核桃壳热裂解产物有机结构演变规律

The Evolution of Organic Structure of Walnut Shell Pyrolysis Products

采用TG-FTIR、Py-GC/MS对核桃壳热裂解过程及产物进行研究,利用1H-NMR和13C-NMR对热解炭结构进行分析,探讨热裂解产物有机结构演变规律。结果表明:核桃壳热裂解分为干燥脱水,快速热裂解和残余物缓慢热裂解三个阶段,快速热裂解阶段是主反应阶段,失重可达总失重的89%。不同热解温度下的液态产物成分不同,且随着热裂解温度的升高,低温下形成的热解液会发生二次反应生成新的热解液成分,热解温度由400℃升至600℃,液态产物完成了由酚类、醇类、酸类向酯类、芳香类的转化。升温核桃壳热裂解过程中的气态产物为H_2O,CO_2,CH_4和CO,在357℃时达到最大产量。随着热解温度由300℃升高到800℃,核桃壳热解炭由以苯环、烷烃链、甲氧基、羟基、羰基为主要结构转化为90%以上的芳香结构。

The pyrolysis process and products of walnut shell was studied by using TG-FTIR、Py-GC/MS. The structure of walnut shell and its bio-char are analyzed by1H-NMR and13C-NMR. The evolution of organic structure of pyrolysis products is discussed. The experimental results show that the pyrolysis of walnut shell is divided into three stages： water evaporation,rapid pyrolysis and slow pyrolysis. The rapid pyrolysis stage is the main reaction stage and the weight loss reaches 89% of the total weight loss. The pyrolysis products are different at different pyrolysis temperature,as the pyrolysis temperature increase from 400 ℃ to 600 ℃,the transformation of the phenols,alcohols,acids are converted to esters and aromatic. The gaseous products in the pyrolysis process of walnut shell are H2O,CO2,CH4 and CO,and reach the maximum yield at 357 ℃. With the pyrolysis temperature increases from 300℃ to 800℃,the structure of bio-char changes from benzene ring,alkane,methoxy,hydroxyl,carbonyl into more than 90% of the aromatic structure.