NOx emission is a serious problem during fossil fuel combustion. Novel reburning fuels, namely, nitrogen-containing tar compounds, including pyridine and pyrrole were taken into consideration for NO reduction and investigated by quantum chemical method. Theoretical calculation results show that pyridine could first decompose into small species, such as CN and hydrocarbon radicals, then reduce NO to N₂. The decomposition of pyridine should overcome quite high energy barrier and adsorb a large amount of heat. This pathway may occur at high temperature zone, such as core flame zone of pulverized coal fired boiler. As soon as pyridine decomposes, the active intermediates (CN radical, etc.) could reduce NO very quickly. The direct reduction of NO by pyridine molecule should overcome lower energy barrier, which could occur at wider temperature range. Pyrrole is less thermostable than pyridine; the energy barriers of pyrrole cracking and direct reduction of NO stay at same level. Therefore, the reburning efficiency of pyrrole may be better at lower temperature than pyridine. Theoretical calculations indicate that nitrogen-containing tar compounds produced during biomass pyrolysis/gasification could have good performance for NO reduction in pulverized coal fired boiler as well as biomass or MSW furnace.

在化石燃料燃烧期间，NOx排放是一个严重的问题。新型的再燃燃料，即包括吡啶和吡咯在内的含氮焦油化合物，被考虑用于NO的还原，并通过量子化学方法进行了研究。理论计算结果表明，吡啶可以先分解为CN和烃基等小分子，然后将NO还原为N _2。。吡啶的分解应克服很高的能垒并吸收大量的热量。该路径可能发生在高温区，例如煤粉锅炉的核心火焰区。吡啶分解后，活性中间体（CN自由基等）很快就会还原NO。吡啶分子直接还原NO应克服较低的能垒，该能垒可能发生在较宽的温度范围内。吡咯的热稳定性不如吡啶。吡咯裂解和直接还原NO的能垒保持在同一水平。因此，在较低的温度下吡咯的再燃烧效率可能比吡啶更好。