Molecular Physics seminar

The selectivity between O2 and Cl2 in the chlor-alkali and chlorate processes Theoretical and experimental studies

by Rasmus Karlsson (Applied Electrochemistry, KTH)

FA31 ()


Chlorine and sodium chlorate are important bulk chemicals, with a yearly production of about 70Mtons and 3Mtons, respectively. They are both produced by electrolysis of NaCl solutions using electrocatalysts consisting of mixed Ru-Ti oxides. The cost of electricity is, in both cases, the main production cost. However, the energy efficiency is limited by the formation of oxygen gas. My work is focused on understanding why and how oxygen forms in these processes, to find ways of improving the energy efficiency. In this talk, I will discuss our recent theoretical and experimental work exploring this issue. The theoretical study has focused on the electrocatalytic properties of mixed Ru-Ti oxides, and through first-principles calculations we find that the selectivity between chlorine and oxygen formation is related to activation of Ti by Ru. The experimental study has focused on understanding how an important intermediate in the chlorate process is decomposed homogeneously and heterogeneously. We find that oxygen and chlorate formation occurs through a shared reaction mechanism and that Co- and Ir-compounds catalyze the decomposition of the intermediate.