More attention to Cu-ZSM-5 zeolite has been paid due to its excellent catalytic activities in removal of NO, and the process it concerned is non-polluting. In this review, the reaction mechanism and catalyst improvement of NO decomposition, selective catalytic reduction of NO with ammonia (NH₃-SCR-NO) and with hydrocarbons (CH-SCR-NO) over Cu-ZSM-5 zeolite are summarized. The possible developing orientations in the field of removal of NO over Cu-ZSM-5 zeolite are also prospected. Direct catalytic decomposition of NO to N₂ and O₂ has been recognized as the most attractive method for removal of NO, which involves redox process of Cu⁺ and formation of N₂O. NH₃-SCR-NO reaction is one of the most efficient and widely-used techniques. Firstly, NO is oxidized to NO₂, and then NH₄NO₃ is formed from the reaction of NO₂ and NH₃. Finally, NH₄NO₃ reacts with NO generating N₂. CH-SCR-NO reaction over Cu-ZSM-5 zeolite is an efficient way for the treatment of automobile-exhaust pollution. The formation of key intermediates such as isocyanate and cyanide species is a necessary process during CH-SCR-NO reaction. However, Cu-ZSM-5 zeolite suffers from poor hydrothermal stability and high sulfur dioxide (SO₂) poisoning property which have suppressed its industrial applications. Introduction of a second metal and fabrication of monolithic catalyst can significantly improve the catalytic performance of Cu-ZSM-5 zeolite. The systematic understanding of reaction mechanism is beneficial to the improvement of Cu-ZSM-5 zeolite and also important for the design of novel,efficient,environmentally-friendly catalysts.

Contents
1 Introduction
2 NO decomposition over Cu-ZSM-5 zeolite
2.1 Reaction mechanism of NO decomposition
2.2 Improvement of Cu-ZSM-5 zeolite for NO decomposition
3 NH₃-SCR-NO reaction over Cu-ZSM-5 zeolite
3.1 Reaction mechanism of NH₃-SCR-NO reaction
3.2 Improvement of Cu-ZSM-5 zeolite for NH₃-SCR-NO reaction
4 CH-SCR-NO reaction over Cu-ZSM-5 zeolite
4.1 Reaction mechanism of CH-SCR-NO reaction
4.2 Choice of reductants of hydrocarbon
4.3 Improvement of Cu-ZSM-5 zeolite for CH-SCR-NO reaction
5 Conclusion and prospects