Kinetics and mechanisms of hydrogen isotope exchange over solid storage media

  • Simon Owens

Student thesis: Doctoral ThesisPhD


Hydrogen isotope separation systems using palladium (Pd) are currently being designed for both reactor designs with the aim of separating and purifying the reactor exhaust products which contain valuable unspent hydrogen isotopes. Hydrogen isotope exchange in Pd offers an efficient, ambient condition process that can produce pure isotopic species in a process far simpler and less costly than the current state of the art cryogenic distillation processes. The method is applicable whether separating hydrogen (protium), deuterium or tritium and any combination of these. If practical fusion devices are ever to be realised it is essential to produce an economical and efficient fuel cycle capable of separating and purifying hydrogen isotopes. Hydrogen isotope exchange in Pd is also of interest to the waste separation and purification industries, in particular those using hydrogen separation membranes which used Pd and Pd-alloy membranes. Understanding hydrogen isotope exchange, with particular regard to the formation of the intermediate (and often unwanted) hydrogen deuteride (HD), will aid significantly in future designs of hydrogen isotope separation systems. Novel hydrogen isotope exchange experiments involving hydrogen and deuterium at a number of temperatures (208 K, 293 K and 373 K) and pressures (1.3 bar – 8 bar) not yet explored are presented in this thesis. The experiments were carried out on a unique piece of laboratory apparatus provided to and further developed at the University of Bath. Alongside experimentation, a novel comprehensive multidimensional multi-physics model has been created to analyse the experimental data obtained using the new apparatus and elucidate the kinetics and mechanisms of the reactions occurring between hydrogen isotopic species and Pd during hydrogen isotope exchange based on Langmuir-Hinshelwood surface reaction mechanism. The surface reaction rates, kinetic rate constants and heat effects have been examined in detail, and in tandem, for the first time.
Date of Award20 Oct 2015
Original languageEnglish
Awarding Institution
  • University of Bath
SponsorsAtomic Weapons Establishment
SupervisorTim Mays (Supervisor), Timothy Barnes (Supervisor) & Barry Crittenden (Supervisor)


  • Hydrogen
  • isotope effect
  • Separations
  • deuterium exchange
  • Hydrogen isotope exchange
  • Packed bed reactor

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