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It is a major challenge to develop the low-temperature catalysts (LTC, <250 • C) with excellent efficiency and stability for selective catalytic reduction (SCR) of NO x by NH 3 from stationary sources. Mn-based LTC have been widely investigated due to its various valence states and excellent redox performance, while the poisoning by H 2 O or/and SO 2 is one of the severe weaknesses. This paper reviews the latest research progress on Mn-based catalysts that are expected to break through the resistance, such as modified MnO x -CeO 2 , multi-metal oxides with special crystal or/and shape structures, modified TiO 2 supporter, and novel carbon supporter (ACF, CNTs, GE), etc. The SCR mechanisms and promoting effects of redox cycle are described in detail. The reaction kinetics will be a benefit for the quantitative study of Eley-Rideal (ER) and Langmuir-Hinshelwood (LH) mechanisms. This paper also introduces the applications of quantum-chemical calculation using density functional theory to analyze the physic-chemical properties, explicates the reaction and poisoning mechanisms, and directs the design of functional catalysts on molecule levels. The intensive study of H 2 O/SO 2 inhibition effects is by means of the combination analysis of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT), and the amplification of tolerance mechanisms will be helpful to design an excellent SCR catalyst.

Introducing oxygen vacancies into metal oxides is a promising strategy to promote their catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, transition metal (M = Fe, Co, and Ni) doping was used to introduce oxygen vacancies in CeO 2 and promote activity for carbonyl sulfide (COS) hydrolysis. Various techniques were performed to accurately characterize the catalyst structure and state. The transition metals successfully entered the crystal lattice of CeO 2 and formed a solid solution structure. The metal-doped CeO 2 (M/CeO 2 ) showed improved reduction properties, more Ce 3+ and oxygen vacancies in comparison with pure CeO 2 . The introduction of transition metal greatly enhanced activity of M/CeO 2 for COS hydrolysis. Among them, the Co/CeO 2 sample displayed the highest activity and H 2 S selectivity. The roles of metal doping in improving activity were explored on the basis of DFT calculations. The strong interaction between doped metals and CeO 2 promotes the spontaneous formation of asymmetric oxygen vacancies in M/CeO 2 . These asymmetric oxygen vacancies facilitate the activation and dissociation of H 2 O and generation of active hydroxyls, which contributes to the enhanced activity for COS hydrolysis. This work provides an attractive method for obtaining nonprecious metal catalysts for COS hydrolysis.