Selective catalytic reduction of NOx with NH3 over titanium modified FexMgyOz catalysts: Performance and characterization

A series of titanium modified FexMgyOz catalysts were prepared by coprecipitation method and impregnation-coprecipitation method with microwave assistant and their catalytic capability in selective catalytic reduction (SCR) was evaluated. Appropriate amount of either titanium or TiO2 could both improve the catalytic performance of FexMgyOz catalyst, especially above 350 degrees C. 7.5%Ti-FexMgyOz catalyst with wide temperature range of 225-400 degrees C could achieve the maximum NOx conversion of 100%, while FexMgyOz/TiO2 (b) catalyst exhibited the best catalytic performance in the present of H2O and SO2. Characterization results exhibited that gamma-Fe2O3 was the main active phase, TiO2 was mainly in the form of anatase TiO2 and both titanium and magnesium existed in amorphous phase. The crystalline grain could be refined with the addition of either titanium or TiO2, as well as the increase of BET surface area and pore volume. The acid sites, redox ability and the chemisorbed oxygen were the most important factors in SCR reaction. The introduction of titanium and TiO2 had the effect of increasing the strength of the acid sites, which could attribute to the improvement of catalytic performance over titanium modified FexMgyOz catalysts. (C) 2018 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.