Catalytic and Physical Properties of Ca²⁺-doped MgO

Ca²⁺ ions loaded on MgO surface markedly promoted catalytic activities of MgO for isomerization of 1-butene, hydrocarbon gasification with CO₂ or O₂, and the reverse water-gas shift reaction, although MgO itself was almost inactive after treatment at 1273K in air. Ca²⁺ ions also increased the basicity and basic strength of MgO. Strong basic sites catalyzed isomerization of 1-butene. In the course of impregnation with Ca(NO₃)₂, MgO (periclase) was completely transformed into hydrate (brucite) by the action of nitrate ions. It is considered that Ca²⁺ ions interfere with the transformation of surface arrangements accompanied with structural transformation from brucite (hcp) to periclase (fcc). It wasm found that most of Ca²⁺ ions aggregated to form particles of CaO on the surface of MgO while Ca²⁺ ions were highly dispersed on the surface of MgO when the MgO was prepared from basic carbonate salt involving calcium as an impurity.