-of-concept, which was then used to develop systems models in Matlab/Simulink. Experiments and drive cycle simulations showed that the storage system meets thirteen 2010 DOE targets in entirety and the remaining four at greater than 60% of the target.

Compact Reverse Water-Gas-Shift Reactor for Extraterrestrial In Situ Resource Utilization

A compact reverse water-gas-shift reactor suitable for extraterrestrial use as part of the in situ propellant production system is reported. The reactor is less than 15 cm 3 in volume and weighs less than 50 g. With an Ru/ZrO 2 -CeO catalyst it produces over 150 g H 2 O/h operating at 800°C. This is near equilibrium conversion at about half-scale of a Mars sample-return mission. Even at these high processing rates, the pressure drop remains low (from 1.6 to 7.6 kPa).

Dynamic Modeling and Simulation Based Analysis of an Ammonia Borane (AB) Reactor System for Hydrogen Storage

Research on ammonia borane (AB, NH3BH3) has shown it to be a promising material for chemical hydrogen storage in PEM fuel cell applications. AB was selected by DOE’s Hydrogen Storage Engineering Center of Excellence (HSECoE) as the initial chemical hydride of study because of its high hydrogen storage capacity (up to 19.6% by weight for the release of three molar equivalents of hydrogen gas) and its stability under typical ambient conditions. A model of a bead reactor system which includes feed and product tanks, hot and cold augers, a ballast tank/reactor, a H2 burner and a radiator was developed to study AB system performance in an automotive application and estimate the energy, mass, and volume requirements for this off-board regenerable hydrogen storage material. Preliminary system simulation results for a start-up case and for a transient drive cycle indicate appropriate trends in the reactor system dynamics. A new controller was developed and validated in simulation for a couple of H2 demand cases.

Chemical Hydrides for Hydrogen Storage in Fuel Cell Applications

Due to its high hydrogen storage capacity (up to 19.6% by weight for the release of 2.5 molar equivalents of hydrogen gas) and its stability under typical ambient conditions, ammonia borane (AB) is a promising material for chemical hydrogen storage for fuel cell applications in transportation sector. Several systems models for chemical hydride materials such as solid AB, liquid AB and alane were developed and evaluated at PNNL to determine an optimal configuration that would meet the 2010 and future DOE targets for hydrogen storage. This paper presents an overview of those systems models and discusses the simulation results for various transient drive cycle scenarios.