Improvements on thermal efficiency of chemical heat pump involving the reaction couple of 2-propanol dehydrogenation and acetone hydrogenation

Rapid catalytic dehydrogenation of 2-propanol by heating with low-quality thermal energy (ca 80 degrees C) and heat removal for fractional condensation of evolved gases at ambient temperature (ca 25 degrees C) make it possible to obtain high-quality thermal energy (ca 200 degrees C) from the hydrogenation heat of acetone. It has been found that the thermal efficiency of such a chemical heat pump can be greatly improved by adopting a Ru or more preferably Ru-Pt catalyst and conducting the reaction in a liquid-film stale for the dehydrogenation (endothermic) process. The evolved gas was found to contain acetone exceeding the chemical reaction equilibrium in the gas phase, even when the reaction was performed under the stationary condition. Under such conditions, quite a high value was attained for both the fraction of heat used for the endothermic reaction (25.6%) and the exergy efficiency (58.6%). Advantages of the proposed catalytic system are discussed. (C) 1997 International Association for Hydrogen Energy.