甘蔗渣两级快速热解特性研究

Study on Two-step Fast Pyrolysis of Bagasse

利用Py-GC/MS(快速热解-气相色谱/质谱联用)装置进行了甘蔗渣的两级快速热解实验,考察了甘蔗渣一级快速热解的产物分布特性以及一级热解温度对后续二级热解产物分布的影响。实验结果表明,甘蔗渣低温一级热解产物富含4-乙烯基苯酚(4-VP),在250℃热解时4-VP的选择性最高(相对峰面积百分比高达48.11%),而在300℃热解时4-VP的产率最大。一级热解温度对后续二级热解产物分布有着较大的影响,随着一级热解温度的升高,二级热解产物中左旋葡聚糖(LG)含量显著增加,而多数其他产物的含量则显著降低;根据产物组成可以判断,300℃下的一级热解固体产物进行二级热解所获得的生物油,与甘蔗渣直接在500℃快速热解获得的生物油相比,具有更高的燃料品位。由此可确定甘蔗渣两级快速热解的应用方式应为:首先在300℃下进行一级快速热解制备4-VP,随后对固体残渣在500℃进行二级热解获得高品位生物油。

Analytical Py- GC/MS （pyrolysis-gas chromatography/mass spectrometry） instrument was used for two-step fast pyrolysis of bagasse, to investigate the product distribution from the first-step fast pyrolysis of bagasse, as well as the effects of the first-step pyrolysis temperatures on the product distribution of the second-step fast pyrolysis Process. The results indicated that the first-step fast pyrolysis of bagasse with low-temperature would obtain abundant 4-vinyl phenol （4-VP）. The highest 4-VP selectivity was obtained at 250℃ with the 4-VP peak area percentage as high as 48.11%, and the maximal 4-VP yield was obtained at 300℃. The first-step pyrolysis temperature affected the second-step pyrolytic products significantly. As the increasing of the first-step pyrolysis temperature, the content of the levoglucosan （LG） in the second-step pyrolytic products increased remarkably, while the contents of most other products decreased significantly. According to the product composition, the bio-oil obtained from the second-step fast pyrolysis of the solid residues from the first-step fast pyrolysis at 300℃ , had better fuel properties than those of the bio-oil obtained from direct fast pyrolysis of bagasse at 500℃. Therefore, the two-step bagasse fast pyrolysis technique was determined, i. e. , the first-step fast pyrolysis at 300℃ to produce 4-VP and second-step fast pyrolysis at 500℃ to produce high-grade bio-oil.