低温氨-选择性催化还原氮氧化物催化剂的研究进展

Research progress in selective catalytic reduction of nitrogen oxides by ammonia at low temperature

氮氧化物(NO_x)的排放对人类健康和植物生长造成了严重危害,对其进行净化治理刻不容缓。火电厂烟气是NO_x的主要来源,氨-选择性催化还原(NH_3-SCR)技术可对其排放进行有效控制。V_2O_5-WO_3(MoO_3)/TiO_2脱硝催化剂的工作温度偏高,不能满足低温宽工作温度窗口等工况的需要,因此,开发具有宽工作温度窗口的低温脱硝催化剂成为研究热点,其中,钒基、锰基金属氧化物催化剂和金属离子交换分子筛催化剂的研究最为广泛。探讨催化剂脱硝性能的关键影响因素、抗水抗硫性能以及反应机理,有助于为高效、实用的低温脱硝催化剂的设计和开发提供科学依据。从钒基金属氧化物催化剂、锰基金属氧化物催化剂、金属离子交换的分子筛催化剂、低温脱硝催化剂的抗水抗硫性能以及低温NH_3-SCR反应机理等方面对近年来国内外低温脱硝催化剂的研究进展进行综述。今后需要解决N_2选择性不够理想、抗水抗硫性能差、低温工作温度窗口较窄和反应机理不统一等问题。

Nitrogen oxides are very harmful to human＇ s health and the growth of plants, so it is an urgent task to control the emission of NOx. NH3-selective catalytic reduction （NH3-SCR） has been proved to be the most efficient technique to remove NOx from flue gas of coal-fired power plant, which is one of the main sources of NOx. However, the operating temperature window of commercial V205-WO3 （ MoO3 ）/TiO2 denitration catalysts is too high to satisfy the requirements of low temperature and wide operating temperature window, and therefore the development of low-temperature denitration catalysts with wide operating temperature window becomes a hot spot of this research field in recent years. Especially, vana- dium-based and manganese-based metal-oxide catalysts as well as metal-ion exchanged zeolite catalysts are widely investigated. Discussing the key influence factors of catalytic performance, H2O and SO2 resistance, and reaction mechanism is conducive to provide some scientific basis for the design and development of efficient and practical low-temperature denitration catalysts. The research progress in low-temperature denitration catalysts, including vanadium-based metal-oxide catalysts, manganese-based metaloxide catalysts, metal-ion exchanged zeolite catalysts, H2O and SO2 resistance of low-temperature denitration catalysts and low-temperature NH3-SCR reaction mechanism was reviewed. Some problems such as the unsatisfactory selectivity to N2, poor performance of water resistance and sulfur resistance, narrow low- temperature operating window, and not uniform mechanisms of the reaction need to be solved in future.