Migration and transformation characteristics of zigzag char-N in lean oxygen environment
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Graphical Abstract
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Abstract
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 N2; 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 N2, and at the same time oxygen and C in the char formation CO2 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 CO2 generation rate increases significantly and the high temperature is conducive to CO2 formation.
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