Influence of lithium on reduction, dispersion and hydrogenation activity of nickel on alumina catalysts

Abstract

The influence of lithium modifier on the physical properties of alumina as well as on the reduction and dispersion of nickel oxide on alumina carrier is discussed. Lithium addition up to 2 wt % helps to improve the reducibility of Ni²⁺ ions, dispersion and metal area. It is explained on the basis of LiAl₅O₈ spinel formation which reduces the interaction between Ni²⁺ ions and alumina. A higher concentration of lithium (> 2 wt %) has a detrimental effect on reduction, dispersion and metal area. An electronic interaction, with the formation of Li–O–Ni, is proposed to explain this phenomenon. Benzene hydrogenation is used as a model reaction to compare the activity of various lithium modified nickel alumina catalysts. The effect of precalcination of the modified catalysts on reducibility is discussed.