Kinetic modelling of methane conversion in DBD plasma-catalysis under quasi-isothermal conditions

Steam methane reforming (SMR) is the primary industrial route for hydrogen production, traditionally driven by thermal catalysis, whereas plasma-catalysis offers an electrified alternative capable of modifying reaction energetics by non-thermal conditions. However, quantitative kinetic analyses under controlled plasma-surface operation remain limited. This work provides the first experimental kinetic study of methane conversion by DBD plasma-catalysis, minimizing the thermal effects from the plasma contribution. A total of 80 experiments were conducted over a Ni/Al 2 O 3 catalyst under quasi-isothermal and differential conversion conditions (<15%), varying plasma power (20–35 W), CH 4 /H 2 O ratio (0.1–10), and incorporating products to the feed (CO, CO 2 and H 2 ). The methane consumption rate (r CH4 ) exhibited an Arrhenius-type dependence with respect to specific energy input, indicating a distinct energetic contribution governed by plasma excitation. r CH4 increased with CH 4 partial pressure (P CH4 ) but decreased with H 2 O (P H2O ), defining an optimal CH 4 /H 2 O ratio that reflects a balance between methane activation and competitive adsorption effects. Product incorporation revealed moderate effects of CO and CO 2 , while H 2 showed a minor influence in r CH4 . An empirical kinetic expression was iteratively derived from experimental data, progressively incorporating adsorption and product terms. The final model reproduced the experimental trends with high precision (R 2 ≈ 0.98, RMSE ≈ 8 × 10 −7 ) and yielded consistent apparent activation energies (E a ≈ 306 kJ·mol −1 ) across tested formulations. Sensitivity and correlation analyses confirmed that plasma energy input and P CH4 dominate the rate response, whereas product terms have a minor contribution within the evaluated range. The resulting rate equation quantitatively correlates the measured CH 4 consumption trends by plasma-catalysis and provides basis for operating condition assessment.