Ammonia synthesis using Co catalysts supported on MgO-Nd2O3 mixed oxide systems: Effect of support composition

This study presents the use of emerging support materials based on mixed magnesium-neodymium oxides for the dispersion of the Co metal for ammonia synthesis. A series of cobalt catalysts using mixed MgO-Nd2O3 oxide supports with different Mg/Nd molar ratios (2, 4, 7, 10, and 12) was successfully prepared. The N2 physisorption, XRD, HR-TEM, STEM-EDX, TPR/TG-MS, H2-TPD, and CO2-TPD studies of these systems revealed a strong cor-relation between the composition of the support and the overall catalyst performance. It was found that varying the Mg/Nd molar ratio caused a gradual change in the textural, structural and adsorption properties. The dif-ference in the activity of the Co/MgO-Nd2O3 catalysts towards ammonia synthesis was mainly attributed to the different surface adsorption properties. The highest number of basic sites on the catalyst surface was noted for the support with the Mg/Nd molar ratio of 10. Also, the highest Co dispersion was obtained on this support, leading to the best distribution of Co particles with the smallest Co particle size. As a result, the Co/ 10MgO-Nd2O3 catalyst demonstrated superior activity for ammonia synthesis compared to other catalysts. The use of a binary composite support consisting of MgO and Nd2O3 with the properly selected ratio of each component is beneficial in terms of catalyst activity, stability and cost compared to single-oxide supports.

Automated summary

This study explores the use of mixed MgO-Nd2O3 oxide supports for the dispersion of Co metal for ammonia synthesis. Different ratios of Mg/Nd were evaluated, and it was found that the support composition significantly influenced the catalyst performance. The catalyst with a Mg/Nd molar ratio of 10 exhibited the highest number of basic sites and the best dispersion of Co particles, resulting in superior activity for ammonia synthesis.