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抽提预处理沙柳的热解失重特性、动力学及产物组分

Pyrolysis Characteristics, Kinetics and Product Components of Extracted Salix cheilophila Schneid.

  • 摘要: 为了控制和改善沙柳原料热解产物品质,对比了热水、1% NaOH和苯-乙醇(苯醇)抽提3种预处理方法,利用热重红外分析法(TG-FT-IR)和热解气质联用(Py-GC/MS)研究了预处理对沙柳热解失重特性及产物生成规律的影响。结果表明:热水和苯醇抽提预处理降低了残炭率,促进了挥发性产物的生成,而1% NaOH抽提预处理增加了残炭率;Coats-Redfern动力学分析发现,抽提预处理沙柳低温段与一级动力学拟合较好,高温段与二级动力学拟合较好,抽提预处理降低了沙柳热解活化能,有利于沙柳热解反应的进行;经过1% NaOH抽提预处理沙柳生成了较多的酚和酮类组分,经过热水抽提预处理沙柳的醛类、酚类、酸类等物质GC含量减少而酯类、醚类GC含量增加,苯醇抽提预处理沙柳各组分GC含量变化不大。

     

    Abstract: Three kinds of extraction pretreatment, including hot-water, 1% NaOH and benzene-alcohol extraction methods, were used to improve the quality of pyrolytic products derived from Salix cheilophila Schneid. The pyrolytic products were investigated by TG-FT-IR and Py-GC/MS. The Results indicated that hot-water and benzene-ethanol extractions decreased the yields of char residues while 1% NaOH extraction was in reverse. The kinetics analysis using Coats-Redfern method showed that low temperature section was fitted well with the first order kinetics, and the high section was fitted well with the second order kinetics. Extraction pretreatments had positive effect to the pyrolysis reaction because of the reduction of the activation energies. GC content of phenols and ketones were increased after the 1% NaOH extraction pretreatment. After the hot-water extraction pretreatment, the GC content of aldehydes, phenols and acids decreased while the content of esters and ethers increased. There was no obvious change in GC content of pyrolysis components with the pretreatment of benzene-ethanol extraction.

     

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