Thermodynamic analysis of autothermal steam and CO2 reforming of methane

Thermodynamic equilibrium of methane autothermal reforming was studied by Gibbs free minimization for methane and H2OH2O or CO2CO2 conversions, H2H2 yield and coke deposition as a function of H2OH2O-to-CH4CH4 ratio, CO2CO2-to-CH4CH4 ratio, O2O2-to-CH4CH4 ratio, reforming temperature and pressure. The optimal reaction conditions for reforming and the ways for coke elimination were given. The results showed that coke formed in CO2CO2 reforming was easier than that formed in steam reforming under similar conditions. Coke elimination should be done by increasing the reaction temperatures in CO2CO2 reforming while by increasing steam content fed in steam reforming. The optimal CH4/CO2/O2CH4/CO2/O2 feed ratios 1:0.8–1.0:0.1–0.2 through the analysis of thermodynamic equilibrium in the oxidative CO2CO2 reforming were corresponding to the reaction temperature higher than 800∘C. Carbon deposition increased with the increase in pressures while a high temperature can suppress this effect.