Flare gases processing over highly dispersed Ni/Ce_0.75Zr_0.25O₂ catalysts for methanotroph-based biorefinery

X wt.% Ni/Ce_0.75Zr_0.25O₂ catalysts (X = 5, 9, 12, 15) have been prepared by the incipient wetness impregnation technique in the presence of ethylene glycol (EG) and tested in the steam reforming of a propane-methane mixture at temperatures below 350 °C. The activity of the catalysts obtained has been compared to the activity of industrial Ni catalysts. Catalytic activity of the samples increased with increasing Ni content and allowed complete propane conversion at 270−300 °C. The catalysts have been characterized by XRD, BET, TEM, TPO and CO chemisorption techniques. High nickel dispersion attributed to EG influence during the preparation step was confirmed. X wt.% Ni/Ce_0.75Zr_0.25O₂ catalysts (X = 9, 12, 15) had lower Ni content than industrial catalysts but higher dispersion which overall resulted in higher catalytic activity. 15 wt.% Ni/Ce_0.75Zr_0.25O₂ catalyst provided complete conversion of propane at a temperature of 275 °C, WHSV of 2500 cm³ h⁻¹ g⁻¹ and molar ratio H₂O/C_C2+ of 2. The resulted mixture after water condensation contained 91 vol.% CH₄, 5 vol.% CO₂ and 4 vol.% H₂ and could be used as a feed for methanotrophs.