The measured CO2 pulses increase in the first 30 pulses, followed by a more or less constant value throughout the first subsequence. This is true for both the peak heights (Figure ) and the integrated intensities (Figure ). The incoming CO2 pulses, in contrast, decay more or less continuously during the first half of this subsequence, indicating that there is a considerable consumption of CO2 at the beginning of the subsequence, which decays with time. In the second and third subsequence, we observed a similar behavior, only at slightly lower absolute intensities. Apparently, the pulse sizes were slightly lower in these subsequences. Hence, the overall decay of the CO2 pulses is largely caused by the decay in incoming pulse size (Figure ). Based on these trends we conclude that significant CO2 consumption occurs at the beginning of each subsequence, indicating that in the time after the first subsequence and the beginning of the second subsequence, i.e., in the absence of H2/CO2/Ar pulses, the original state of the catalyst, before the first subsequence, is partly recovered again. The same occurs also after the second subsequence.