The catalytic experiments were evaluated calculating the absolute and transient molar flow rates, 𝑛̇ , and 𝑛̇ , , respectively. The measured ionic currents from the MS were converted via calibration into molar fractions. Via eq. ( ), the total outlet molar flow rate, 𝑛̇ , is calculated from the measured molar fraction and known molar flow rate of the external standard Ne, 𝑥 and 𝑛̇ , respectively. By that, also the non-equimolarity of the reaction is considered and the outlet molar flow rates of all other components can be calculated by eq. ( ).