Ammonia synthesis over multi-promoted iron catalysts obtained by high-energy ball-milling

The feasibility of producing ammonia synthesis catalysts from high-energy b all-milling of a simple mixture of the constituent oxides has been investig ated. The effect of ball-milling the fused oxidic precursor of the industri al KM1 ammonia synthesis catalyst has also been studied. The results show t hat high-energy ball-milling offers some interesting possibilities for prep aring novel catalytic materials. It is observed that ball-milling of the po wder oxides mixture leads to formation of solid solutions and the catalytic activity is significantly higher than that of the starting material. Furth ermore, ball-milling of fused oxidic KM1 precursor is seen to give rise to more homogeneous promoter distribution and slightly higher activity. The qu ite small activity increase observed in this case probably reflects the fac t that the fusion process has already resulted in a close to optimal promot er distribution. The choice of atmosphere during ball-milling is also seen to offer possibilities for regulating the phase composition.