Thermal plasma technology can be used in the production of hydrogen and hydrogen-rich gases from a variety of fuels. This paper describes experiments and calculations of high-temperature conversion of methane using homogeneous and heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely high temperatures (several thousand degrees Celsius) and high degree of ionization. The high temperatures accelerate the reactions involved in the reforming process. Plasma reformers can be operated with a broad range of fuels, are very compact and are very light (because of high power density), have fast response time (fraction of a second), can be manufactured with minimal cost (they use simple metallic or carbon electrodes and simple power supplies), and have high conversion efficiencies. Hydrogen-rich gas (50−75% H2, with 25−50% CO for steam reforming) can be efficiently made in compact plasma reformers. Experiments have been carried out in a small device (2−3 kW) and without the use of efficient heat regeneration. For partial oxidation it was determined that the specific energy consumption in the plasma reforming processes is 40 MJ/kg H2 (without the energy consumption reduction that can be obtained from heat regeneration from an efficient heat exchanger). Larger plasmatrons, better reactor thermal insulation, efficient heat regeneration, and improved plasma catalysis could also play a major role in specific energy consumption reduction. With an appropriate heat exchanger to provide a high degree of heat regeneration, the projected specific energy consumption is expected to be ∼15−20 MJ/kg H2. In addition, a system has been demonstrated for hydrogen production with low CO content (∼2%) with power densities of ∼10 kW (H2 HHV)/L of reactor, or ∼4 m3/h H2 per liter of reactor. Power density should increase further with power and improved design.

A set of effective chemical potentials (ECPs) are derived that connect energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides calculated at 0 K from density functional theory (DFT) to free energies in high temperature and pressure water. The ECPs are derived and validated by solving a system of linear equations that combine DFT and experimental free energies for NiO, ZnO, Fe2O3, Fe3O4, FeO(OH), CoFe2O4, ZnFe2O4, NiFe2O4 and H2O. To connect to solution phase chemistry, a set of ECPs are also derived for solvated Ni(2+), Zn(2+), Fe(2+) and Fe(3+) ions using an analogous set of linear equations and the solid ECPs. The ECPs are used to calculate free energies of low index stoichiometric surfaces of nickel oxide (NiO) and nickel ferrite (NiFe2O4) in water as a function of temperature from 300 to 600 K at a pressure of 155 bar. Surface denuding at high temperatures is predicted, the implications of which for the formation of oxide corrosion products on heat transfer surfaces in light-water nuclear reactors are discussed.

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Inhomogeneous chemical segregation to grain boundaries in nanocrystalline metals can lead to a new toughening mechanism called compositional crack arrest.