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

Ni supported catalysts were prepared by the solid phase crystallization (sp c) method starting from hydrotalcite (HT) anionic clay based on [MgsAl(2)(O H)(16)CO32-].H2O as the precursor. The precursors were prepared by the co-p recipitation method from nitrates of the metal components, and then thermal ly 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 rep lace the Mg2+ site in the hydrotalcite, resulting in the formation of highl y dispersed Ni metal particles on spc-Ni/Mg-Al. The spc-catalyst thus prepa red showed higher activity than those prepared by the conventional impregna tion (imp) method such as Ni/alpha -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/alpha -Al2O3 an d 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 incor poration 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 spec ies and afford high activity on the imp-Ni/Mg-Al.