Coupling exothermic and endothermic reactions in an ethanol microreformer for H2 production

Abstract

The steam reforming of ethanol is carried out in a microreactor for hydrogen production. The heat for the endothermic reactions is supplied by means of ethanol combustion in air, which is carried out in contiguous microchannels. The same Pd-based catalyst is assumed to be coated on both reforming and combustion channels. By means of a 1D heterogeneous mathematical model, the influence of the feed temperatures of both streams on the reactor performance is analyzed. The results show that the degree of preheating of both streams has a strong influence on the hydrogen yields and maximum temperatures. The effect of the flowrate and composition of the fuel stream on the hydrogen yields is also studied. Fairly high hydrogen yields were obtained (2.6< nH2 < 3.4) with low methane slips, within a feasible range of temperatures for the Pd catalyst (700 < TMAX < 770 ºC) to avoid catalyst deactivation. These maximum temperatures could still be further reduced by means of an optimal selection of the air flowrate and ethanol molar fraction on the fuel side, or using distributed feed of fuel along the reactor length.