摘要
选择性催化还原(SCR)系统中的尿素沉积物可通过调整喷嘴参数、增加混合器和管道内涂覆催化剂等策略进行有效抑制.针对船用SCR系统尿素沉积物、V_(2)O_(5)-WO_(3)/Ti O_(2)催化剂和纯净尿素(CH_(4)N_(2)O)等样品,首先利用热重分析(TGA)和傅里叶红外光谱(FT-IR)等表征技术分析了尿素等物质的催化分解特性,以及样品的化学成分;其次,基于密度泛函理论(DFT)提出了一种详细的尿素分解机理,该机理补充了三聚氰酸(C_(3)H_(3)N_(3)O_(3))及其同系物的形成与分解路径;最后,利用TGA试验数据和化学反应动力学方法开发了一套尿素非催化和催化相耦合的动力学模型.结果表明:船用SCR系统尿素沉积物化学成分主要是三聚氰酸及其同系物,以及三聚氰酸一酰胺(C_(3)H_(4)N_(4)O_(2));增加催化剂用量可以加速尿素分解,阻断尿素和缩二脲(C_(2)H_(5)N_(3)O_(2))向三聚氰酸转化,但副产物分解温度越高,催化剂用量也越大.
Urea deposits in a selective catalytic reduction(SCR)system can be effectively suppressed by adjusting injector parameters,adding mixers,and coating catalysts on the pipe wall.Based on samples of urea deposits in a marine SCR system,V_(2)O_(5)-WO_(3)/TiO_(2) catalyst and pure urea(CH_(4)N_(2)O),etc.,the urea catalytic decomposition characteristics and the chemical composition of samples were firstly analyzed using characterization techniques such as thermogravimetric analysis(TGA)and Fourier transform infrared spectroscopy(FT-IR).Secondly,based on density functional theory(DFT),a detailed urea decomposition mechanism was proposed,which complemented the formation and decomposition path of cyanuric acid(C_(3)H_(3)N_(3)O_(3))and its homologue.Finally,a non-catalytic and catalytic coupled kinetic model of urea was developed using TGA experimental data and chemical reaction kinetics methods.The results showed that the main chemical components of urea deposits in marine SCR system are cyanuric acid and its homologue,and ammelide(C_(3)H_(4)N_(4)O_(2)).Increasing the quantity of catalyst can accelerate urea decomposition,thereby blocking the conversion of urea and biuret(C_(2)H_(5)N_(3)O_(2))to cyanuric acid.However,as the decomposition temperature of the by-products increases,a greater amount of catalyst is required.
作者
夏冲
朱元清
周松
冯永明
Xia Chong;Zhu Yuanqing;Zhou Song;Feng Yongming(College of Power and Energy Engineering,Harbin Engineering University,Harbin 150001,China)
出处
《内燃机学报》
2025年第2期144-152,共9页
Transactions of CSICE
基金
国家自然科学基金资助项目(51979060)
黑龙江省优秀青年科学基金资助项目(YQ2023E034)
博士研究生科研创新基金资助项目(3072023GIP0301)。
关键词
选择性催化还原
尿素沉积物
催化分解
分解机理
动力学模型
selective catalytic reduction
urea deposits
catalytic decomposition
decomposition mechanism
kinetic model
