Experimental Investigation of DBD Parameters and Ru/-Al₂O₃ Catalyst on Plasma-Assisted Ammonia Synthesis

Under the normal temperature and pressure conditions, ammonia (NH3) synthesis experiments were conducted by the self-developed dielectric barrier discharge (DBD) plasma device. The effects of typical processes and discharge parameters, including the total flow rate of reaction gas, volume ratio of reaction gas, discharge power, discharge frequency, plasma volume on NH3 synthesis rate, and yield, were studied and analyzed. In addition, the effect of Ru/gamma-Al2O3 catalysts was investigated on nonthermal plasma-assisted ammonia synthesis. The results show that the NH3 synthesis rate and yield are relatively high when the total flow rate of reaction gas is about 120 mL min(-1) and the volume ratio of N-2 and H-2 is 1:2. With the discharge power of 33.6 W and a plasma volume of 18.37 mL, the system exhibits uniform and stable discharge, resulting in an energy yield of approximately 190 mg kW(-1) h(-1). By adjusting the discharge frequency to 8.2 kHz, which is in resonance with the experimental system, the NH3 synthesis rate reaches its maximum. The use of 2%Ru/gamma-Al2O3 as a catalyst resulted in the highest NH3 synthesis rate of 34.3 mu mol min(-1), which is 3.5 times higher than that obtained without a catalyst.