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Determining Factors Involved in the Preliminary Design of a Non-Isothermal Membrane Reactor

Giovanni Chiappetta, Gabriele Clarizia, and Enrico Drioli. Research Institute on Membrane Technology, ITM-CNR, via P. Bucci, 17/C, c\o University of Calabria, Arcavacata di Rende (CS), 87030, Italy

The growing demand of energy in many industrial fields requires the conceiving of more efficient production and utilisation systems in a logic of sustainable development. Hydrogen results one of the more attractive energy carrier for its use in different refinery processes and for its application as clean fuel. Palladium-based membrane reactors, combining the separation and reaction steps in a single unit, can be successfully used for the selective removal of the hydrogen produced in the water gas shift reaction. In this work radial and axial concentration and temperature profiles, obtained by means of a two–dimensional mathematical model, have been used to describe the behaviour of a non isothermal tubular membrane reactor as a function of different operating conditions and design parameters. An increase of the feed pressure enhances the CO conversion dumping the temperature hot spot that occurs along the membrane reactor. Also an appropriate choice of the sweep gas flow rate and temperature has a beneficial effect on both the driving force for hydrogen permeation and temperature profile, controlling the dangerous temperature hot spots without conversion loss. The dependence of the CO conversion and maxima of temperature on the characteristic geometric parameters of the reactor affects the productivity of a membrane reactor allowing a better operability and risk management.