Studies on water–gas-shift enhanced by adsorption and membrane permeation

A new sorption enhanced membrane reactor (SEMR), consisting of a packed adsorbent-catalyst bed (10% CuO/CeO2 catalyst and a hydrotalcite-derived Mg–Al mixed oxide) around a tubular Pd/Ag hollow fibre membrane, has been proposed to obtain high purity H2 and simultaneous capture of CO2 during the water gas shift reaction. For comparison purposes, catalytic activity tests were carried out at atmospheric pressure and operating temperatures between 100 ◦C and 550 ◦C in three different catalytic reactors: (1) a fixed-bed reactor (FBR), (2) a sorption enhanced reactor (SER) and (2) a new SEMR. In all cases, the feed mixture Ar/CO/H2O ratio was 11/1/0.75 with a space velocity of 22 L/g h. The performance of the FBR was used as a reference to compare with the results obtained from the SER and SEMR. The H2 yield at 350 ◦C using the SER was 80%, which is 33% higher than that obtained in the traditional FBR and 18% higher than the corresponding thermodynamic equilibrium. However, due to the high CO/H2O ratio (R > 1), indesirable side-reactions such as C deposition become important at temperatures higher than 400 ◦C. A similar behaviour was observed using the SEMR, however in this case, a high purity COx free H2 production was obtained. This preliminary study shows relevant data obtained using a SER and the new SEMR, which allows for the better understanding and design of multifunctional catalytic reactors.