Development of a combined catalyst and sorbent for the water gas shift reaction

A combined catalyst and sorbent was developed for reacting CO with steam to produce H2 in a single reaction stage at 600 °C by employing the water gas shift (WGS) reaction. The combined material was in the form of spherical pellets where each pellet consisted of a CaO core for absorbing byproduct CO2 surrounded by a porous shell of Al2O3 which supported a Ni catalyst. The best results were achieved by incorporating 5 wt % limestone in the shell material to suppress coking. By employing the best core-in-shell pellets and supplying a 3:1 mol ratio of steam to CO at 600 °C, more than 97% of the CO was converted to H2 by the WGS reaction and less than 1% was converted to CH4 by a side reaction. Also, none of the CO was converted to coke. ■ INTRODUCTION The water gas shift (WGS) reaction shown below is frequently employed for the production of hydrogen (H2) by reacting steam (H2O) with carbon monoxide (CO) that is produced either by reforming hydrocarbons or by gasifying coal or biomass. + ↔ + Δ = − ° H CO(g) H O(g) H (g) CO (g) 41 kJ/mol 2 2 2 25 C