Design of an Air-Cooled Sabatier Reactor for Thermocatalytic Hydrogenation of CO2: Experimental Proof-of-Concept and Model-Based Feasibility Analysis

This study assesses the techno-economic feasibility of using a single-pass, air-cooled Sabatier reactor for the thermocatalytic conversion of CO2 into renewable natural gas (RNG). The reactor was first analyzed numerically using a dynamic mathematical model. Effects of the feed rate, coolant type (compressed air vs molten salt), and cooling rate on the reactor performance were investigated. Next, the experimental proof-of-concept was provided using an autonomous Sabatier reactor (62 g of Ni/Al2O3 catalyst), including stability tests up to 100 h time-on-stream. Both simulations and experimental investigation have shown that, with a proper selection of operating parameters, it is possible to achieve CO2 conversions higher than 90%, while keeping the selectivity to CH4 production at 100%. On the basis of these results, a large-scale system for RNG generation from landfill gas has been designed, simulated, and analyzed, resulting in the RNG production cost as low as $15/GJ for the electricity price of $0.05/kWh.