污泥中典型氨基酸热解生成NO_(x)前驱体的反应机理研究  

Study on the pyrolysis reaction mechanism of glycine and glutamic acid to produce NO_(x) precursors

作　　者：付延春 李丽君[2] 孟瑞红 杨阳 高腾飞 FU Yan-chun;LI Li-jun;MENG Rui-hong;YANG Yang;GAO Teng-fei(China Energy Investment New Energy Technology Research Institute Co.»Ltd,Beijing 102209,China;School of Foreign Languages,North China Electric Power University,Beijing 102206,China)

机构地区：[1]国家能源集团新能源技术研究院有限公司,北京102209 [2]华北电力大学外国语学院,北京102206

出　　处：《分子科学学报》2022年第2期165-173,共9页Journal of Molecular Science

基　　金：国家自然科学基金资助项目(52006069)。

摘　　要：污泥热解是实现污泥减量化、无害化和资源化的重要技术.城市污泥含氮量高,在热解过程中含氮物质会转化成NO_(x)前驱体(NH_(3),HCN),限制了污泥热解技术的应用和推广.本研究选取污泥中氮的基本存在单元甘氨酸和谷氨酸作为污泥的含氮模型化合物,采用B3LYP方法和6-31++G(d,p)基组,探究了甘氨酸和谷氨酸热解形成NO_(x)前驱体的机理.结果表明,甘氨酸热解生成NO_(x)前驱体有2种反应方式,一是甘氨酸发生脱氨反应生成NH_(3);二是甘氨酸发生脱水反应生成甘氨酸酐(DKP).谷氨酸在热解过程中直接发生脱氨反应生成NH_(3).同时发现NH_(3)和HCN存在竞争关系.根据生成NH_(3)和HCN的难易程度可知甘氨酸和谷氨酸热解得到NO_(x)的前驱体主要是NH_(3),并根据不同氨基酸热解时的脱基团反应机理提出了加入水蒸气的建议来减轻污泥热解中氮氧化物的产生.The pyrolysis of sludge is an important and state-of-the-art technology to achieve the reduction,harmlessness and resource utilization of municipal wastes such as sludge.It is widely accepted that municipal sludge contains a relatively high nitrogen species content such as protein,which can be converted into NO_(x)precursors such as NH_(3)and HCN during the pyrolysis process,thus limiting the application of sludge pyrolysis technologyinmanyindustries.Inthisstudy,glycineandglutamicacid,thebasicunitsofnitrogenin sludge,were selected as the typical nitrogen-containing model compounds of protein in sludge.Based on density functional theory(DFT),the B3LYP/6-31++G(d,p)method was adopted to comprehensively calculate the detailed pyrolysis pathways of proteins of sludge from a molecular level.The mechanism of pyrolysis of glycine and glutamic acid to form NO_(x)precursors was deeply investigated,and various pyrolysis pathways were proposed.The calculation results show that the pyrolysis of glycine mainly produces NO_(x)precursors in two ways.One is the deamination reaction of glycine to produce NH_(3),while the other is dominated by the dehydration reaction of glycine to produce glycine anhydride(DKP),which would then be converted into HCN.For the other model compound glutamic acid,the key step of the precursor-producing process to form NO_(x)during sludge pyrolysis was the direct deamination reaction of glutamic acid to produce NH_(3).Based on the above calculation results,the competitive relationship between the forming of NH_(3)and HCN can be observed in the obtained reaction pathways.The primary precursor for NO_(x)generating was NH_(3)during the pyrolysis of glycine and glutamic acid,since the generating barriers for NH_(3)were much lower than those of HCN.Finally,according to the de-group reaction mechanism of different amino acids during pyrolysis,some suggestions were proposed to further regulate the NO_(x)producing rate during the pyrolysis of sludge,since HCN was a less preferable processor of NO_(x)than NH_(3)

关 键 词：污泥热解 氮迁移 密度泛函理论 甘氨酸 谷氨酸 

分 类 号：O641[理学—物理化学]