ON THE RATE-DETERMINING STEP AND THE ROLE OF POTASSIUM IN THE CATALYTIC SYNTHESIS OF AMMONIA

The simple concept of a single rate-determining step, the dissociation of N2(a), in ammonia synthesis is inconsistent with experimental results. It is proposed that three reaction steps, N2(a) --> 2N(a) (1) N(a) + H(a) --> NH(a) (2) NH3(a) --> NH3(g) (3) are dominant in determining the rate of synthesis. Under industrial conditions reactions (2) and (3) are more important than (1). The role of K+ as promoter in these reactions is discussed, especially as an "anchor" for adsorbed oxygen.