Mechanisms of HCN and NH₃ formation
during rapid pyrolysis of pyridinic nitrogen containing substances

The Mayer bond orders of 4 typical pyridinic-nitrogen structures in coal and their intermediate products were calculated with considering the combination forms of pyridine cycle with other heterocycles. On the basis of the Mayer bond orders, the bonds apt to crack during pyrolysis were deduced and the mechanisms for the release of nitrogen during pyridinic-N pyrolysis were analyzed. The result showed that pyridinc-N tends to release as HCN during pyrolysis. The diversity of the combination forms of pyridine cycles with other cycles can also lead to a variety of nitrogen release processes. Rapid pyrolysis of pyridine and acridine as pyridinic-N model compounds was conducted experimentally in a high frequency furnace; it suggested that a small quantity of NH₃ is formed during pyridine and acridine pyrolysis, but HCN is the dominant nitrogen containing product. Current experimental results provide some evidences to support the calculation results.