Methanol steam reforming for hydrogen production over Ni/ZrO₂ catalyst: Comparison of thermal and non-thermal plasma catalysis

Hydrogen (H₂) is the promising clean energy which can contribute to the achievement of the Net Zero goals. Herein, the Ni/ZrO₂ catalyst was developed for methanol steam reforming for H₂ production. The catalyst possesses the features of good redox property, and the presence of surface chemisorbed oxygen, and large specific surface area. The Ni/ZrO₂ composite together with the control of NiO and ZrO₂ were assessed by thermal and non-thermal plasma (NTP)-activated methanol steam reforming reactions, and the results showed that NTP itself was able to initiate methanol conversion, whilst the inclusion of the composite catalyst did not improve the reaction significantly, e.g., hydrogen production rate = 0.162 mmol·min⁻¹ over Ni/ZrO₂ under the plasma condition (at 90 ℃ and 9.4 kV). This could be attributed to the change of reaction pathways for methanol conversion in the presence of Ni/ZrO₂ under the NTP condition, compared to the thermal systems employing Ni/ZrO₂. Comparatively, the thermal catalytic system was not active at 90 °C regardless the catalysts used. At 400 °C, the Ni/ZrO₂ catalyst showed satisfactory activity with a hydrogen production rate of 0.708 mmol·min⁻¹. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and DFT calculations were performed to understand the relevant reaction mechanisms, revealing that methoxy and formic acid species were the key intermediates for methanol steam reforming.