POTENTIAL INDUSTRIAL APPLICATIONS OF MAGNESITE-PRODUCING REACTIONS IN FUTURE, HYDROGEN-BASED GLOBAL ECONOMIES*

The magnesite-producing reactions

Mg(OH)2 + NaHCO3 → MgCO3 + NaOH + H2O

(1)

and

Mg(OH)2 + CO2 → MgCO3 + H2O

(2)

may be widely applied industrially in future, hydrogen-based world economies. Together they form the final two steps of a new, energy-efficient chemical process** for converting serpentine to magnesite. Reaction 2 is also the first reaction in a thermo-electrochemical cycle in which magnesium and hydrogen are produced by the reactions

MgCO3 → Mg + CO2 + ½O2

(3)

and

Mg + 2H2O → Mg(OH)2 + H2.

(4)

Reaction 4 proceeds readily at 1 atm, T > 100°C, and is strongly exothermic. Consequently, in a future industrial reactor for producing hydrogen it could provide most of the heat required to form magnesite by Reaction 2. On the other hand, a substantial energy input is necessary to induce Reaction 3. If magnesite can be dissolved in a suitable low-temperature ionic liquid, this reaction could, in principle, be carried out in an electrochemical reactor, with the required energy supplied by solar cells, or by solar-powered turbines.

*Research sponsored by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract DE-AC05-00OR22725, Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC.

**Patent pending.