作　　者： (范鲁艳）; (汪安东）; (曲大为）; (马军彦）;

机构地区： 吉林大学汽车仿真与控制国家重点实验室,长春130022

出　　处： 《西安交通大学学报》 2017年第9期44-53,共10页

摘　　要： 通过开展选择性催化还原(SCR)系统中铵盐的热解及动力学特征研究,为固态铵SCR氨气生成及氨气供给系统的设计提供理论依据及技术支撑,采用热重实验和分解平衡压实验分析了3种铵盐的分解温度、分解速率等热解特性,利用等温法和积分法计算了氨基甲酸铵和碳酸铵的分解动力学参数。碳酸铵和氨基甲酸铵的受热分解就是在恒定温度下测定其剩余质量比与受热时间的关系,再在热重分析曲线中通过反应时间下的剩余质量比求得速率常数和反应级数。研究结果表明:氨基甲酸铵分解速率大于碳酸铵和碳酸氢铵;氨基甲酸铵分解反应级数为1/2,碳酸铵的为2/3,氨基甲酸铵活化能为56kJ/mol,碳酸铵的为62kJ/mol;氨基甲酸铵和碳酸铵均适合作为固态铵选择性催化还原(SSCR)系统还原剂的来源,氨基甲酸铵优势更明显。相比尿素SCR技术,固态铵SCR技术在发动机低排气温度条件下能够提供足量的还原剂,有效提高低温NOx转化效率。 The pyrolysis and kinetic characteristics of ammonium salts in solid ammonium selective catalytic reduction （SCR） system are investigated to provide theoretical and technical supports for design of solid ammonia SCR gaseous ammonia production and supply system. The pyrolysis characteristics of three kinds of ammonium salts, including decomposition temperatures and rates, are analyzed by thermogravimetric test and decomposition equilibrium pressure test, and the decomposition kinetics parameters of ammonium carbamate and ammonium carbonate are calculated with isothermal method and integral method. The thermal decomposition of ammonium carbonate and ammonium carbamate are completed at constant temperature to determine the relationship between the residual mass ratio and the heating time, and the rate constants and reaction orders are obtained by the mass ratio versus reaction time in thermogravimetric analysis curves. The results show that the decomposition rate of ammonium carbamate gets higher than that of ammonium carbonate and ammonium bicarbonate; the reaction order of ammonium carbamate is 1/2, and that of ammonium carbonate is 2/3; the activation energy of ammonium carbamate and ammonium carbonate reaches respectively 56 kJ/mol and 62 kJ/mol; ammonium carbamate and ammonium carbonate are suitable to be the source of the reducing agent of SSCR system, and the advantage of ammonium carbamate is more obvious. Compared with urea SCR technology, solid-state ammonium SCR technology can provide more sufficient amount of reducing agent when the engine is at low exhaust temperature, so that the conversion efficiency of low-temperature NO, is effectively improved.

关 键 词： 固态铵 选择性催化还原 铵盐 热解特性 动力学参数