Efficient photothermochemical dry reforming of methane over Ni supported on ZrO2 with CeO2 incorporation

Abstract

Solar-driven photothermochemical dry reforming of methane (PTC-DRM) has attracted increasing attention to address global climate issues yet still faces challenges of poor stability, especially for Ni-based catalysts. Herein, we developed a strategy to improve PTC-DRM activity and stability of Ni-based catalysts by supporting Ni nanoparticles on CeO2 incorporated ZrO2. At 700 °C under 30 suns light irradiation, the resulting Ni-CeO2/ZrO2 exhibited elevated and stable PTC-DRM with H2 and CO production rates of 713 and 693 mmol g−1 h−1 during a continuous 48 h test, respectively, much higher than those of Ce-free Ni/ZrO2 (542 mmol g−1 h−1 for H2 and 534 mmol g−1 h−1 for CO in a 24 h test). The comparisons between photothermochemical and thermochemical performance at the same temperatures indicate that introducing a small amount of CeO2 lowers the activation energies of CH4 and CO2 conversions from 68.6 and 62.9 kJ mol−1 in the dark to 54.7 and 57.7 kJ mol−1 under light, respectively. Mechanism investigation was performed through in situ DRIFTS and catalysts characterization before and after the PTC-DRM reaction, revealing that the plasmonic effect from Ni mitigates coke deposition and benefits the DRM activities and stability under light illumination. CeO2, serving as a promoter, enhances metal-support interaction, which also plays beneficial effects in continuously generating oxygen vacancies, facilitating the dissociation of carbonate intermediates, and mitigating coke deposition under light irradiation, thus boosting PTC-DRM activity and stability. This study is essential for designing cost-effective Ni-based catalysts and reaction systems for greenhouse gases conversion to produce syngas using sustainable solar energy.