Temperature overshoots and undershoots were found for a Pd on alumina catalyst pellet in its course towards a new steady state after a change in concentration of one of the reactants ethylene or hydrogen. When cooling the pellet, after heat-up by reaction, with pure hydrogen a sudden temperature peak appears after a short time. A mathematical model is introduced, which can explain the over- and undershoots by slow ad- or desorption on the active sites of the catalyst of one of the reactants.
Westerterp, K. R., Loonen, R. A., & Martens, A. (1986). Rare behaviour of a catalyst pellet catalyst dynamics. Chemical engineering science, 41(4), 1117-1122. https://doi.org/10.1016/0009-2509(86)87200-1