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 CO ₂ 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.