Enhancing ammonia catalytic production over spatially confined cobalt molybdenum nitride nanoparticles in SBA-15

Ternary Co3Mo3N nitrides are reported to exhibit high catalytic activity in ammonia synthesis. However, synthesis of ternary nitrides requires thermal treatments at elevated temperatures and reactive atmospheres that lead to unavoidable surface reduction (similar to 10 m(2) g(-1)). In this work, we have developed a novel approach to improve the catalytic activity of Co3Mo3N through its dispersion into a high surface area silica-based support (SBA-15). During ammonolysis and ammonia synthesis conditions reaction, SBA-15 demonstrated good thermal and chemical stability maintaining an ordered porous structure and high surface area (> 500 m(2) g(-1)). For application in ammonia synthesis, SBA-15 supported cobalt molybdenum catalysts with different metal loading (10, 20 and 30 wt%) were prepared by a modified impregnation-infiltration protocol and their catalytic activity studied. The dispersion of CoMo nitride nanoparticles into SBA-15 structures resulted in the improvement of their structural and textural properties of nitrides as evidenced by XRD analysis, STEM-EDS, and N2- physisorption (e.g. 10-CoMo-N/SBA-15: 348 m(2) g(-1)). Nevertheless, the surface composition of CoMo-N/SBA-15 catalysts was found to be similar to the non-supported Co3Mo3N. Furthermore, supported CoMo-N/SBA-15 displayed enhanced catalytic activity in ammonia synthesis (1714, 1429 and 810 mu mol g(active) (-1)(phase) h(-1) corresponding to the CoMo oxide loadings of 10, 20, 30 wt% respectively) that outperform the classical Co3Mo3N catalyst (259 mu mol g(catalyst)(-1) h(-)1). The results reported in this work highlights a novel approach for the design of nitride-based catalysts with superior catalytic properties in ammonia synthesis.

Automated summary

In this study, the catalytic activity of Co3Mo3N was improved by dispersing it into a high surface area silica-based support (SBA-15). SBA-15 demonstrated good thermal and chemical stability, and supported CoMo-N/SBA-15 catalysts exhibited enhanced catalytic activity in ammonia synthesis compared to the classical Co3Mo3N catalyst.