Study of unreduced and reduced iron catalysts containing zirconium and calcium for ammonia synthesis has been made by using Mssbauer spectroscopy.An analysis of the Mssbauer paramaters shows that Zr4+ enters in to octahedral B sites of Fe3O4 and results in expansion of B sites.This is propitious to reduction of the catalysts.As a result of combination of Zr with Ca each other the Fe on A sites in sample containing Zr and Ca is reduced more rapidly,this is ascribed to electron conductivity.These exhibitions are more evident in the spherical catalyst cooled quickly by water.
