Microwave‐Pyrolysis‐Assisted Preparation of Magnetic Iron‐Titanium Mixed Oxide Catalyst for Selective Catalytic Reduction of NOx with NH3

A kind of magnetic iron‐titanium oxide catalyst for selective catalytic reduction (SCR) of NOx with NH3 is obtained by the microwave‐pyrolysis co‐precipitation method. This catalyst is characterized in detail by various techniques such as X‐ray diffraction, N2 adsorption–desorption, X‐ray photoelectron spectroscopy, temperature‐programmed reduction of H2, and temperature‐programmed desorption of NH3/NO to investigate the influence of titanium oxide addition on the NH3‐SCR activity of magnetic iron oxide. Furthermore, the NH3‐SCR reaction mechanism over magnetic iron‐titanium oxide is also revealed. The NH3‐SCR activity over magnetic iron oxide is enhanced by the addition of titanium oxide, especially the low‐temperature activity. The addition of titanium oxide depresses the oxidization of γ‐Fe2O3 to α‐Fe2O3 in the precursor obtained through microwave‐pyrolysis co‐precipitation during the aging process, and also reduces the absorption ability of SO42− to the precursor. The crystallite of iron oxide in magnetic Fe1‐xTixOz‐500 (x = 0.25, 0.5, and 0.75) catalysts is mainly γ‐Fe2O3. Among these magnetic catalysts, magnetic Fe0.75Ti0.25Oz‐500 has two distinctive peaks in the pore size distribution curve and more active iron‐based sites on its surface for NH3‐SCR reaction. This catalyst shows the highest NH3‐SCR activity. The NH3‐SCR reaction over magnetic Fe0.75Ti0.25Oz‐500 at low‐temperature obeys both the Eley–Rideal mechanism and the Langmuir–Hinshelwood mechanism. An economical and time‐saving method developed to obtain a magnetic iron‐based mixed oxide catalyst is critical to control NOx (NO and NO2) emission from coal‐fired power plants. A magnetic iron–titanium mixed oxide catalyst is prepared through microwave‐pyrolysis co‐precipitation with FeSO4·7 H2O as the iron precursor. This catalyst shows higher low‐temperature NH3‐SCR activity to reduce NOx emission from coal‐fired power plants.