温度对麦秆湿解产物特性的影响

Influence of Temperature on Product Characteristics Associated With the Hydrothermal Treatments of Wheat-Straw

湿解是一种模拟自然煤化的热化学转化工艺，为研究生物质湿解过程中产物的物化特性，该文以麦秆为原料，在高压反应釜中，进行了反应温度160~240℃，停留时间60 min条件下的湿解实验。研究发现，随温度的升高，固体产物产率逐渐减少，而液体产物产率增加，且在高于220℃以后，变化速度加快，如以生产固体生物炭为主，温度应控制在220℃左右。固体产物中有机官能团随温度的升高而减少，而碳碳双键、羰基和难降解的芳环结构，随温度的升高，红外吸收加强；固体表面的孔隙和微球显示其具有生物炭的结构；200℃的固体产物展现出相对较好的热稳定性。液体产物中含有还原性糖、乙酸、糠醛、5-羟甲基糠醛和5-甲基糠醛，其中还原性糖浓度较高，可以作为液体燃料的原料，随温度的升高，还原糖浓度逐渐增加，200℃后，浓度变化不大。

ABSTRACT：Hydrothermal treatment is a thermochemical conversation process to simulate natural coalification. To investigate the physic-chemical characteristics of products from biomass hydrothermal treatments, the hydrothermal experiments were performed using wheat straw as feedstocks in a pressure reactor at various temperatures （160~240℃） in period of 60min. The results show that with the temperature increasing, the solid production rate decreases gradually, and the liquid production rate increases. Moreover, the changes are remarkable above 220℃.The operating temperature should be controlled at about 220℃when the hydrothermal reaction is mainly for producing solid biochar. The organic functional groups of solid products reduce slowly, however, the adsorption of C=C, C=O and aromatic rings enhances gradually; the pore and microsphere on the surface of the solid products is comparable to the structure of biochar. The solid products at 200℃ exhibits good thermal stability. The liquid products mainly contain reducing sugars, acetic acid, furfural, 5-（hydroxymethyl）-2-furancarboxaldehyde and 5-methyl-2- furancarboxaldehyde, in which the concentration of the reducing sugars is high and can be used as raw material of liquid fuel. The concentration of the reducing sugars increases with the temperature increasing. When the temperature is above 200℃, it changes slightly.