Plasma-Catalyzed Ammonia Decomposition Over Metalic Ruthenium-Supported Catalysts For H₂ Production

As a potential non-carbon-based hydrogen source for fuel cells,ammonia gas has attracted more and more attention in ammonia decomposition to produce hydrogen in recent years.Noble metal Ru catalyst used for cracking ammonia gas for hydrogen production is expensive,but it is still undeniable that it is the most active single metal catalyst for hydrogen production from ammonia decomposition in traditional thermal catalysis.Compared with cheap metals,Ru-based catalysts still have great research value in some extreme and low temperature environments.Dielectric barrier discharge（DBD）is an effective method to generate non-equilibrium plasma at normal temperature and pressure,which can effectively activate particles in reaction space.In particular,the electrons obtain very high energy（1～10eV）through the acceleration of electric field,and collide with other particles in the plasma space to form the reactive species of high-energy activated state and maintain a low temperature on the whole.The combination of plasma and catalyst method can effectively utilize the advantages of plasma activation reaction species and high selectivity of catalyst,and may produce a good synergistic effect.In this work,dielectric barrier discharge（DBD）plasma was adopted to promote the catalytic ammonia decomposition using supported Ru catalysts（Ru/Y₂O₃,Ru/La₂O₃,Ru/CeO₂ and Ru/SiO₂）.The experiments of thermal catalysis,plasma and plasma-catalysis were carried out successively.The experimental results show that the pyrolysis performance of ammonia under plasma catalysis mode is much higher than the sum of thermal catalysis and plasma mode.The combination of plasma and Ru catalyst significantly improved the ammonia conversion at low temperatures,showing synergistic effect between plasma and catalyst.The threshold temperature and the full conversion temperature for NH₃ decomposition on Ru catalysts were both found to decrease remarkably with the help of DBD plasma.The dielectric constant of supporting material and the catalyst morphology were found to influence the plasma-catalytic reactivity greatly.Ru catalysts supported on La₂O₃ exhibited higher plasmacatalytic reactivity than the other three catalysts.At ammonia flow rate of 40 mL/min and AC supply power of 25.6W,the rate and energy efficiency for H₂ production of 53.6 mol·gRu^-1.h^-1 and 1970 mol·gRu^-1·（kW·h）^-1 was obtained using 3‰-Ru/La₂O₃ catalyst.