Combined steam and dry reforming of methanol process to syngas formation: Kinetic modeling and thermodynamic equilibrium analysis

Abstract

In the present study, the combined steam and dry reforming of methanol (CSDRM) process were performed in the temperature range of 400 °C-900 °C, CO2/H2O ratio of 0.5–2.5 and (CO2+H2O)/CH3OH ratio of 0.5–2.5 at the atmospheric pressure over a Pt/ZrO2 catalyst in fixed bed reactor. The experimental data was applied to model the kinetic of CSDRM reaction based on Langmuir-Hinshelwood (LH) isotherm with one active site on the catalyst surface taking into account. By comparing the two experimental and calculated values, it was seen that error of kinetic model in predicting the experimental methanol conversion was lower (7.97%) than other responses. An almost completed methanol conversion was attained above 800 °C at all values of CO2/H2O ratios except for (CO2 + H2O)/CH3OH ratio of 0.5. The temperature had a positive impact on the H2 and CO yields, however; the dependency of CO yield to temperature was higher than H2 yield. CO2 conversion slightly decreased from 400 °C to 500 °C, while started to increase at temperatures above 500 °C regardless of (CO2+H2O)/CH3OH and CO2/H2O ratios. H2/CO ratio near to 2 which is suitable for Fischer–Tropsch synthesis (FTS) reaction was obtained at (CO2+H2O)/CH3OH ratios bigger than 1.5, a CO2/H2O ratio of 1 and temperature above 800 °C. The methanol conversion values obtained from thermodynamic equilibrium were equal with the experimental data. The reverse water-gas shift reaction quickly happened at temperatures above 700 °C, higher values of CO2/H2O ratio and under excess oxidizing agent, which led to increasing the gap between the experimental data and measured from thermodynamic equilibrium analysis.