Improvement of Ni dispersion on alumina by ethylene glycol applied for CO₂ reforming of CH₄

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Ethylene glycol (EG) was added to an aqueous solution of nickel nitrate and that of nickel and lanthanum nitrates, and Ni/Al₂O₃ and Ni–La/Al₂O₃ catalysts were prepared by an impregnation method using the respective aqueous solution and commercial alumina. It was shown, by CO chemisorption, TEM, and STEM-EDS mapping, that finer nickel particles were formed by EG, and improved Ni dispersion and decreased distribution width of nickel diameter profile were also obtained. Owing to the fine nickel particles, carbon formation during CH₄–CO₂ reforming was suppressed. It was speculated that EG bound and/or interacted with surface hydroxyl groups and coordinately unsaturated Al³⁺ sites of alumina, thereby aggregation of nickel and lanthanum during the decomposition of the nitrates was suppressed due to the physical interfering by EG.