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Hydrogen production from water splitting remains difficult due to the low equilibrium constant (e.g., Kp ≈ 2 × 10−8 at 900 °C). The coupling of methane combustion with water splitting in an oxygen transport membrane reactor can shift the water splitting equilibrium toward dissociation by instantaneously removing O2 from the product, enabling the continuous process of water splitting and continuous generation of hydrogen, and the heat required for water splitting can be largely compensated for by methane combustion. In this work, a CFD simulation model for the coupled membrane reactor was developed and validated. The effects of the sweep gas flow rate, methane content and inlet temperature on the reactor performance were investigated. It was found that coupling of methane combustion with water splitting could significantly improve the hydrogen generation capacity of the membrane reactor. Under certain conditions, the average hydrogen yield with methane combustion could increase threefold compared to methods that used no coupling of combustion. The methane conversion decreases while the hydrogen yield increases with the increase in sweep gas flow rate or methane content. Excessive methane is required to ensure the hydrogen yield of the reactor. Increasing the inlet temperature can increase the membrane temperature, methane conversion, oxygen permeation rate and hydrogen yield.

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The oxygen transport membrane reactor technology enables the stable combustion of syngas and reduction in NOx emission. Applying the syngas combustion membrane reactor to fire tube boiler can integrate oxygen separation, syngas combustion, and steam generation in a single apparatus. In this study, a CFD model for oxygen permeation and syngas combustion in a two-pass LSCoF-6428 tubular membrane reactor for fire tube boiler application was developed to study the effects of the inlet temperature, the sweep gas flow rate, and the syngas composition on the reactor performance. It is shown that the inlet temperature has a strong effect on the reactor performance. Increasing the inlet temperature can efficiently and significantly improve the oxygen permeability and the heat production capacity. A 34-times increase of oxygen permeation rate and a doubled thermal power output can be obtained when increasing the inlet temperature from 1073 to 1273 K. The membrane temperature, the oxygen permeation rate, and the thermal power output of the reactor all increase with the increase of sweep gas flow rate or H2/CO mass ratio in syngas. The feasibility of the syngas combustion membrane reactor for fire tube boiler application was elucidated.

A CFD model for oxygen permeation and partial oxidation of methane (POM) to syngas in a La0.6Sr0.4Co0.2Fe0.8O3-δ tubular membrane reactor was adopted to investigate the effects of the methane space velocity (MSV) and the feed composition on the reactor performance. It is shown that coupling POM reaction with carbon dioxide and steam reforming of methane (CRM and SRM), which is realized by co-feeding CH4 with CO2, H2O or CO2-H2O mixture into the reactor, can significantly enhance the methane conversion and syngas production rate and alter the H2/CO ratio as compared with feeding CH4 alone. For co-feeding CH4 with CO2, H2O or CO2-H2O mixture, the maximum syngas production rate is 2.3, 2 and 1.8 times that of feeding CH4 alone. Also, when POM is coupled with CRM and SRM, the temperature inside the reactor can be maintained above 973 K which is required for proper functioning of the membrane and catalyst.