We then investigated the temperature dependence of maleate depletion (Fig. , blue circles) and fumarate formation (red At temperatures lower than 317 K (40 ºC), the apparent activation energy (∆Ea ‡ ) of the radical process was experimentally determined to be 48-67 kJ mol -1 for maleate depletion and 106-136 kJ mol -1 for fumarate formation. This indicates that the rate-determining step is the later stage involving the formation of fumarate. Interestingly, the traces overlap at reaction temperatures above 317 K, which indicates that the overall reaction switched from fumarate formation-limiting to maleate consumption-limiting as the temperature increased for both catalysts. The ∆Ea ‡ values for the decay of maleate under the radical conditions (Fig. , blue line) are close to those under the non-radical process of 44 kJ mol -1 (Fig. ).