Denitrification characteristics and reaction mechanism of Ce-doped Fe-based catalysts from modified metallurgical dust containing iron

Abstract

Metallurgical dust (MD) was used as raw material to prepare rare earth Ce-doped Fe-based catalysts. The results show that the Ce_0.1/AMD-300 °C catalyst prepared from acid-modified diatomite (AMD) with m_Ce/m_MD = 0.1 (m_Ce and m_MD are the mass of Ce and MD, respectively) after being roasted at 300 °C can reach 99% NO_x removal rate in the wide temperature range of 230–430 °C and exhibits excellent SO₂ and H₂O resistance. The MD effectively removes alkali metal elements by the modification process, increases the specific surface area and optimizes the pore structure of MD. The doping of Ce element makes Fe-based catalysts have more surface adsorbed oxygen O_α and a higher Ce³⁺/Ce⁴⁺ ratio. Through ammonia temperature-programmed desorption and hydrogen temperature-programmed reduction, it was found that the strong interaction between cerium and iron promotes the formation of more oxygen cavities in the catalyst, thereby generating more active and easily reducible oxygen species and promoting the transformation of Brønsted acid site to Lewis acid site. The research results provide a theoretical basis for the preparation of efficient and inexpensive Fe-based catalysts from MD.