Sulfur resistant LaxCe1-xNi0.5Cu0.5O3 catalysts for an ultra-high temperature water gas shift reaction

A series of LaxCe1-xNi0.5Cu0.5O3 catalysts was synthesized to study the effect of Ce substitution for La. XRD results show that only a small amount of Ce ( 10%) is allowable to substitute La to maintain the perovskite structure. The La0.9Ce0.1Ni0.5Cu0.5O3 catalyst has the smallest metal particle size and the highest oxygen mobility among all tested catalysts as observed from the XRD, TPD-O-2, and XPS results of reduced catalysts. These two factors are very important in achieving the highest catalytic activity of the La0.9Ce0.1Ni0.5Cu0.5O3 catalyst in a water gas shift reaction at 450-650 degrees C. In the presence of H2S, the catalytic activity at lower temperature was suppressed due to the formation of stable SO42- species on the metal. However, since the amounts of surface oxygen species and adsorbed H2S are much lower at high temperature, the formation of SO42- species is not observed, resulting in higher catalytic activity. The presence of H2S at high temperature enhances the formation of formate species, which can decompose to produce methane as the side product of the water gas shift reaction.