Low-temperature conversion of NO to N 2 by use of a novel Ni loaded porous carbon

Abstract

Porous carbons with highly dispersed metal could be prepared by the carbonization of ion exchange resins exchanged by different cations and they were used as catalysts for NO removal from flue gas. Ni 2+-type resin carbonized at 500°C had high activity for converting NO to N 2 in the absence of any gaseous reducing agents at as low as 300°C. The active site was found to be highly dispersed metal Ni. It was clarified that NO was first chemisorbed on the metal Ni to form NO–Ni complex and then the complex was decomposed to form N 2 and NiO. The activity of deactivated sample was believed to be lowered by the oxidation of Ni to NiO. The deactivated catalyst was well regenerated by reducing agents such as CO without losing the carbon of the catalyst. This presented the possibility to utilize the catalyst in practical applications. In the presence of CO, the high activity could be maintained for a long time because the regeneration reaction occurred simultaneously by minimizing the loss of carbon. The reason why the carbonized Ni 2+ type resin had high activity for the removal of NO is that a fairly large amount of Ni (∼50 wt%) could be loaded on the surface of porous carbon in highly dispersed state by our method.