In contrast, the response of CO is slightly delayed compared to the RTD, while H2O first appears several seconds later, when the other products already start to decrease again. This indicates a significant storage amount of carbon and oxygen on the catalyst surface, which will be discussed in detail later. In a previous investigation with the same catalyst under CO2 methanation conditions, it was observed that the TiO2 support has a high adsorption capacity for H2O. Hence, we also assume that the delay in the H2O molar flow rate is caused by its adsorption on the support material.