Here, we see that the α-peak is unaffected by the varied build-up duration. Additionally, the β-peak is completely absent for a buildup phase of 15 s. From these results, we conclude that the less reactive species Cβ builds up slowly on the catalyst surface, since the β-peak is only visible for longer build-up durations (> 15 s TOS for C3 and > 1 min for C2). Furthermore, we assume that Cβ blocks active sites for other species, as the overall reaction rate decreases with increasing build-up duration (see also fig. ). At the same time Cα is formed almost immediately after the switching event and the Cα coverage is unaffected by Cβ, since the height of the α-peak stays almost constant for all build-up durations. Hence, we suspect different adsorption sites for both carbon species. Furthermore, Cβ takes part in the chain growth reaction, as the increase of the respective peak in the back-transient phase is most pronounced for C2 and C3+. However, the hydrogenation of Cβ to CH4 is also possible, as the transient molar flow rate of CH4 is also increasing with raising build-up duration.