Preparation and evaluation of catalysts of highly dispersed zerovalent iron (Fe0) supported on activated carbon for NO reduction

Abstract

Catalysts of highly dispersed zerovalent iron (Fe0) supported on activated carbon were prepared and their catalytic activity in NO reduction by CO was studied in a fixed-bed reactor. The catalytic activity improved with increasing temperature, Fe loading and dispersion. At 325 °C, the NO conversion reached 85% in the presence of CO. N2 adsorption–desorption, XRD, SEM, TEM, XPS, ICP-AES, TGA-MS/FTIR and In-situ XRD were applied to characterise the fresh and spent catalysts. Fe0 in the catalyst is better dispersed at lower Fe loadings and at lower calcination temperatures. The mechanism of NO reduction with or without CO was different. Increasing Fe0 dispersion improves the catalytic activity in the presence of CO, while increasing Fe loading is more important in maintaining the catalytic activity in the absence of CO. Catalyst deactivation is attributed to NO oxidation of Fe0 and activated carbon support as well as Fe sintering and agglomeration. CO in the reacting stream plays an important role in enduring the catalytic performance by protecting Fe0 from being oxidised by NO.