无氧/低氧环境中zigzag型焦炭N的迁移转化特性

Migration and transformation characteristics of zigzag char-N in lean oxygen environment

采用量子化学方法探究了还原区高浓度NO存在下zigzag结构焦炭氮中N的迁移转化规律,并通过构建含羟基焦炭N模型,从分子层面对氧存在下焦炭N的转化特性进行了系统的理论计算。结果表明,还原区NO的存在会与焦炭中的N结合为N 2释放;并且氧的存在增强了焦炭表面化学活性,进一步促进了焦炭中N的析出。还原区氧和NO的共存使得焦炭中N的释放与C的燃烧同时发生,表现为NO与焦炭中N结合为N 2的同时,伴随有氧将焦炭中C氧化成CO 2或CO。动力学计算C燃烧产物的限速步速率常数发现,低温低氧条件下C更容易氧化生成CO;随着温度的升高,CO 2生成速率明显增大,高温更利于CO2的生成。

The migration and transformation of N in zigzag char-N with the presence of high concentration NO in the reduction zone is investigated by quantum chemistry method.Transformation characteristics of N in lean oxygen environment are systematically calculated from the molecular level by constructing a char-N model containing a hydroxyl group.The results show that NO in the reduction zone can combine with N in the char to form N 2;and the presence of oxygen enhances the char chemical activity and further promotes the release of N in the char.The co-existence of oxygen and NO in the reduction zone makes the release of N and the combustion of C occur simultaneously,which is manifested by NO and N in the char combining to form N 2,and at the same time oxygen and C in the char formation CO 2 or CO.The kinetic calculations of the rate-limiting step rate constants of the C combustion products show that C is easily oxidized to CO under low temperature and lean oxygen conditions,and with the temperature rise the CO 2 generation rate increases significantly and the high temperature is conducive to CO 2 formation.