生物质气化过程中热解焦油的生成及其均相转化机理

Formation and homogeneous conversion mechanism of biomass pyrolysis tar

以两段式下吸气化炉焦油的衍化规律为背景对焦油的生成规律、均相转化过程中芳烃环的形成及增长机制等进行了阐述和总结。阐述了纤维素、半纤维素、木质素的热解特性及主要热解产物的生成规律,并与稻秆在200~500℃热解实验中检测得到的焦油成分进行了对比分析,两者结果基本一致。主要从官能团衍化角度分析了不同种类初级焦油的均相转化机理,阐述了单环芳香烃生成、单环向多环芳香烃转化及多环芳烃进一步聚合转化过程中的脱氢环化、脱氢加乙炔、氢转移、异构化及苯酚转化等机制。基于已有转化机理,初步构建了焦油均相转化路径图。

Pyrolysis tar formation and its conversion in the two-stage downdraft gasifier were systematically discussed,and varied aromatic formation and growth mechanisms under homogeneous conversion were also summarized.In the aspects of pyrolysis tar formation,pyrolysis characteristics of cellulose,hemicellulose and lignin and their pyrolysis products were concluded.It was in a good agreement with the experimental results of rice straw pyrolysis within the temperature range of 200~500℃.In the aspects of pyrolysis tar homogeneous conversion,homogeneous conversion mechanisms for varied species of primary pyrolysis tar were summarized from the perspective of functional group evolution.Detailed conversion mechanisms such as onering aromatics formation,one-ring aromatics growth and PAHs polymerization were elaborated.More attentions were paid on the mechanisms of cyclodehydrogenation,H-abstraction C2H2-addition and hydrogen shift.Isomerization and phenol polymerization were also included.A simplified roadmap of primary pyrolysis tar formation and their homogeneous conversion in biomass gasifier were constructed.