Modelling and optimization of a WGS reactor at low temperature using a Cu/Zn/Ba/Al2O3 catalyst

P. GIUNTA, N. AMADEO, M. LABORDE

La Habana, Cuba

Simposio; HYPOTHESIS VI; 2005

In the last years, a renewed interest in the low temperature water gas shift (WGS) reaction has arisen due to its application on fuel cells. In this work, a simulation of a fixed bed reactor for this reaction, which form part of a hydrogen production-purification train for a 10 kW PEM fuel cell and using ethanol as raw material is carried out. A commercial Cu/Zn/Ba/ Al2O3 catalyst was employed and the one-dimensional heterogeneous model was applied for simulation. The catalyst deactivation due to thermal factors (sintering) was taken into account in the model. Isothermal and adiabatic regimes were also analyzed. Results of simulation indicate that the pellet can be considered isothermal; nevertheless, temperature gradients in the film cannot be disregarded. On the other hand, concentration gradients in the film can be ignored but CO profiles are established inside the pellet. Adiabatic operation can be recommended because of its simplicity of operation and construction. The reactor volume is strongly sensitive to the CO outlet concentration, particularly for CO levels lower than 6000 ppm. For a 10 kW PEM fuel cell, using the adequate pellet size and taking into account the catalyst deactivation, a reactor volume of 0.64 liters would be enough to obtain an outlet CO concentration of about 7160 ppm. This concentration value can be handled by the next purification stage – COPROX –.