Cu-based metal oxide catalysts for NH₃-SCR of NO : From fundamentals to mechanistic insights

In today's world, emissions from automobile exhaust and industrial chimneys are the major contributors to atmospheric nitrogen oxides (NO x ). NO x has detrimental effects on both plants and animals and can cause various diseases. Ammonia (NH 3 )-based selective catalytic reduction (SCR) is a highly effective method for controlling and mitigating NO x emissions. Cu-based oxides are extensively utilized in NH₃-SCR processes due to their widespread availability, cost-effectiveness, and outstanding redox capabilities, making them a preferred choice among MO catalysts. The presence of copper in both Cu 2+ and Cu + oxidation states offers favorable potential for combination with other transition elements, enhancing catalytic performance. In addition, the synthesis methods use in the SCR process, regeneration, and disposal of Cu-oxide-based catalysts are more cost-effective and environment friendly than those of precious metal oxide SCR catalysts, making Cu-based technology a more sustainable and economical choice. While numerous review papers have explored the role of copper in zeolite-based catalysts for NO x reduction but concise reports focusing on Cu in MO-based catalysts for SCR remain scarce. Therefore, in this work, we aim to review the synthesis methods, reaction mechanisms, structure-activity relationships, economic feasibility, environmental impact assessment and durability of Cu-based oxide catalysts in NH₃-SCR, particularly against water, alkali and alkaline earth metals , SO₂, and other relevant factors. • This review, for the first time, explores the role of Cu-based metal oxide catalysts in NH₃-SCR, addressing a critical research gap in sustainable NOx emission control technologies. • Detailed discussion on synthesis strategies, reaction mechanisms, structure-activity relationships, and catalyst durability under challenging conditions. • Highlights the dual oxidation states of copper (cu2+/Cu+) and their synergy with other transition metals, enhancing catalytic activity and surface acidity • Evaluates the resilience of Cu-based oxides to real-world challenges like water, alkali metals, and SO₂, showcasing their potential for industrial applications.