The methanation facility at atmospheric pressure consists of a fixed-bed reactor of 1 kW_H2 capacity, which is supplied with a controlled mixture of H₂ and CO₂. A gas analyzer measures the gas composition (vol%) before and after the methanation reaction (Figure 1). The CO₂ and H₂ cylinders are connected to their respective mass controller: (i) EL-Flow Bronkhorst® model F-201CV-RAD-22-K, measurement range of 0.16 – 0.80 kg/h for CO₂ and (ii) EL-Flow Bronkhorst® model F-201AV-RAD-22-V, measurement range 0.003 – 0.15 kg/h for H₂. Those cylinders are located outside the building. Prior to being fed into the reactor, the mixture of CO₂ and H₂ is preheated by a ceramic heater to a temperature below 400 ºC.

The fixed-bed reactor is a self-designed tubular reactor (30 mm diameter and 620 mm length) made of 310 stainless steel and sealed with two 304 stainless steel flanges. The reactor is surrounded by two heating tapes (model HCVD-02502000-03, Termya) for temperature control. Each heating tape has a length of 1.5 m and a power rating of 600 W, operating at 250 V. Both the reactor and the gas feed duct from the ceramic heater are thermally insulated using rock wool.