The present master thesis deals with the detail engineering of a bench scale unit for the catalytic methanation of CO2. Starting point was a principal flow chart with three reactors in a reactor cascade, with optional bypasses and addition of educt gases respectively water vapour. In a literature research about similar plants and technologies, parameters for this type of catalytic process were found. With these parameters and with a certain geometry of the catalytic converter the geometries of the reactors were determined. In addition to that an operating window was defined. In consequence of the definition of certain operating conditions in relation to pressure and temperature it was possible to dimension pipes, fittings and mountings. A concept for the measurement and control technologies was developed and the position of these in the plant was determined. The integration of the plant at the designated site was reviewed and actions for the adaption were set up. The result of this work is a detailplan of the plant with all the required components for the realisation and a budget plan.