Modeling and performance assessment of Pd- and Pd/Au-based catalytic membrane reactors for hydrogen production

A mathematical steady-state modeling framework for the isothermal operation of a membrane reactor for methane steam reforming is developed, and a comparative performance assessment of the catalytic membrane reactor (CMR) versus a conventional packed bed reactor (PBR) is accordingly conducted. A detailed literature benchmarking suggests that the models developed in the present study predict total methane conversion levels within 99% of the experimental values reported in the literature. The proposed Pd- and Pd/Au-based CMR model is utilized for the aforementioned performance analysis under a broad range of reactor operating conditions such as temperature (350-750 degrees C), pressure (2-30 bars), steam to methane ratio (1-15), membrane thickness (1-50 mm), and permeate-side sweep ratio (1-100). In all simulation runs conducted, the superior performance of both the Pd- and Pd/Au-based CMR over the PBR was amply demonstrated. Furthermore, within the proposed CMR modeling framework, an index-based analysis is conducted that concretely quantifies progress towards the attainment of key process intensification objectives. In particular, by appropriately defining the Delta-index, which explicitly captures potential performance and process intensification benefits associated with attainable total CH4 conversion levels under different reactor operating conditions, it is shown that the optimum CMR performance is achieved at high pressure and low temperature operating conditions, which was particularly suitable for the attainment of key process intensification objectives as well as optimum performance target levels.