CO2 reforming of CH4 over Ni/Mg–Al oxide catalysts prepared by solid phase crystallization method from Mg–Al hydrotalcite-like precursors

Abstract

Ni supported catalysts were prepared by the solid phase crystallization (spc) method starting from hydrotalcite (HT) anionic clay based on [Mg₆Al₂(OH)₁₆CO₃ ²⁻]⋅H₂O as the precursor. The precursors were prepared by the co-precipitation method from nitrates of the metal components, and then thermally decomposed, in situ reduced to form Ni supported catalysts (spc-Ni/Mg–Al) and used for the CO₂ reforming of CH₄ to synthesis gas. Ni²⁺ can well replace the Mg²⁺ site in the hydrotalcite, resulting in the formation of highly dispersed Ni metal particles on spc-Ni/Mg–Al. The spc-catalyst thus prepared showed higher activity than those prepared by the conventional impregnation (imp) method such as Ni/α-Al₂O₃ and Ni/MgO. When Ni was supported by impregnation of Mg–Al mixed oxide prepared from Mg–Al HT, the activity of imp-Ni/Mg–Al thus prepared was not so low as those of Ni/α-Al₂O₃ and Ni/MgO but close to that of spc-Ni/Mg–Al. The relatively high activity of imp-Ni/Mg–Al may be due to the regeneration of the Mg–Al HT phase from the mixed oxide during the preparation, resulting in an occurring of the incorporation of Ni²⁺ in the Mg²⁺ site in the HT as seen in the spc-method. Such an effect may give rise to the formation of highly dispersed Ni metal species and afford high activity on the imp-Ni/Mg–Al.