Autothermal reforming of ethanlol in a fluidized bed membrane reactor for ultra-pure hydrogen production

In recent years, many efforts have been made to develop processes and reactor technologies for the prodn. of cheap, ultra-pure hydrogen that can be used in efficient PEM fuel cells. Nowadays, hydrogen is mainly produced by steam reforming of natural gas in multi-tubular reactors. The main drawback of natural gas reforming is that this reaction leads to a H2 rich gas mixt. also contg. carbon oxides and other byproducts. Consequently, in order to produce pure H2, chem. processes are carried out in a no. of reaction units (typically high temp. reformer, high and low temp. shift reactors) followed by sepn. units (mostly pressure swing adsorption units are used). An attractive way to produce hydrogen is the reforming of renewable fuels (e.g. bio-ethanol) inside membrane reactors, where hydrogen prodn. and hydrogen sepn. through selective membranes are integrated in one app. In this paper the prodn. of ultra-pure hydrogen via autothermal reforming of ethanol in a fluidized bed membrane reactor has been studied. The steam reforming of ethanol is an endothermic reaction requiring a great amt. of heat. The needed energy for the steam reforming is obtained by burning part of the hydrogen recovered via the hydrogen perm-selective membrane. In this configuration, the air used for the combustion is never in contact with the reacting mixt., which makes thus autothermal reforming with integrated CO2 capture feasible. Simulation results based on a phenomenol. model show that it is possible to obtain overall autothermal reforming of ethanol while 100% of hydrogen can in principle be recovered at relatively high temps. and at high reaction pressures. At the same operating conditions, ethanol is completely converted, while the methane produced by the reaction is completely reformed to CO, CO2 and H2