Plasma-assisted NH3 cracking in warm plasma reactors for green H2 production

• Warm plasma systems are more efficient at NH 3 cracking than cold plasma reactors. • NH 3 cracking in warm plasma reactors mainly occurs via thermal chemistry. • Heat integration is required to improve cracking efficiency and maintain reactor integrity. NH 3 is emerging as a carrier of green H 2 , but it requires a green and economical NH 3 cracking process based on renewable energy. Plasma technology is promising for this purpose, as it can crack NH 3 without the need for a catalyst and is highly compatible with renewable electricity, reducing the environmental footprint of the cracking process. This work investigates the NH 3 cracking performance of four different warm plasma reactors with different configurations and operating in a wide range of conditions. We show that the NH 3 conversion in warm plasma reactors is primarily determined by the specific energy input, with the main difference observed in the energy cost (EC) of cracking. The lowest EC obtained is 146 kJ/mol but at a conversion of only 8 %. A more reasonable conversion of around 50 % yields an EC of around 200 kJ/mol in two of the reactors investigated. Plasma reactors operating at higher feed flow rates are more efficient and yield a higher H 2 production rate. Our data indicate that NH 3 cracking in these warm plasma reactors occurs mainly via thermal chemistry, with non-thermal plasma chemistry playing a less prominent role. NH 3 decomposes not only inside the plasma core but also in a hot volume around it, which reduces the EC. Our study shows that warm plasmas are significantly more efficient for NH 3 cracking than cold plasmas, even when the latter are combined with catalysts.