预处理棉秆和低密度聚乙烯的共热解:演化产物和热解机理分析

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS Journal of The Energy Institute Pub Date : 2024-08-10 DOI:10.1016/j.joei.2024.101775
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引用次数: 0

摘要

利用棉秆和农用残膜共热解技术制备生物油,可实现资源回收和能源转化,具有重要的研究价值和意义。本研究使用 NaOH、HCl 和 H2O 溶液对棉秆进行了不同的化学预处理,以了解其结构变化和热解特性。此外,棉秆的 H/C 比值较低,导致热解油中氧含量较高,限制了其高效清洁利用。因此,研究了经预处理的棉秆和 LDPE(低密度聚乙烯)热解产物的特性和热解动力学。结果表明,碱预处理棉秆的灰分含量降低了 1.24%,棉秆的致密结构明显松弛。NaOH 预处理可有效去除半纤维素糖并使其裂解。在共热解过程中,当 NaOH-CS/LDPE 的比例为 50/50 时,协同效应更加明显,产油量比理论值提高了 2%。热解气体中 CO 和 CO2 的氧含量高于理论值,分别为 10.4 % 和 14.1 %。生物油对碳氢化合物的协同效应最为显著,达到 18.9%。更多的氢和更少的氧迁移到共热解油中,导致碳氢化合物增加,含氧化合物减少,提高了生物油的质量。电子顺磁共振(EPR)结果表明,添加 LDPE 可能会增加稳定自由基的数量。傅立叶原位红外光谱法(FTIR)分析了 NaOH-CS 与 LDPE 共热解行为的官能团演变机理,发现随着温度的升高,C-O-C、C=O 和 O-H 会因脱氢、脱羧、脱羰基和脱甲氧基反应而减少,表明 NaOH-CS 与 LDPE 共热解存在协同效应。无模型法测定了 NaOH-CS、低密度聚乙烯及其混合物的热解动力学。LDPE 的引入可降低 NaOH-CS 单独热解的活化能,三维扩散(D3)模型适用于它们的混合物。
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Co-pyrolysis of pretreated cotton stalk and low-density polyethylene: Evolved products and pyrolysis mechanism analysis

The preparation of bio-oil from cotton stalks and agricultural residue films using co-pyrolysis technology can achieve resource recovery and energy conversion, which has important research value and significance. In this study, cotton stalks were subjected to different chemical pretreatments using NaOH, HCl, and H2O solutions to understand their structural changes and pyrolysis characteristics. In addition, the lower H/C ratio of cotton stalks resulted in higher oxygen content in the pyrolysis oil, which limited its efficient and clean utilization. Therefore, the characteristics and pyrolysis kinetics of the pyrolysis products of pretreated cotton stalks and LDPE (low-density polyethylene) were studied. The results showed that the ash content of alkali pretreatment cotton stalks decreased by 1.24 %, and the dense structure of cotton stalks significantly relaxed. NaOH pretreatment effectively removed hemicellulose sugars and cracked them. During the co-pyrolysis process, when the ratio of NaOH-CS/LDPE was 50/50, the synergistic effect was more pronounced, and the oil yield increased by 2 % compared to the theoretical value. The oxygen content of CO and CO2 in the pyrolysis gas was higher than the theoretical value, at 10.4 % and 14.1 % respectively. The synergistic effect of bio-oil on hydrocarbons was the most significant, reaching 18.9 %. More hydrogen and less oxygen migrated into the co-pyrolysis oil, resulting in an increase in hydrocarbons and a decrease in oxygen-containing compounds, and improving the quality of bio-oil. Results from electron paramagnetic resonance (EPR) indicated that adding LDPE might raise the quantity of stable free radicals. The evolution mechanism of functional groups of NaOH-CS and LDPE co-pyrolysis behavior was analyzed by Fourier in-situ infrared spectrometry (FTIR), and it was found that C–O–C, C=O, and O–H decreased due to dehydroxylation, decarboxylation, decarbonylation, and demethoxy reactions with the increase of temperature, indicating that there was a synergistic effect between NaOH-CS and LDPE co-pyrolysis. The pyrolysis kinetics of NaOH-CS, LDPE and their blends were determined by the model-free method. The introduction of LDPE can reduce the activation energy of NaOH -CS pyrolysis alone, and the 3D diffusion (D3) model is suitable for their blends.

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来源期刊
Journal of The Energy Institute
Journal of The Energy Institute 工程技术-能源与燃料
CiteScore
10.60
自引率
5.30%
发文量
166
审稿时长
16 days
期刊介绍: The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include: Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies Emissions and environmental pollution control; safety and hazards; Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS; Petroleum engineering and fuel quality, including storage and transport Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems Energy storage The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.
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