Effect of loading potassium and palladium over iron-based catalyst for low temperature water-gas shift reaction

We investigated the effect of loading potassium over iron-based catalysts for water-gas shift (WGS) reaction at 573 K. The iron-based water-gas shift catalyst has been known as a redox-mechanism catalyst. Therefore, to promote the redox reaction over iron oxide, we impregnated a small amount of Pd on various iron oxides. Results revealed that coexisting potassium and palladium accelerated the WGS reaction over iron-oxide catalyst. We examined the optimum amount of potassium over Pd/iron catalyst, and we found that the optimum molar ratio was about 2 (K/Pd molar ratio). From the viewpoint of reducibility of the catalyst, the addition of small amount of Pd onto iron oxide promotes reduction from Fe₂O₃ to Fe₃O₄. However, impregnation of potassium on iron oxide makes the catalyst structure robust. The promotion effect of Pd and potassium was not observed on SiO₂ support. We therefore concluded that the synergetic effect among Pd, K, and iron oxide, was important for the WGS reaction.