Improving CO2 methanation performance by distributed feeding in a Ni-Mn catalyst fixed bed reactor

[Display omitted] •An alternative, aside from catalysts, for upgrading CO2 methanation reactors.•Side feeding CO2 leads to enhanced conversions and selectivities to CH4.•Thermal gradients along the bed are reduced by distributed feeding.•Proven influence of side distributed feeding on CO2 methanation performance. It has been successfully demonstrated the effect of feeding reactants in distributed manner for the reaction of methanation of CO2. This operation mode has improved not only the selectivity towards CH4, but also the overall process performance. A fixed bed reactor, loaded with Ni-Mn based catalyst, was operated co-feeding both CO2 and H2, but alternatively feeding one of them through several lateral inlets. Preserving the same global W/FCO2 ratio, the side distribution of CO2 allowed to clearly increase the activity of the process (e.g., at 375 °C, the conversion with distributed feeding was around 35% higher than that for the conventional one: XCO2 = 0.12 vs. XCO2 = 0.09). Furthermore, a substantially lower selectivity towards non-desired CO was obtained at any conversion level (e.g., SCO = 0.45 vs. SCO = 0.70, when XCO2 = 0.10). In addition, a more homogeneous temperature profile could be achieved in the bed without increasing the severity of hot spots appearance. On the contrary, side distribution of H2 always led to similar or worse results than for the conventional co-feeding configuration.