TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The control or regulating device is adapted to adjust the stoichiometric factor of the educt gas. The device further comprises a sensor device for obtaining measurement information for the control or regulating device, where the sensor device comprises: apparatus for detecting at least one of the measured values of gas comprising flow rate, gas composition, pressure and temperature of at least one of the gases comprising educt gas, retentate gas, permeate gas and feed gas; and/or a device for measuring pressure and/or temperature in the methanation reactor in the gas flow direction and successively pressure or temperature measuring points.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: A stoichiometric factor of the educt gas, which is defined as the ratio of the percentage difference between the hydrogen and carbon dioxide to sum of carbon monoxide and carbon dioxide content is more than 3 and less than 15. Preferred Method: The parameters comprising flow rate of the educt gas, composition of the educt gas, pressure of the educt gas, flow rate of the feed gas, composition of the feed gas, pressure of the feed gas, flow rate of the retentate gas, composition of the retentate gas, pressure of the retentate gas, flow rate of the permeate gas, composition of the permeate gas, pressure of the permeate gas, temperature of the educt gas, temperature of the feed gas, temperature of the retentate gases, temperature of the permeate gas, pressure and temperature in the methanation reactor in the gas flow direction and successively associated pressure or temperature measuring points, are measured and are adjusted depending on an amount of supplied feed gas, an amount of the recirculated permeate gas, hydrogen content of the supplied feed gas, a pressure in the methanation reactor while performing methanation reaction and/or a gas separation differential pressure. The permeate gas mixing is regulated depending on a given carbon dioxide/carbon monoxide gas-flow rate of the feed gas and a predetermined pressure difference of retentate gas and permeate gas to achieve carbon dioxide/carbon monoxide minimum turnover. A mixture of carbon dioxide/carbon monoxide rich gas and hydrogen gas is used as feed gas, where the carbon dioxide/carbon monoxide rich gas is metered depending on the amount and/or composition of the carbon dioxide/carbon monoxide gas and the amount and/or composition of the recycled and the use of gas admixed permeate gas. The methanation reactor is monitored for the occurrence of catalyst deactivation and/or a hot-spot displacement, and the gas pressure in the methanation reactor increases upon detection of catalyst deactivation or hot-spot displacement, where water vapor content in the reactant gas and/or the reactor temperature is adjusted. EXAMPLE - No suitable example given.