Concerning actuators and sensors, RS Pro PT100 resistance thermometers are installed to measure gas temperatures at the reactor inlet and outlet, as well as packed bed temperatures at different positions (detailed positions in the ESI †). Omega PXM459 pressure transducers are used to measure pressure in the reactor and feed line. Bronkhorst El-Flow Prestige FG-111AC flow meters determine inlet and outlet mass flow rates. The flow meter at the reactor outlet additionally serves as a flow controller (FIC). Both FI and FIC are pressure-compensated. The mole fraction of CO 2 is measured using two Smartgas Flow Evo infrared CO 2 sensors with ranges of 0-50 mol% and 0-100 mol%, respectively. These sensors can be mounted in three different positions, as shown in Fig. , depending on the mode of operation and the subject of investigation. Ball and needle valves for high-pressure applications (Swagelok, Type SS-43GS4 and SS-20VS4) are installed to open and close selected lines and to adjust the operating mode. Detailed process specifics including the valves' positions are contained in the ESI †. The uncertainty of the relevant instruments is evaluated for all measurements conducted and listed together with the measurement range in Table . Uncertainties of derived quantities are determined using linear error propagation as implemented in the Python library uncertainties .