The Effect of CO2 Co-feeding in Steam Reforming of Methane: A Thermodynamic Equilibrium Analysis

The effect of co-feeding of carbon dioxide in steam reforming of methane on the syngas product composition and coke formation tendency was studied by thermodynamics equilibrium analysis using constrained Gibbs free energy minimization method (T=800°C, P=20 bar). Side reactions including water-gas shift and solid carbon (coke) formation were also taken into account. Replacing steam with equivalent amount of CO2 (by maintaining a constant (CO2+H2O)/CH4 ratio in the feed) increases the susceptibility to coke formation illustrating the higher potential of steam as a coke removing agent compared to carbon dioxide. The equilibrium calculation results were compared with literature data for combined reforming of methane over a variety of catalysts under same reaction conditions. Favorable agreements with experimental results were observed. The findings of this work would be useful for designing experimental conditions for catalytic process development under which the reactant conversions are maximized while coke formation (and thus, catalyst deactivation) is minimized.

Keywords:

Natural Gas Conversions , Steam Reforming , Carbon Dioxide , Thermodynamic Equilibrium , Coke Formation