MCM-41 modified with iron by template ion-exchange method as effective catalyst for DeNOx and NH3-SCO processes

Abstract

Iron was deposited on MCM-41 using template ion-exchange (TIE) method. Solutions of FeCl2 and [Fe3(OAc)6O(H2O)3]NO3 were used as precursors of deposited iron species. It was shown that deposition of significant amount of iron, in some cases above 10wt.% in recalculation to Fe2O3, on MCM-41 or Ti-MCM-41 resulted only in a relatively small decrease of the specific surface area and porosity of the mesoporous silica supports. Moreover, in case of iron acetate oligocations deposition, the formation of iron oxide micro-rods outside of the MCM-41 structure was found. Such effect was not observed when a solution of FeCl2 was used for iron deposition. MCM-41 and Ti-MCM-41 modified with iron by TIE method were found to be active catalysts for the process of the selective oxidation NH3 to N2 (NH3-SCO). In this process, the catalysts effectively operated in the high-temperature range with a very high selectivity to dinitrogen (above 90% at 550°C). Some differences in catalytic performance, related to type of the mesoporous support as well as iron loading and precursor used for deposited iron species, were observed.