The Rate Equation of Ammonia-Synthesis on Iron-Type Catalysts of Different Composition

Investigations on the rate equation of ammonia synthesis on iron catalysts have been carried out. The results agree in a general way with the rate equation of Temkin and Pyzhev. An improvement of this equation is given, which leads to a better agreement between observed and calculated synthesis rates. Experiments carried out at low temperatures show that the rate equation is the same for the three catalysts which have been investigated: (1) pure iron, (2) iron containing 3 percent alumina, and (3) iron containing 3 percent alumina and 2 percent potassium oxide. By means of the improved Temkin and Pyzhev equation a formal explanation can be given for the results obtained by Love and Emmett on ammonia decomposition on a singly promoted iron catalyst between 400 and 450C.