Preparation of Egg-shell type Ni-supported catalysts and their application for the reforming of CH_4

摘要

Egg-shell type supported Ni catalyst was successfully prepared by applying the spc-method (solid phase crystallization method) on the surface layer of the Mg-Al mixed oxide prepared from Mg-Al hydrotalcite (HT) anionic clay as the precursor, and tested for the steam reforming and oxidative steam reforming of CH_4. The precursor based on ([Mg_3Al (OH)_8]_1/2 CO_3~(2-) centre dot 2H_2O was prepared by co-precipitation method and then thermally decomposed to give the Mg-Al mixed oxide. The mixed oxide was impregnated in aqueous solution of Ni nitrate, washed, dried, and calcined. During the impregnation, the surface layer of the mixed oxide particle was reconstructed to hydrotalcite structure, which contained Ni species at the Mg site. The precursor thus obtained was calcined and reduced to form the catalyst particle loaded by Ni in Egg-shell type. This egg-shell type Ni supported catalyst showed high activity even at high space velocity in both steam reforming and oxidative steam reforming of CH_4. The high CH_4 conversion of the egg-shell type Ni supported catalyst is due to the formation of highly dispersed Ni metals on the surface of catalyst.