Determination of the operating range of CO2 conversion and syngas production in dry auto-thermal reforming

•CO2 reforming and syngas production are studied in a PM-catalyst hybrid reformer.•The CO2 conversion efficiency is enhanced by internal heat recirculation.•The best CO2 conversion can be obtained with O2/CO2 ratio of approximately 0.5.•The CO2 conversion efficiency can reach 13% without external heat addition.

A porous medium-catalyst hybrid reformer for CO2 conversion by dry auto-thermal reforming (DATR) was investigated in this study, and its operating range was discovered. The hybrid design was used to enhance the oxidative heat release by internal heat recirculation during exothermic reaction conditions, thereby increasing the CO2 conversion efficiency. The experimental results show that the CO2 conversion could be enhanced with higher catalyst inlet temperatures. The examination of the operating range of DATR showed that the CO2 conversion efficiency increased at higher reaction temperatures and CO2/CH4 ratios (≧1). Moreover, DATR in high temperature conditions must be carried out with high O2/CH4 ratios. Under these conditions of high oxygen content, CO2 generation and reduction reactions occur simultaneously. Overall, optimal CO2 conversion can be obtained with an O2/CO2 ratio of approximately 0.5. At these conditions, CO2 conversion efficiency can reach approximately 13% without external heat addition.