Low temperature studies for the sulphuric acid decomposition step in the HyS and SI thermochemical cycles

Hydrogen is a promising element for the transition from fossil fuels, even though the majority of industrial hydrogen production methods are not carbonneutral. There are, however, alternatives which could produce this CO2 free fuel on a massive scale. In particular, thermochemical cycles, including the Hybrid Sulfur (HyS) and Sulfur-Iodine (SI) cycles, which share a common sulphuric acid decomposition step. This project continues the work done by Shaw (2008), which involved the acquisition of experimental data relevant to the production of Hydrogen in the sulphur family of thermochemical cycles. This also lays the framework needed to continue the thermodynamic calculations needed for the design of equipment relevant to the SO2/O2/H2O separation. The model was developed simultaneously with the design of the next generation equilibrium still that was able to incorporate in-situ analysis. Several technical design milestones were achieved in the process, including the development of a sapphire liquid gas cell, a glass reinforced single pass 10 cm Zinc Selenide gaseous cell, several iterations of Raman Spectroscopy probes with ranging capabilities for different purposes, mostly high pressures and temperatures. It was also confirmed that with the low temperature separation approach, materials become an important factor for the success or failure of the process. Based on the results comparison between the calculations of the Mathematica® model, the GFE model, the available experimental data and general tendencies in the literature, it is concluded that the calculations, as well as the experimental techniques used throughout this project, are successful for their purpose, which is the aiding of equipment design for the HyS and SI cycle. Further efforts can be done to implement this model into process modelling software.