(258e) Applicability of Inorganic Membranes for the Production of Hydrogen Using Nuclear Energy

The
efficient separation of gases at high temperatures can improve the efficiency
of two of the leading processes for producing hydrogen using the heat from a
nuclear reactor, thermochemical water splitting and high temperature
electrolysis.  The Sulfur-Iodine (SI) thermochemical process
thermocatalytically cracks water yielding hydrogen and oxygen. The SI process
consists of a series of chemical reactions where all the chemicals are recycled
in the process except for water. The SI process is efficient, scalable to large
sizes, and uses no expensive chemical reagents; however, it has one major
disadvantage.  The thermal decomposition of sulfuric acid requires high
temperatures (800 to 900 °C).  However, there is a potential to lower the peak
temperature by 200+ °C if the decomposition products of sulfuric acid, O₂,
H₂O, and SO₂, can be separated from SO₃ using
an inorganic membrane. First generation membranes have been fabricated and we
will present preliminary separation data showing the potential to separate the
product gases from SO₃.  We will also present results of the stability
of these membranes under simulated operational conditions.

High
temperature electrolysis uses a solid oxide electrolyzer to split water into
hydrogen and oxygen.  The oxygen is removed by the electrolyzer with the
remaining gas being a mixture of product hydrogen and the residual steam.  The
efficiency of this process can be improved if a large fraction of the hydrogen
can be removed at the operating temperature of 800 °C while the reject steam
and residual hydrogen is recycled back to the feed of the electrolyzer without
costly cooling and reheat steps.  Preliminary data showing membrane separation performance
and thermal stability will be presented.