The reactor can be fed from two gas lines with different gas compositions consisting of H2 (5.0 purity, MTI), CO2 (4.8 purity, MTI), Ar (5.0 purity, MTI), CO/Ar (90 vol-% CO 3.8 purity in Ar 5.0 purity, Air Liquide) and He (5.0 purity, MTI). The gas mixtures are provided by two dosing sections with 4 mass flow meters (EL-Flow Prestige, Bronkhorst), each. The feed gas can be switched by a pressure actuated high speed valve (Fitok, BOSS-4C) between both gas lines with high frequencies. The switching is not affecting the gas flow in the reactor, since both gas lines are controlled to exhibit the same pressure.