Improvement of sulphur dioxide yield from the sulphuric acid thermal decomposition process by membrane separation.

This work investigates the feasibility of applying high temperature oxygen separation to the sulphuric acid decomposition process, a step used in large scale hydrogen production processes currently under development. Porous and dense membranes are both considered. Equilibrium calculations show yttria-stabilised zirconia (YSZ), combined with platinum electrodes, to be a candidate membrane. Process simulations show the potential sulphur dioxide yield increases that could be achieved through the use of a high temperature oxygen separation membrane in two different configurations. Bespoke experimental apparatus was designed, procured and assembled in order to investigate the oxygen flux through YSZ membranes in the presence of sulphur dioxide, during external voltage application. Experiments were performed in the 700 - 900°C temperature range. Results show that oxygen permeation through YSZ membranes occurs under these conditions. A decrease in oxygen permeation with time was observed and attributed to sulphur dioxide adsorption on to the platinum electrodes. Future work would concentrate on using variable applied voltages to reduce this performance decrease.