Abstract:

The influences of Fe₂O₃ on glycine pyrolysis characteristics, generation mechanisms of NO _x precursors and transformation characteristics of nitrogen were investigated by DSC-MS and fixed bed experiment. The results indicated that the first thermal weightlessness stage of glycine (Gly) was divided into two parts by Fe₂O₃, so that the whole pyrolysis process was increased from 2 to 3 stages. Moreover, Fe₂O₃ can not only reduced the pyrolysis initiation temperature and the temperature of gas evolution by 50℃, but also promoted the secondary cracking reaction of char, which increased the weight loss rate of Gly by 23%. Furthermore, the evolution process of N-containing gases was divided into three independent stages by Fe₂O₃, which was corresponded to the Gly pyrolysis process. In the fixed bed experiment, most effective suppression of Fe₂O₃ on NO _x precursors (NH₃ and HCN) was achieved when the molar ratio of Fe₂O₃ to N is 0.5, which was decreased by 30%. Since Fe₂O₃ promotes peptide dehydration condensation, cyclization and aromatization reaction, more P-N, N-5 and N-6 are fixed in the semi-coke, and the semi-coke nitrogen residual rate is increased by 5%.

Key words: glycine, fixed-bed, pyrolysis, gas, Fe₂O₃, NO _x precursors

摘要：

选用污泥中典型氨基酸-甘氨酸（Gly）为研究对象，利用差式热值分析-质谱联用技术（DSC-MS）和固定床实验研究了Fe₂O₃对甘氨酸热解特性、NO _x 前驱物生成规律以及氮转化特性的影响。结果表明：热解特性实验中，由于Fe₂O₃将Gly的第一热失重阶段一分为二，导致其热解过程由2个阶段增至3个；Fe₂O₃使Gly热解起始温度及气体析出温度降低50℃，并通过促进半焦的二次裂解反应使Gly失重率增加23%。与Fe₂O₃对Gly热解过程的影响一致，Fe₂O₃将含N气体析出过程同样分成3个独立的阶段。固定床实验中，在Fe₂O₃/N=0.5时，Fe₂O₃最大程度地抑制了NO _x 前驱物（NH₃和HCN）析出，使其减少30%。由于Fe₂O₃促进肽脱水缩合、环化和芳香化反应，使得更多P-N、N-5和N-6固定在半焦中，半焦氮残留率增加5%。

关键词: 甘氨酸, 固定床, 热解, 气体, Fe₂O₃, NO _x 前驱物