Abstract
To elucidate the formation process of HCN from the pyrolysis of glycine, the small molecule gaseous pyrolysates, H2O, NH3, CO2, CO, HNCO, and HCN, were analyzed in real-time by TG-FTIR. The appearance of the volatile pyrolysis products and the solid residue was determined in real-time at their corresponding formation temperatures by online Py-two-dimensional GC-MS with heart-cutting and LC-MS/MS. The pyrolysis of 2,5-diketopiperazine, a thermolytic by-product of glycine pyrolysis, was also studied. The results showed that: (1) the pyrolysis of glycine can be divided into three temperature ranges 200-300, 300-440, and 440-900 A degrees C; HCN forms in each range with three peaks appearing at 273, 422, and 763 A degrees C, respectively. (2) The mechanistic pathways of HCN formation from glycine in the low- and high-temperature heating stages are different. Below 273 A degrees C, glycine undergoes a decarboxylation reaction to produce methylamine, which subsequently forms HCN by means of dehydrogenation. Above 300 A degrees C, glycine gives relatively large amounts of HCN via 2,5-diketopiperazine and subsequent HNCO or methylenimine formation.
Published Version
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