The selective catalytic oxidation of ammonia into nitrogen and water vapor (NH₃‐SCO) has proven to be the most efficient technique for the removal of NH₃ from the oxygen‐containing diesel exhausts. Until now, two reviews over investigated catalysts have been published in 2015–2016 (Jabłońska et al., RCS. Adv. 2015; Appl. Catal. B: Environ. 2016). Among various NH₃‐SCO catalysts, Cu‐ and/or Fe‐containing zeolites are considered as promising candidates due to their benign nature, NH₃ storage capacity, very high NH₃ conversion and N₂ selectivity. The present review focusses only on the Cu‐containing zeolites (mainly on chabazite (CHA): SSZ‐13, SAPO‐34) catalysts) applied in NH₃‐SCO starting from 2015. The synthesis/preparation methods and the state of Cu in catalysts on the activity and selectivity are highlighted. The advantages of the understanding of the reaction mechanism are reviewed. Finally, an outlook is given together with expected inspirations for future research directions in developing zeolite‐based catalysts.

Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with copper ions (Cu²⁺ and Cu⁺), the Cu-SSZ-13 catalysts were characterized to explore their framework composition (XRD, solid-state NMR, ICP-OES), texture (N₂-sorption, SEM) and acid/redox properties (FT-IR, TPR-H₂, DR UV-Vis, EPR). Finally, the materials were tested in the selective catalytic reduction of NO_x with ammonia (NH₃-SCR). The main difference between the Cu-SSZ-13 catalysts was the number of Cu²⁺ in the double six-membered ring (6MRs). Such copper species contribute to a high NH₃-SCR activity. Nevertheless, all materials show comparable activity in NH₃-SCR up to 350 °C. Above 350 °C, NO conversion decreased for Cu-SSZ-13(2–4) due to side reaction of NH₃ oxidation.

A recent development for selective ammonia oxidation into nitrogen and water vapor (NH₃-SCO) over noble metal-based catalysts is covered in the mini-review. As ammonia (NH₃) can harm human health and the environment, it led to stringent regulations by environmental agencies around the world. With the enforcement of the Euro VI emission standards, in which a limitation for NH₃ emissions is proposed, NH₃ emissions are becoming more and more of a concern. Noble metal-based catalysts (i.e., in the metallic form, noble metals supported on metal oxides or ion-exchanged zeolites, etc.) were rapidly found to possess high catalytic activity for NH₃ oxidation at low temperatures. Thus, a comprehensive discussion of property-activity correlations of the noble-based catalysts, including Pt-, Pd-, Ag- and Au-, Ru-based catalysts is given. Furthermore, due to the relatively narrow operating temperature window of full NH₃ conversion, high selectivity to N₂O and NO_x as well as high costs of noble metal-based catalysts, recent developments are aimed at combining the advantages of noble metals and transition metals. Thus, also a brief overview is provided about the design of the bifunctional catalysts (i.e., as dual-layer catalysts, mixed form (mechanical mixture), hybrid catalysts having dual-layer and mixed catalysts, core-shell structure, etc.). Finally, the general conclusions together with a discussion of promising research directions are provided.

The good performance of modern diesel engines and their low fuel consumption have caused a continuous increase in the diesel engine vehicle population. However, under oxygen-rich conditions the conventional three-way catalysts are not able to reduce NO_x (NO + NO₂) emissions and a different approach is required. Presently, the lean NO_x trap (LNT, NSR) and selective catalytic reduction (SCR) are the most powerful methodologies to remove NO_x from lean-burn engines. The favourable method for the still unregulated N₂O abatement is nitrous oxide decomposition (deN₂O). Herein, we discussed the potential of perovskite-based catalysts to reduce nitrogen oxide emissions. The wide range of elemental compositions together with high thermal stability in oxidizing environments and low cost make these materials very attractive for automotive applications. This review is devoted to the aftertreatment system of the exhaust gases to reduce the nitrogen oxide emissions from diesel vehicles. In the following sections, we provide a review on the development of NSR, SCR and deN₂O over perovskite-based catalysts. The review emphasises the property–activity correlations in such catalytic applications. Finally, major conclusions are drawn and some research challenges are highlighted.

The progress of Cu-containing SSZ-13 regarding preparation methods, hydrothermal resistance and poisoning as well as reaction mechanisms in NH₃-SCR-DeNO_x and NH₃-SCO.

Cu–Al–O_x mixed metal oxides with intended molar ratios of Cu/Al = 85/15, 78/22, 75/25, 60/30, were prepared by thermal decomposition of precursors at 600 °C and tested for the decomposition of nitrous oxide (deN₂O).