On the modeling of one-dimensional membrane reactors: Application to hydrogen production in fixed packed bed

Hydrogen production by steam-methane reforming in membrane-assisted reactors has attracted substantial interest over the years. A variety of models for membrane-assisted reactors have been developed and suggested in the literature. In particular, examining the membrane models applied to the fixed packed bed reactor concept, there is no consensus or guidelines in the literature regarding the formulation of the heat balances (in terms of temperature). Thus, in the present study, different mathematical models for a fixed packed bed reactor with an integrated membrane have been compared in order to elucidate the effects of different model assumptions formulating the heat balance. The model formulations were examined by application to the steam-methane reforming process with hydrogen removal. The main findings of the present theoretical study are: With an increased temperature difference between the reaction and permeation zones, the enthalpy associated with the mass flux across the membrane has an increased effect on the temperature in the permeation zone. The temperature profile in the reaction zone is not influenced by the enthalpy difference across the membrane. Hence, in cases where it is not required with an accurate model prediction of the sweep gas temperature, the membrane reactor model can be simplified assuming isothermal condition in the permeation zone. The present study presents a rigorous derivation and examination of cross-sectional averaged models for membrane-assisted fixed packed bed reactors. Considering the level of details in the model formulations analyzed in this study, there exists currently no appropriate experimental data for model validations. (C) 2017 Elsevier Ltd. All rights reserved.