Hydrogen transport, solid state

Guan, J., Dorris, S.E., Balachandran, U., and Liu, M., Transport properties of BaCeo95Yoo503 mixed conductors for hydrogen separation. Solid State Ionics, 100, 45-52 1997. 

Schober, T. (2001). Tubular high-termperature proton conductors transport numbers and hydrogen injection. Solid State Ionics 139,95-104. 

Although the continuous-countercurrent type of operation has found limited application in the removal of gaseous pollutants from process streams (Tor example, the removal of carbon dioxide and sulfur compounds such as hydrogen sulfide and carbonyl sulfide), by far the most common type of operation presently in use is the fixed-bed adsorber. The relatively high cost of continuously transporting solid particles as required in steady-state operations makes fixed-bed adsorption an attractive, economical alternative. If intermittent or batch operation is practical, a simple one-bed system, cycling alternately between the adsorption and regeneration phases, 1 suffice. 

Storage of liquid hydrogen is achieved in large well-insulated tanks from which it is dispensed to liquid tankers for transport over the road. The use of hydrogen sensors (mostly flammable sensors) in and around such facilities is a common safety practice today. As hydrogen-specific sensors and solid-state sensors become more reliable, and if their cost is reduced they will replace the more common flammable gas sensors. 

Traditionally, hydrogen has heen stored, transported and used in the form of compressed gas or cryogenic liquid. Recharge-ahle metal hydrides have heen proposed as an alternative solid state storage method. A dynamic research community has assembled to explore the scientific basis and evaluate the technology of this hydrogen-metal reaction Metal hydride topics have... 

Occasionally, some residual homopolar bonds remain in metals, for example a small per cent of the molecules Li—Li, Na—Na, etc. are found in the vapours of these metals, analogous to the hydrogen molecule, but there is no trace of them in the solid state. The most characteristic property of metals, in which the smallest potential difference produces an electric current, is their electrical conductivity. Since no transport of mass takes place in a metallic conductor, a metal must contain free electrons, from which it follows that positive ions must also be present. The picture of a metal is thei efore one in which the lattice is composed of positive ions held together by electrons which move freely in the space between. It is as though the ions were cemented together by an electronic gas. 

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