In order to implement renewable energy sources into the energy infrastructure, their inherent fluctuating availability must be compensated for. One way of doing this is to convert surplus electrical energy into easy storable chemical energy, also known as the power-to-x (PtX) concept . In this process, hydrogen (H2) is obtained from the renewable electrical energy using electrolysis in a first step. Since H2 is difficult to be stored in the long term and suitable infrastructure is not yet available, it is advantageous to further convert it into methane (CH4), which can be stored, distributed and used in the existing natural gas grid. This requires a carbon source, for which both carbon monoxide (CO) and carbon dioxide (CO2), as well as mixtures of both (COx), are suitable and available in sufficient amounts from industrial exhaust gases . The stoichiometric equations for the methanation of CO and CO2 are given in equations ( ) and (2), respectively, while equation (3) represents the water gas shift reaction -a linear combination of both methanation reactions .