Closed-cycle HCl/H 2/Cl 2 energy storage and power generation system using a [formula omitted] catalyst

Abstract

An energy storage system based on HCl-H 2-Cl 2 chemistry is described. When dry HCl gas is passed over a copper surface, H 2 is released and Cu is oxidized to CuCl. Subsequently, upon heating to high temperatures, the CuCl bed is decomposed back to Cu, releasing Cl 2. The release of H 2 from HCl on a Cu surface was studied as a function of temperature, flow rate, and specific surface area. The products H 2 and CuCl were measured between 400 and 600 K; temperature has only a small effect on the reaction rate, at most T 1 2 . The surface geometry and gas flow allowed several thousand gas-surface collisions per HCl molecule for complete conversion of HCl to H 2. The thickness of the CuCl layer is not the limiting factor in the reaction probability for layers less than a few thousand monolayers deep. Recovery of Cl 2 by the thermal decomposition of CuCl was examined as a function of temperature and pressure. Useful Cl 2 yields were found only for system pressures below ca. 10 torr, at temperatures above 700 K, and using a flow of inert gas to sweep out the product.