Study on NH₃ and HCN formation mechanisms during rapid pyrolysis of pyrrolic nitrogen

5 typical pyrrolic-nitrogen compounds were chosen as the investigating objects according to the different pyrrole cycle combination forms with other heterocycles in coal. The Mayer bond orders of these 5 pyrrolic-nitrogen compunds and their intermediate pyrolysis products were calculated. By comparing the Mayer bond orders, the bonds cracking during pyrolysis were deduced, and NH₃ and HCN formation mechanisms during pyrrolic-N pyrolysis were analyzed consequently. The results show that the pyrrolic-nitrogen is released in -NH and -NH₂ free radicals, which mainly form NH₃. The diversity of pyrrole cycles combination forms with other cycles can lead to the variety of nitrogen release processes. To verify the conclusions from calculation, the rapid pyrolysis of pyrrolic-N model compounds pyrrole and carbazole was carried out in a drop style high frequency furnace. The experiment results show that both NH₃ and HCN are formed during pyrolysis of pyrrole and carbazole, but NH₃ is the main nitrogen containing gaseous product. The conclusions deduced from calculation can get some supports from the experiment results.