Plasma-Promoted Ammonia Decomposition over Supported Ruthenium Catalysts for CO_x-Free H₂ Production

The efficient decomposition of ammonia to produce COx-free hydrogen at low temperatures has been extensively investigated as a potential method for supplying hydrogen to mobile devices based on fuel cells. In this study, we employed dielectric barrier discharge (DBD) plasma, a non-thermal plasma, to enhance the catalytic ammonia decomposition over supported Ru catalysts (Ru/Y2O3, Ru/La2O3, Ru/CeO2 and Ru/SiO2). The plasma-catalytic reactivity of Ru/La2O3 was found to be superior to that of the other three catalysts. It was observed that both the physicochemical properties of the catalyst (such as support acidity) and the plasma discharge behaviours exerted significant influence on plasma-catalytic reactivity. Combining plasma with a Ru catalyst significantly enhanced ammonia conversion at low temperatures, achieving near complete NH3 conversion over the 1.5 %-Ru/La2O3 catalyst at temperatures as low as 380 degrees C. Under a weight gas hourly space velocity of 2400 mL g(cat)(-1) h(-1) and an AC supply power of 20 W, the H-2 formation rate and energy efficiency achieved were 10.7 mol g(Ru)(-1) h(-1) and 535 mol g(Ru)(-1) (kWh)(-1), respectively, using a 1.5 %-Ru/La2O3 catalyst.