氢内燃机具有零碳排放的特点，是实现低成本碳中和的重要手段。但是缸内燃烧的高温环境会生成大量的氮氧化物(NO_x)排放，在日益严苛的排放法规要求下，利用选择性催化还原（SCR）NO_x的后处理技术是拓展氢内燃机大规模应用、不断提升其动力性和经济性的必要手段。首先通过试验验证了Cu基分子筛的NH₃-SCR后处理系统是一种高效的针对直喷氢内燃机的NO_x净化方案，接着使用简化反应机理对NH₃-SCR反应过程进行了建模仿真，并研究了反应温度、空速和氨氮比对氢内燃机边界下NH₃-SCR还原NO_x的影响。研究结果表明：在稀燃缸内直喷氢内燃机边界下，NH₃-SCR低温活性仍保持良好，后处理系统起燃温度（T₅₀）为110 ℃，活性窗口（T₉₀）范围为150~425 ℃；在空速大于25 000 h^－1时， NOx转化效率都大于95%；当控制氨氮比为0.5，并保持反应温度在350~400 ℃时可保证最高的NOx转化效率，实现直喷氢内燃机的近零NOx排放。

The hydrogen internal combustion engine has the characteristics of zero carbon emission and is an important method to achieve low cost carbon neutrality. However, the high temperature environment of incylinder combustion will generate a large amount of nitrogen oxide(NO_x) emissions. The use of selective catalytic reductio(SCR) reducing NO_x technology is a necessary method to expand its large scale application and continue improving power and economy performance. The experiment verified that the NH₃-SCR aftertreatment system of Cubased molecular sieve was an efficient NO_x purification scheme for direct injection hydrogen engine. A simplified reaction mechanism was used to model and simulate the NH₃-SCR reaction process, and the effects of reaction temperature, space velocity and NH3nitrogen ratio on NO_x reduction by NH₃-SCR were studied under the boundary of hydrogen internal combustion engine. The results show that the lowtemperature activity of ammonia SCR is still good under the boundary of lean burn hydrogen combustion engine with direct injection. The ignition temperature(T₅₀) of aftertreatment system is 110 ℃, and the activity window(T₉₀) ranges from 150 ℃ to 425 ℃. When the airspeed is greater than 25 000 h^－1, the NO_x conversion efficiency remains greater than 95%. When the ammonia nitrogen ratio is 0.5 and the reaction temperature maintains at 350-400 ℃, the highest NO_x conversion efficiency can be guaranteed and the nearzero NO_x emission of direct injection hydrogen combustion engine can be achieved.