(570ai) A Non Isothermal Maxwell-Stefan Diffusion Model for Design of Catalytic Membrane for Hydrogen Production From Ethanol Reforming

This research explores the use of non-permselective catalytic membranes for simultaneous production and purification of hydrogen via ethanol steam reforming. Conventional reactor designs make use of expensive permselective membranes (e.g., Palladium) in series with steam reforming to purify hydrogen. Catalytic membranes can be used to achieve conversions above original equilibrium by coupling selective separation and catalytic activities while externally controlling feed and sweep boundary conditions [1]. These catalytic membranes have attractive features for fast and highly exothermic reactions and can improve selectivity for multiple reaction networks [2]. In this poster, the authors detail the development of a one dimensional non-isothermal model based on a single cell reactor employing Maxwell-Stefan diffusion equations for multi-component gas mixture coupled with heat conduction across the catalytic membrane. Ethanol steam reforming is assumed to be taking place via network of three simultaneous reactions; (i) Ethanol pyrolysis, (ii) Water gas shift reaction and (iii) methane steam reforming. All reactions in this model are assumed to be occurring on Rh/Al2O3 catalyst, which is not permselective for any species in reaction. Transmembrane fluxes and temperature effects are calculated by solving coupled non linear differential equations in COMSOL Multiphysics using Chemical Engineering module. This model is employed to investigate the influence of steam concentration on sweep and feed sides, flow rate of feed and sweep inlet and the effect of temperature profiles either developed within or externally applied, upon hydrogen yield and purity on the sweep side of the membrane. The same model will be modified to describe the use of different catalysts specifically selective for one or more reactions in series. Lastly, experimental results to-date employing a single-cell reactor to verify model predictions will be presented.

References:

[1] Catalytic Membrane for Simultaneous Chemical Reaction and Separation Applied to a Dehydrogenation Reaction. Yi-Ming Sun and Soon-Jai Khang. Ind. Eng. Chem. Res, 1988 (27).

[2] Applications of a non-permselective, catalytically active membrane. A Model study. J. W. Veldsink, R. M. J. Van Damme, G. F. Versteeg and W. P. M. Van Swaaij. Chem. Eng. Comm. 1996. Vol 169.