(252g) Development of High Entropy Alloy and Multifunctional Catalysts for Simultaneous NH3 and N2o Decomposition

Many chemical processes produce a multitude of byproducts that need to be appropriately dealt with to meet emission guidelines. One specific case is the processing of nuclear waste, which can produce NH₃ and N₂O in variable amounts, depending on the system. This complex system allows for three possible reaction pathways to enhance the nuclear waste clean-up: direct NH₃ decomposition, direct N₂O decomposition, and NH₃-N₂O SCR. One avenue is the synthesis and utilization of multifunctional materials, which could be in the form of high entropy alloy (HEA) catalysts. HEA’s are materials that comprise of five or more elements and are leveraged for the “synergy” of all components in the alloyed nanoparticle to enhance catalytic activity¹.

Here, we investigated the synthesis and development of various HEA catalysts and multi-metallic catalysts after surveying literature for active elements in the NH₃ decomposition, N₂O decomposition, and NH₃-N₂O SCR reactions. We utilized a combination of various platinum group metals (PGMs) as well as transition metals, such as ruthenium, platinum, palladium, nickel, and cobalt, to decrease the PGM amounts. In this study, we looked at the applicability of utilizing a solvothermal synthesis of these materials^2,3. We then analyzed their performance in a single-channel reactor system to determine the catalyst’s ability to decompose these nitrogen containing species into their constituent elements at atmospheric pressure between 250-500°C. These catalysts were compared to traditional decomposition catalysts. This work led to a better understanding of the possibility of creating HEA nanoparticles with increased catalytic activity for complex catalytic systems.

1. Sun, Y. and Sheng, D. Adv. 2021, 7(20).
2. Bondesgaard, M., et. al. Adv. Funct. Mater. 2019, 29(50).
3. Broge, N., et. al. Chem. Mater. 2023, 35,144-153.