Method for separating off and immobilizing carbon dioxide and/or carbon monoxide from an exhaust gas

A process for separation and immobilization of carbon dioxide and/or carbon monoxide from an offgas, wherein the offgas is obtained by combustion of fossil fuels in a power plant, as a byproduct in an industrial process or as an extraction gas in the extraction of fossil fuels, comprising the steps of:

• a) establishing a stoichiometric ratio of carbon dioxide to hydrogen and/or of carbon monoxide and hydrogen which is suitable for a methanization reaction by supplying the offgas with a corresponding amount of hydrogen or alternatively carbon dioxide and/or carbon monoxide by an additive gas,
• b) performing a catalytic reaction in which the reactants carbon dioxide and/or carbon monoxide and also hydrogen are converted into methane and water,
• c) separating the methane from the product of the catalytic reaction, wherein remaining residual gases are discharged into the atmosphere,
• d) cracking the methane into carbon and hydrogen, wherein the carbon is generated as a solid,
• e) collecting the cracked carbon, and
• f) landfilling the collected carbon
• wherein the offgas is a mixture of at least two components, wherein the offgas comprises at least carbon dioxide or carbon monoxide as one component and the offgas comprises at least one inert gas as a further component which remains in the offgas after the separation according to step c),
• wherein to establish the stoichiometric ratio the proportions of carbon dioxide and/or of carbon monoxide present in the offgas are measured, wherein the proportion of hydrogen present in the offgas is optionally also measured.