Magnetic hyperfine field structure of iron Urushibara type catalysts

We have utilized the Mossbauer effect to study the hyperfine field structure of iron Urushibara catalysts. The Mossbauer spectra of those catalysts prepared using zinc show that they consist of a mixture of magnetic and non‐magnetic Fe‐Zn alloys. Both the magnetic field distribution in the magnetic phase and the relative amounts of magnetic and non‐magnetic phases depend on the Fe‐Zn ratio used in the preparation of the catalyst. This dependence on Fe–Zn ratio is in contrast to iron Urushibara catalysts prepared using aluminum (and Raney iron type catalysts) in which the active phase is almost pure α‐fe, irrespective of the Fe‐Al ratio. The activity of zinc prepared iron Urushibara catalysts for certain hydrogentation reactions is known to be greater than that of aluminum prepared iron Urushibara catalysts and the above results suggest a relationship between activity and the modification of the iron catalyst by alloyed zinc. The alloying behavior of the Fe‐Zn particles may be analogous to that of the so‐c...