Development of cobalt catalyst supported on MgO–Ln2O3 (Ln = La, Nd, Eu) mixed oxide systems for ammonia synthesis.

The binding of hydrogen with nitrogen in the ammonia molecule has enormous potential as a hydrogen storage method. The development of efficient ammonia synthesis catalysts with high activity and stability is essential for this reaction. In this study, a series of MgO–Ln 2 O 3 (Ln = La, Nd, Eu) mixed oxides was designed and applied as the support of cobalt catalysts. The tuning of the support composition by selecting lanthanide elements differing in electronegativity led to changes in the physicochemical properties of the catalysts, such as the active phase dispersion, accessibility of active sites for hydrogen, surface density of basic sites. The Co/MgO–Nd 2 O 3 catalyst showed better activity than other studied catalysts in NH 3 synthesis reaction at 470 °C, 6.3 MPa. Its excellent performance is ascribed to the increased density of medium basic sites and the enhancement of electron-donating ability. [Display omitted] • Ammonia synthesis over Co catalysts supported on MgO–Ln 2 O 3 (Ln = La, Nd, Eu) composites. • Variable basic sites and tunable basicity of MgO–Ln 2 O 3 mixed oxides. • A strong influence of support basicity on properties of Co/MgO–Ln 2 O 3 catalysts. • The highest activity and stability of Co supported on MgO–Nd 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]