Catalytic activities of iron phosphide for NO dissociation and reduction with hydrogen

Iron phosphide (Fe2P) was synthesized by H2-temperature-programmed reaction, and it was first used as catalyst for NO dissociation and reduction with hydrogen. The structural properties of the catalyst were studied using X-ray diffraction (XRD), temperature-programmed decomposition, temperature-programmed oxidation as well as O2-chemisorption techniques. No matter what it was in 0.1%NO/He, 0.1%NO/0.1%H2/He or 0.1%NO/0.2%H2/He gas stream at 400 °C, the Fe2P catalyst showed a stable NO conversion to N2 (around 100%) within a test period of 32 h. We applied the XRD technique to examine the structural changes of Fe2P during the reactions. The results indicated that NO dissociation in the absence of H2 proceeded non-catalytically, and heavy accumulation of surface oxygen generated from NO dissociation resulted in gradual diffusion of oxygen into the Fe2P lattice and caused the ultimate oxidation of its bulk. With the addition of H2 in feed gas, the catalytic cycle could be established over Fe2P catalyst, and a H2/NO ratio of 2/1 was needed to avoid bulk oxidation of Fe2P catalyst for catalytic dissociation of NO.