In fig. , the transient molar flow rates (see eq. ( )) of all relevant components are shown. For CO (see fig. ), we see negative transient molar flow rates, as expected from increased consumption after the switch to H2. The build-up duration does not influence the back-transient behavior of CO and H2O significantly, see SI fig. . In contrast, for the carbonaceous products, the longer the build-up duration is, the higher the maximal transient molar flow rates in the back-transient phase are. For CH4 and short build-up durations below 7 min (fig. ), the peak of the transient molar flow rate broadens, while the maximum stays approximately at the same position. For the buildup duration of 4 h the maximum shifts slightly in time. The signal of C2 (fig. and) shows one single peak for short build-up durations of 1 min and below, which is broadening and develops a shoulder and even a second peak for increasing durations. After 4 h, the first α-peak merges with the second β-peak. For C3+ (fig. and), a similar behavior is observed. However, the α-peak is much less pronounced compared to C2, while the increase of the β-peak is more pronounced (compare fig. and).