H2 production and CO2 separation

A promising technology for H2 production and CO2 separation is based on water gas shift reaction operated in water gas shift membrane reactor (WGSMR). In such a reactor the synthetic gas reacts with steam in a catalytic bed to produce additional hydrogen and CO2. A H2 selective membrane allows the simultaneous production of hydrogen at a high purity level and a stream of concentrated CO2. The performance of such a reactor is defined in terms of CO conversion fraction, H2 recovered fraction and produced H2 flow rate. The chapter deals with the modelling of a WGSMR. A model developed to assist the design of a pilot scale, tube-in-tube reactor, is described. Simulations with the model are presented and discussed. The simulations were performed to analyse the effect of operating conditions (H2O/CO ratio, temperature, pressure and syngas flow rate), catalyst characteristics (catalytic bed efficiency, void fraction) and membrane length, on the reactor performance. The results provide quantitative information to define the set of conditions to obtain the target value of the H2 flow rate, with high values of CO conversion fraction and H2 recovered fraction, minimising the length of the H2 selective membrane. A last paragraph is dedicated to a short analysis of the main issues and foreseen solutions for the industrial application of the technology. © Springer-Verlag London Limited 2011.