Abstract
The Bunsen reaction using an electrolysis cell separated by a cation exchange membrane has been recently proposed as a promising approach to increasing the thermal efficiency of the IS process. We prepared new cation exchange membranes for possible use in this so–called electrochemical Bunsen reaction by the radiation–induced graft copolymerization of styrene and divinylbenzene (DVB) into poly(ethylene–co–tetrafluoroethylene) films and subsequent sulfonation. Quantitative sulfonation of the DVB–crosslinked polystyrene graft–chains led to the preparation of membranes with various ion exchange capacities, thereby making it possible to control their proton conductivities over a wide range. The resulting membranes also exhibited lower water uptake and, therefore, a reduced water flux compared to the non–crosslinked and Nafion membranes. Both H2SO4 in the anolyte and HI in the catholyte were continuously concentrated during the electolysis for 3 h. Reaction overpotential values were similar between our and Nafion membranes. These results demonstrate the applicability of the radiation–grafted cation exchange membranes to the electrochemical Bunsen reactor.
