Cu-based metal oxide catalysts for NH₃-SCR of NO : From fundamentals to mechanistic insights
Sher Ali, Sharafat Ali, Ahmed Ismail, Muhammad Zahid, Fazal Raziq, Liang Qiao
Abstract
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.