Study The Formation Of HCN And NH₃ From Fuel-N Using Model Compounds

In this paper, Pyridine and Acridine have been used as model compounds to study the mechanism of HCN and NH3 from coal-N and char-N. Some experiments were carried out in a tubular quartz reactor at the temperature of 600~1300 C, and have discussed the factors that affect the nitrogen distribution, including the temperature, resident time and H/N (mol ratio of steam and model compounds). The ion chromatograph system was used to measure pyrolysis and steam gasification of the content of HCN and NH3 yield from model compounds. FTIR and GCMS were used to measure the liquid products from experiments. Some useful results and conclusions are acquired as following:1). HCN and NH3 can be yield from both the pyrolysis and steam gasification reaction. This result is very similar to the coal volatile's experimental results that we have got previously. The temperature, residenttime and the H/N are main factors influencing the formation of HCN and NH3.2). The yield of HCN and NH3 increasing with the temperature increasing, and more long resident time and high H/N can made more NH3 yield from reaction. It is also can be found that the conversion of pyridine are similar for both pyrolysis and gasification reaction. For the case of Acridine, NH3 can yield from both pyrolysis and steam gasification reaction. But the NH3 yield increased tremendously in steam.3).The liquid products have been analyzed using FTIR and GCMS. The analysis of FTIR show that there are nitrile group in both the samples from pyridine pyrolysis and steam gasification experiments, but can not found in the samples from Acridine experiments. This is clearly reveal that the thermal cracking of Acridine is difficult to process when the reaction temperature low of 1100 C, which is the reason that the HCN can hardly yield from Acridine experiments. GCMS results show that there are 2, 4-pentadlenenitrile can be detected in the samples of pyridine experiments. And the 2-methoxy-pyridine can be detected in the sample of pyridine gasification.4). Based on the results above, the conclusions can be listed as following: The model compoundsexperimental results were resembled with the coal pyrolysis and gasification results. These can be used to explain the routes of fuel-N transform to gas-N. All of the results seemly reveal that HCN comes from the thermal cracking of pyridine and NH3 is the product of the hydrolyzation of nitrile.