Study On The Mixed-conducting Membranes For Thermal Decomposition Of Carbon Dioxide

Carbon dioxide, which is considered as the main contributor to the warming of the global atmosphere, and natural gas utilization have been drawing considerable attention recently due to the gradual shortage of petroleum resource day and night. In order to deal with excessive carbon dioxide and provide a novel route for reasonable utilization of natural gas, in this paper, based on literatures and previous work in our laboratory, we performed studies on mixed-conducing membrane reactors for the thermal decomposition of carbon dioxide (TDCD) coupling with partial oxidation of methane to syngas (POM). We focused on both the effect of packing amount of catalysts on POM reaction and the realization of TDCD coupling with POM in a ceramic membrane reactor.1. Study on the effect of packing amount of catalysts on POM reactionIn the previous research, we developed a new series of perovskite-type mixed-conducting oxides of SrCo₀.4Fe₀.6-xZr_xO₃-δ (0 ≤ x ≤ 0.2). The incorporation of Zr and its effect on the crystal chemistry, oxygen permeation, and structural stability of SrCo₀.4Fe₀.6-xZr_xO₃-δ were studied. It was found that substitutions of 10mol % Zr were considered to be enough for the structural stability with higher oxygen permeability. The objective of this work, therefore, was to study the performance of the POM to syngas in a disk-shaped SrCo₀.4Fe₀.5Zr₀.1O₃-δ (SCFZ) membrane reactor packed with different amount of NiO/Al₂O₃ catalysts by experiment and simulation.The SCFZ membranes packed with different amounts of catalysts were investigated for the POM reaction. A mathematical model developed based on the experiment was presented to simulate the performance of the membrane reactor. Good agreement was obtained between the experimental data and simulating results. It was found that the amount of catalysts packed on the top of membrane surface had an obvious effect on the performance of POM reaction, and that the oxygen flux, CH4 conversion and CO selectivity increased with increase in temperature and the amount of catalysts.2. Study on membrane reactors for TDCD reactionFirstly, from the viewpoint of thermodynamics, the TDCD reaction cannot be conducted on traditional fixed-bed reactors successfully. With the development ofmixed-conducting membrane reactors, this can be realized on ceramic membrane reactors easily. Therefore, the perovskite-type oxide of SrCoo.4Feo.5Zr