Catalytic decomposition of NH3 as a by-product of magnetically confined nuclear fusion

Abstract

A statistical design of experiments was conducted to optimize a trimetallic catalyst formulation consisting of ruthenium, yttrium, and potassium on γ-Al₂O₃ (RuYK/ γ-Al₂O₃) for use as ammonia (NH₃) decomposition catalyst in the hydrogen isotope impurity processing for magnetically confined nuclear fusion systems. Optimal weight loadings of 6.9 wt-% Ru, 4.3 wt-% Y, and 12 wt-% K were determined through the design of experiments. The thermal stability of the catalyst was investigated through thermal cycling of the catalyst over 30 cycles. The optimized catalyst remained stable over the cycles under reducing conditions. As oxygen, carbon dioxide and water are the primary impurities in the Tokamak exhaust, the chemical stability of the catalyst was determined against these impurities. While these impurities initially decreased the NH₃ decomposition activity, the initial activity was attained once the impurity was removed from the stream.