In Figure , a respective step response for CH4 after 1 and 10 h TOS can be seen, whereby the switch from H2/He to H2/CO2/He/Ar is performed at 𝑡 = 0 and vice-versa at 𝑡 = 120 𝑠. Here, the sharp increase of CH4 formation at the beginning of each build-up half-period can be seen, as well as the subsequent slower decrease in the back-transient half-period. After the initial transient progression after the switching event, the CH4 formation enters a pseudo steadystate after about 30 s. The last 10 s of this pseudo-steady-state were averaged for each period individually to get a measurement point for the comparison of this period to the steady-state operation (Figure ). During 10 h, a clear decrease of CH4 formation can be seen, corresponding to a deactivation over this time period.