The microkinetics of ammonia synthesis: the effect of surface coverage on apparent activation energy and reaction order

We investigated the coverage effect on the experimental results using Ru and Ru+K for ammonia synthesis at 0.1 MPa and 380~460℃. Especially for Ru+K, the reaction order changed significantly with temperature, and the rate-limiting step was also affected by temperature. The apparent activation energy decreased as the gas flow rate decreased, even when the total pressure was the same. We showed through experimental techniques that even relatively small changes in experimental conditions on a laboratory scale can change the coverage and have a non-negligible effect on the reaction order and apparent activation energy.