Effective Thermal Design Concept of Sabatier Reactor by Controlling Catalyst Distribution Profile

This study presents the effective thermal design concept of exothermic Sabatier reactor, which shall convert carbon dioxide with hydrogen to produce water and methane (so-called “methanation”) assisted by the catalytic activity. Pellet type of Ru-based catalyst is packed in the preheated reactor tube and stoichiometric reactant gas mixture (CO2 and H2) flows at the prescribed flow rate. By employing the present system, steady 1-D reaction field is successfully achieved. Bundled thermocouples are inserted from the downstream through the sealed yet movable connectors to obtain the steady-state temperature profile in the reactor. End gas is analyzed by gas chromatography to check the conversion performance. The following two series of reactor are tested; it has (1) uniform or (2) stepwise catalyst distribution. By using uniform catalyst bed, relatively strong peak in the temperature profile is appeared at the inlet and thermal damage of catalyst is highly expected to lose the durability. No significant improvement on reduction of the peak as well as the conversion performance even when the shorter heating regime is employed, although the peak location moves to downstream. Adopting the non-uniform (stepwise) catalyst distribution are effectively modifying the thermal structure in the reactor having the less-peak in the temperature profile without losing the conversion performance. Our study reveals the control of catalyst distribution is simple yet effective approach to achieve the uniform temperature profile even in 1-D flow reactor design at high conversion performance. The reactor temperature profile was achieved to be uniform by adopting stepwise catalyst distribution to prevent hot spots in the Sabatier reactor.