Thermodynamic Analysis on Reaction Characteristics of the Coupling Steam, CO_2 and O_2 Reforming of Methane

摘要

This study presents an analysis of coupling steam, CO2 and O-2 reforming of CH4 using the thermodynamic equilibrium constant method. Effects of molar ratio of O-2/CH4, H2O/CH4 and CO2/CH4 on reforming characteristics in both carbon deposition and carbonfree systems are analyzed. The results indicate that CH4 conversion rate, H-2, and CO yield increase with increasing O-2/CH4 molar ratio in two systems. In addition, the carbon elimination is achieved when O-2/CH4 ratio increases to 0.31, and changing the amount of O-2 can be an effective way to alter n(H-2)(CO) ratio in the carbon deposition systems. CH4 conversion rate increases with increasing H2O/CH4 ratio in the carbon-five system, while it declines in the carbon deposition system. H2O plays a role of altering n(H-2(CO) ratio, and its effects on two systems are opposite. The deposited carbon is totally eliminated when H2O/CH4 ratio increases to 0.645. The increase of CO2/CH4 molar ratio leads to a rapid increase of CO2 conversion when CO2/CH4 ratio is less than 0.5. A slightly change of CO2/CH4 ratio can result in a huge difference on n(H-2)(CO) ratio in both systems, and carbon elimination is achieved at CO2/CH4 = 0.99. The analyzed results have theoretical significance to efficiently catalyze methane coupling.