Microwave‐Pyrolysis‐Assisted Preparation of Magnetic Iron‐Titanium Mixed Oxide Catalyst for Selective Catalytic Reduction of NO x with NH 3

A kind of magnetic iron‐titanium oxide catalyst for selective catalytic reduction (SCR) of NO x with NH 3 is obtained by the microwave‐pyrolysis co‐precipitation method. This catalyst is characterized in detail by various techniques such as X‐ray diffraction, N 2 adsorption–desorption, X‐ray photoelectron spectroscopy, temperature‐programmed reduction of H 2 , and temperature‐programmed desorption of NH 3 /NO to investigate the influence of titanium oxide addition on the NH 3 ‐SCR activity of magnetic iron oxide. Furthermore, the NH 3 ‐SCR reaction mechanism over magnetic iron‐titanium oxide is also revealed. The NH 3 ‐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‐Fe 2 O 3 to α‐Fe 2 O 3 in the precursor obtained through microwave‐pyrolysis co‐precipitation during the aging process, and also reduces the absorption ability of SO 4 2− to the precursor. The crystallite of iron oxide in magnetic Fe 1‐ x Ti x O z ‐500 ( x  = 0.25, 0.5, and 0.75) catalysts is mainly γ‐Fe 2 O 3 . Among these magnetic catalysts, magnetic Fe 0.75 Ti 0.25 O z ‐500 has two distinctive peaks in the pore size distribution curve and more active iron‐based sites on its surface for NH 3 ‐SCR reaction. This catalyst shows the highest NH 3 ‐SCR activity. The NH 3 ‐SCR reaction over magnetic Fe 0.75 Ti 0.25 O z ‐500 at low‐temperature obeys both the Eley–Rideal mechanism and the Langmuir–Hinshelwood mechanism.