Effect of Transition Metal Mixing on Reactivities of Magnesium Oxide for Chemical Heat Pump

Abstract

The mixing effect of transition metal ion into magnesium hydroxide on dehydration and hydration reactivity was studied to develop a new material for chemical heat-storage, because the mixing effect was expected to reduce dehydration-temperature, corresponding to heat-storage temperature, of authentic magnesium hydroxide. Two-components composite materials mixed with some content of nickel ion or cobalt ion into magnesium hydroxide were tested, respectively. It was demonstrated that the dehydration-temperatures of the composites were shifted to lower temperature below 300°C with increase of nickel or cobalt content in comparison with dehydration-temperature of authentic magnesium oxide of 350°C. These composites showed higher hydration reactivity than that for authentic magnesium oxide under the same reaction condition, and were expected to be applicable to heat utilization of middle-temperature waste heat less than 300°C.