Process for generating chlorine and caustic soda using a membrane electrolysis cell coupled to a membrane alkaline fuel cell

摘要

A process for making chlorine gas and concentrating caustic soda comprising:PP(1) feeding a brine to the anolyte compartment solution and a dilute NaOH solution to the catholyte compartment of an electrolysis cell comprising a cation-transporting membrane, thereby generating chlorine at the anode, hydrogen at the cathode, and concentrating NaOH in the catholyte solution;P P(2) coupling the membrane electrolysis cell to a cation-transporting membrane alkaline fuel cell by providing at least some of the hydrogen generated in the electrolysis cell to the anode of the fuel cell, and splitting the catholyte flow from the catholyte compartment of the electrolysis cell so that it feeds into both the catholyte chamber and the anolyte chamber of the fuel cell in an unequal amount with a greater proportion of the catholyte going into the anion chamber;P P(3) concentrating the NaOH in the fuel cell by providing an oxygen source to the catholyte chamber of the fuel cell, and using the oxygen and the hydrogen to generate a current in the fuel cell, thereby causing Na.sup.+ to be transported across the membrane and concentrating NaOH in the catholyte chamber; andPP(4) collecting the chlorine from the electrolysis cell and the concentrated NaOH from the fuel cell is disclosed.PPIn a preferred embodiment, the dilute caustic solution from the anolyte chamber of the fuel cell is recycled to the catholyte compartment of the electrolysis cell, thereby providing a closed system.