(569br) Modeling of Calcium Ferrite Reactions in Chemical Looping Applications of Fossil Fuel Conversion to Hydrogen

Steady state process simulations and reactor design are pivotal tools used in the development of process concepts and screening their efficiency. In order to use these tools, reaction networks and rate expressions for the discrete reactions need to be understood and developed accompanied by targeted integration strategies for the tool. This work discusses the process for developing necessary reaction emulation information to enable more detailed process simulation of a chemical looping H₂ production system from fossil fuels using CaFe₂O₄ as the oxygen carrier material. Rate parameters for the reduction and oxidation reactions of CaFe₂O₄ and descendent phases of Ca₂Fe₂O₅, FeO, Fe₃O₄, Fe, and CaO to emulate reaction behavior in a looping-based process environment were developed. This included direct reduction using CH₄, H₂, and CO, and direct oxidation reactions with steam, CO₂ and O₂. The work extends further, transcribing the rate expressions into usable forms for implementation into widely used simulation tools such as Aspen Plus. Three potential configurations for an H₂ production system were explored and the trade-offs with certain approaches quantified. Of the three cases, the most promising system was a syngas-based production system designed around leveraging Ca₂Fe₂O₅’s reaction pathway and desirable kinetics leading to a potential yield upwards of 2.78 moles of H₂/mole of CH₄. Other approaches employed the use of inert dilution with CaFe₂O₄ based process for syngas generation and the third used a three-reactor configuration for direct H₂ generation from water splitting which had yields of 1.4 and 1.2 moles H₂/mole CH₄ respectively.