CLOSED-CYCLE HCL H-2/CL-2 ENERGY-STORAGE AND POWER-GENERATION SYSTEM USING A CU/CUCL CATALYST/

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 temperatur es, 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 temperat ure, flow rate, and specific surface area. The products H-2 and CuCl w ere measured between 400 and 600 K; temperature has only a small effec t on the reaction rate, at most T-1/2. The surface geometry and gas fl ow allowed several thousand gas-surface collisions per HCl molecule fo r complete conversion of HCl to H-2. The thickness of the CuCl layer i s not the limiting factor in the reaction probability for layers less than a few thousand monolayers deep. Recovery of Cl-2 by the thermal d ecomposition of CuCl was examined as a function of temperature and pre ssure. Useful Cl-2 yields were found only for system pressures below c a. 10 torr, at temperatures above 700 K, and using a flow of inert gas to sweep out the product. (C) 1997 International Association for Hydr ogen Energy.