生物质在热解过程中会产生含氮化合物,进而转化为NO_x,严重危害环境安全。因此,解析生物质热解过程中氮的释放特性,寻求有效调控手段,以减少NOx排放量、消除环境污染是生物质能源清洁利用研究的重要内容。本文首先总结分析不同生物质中氮的含量及在生物质不同部位的分布情况,并对生物质中氮赋存形态的研究方法、结论及存在的问题进行讨论;继而,重点综述生物质热解过程中氮的释放特性和影响因素,梳理生物质热解过程中氮的释放路径,讨论温度、升温速率、原料中氮的赋存形态及含量等因素对氮元素迁移的影响规律;最后,对热解过程中氮在产物中的分配机制进行总结分析,并对生物质热解清洁转化研究进行展望。

The pyrolysis is one of the promising methods to convert biomass to bio-oils as fuels and chemicals. During the pyrolysis of biomass, some nitrogen species are released, as the precursors of NO_x with potential environment pollution. The release characterization of nitrogen species during biomass pyrolysis is reviewed in this paper. Firstly, the content and the distribution of nitrogen in various biomass materials are classified, and the research methods, the conclusions and the problems that remain to be solved concerning the chemical forms or the nitrogen functionalities in different biomass materials are discussed. And then we discuss the release characterization, as well as the factors affecting the nitrogen evolution during pyrolysis. The evolution route of nitrogen in biomass during pyrolysis is elaborated in detail, and the operating parameters such as the temperature, the heating rates and the nitrogen forms and content are shown to contribute to the nitrogen release., The nitrogen distribution in products in gas phase, liquid phase and solid phase is analyzed as well. In the end, some prospective developments are commented for the research of pyrolysis convention of biomass.