Syngas methanation for substitute natural gas over Ni–Mg/Al2O3 catalyst in fixed and fluidized bed reactors

•Comparison was conducted between fixed and fluidized bed (FB) syngas methanation.•FB methanation showed always higher CO conversion and CH4 yield.•FB methanation has less sensitivity to temperature and space velocity variation.•Low and easy-oxidizing carbon was deposited on spent catalyst of FB methanation.

A comparative study was conducted for laboratory syngas methanation over a self-made Ni–Mg/Al2O3 catalyst to demonstrate the technical advantages of fluidized bed over fixed bed reactor. At different reaction temperatures, gas velocities and pressures, the CO conversion and selectivity to CH4 in fluidized bed were shown to be higher than in fixed bed, and much closer to the thermodynamic equilibriums. The spent catalysts from fluidized bed methanation had distinctively low and easy-oxidizing deposited carbon in comparison with that from fixed bed. The results were attributed to the bigger effective catalytic surface, better heat and mass transfer in fluidized bed reactor.

Graphical abstractPerformance comparison between fixed and fluidized bed reactors for atmospheric methanation at different bed temperatures under SV = 60 NL/(g·h) shows that for each given temperature, the fluidized bed methanation resulted always in the higher conversion and selectivity than the fixed bed did, and the performance data of the fluidized bed reactor were thus closer to their thermo-equilibrium values.Figure optionsDownload full-size imageDownload as PowerPoint slide