唐飞，钱叶剑，孟顺，余自洋，边顺.当量比燃烧天然气发动机铑基三效催化器次生污染物研究[J].内燃机工程,2021,42(6):70-79.
当量比燃烧天然气发动机铑基三效催化器次生污染物研究
Investigation on Generation of Secondary Pollutant from Rh-Only Three Way Catalytic in a Natural Gas Engine Under Stoichiometric Conditions
DOI：10.13949/j.cnki.nrjgc.2021.06.010
关键词:当量比燃烧  天然气发动机  三效催化器  N2O排放  NH3生成
Key Words:stoichiometric combustion  natural gas engine  three way catalytic(TWC)  N2O emission  NH3 formation
基金项目:国家自然科学基金项目(51676062)
作者单位
唐飞，钱叶剑，孟顺，余自洋，边顺 合肥工业大学 动力机械及工程系，合肥 230009 
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摘要:建立了一种适用于当量比燃烧天然气发动机的Rh基三效催化器(three-way catalytic converter, TWC）整体模型，研究了排气温度和组分对TWC系统次生污染物N2O和NH3生成特性的影响。结果表明：N2O主要在起燃和低温(400K～605K）阶段通过CO还原NO反应生成；高温状态下(>850K）NH3通过H2还原NO反应生成，H2来源于蒸汽重整(steam reforming, SR）和水煤气变换(water gas-shift, WGS）反应。H2体积分数的增加促进了N2O和NH3生成，高温下N2O会与H2发生还原反应，H2体积分数越高，N2O生成反而越低。H2O和CH4对N2O和NH3生成的影响随着温度变化而变化。在一定范围内，随着O.2体积分数增加，NH3生成减少，N2O生成增加；高温下，O.2体积分数过高时，N2O生成反而减少。研究还发现，排气中O.2体积分数在4000×10-6左右时，排温控制在580K～850K，能实现N2O和NH3近零排放。
Abstract:A global model of Rh only three way catalytic（TWC） suitable for a stoichiometric natural gas engine was established, and the effects of exhaust temperature and composition on the generation characteristics of side-products N2O and NH3 were investigated. The results show that N2O is primarily formed during light-off and low temperature period（400K～605K）, which proceeds via reduction of NO by CO. NH3 is observed at high temperature（＞850K） via reduction of NO by H2, and the H2 required to produce NH3 is generated via steam reforming and water gas-shift reactions over the catalysts. The increase of H2 concentration promotes the production of N2O and NH3. At high temperature, the N2O production will react with H2, and the higher the H2 concentration, the lower the N2O generation. The effect of H2O and CH4 on the formation of N2O and NH3 varies with temperature. Within a certain temperature range, as the O2 concentration increases, the NH3 production decreases and the N2O production increases. At high temperature, the N2O production decreases when the O.2 concentration is too high and under 4000×10-6 O2 concentration, the zero emission of N2O and NH3 can be achieved by controlling the exhaust temperature at 580K～850K range.
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