Experimental Investigation on Supported Iron Catalyst for High Temperature NH3-SCR of NOx in Regard to Aviation

Abstract While much of the focus on emissions control is towards carbon emissions to achieve net-zero carbon emissions by 2050 set by the International Civil Aviation Organization. NOx emissions, N2O specifically, have a global warming potential 273 times greater than that of carbon dioxide on a 100-year timescale. Selective Catalytic Reduction (SCR) has been an effective way to reduce or even completely eliminate NOx emissions in the transportation and power generation industry for the better part of two decades. The use of ammonia as a hydrogen carrier for air travel is one of the pathways being considered to achieve net-zero carbon emissions. With ammonia already on board, a small amount could be allocated to an SCR system to aim for not only zero carbon emissions but also zero NOx emissions as well. Commercial Jet Engines have the unique challenge of large flowrates in the core exhaust flowing through a small volume that is available to integrate an SCR system. With this, little experimental research has been done to see the effectiveness of catalysts within the pressure and temperature ranges found in these exhausts at cruise conditions. Iron catalysts have been found to be one of the more effective SCR catalysts at higher Gas Hourly Space Velocities (GHSV) and have a wide temperature range. This paper investigates the SCR potential of an iron oxide catalyst supported by 2D functional boron at typical jet engine conditions found at cruise with ammonia-hydrogen as the fuel as well as understand how ammonia cracked by the catalyst can influence H2-SCR as well. Promising results could lead to an effective way to eliminate NOx emissions from current and future notional jet engines. It was found that 5% Iron oxide over 2D functionalized boron cracks around 7.6% of ammonia to hydrogen. This could promote H2-SCR and further increase the NOx reduction capabilities of the catalyst though by how much is yet to be determined. Initial tests find that SCR is occuring with the catalyst leading to a decrease in NO and an increase in H2O.