Preparation, characterization, and catalytic activity of NiMg catalysts supported on mesoporous alumina for hydrodechlorination of o-dichlorobenzene

Chemical templates containing binary metal components were prepared by controlling pH of a mixed solution of magnesium stearate and nickel salt. The resulting templates were used as structure-directing agents and bimetallic sources in the preparation of porous NiMg-Al₂O₃ catalysts, where Al(OBu)₃ was used as an aluminum source. Both NiMg-NP (a NiMg-Al₂O₃ catalyst templated by a NH₄OH- treated precipitate) and NiMg-HS (a NiMg-Al₂O₃ catalyst templated by a HCl-treated solution) catalysts showed almost the same physical properties. However, chemical properties of these catalysts such as metal reducibility and metal-support interaction were different depending on the identity of templates. Compared to the NiMg-NP catalyst, the NiMg-HS catalyst exhibited weak interaction between metal and support, resulting in more intensive metal aggregation. For comparison purpose, Ni and NiMg catalysts supported on mesoporous alumina were also prepared by a conventional impregnation method. In the hydrodechlorination of o-dichlorobenzene, the secondary metal component (magnesium) enhanced the catalytic activity and inhibited the catalyst deactivation. Among the catalysts employed in this work, the NiMg-NP catalyst, which retained a homogeneously mixed metallic state, was the most active in the catalytic reaction and was the most resistant against deactivation.