A NEW MEMBRANE PROCESS FOR AIR POLLUTION MINIMIZATION IN CHLOR-ALKALI PLANTS

CHLORINE RANKS AMONG THE TEN MOST IMPORTANT COMMODITY CHEMICALS. APPROXIMATELY 54% OF THE TOTAL U.S. CHLORINE PRODUCTION IS LIQUEFIED FOR SALE OR FOR IN-PLANT TRANSPORT. TAIL GAS PRODUCED FROM THE CHLORINE LIQUEFACTION PROCESS IS THE PRINCIPAL SOURCE OF CHLORINE-CONTAINING WASTE GAS STREAMS PRODUCED BY CHLOR-ALKALI PLANTS. CURRENTLY, SUCH STREAMS ARE TREATED BY ABSORPTION IN CARBON TETRACHLORIDE; HOWEVER, CARBON TETRACHLORIDE HAS A HIGH OZONE DEPLETION POTENTIAL. IT IS ESTIMATED THAT AT LEAST 8.8 X 10(6) LB/YR OF CARBON TETRACHLORIDE ARE EMITTED BY CHLORINE LIQUEFACTION TAIL GAS TREATMENT. BECAUSE OF THE SERIOUS ENVIRONMENTAL THREAT OF CARBON TETRACHLORIDE EMISSIONS THE ENVIRONMENTAL PROTECTION AGENCY HAD MANDATED THAT THESE EMISSIONS BE ELIMINATED; CARBON TETRACHLORIDE PRODUCTION WILL CEASE AFTER 1995. THEREFORE, THE CHLOR-ALKALI INDUSTRY MUST FIND AN ALTERNATIVE TREATMENT TECHNOLOGY. MEMBRANE TECHNOLOGY AND RESEARCH, INC. (MTR), PROPOSES TO DEVELOP A NEW MEMBRANE PROCESS TO RECOVER CHLORINE FROM TAIL GAS STREAMS IN THE CHLOR-ALKALI INDUSTRY THAT WILL ELIMATE THE USE OF CARBON TETRACHLORIDE. THE CHLORINE RECOVERY WILL BE RECYCLED BACK TO THE PLANT. PRELIMINARY STUDIES AT MTR HAVE DEMONSTRATED THAT RUBBERY MEMBRANES ARE HIGHLY SELECTIVE FOR CHLORINE. IN THE PHASE I PROGRAM, A LABORATORY SYSTEM USING THESE MEMBRANES WILL BE TESTED FOR ITS CHLORINE REMOVAL EFFICIENCY. AN APPLICATION STUDY WILL BE PERFORMED TO IDENTIFY THE MOST EFFICIENT METHODS TO CAPTURE CHLORINE FROM LIQUEFACTION TAIL GAS.