Sorption-enhanced carbon dioxide reforming and partial oxidation of biogas

Abstract

This work investigates the advantages of utilizing CaO as a CO2 sorbent in the combined carbon dioxide reforming and partial oxidation of biogas over Ni/SiO2.MgO catalyst. The catalytic performance in term of hydrogen yield of the integrated sorption-reaction systems was operated under 3 modes; i.e. i) Ni/SiO2.MgO before CaO, ii) CaO before Ni/SiO2.MgO and iii) mixture of CaO and Ni/SiO2.MgO, is compared with that of the conventional system without CaO sorbent. The results indicate that the mode of mixture of CaO and Ni/SiO2.MgO shows the best performance among the different sorption enhanced systems. However, the results from simulation indicated that the addition of oxygen caused decrease in H2:CO ratio, hydrogen yield and concentration, but increase in exothermic heat. The addition of water was able to enhance H2:CO ratio, hydrogen yield and endothermic heat; however, hydrogen concentration was declined. The CaO addition can improve H2:CO ratio, hydrogen yield and concentration including more exothermic heat. The temperature effect, H2: CO ratio, hydrogen yield and concentration decreased but the overall enthalpy increased at high temperature. For thermal-neutral operation, the condition which gives optimum hydrogen yield of 89.3% with H2:CO = 8.98 are O2:CH4 = 0.00013, H2O:CH4 = 4.8 and CaO:CH4 = 1 at 973 K.