In recent years, low-temperature SCR (Selective Catalytic Reduction) denitrification technology has been popularized in non-power industries and has played an important role in the control of industrial flue gas NO_x emissions in China. Currently, the most commonly used catalysts in industry are V₂O₅-WO₃(MoO₃)/TiO₂, MnO₂-based catalysts, CeO₂-based catalysts, MnO₂-CeO₂ catalysts and zeolite SCR catalysts. The flue gas emitted during industrial combustion usually contains SO₂, moisture and alkali metals, which can affect the service life of SCR catalysts. This paper summarizes the mechanism of catalyst poisoning and aims to reduce the negative effect of NH₄HSO₄ on the activity of the SCR catalyst at low temperatures in industrial applications. It also presents the outstanding achievements of domestic companies in denitrification in the non-power industry in recent years. Much progress has been made in the research and application of low-temperature NH₃-SCR, and with the renewed demand for deeper NO_x treatments, new technologies with lower energy consumption and more functions need to be developed.

Heteropoly acids (HPAs) with the Keggin structure have been widely used in NO_x removal. Two kinds of catalysts (those with and without the Keggin structure) are prepared for studying the effect of the Keggin structure on the NH₃-SCR reaction. A series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analyses are conducted to investigate the surface-adsorbed species on the catalysts during the SCR reaction. The mechanism for enhancing low-temperature activity of the catalysts is proposed. Furthermore, the effect of NH₄⁺ in the Keggin structure is also investigated. Results indicate that both the Langmuir–Hinshelwood (L-H) and Eley–Rideal (E-R) mechanisms occurred in the NH₃-SCR reaction over the catalyst with the Keggin structure (Cat-A); in addition, when more acid sites are provided, NO_x species activity is improved and more NH₄⁺ ions participate in reaction over Cat-A, thus promoting SCR activity.

Developing a catalyst with high SO₂ and H₂O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO₂/H₂O-DRIFTS, XPS, TEM, SEM, NH₃/SO₂-TPD, H₂-TPR, and ICP techniques revealed that the high SO₂ and H₂O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO₂ adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.