Upgrade of bio-oil produced from the sisal residue composting

The present work studies the composting effects on the chemical characteristics of bio-oil produced by pyrolysis of sisal residue. Three systems were composted with sisal residue proportions to sisal fiber powder of 100:0, 90:10, and 75:25, respectively. The systems showed reductions of 33–48% (extractive), 70–80% (hemicellulose), and 80–90% (cellulose) after composting. An increase in lignin content was observed in all systems. The pyrolysis of the composted systems was performed at 450 and 550 °C. At both temperatures, this process was selective in producing a large concentration of hydrocarbons (>160% increase), mainly alkanes and alkenes, reducing the concentrations of ketones, aldehydes, and phenolics (>50%) and eliminating esters, furans, and acetic acid to composted biomasses. The higher temperature favored aromatics and cyclic hydrocarbon production from the pyrolysis of composted samples. In addition to these results, composting helped reduce the oxygenated bio-oil species by approximately 44 - 75% at the lowest and ~ 69% at the highest temperatures. These results indicate that composted sisal residue can produce bio-oils that are more suitable for biorefineries since they are rich in aliphatic hydrocarbons and non-oxygenated species.

Methods
Samples were analyzed using a pyrolysis apparatus (Frontier® model EGA-PY-3030D) coupled to a GC-MS (Shimadzu® model QP-2020 NX). The column was RTX1701 (60 m, 0.25 mm, 0.25 µm) used at 20 to 280 °C. The peaks from chromatographic analysis were identified with a minimum of 80% similarity.

本研究探讨了堆肥处理对剑麻残渣热解制备生物油化学特性的影响。实验设置3组堆肥体系，剑麻残渣与剑麻纤维粉的质量配比分别为100:0、90:10和75:25。堆肥处理后，各体系的抽提物、半纤维素和纤维素含量分别降低33%~48%、70%~80%和80%~90%；所有体系的木质素含量均有所提升。随后对堆肥后的样品分别在450℃和550℃下开展热解实验。在两个热解温度下，该过程均选择性生成高浓度烃类物质（含量提升超160%），主要成分为烷烃与烯烃；同时酮类、醛类及酚类物质浓度降低超50%，且堆肥生物质的热解产物中不再检出酯类、呋喃类物质与乙酸。较高的热解温度更利于堆肥样品热解生成芳烃与环烃类物质。此外，堆肥处理可使含氧生物油组分在低温热解时降低约44%~75%，在高温热解时降低约69%。上述结果表明，经堆肥处理的剑麻残渣可用于制备更适配生物炼制厂的生物油，此类生物油富含脂肪烃与非含氧组分。

实验方法
采用热解装置（Frontier® EGA-PY-3030D型）与气相色谱-质谱联用仪（Gas Chromatography-Mass Spectrometry，GC-MS，Shimadzu® QP-2020 NX型）联用的分析系统对样品进行检测。色谱柱选用RTX1701柱（60 m，0.25 mm，0.25 µm），升温程序为从20℃升至280℃。色谱分析所得峰通过相似度不低于80%的标准完成定性识别。