Development of an Electrolytic Cation Exchange Module for the Simultaneous Extraction of Carbon Dioxide and Hydrogen Gas from Natural Seawater

摘要

An electrolytic cation.exchange process has been developed to extract large quantities of carbon dioxide (CO2) from natural seawater where it is in the form of bicarbonate and carbonate, and to simultaneously produce H-2 gas in quantities and ratios (3:1 H-2 to CO2) intended for future synthesis of hydrocarbons. During the early stages of development, optimizing the energy efficiency and, CO2 production efficiency of the process is key to its future practical implementation. Both efficiencies are impacted specifically by the amount of time needed to re-establish equilibrium conditions in the module after a polarity reversal. Three electrolytic cation exchange module (E-CEM) configurations were tested and evaluated to determine the parameters that had the most significant effects on shortening the re-equilibration times after polarity reversal. From these evaluations, a new fourth custom E-CEM was designed, built, and tested that lowered seawater pH 65% faster so that carbonate and bicarbonate in the seawater were re-equilibrated to CO2 gas for recovery and the electrical resistance was reduced by 31%. These results are important for the future scale-up and implementation of such a process.