Modeling and analysis of ceramic–carbonate dual-phase membrane reactor for carbon dioxide reforming with methane

A new high temperature tube–shell membrane reactor (MR) design for separation and utilization of CO2 from the flue gas and for simultaneous production of syngas through carbon dioxide reforming of methane (CRM) is reported. The MR is based on a dual-phase CO2 permeation membrane consisting of mixed-conducting oxide and molten carbonate phases. High temperature CO2-containing flue gas and CH4 are respectively fed into the shell and tube sides of the reactor packed with a reforming catalyst. Under performance conditions, CO2 permeates selectively through the membrane from the shell side to the tube side and reacts with CH4 to produce syngas. Additionally, the heat from the flue gas can transfer directly through the membrane to provide energy for the endothermic CRM reaction. An isothermal steady-state model was developed to simulate and analyze CRM in the MR in this work. The effect of the design and operational parameters, such as inlet CH4 flow rate, shell side CO2 partial pressure and the flue gas composition, i.e., containing O2 or not, as well as the membrane thickness on the reactor performance with respect to the CH4 conversion and the CO2 permeation flux were investigated and discussed. The results show that the MR has a high efficiency in separating and utilizing CO2 from the flue gas. For a CH4 space velocity of 3265.31 h−1, with a membrane thickness of 0.075 mm and the shell side CO2 partial pressure of 1 atm, a CH4 conversion of 48.06% and an average CO2 permeation flux of 1.52 mL(STP) cm−2 min−1 through the membrane tube at 800 °C are obtained. Further improvement of the MR performance can be achieved by involving O2 in the permeation process.