Enhanced Hydrogen Production via Methane Cracking in a Dielectric Barrier Discharge Plasma Reactor: Structural and Operational Parameter Optimization

To investigate the application potential of nonthermal plasma technology in methane cracking for hydrogen production, this study systematically examined the effects of key experimental conditions on methane conversion, hydrogen selectivity, and yield. This study employed a dielectric barrier discharge reactor, focusing on the synergistic mechanisms of multiple variables─including discharge power, reaction gas flow rate, external electrode length, external electrode material, discharge gap, and dielectric material─on the hydrogen production process. In-depth studies were conducted on the stability of the reaction and the solid product. The experimental results show that optimizing the reactor structure and operating parameters can significantly improve the hydrogen production efficiency. When the length of the outer electrode copper mesh was 5 cm, the flow rate was 10 mL/min, the input power was 30 W, the methane conversion rate was 69.8%, the hydrogen yield was 34.7%, and the hydrogen selectivity was 49.7%. Increasing the input power, reducing the flow rate, and increasing the length of the outer electrode can effectively improve methane conversion and hydrogen yield. The external electrode material had no significant effect on methane conversion at high power. Reducing the discharge gap increases methane conversion, while decreasing hydrogen selectivity. The introduction of BaTiO3 as a dielectric material inhibits methane coupling and promotes hydrogen formation. The effective conversion of methane over 600 min demonstrates the long-term operational stability of the plasma reaction system. The solid byproduct obtained from the reaction mainly consists of carbon black, with an ID/IG value of 0.97. This study provides important experimental evidence for the design and process optimization of high-efficiency plasma methane hydrogenation reactors.