{"title":"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","authors":"","doi":"10.1016/j.joei.2024.101775","DOIUrl":null,"url":null,"abstract":"<div><p>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 H<sub>2</sub>O 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 CO<sub>2</sub> 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.</p></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":null,"pages":null},"PeriodicalIF":5.6000,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Co-pyrolysis of pretreated cotton stalk and low-density polyethylene: Evolved products and pyrolysis mechanism analysis\",\"authors\":\"\",\"doi\":\"10.1016/j.joei.2024.101775\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>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 H<sub>2</sub>O 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 CO<sub>2</sub> 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.</p></div>\",\"PeriodicalId\":17287,\"journal\":{\"name\":\"Journal of The Energy Institute\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.6000,\"publicationDate\":\"2024-08-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of The Energy Institute\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1743967124002538\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ENERGY & FUELS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of The Energy Institute","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1743967124002538","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
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.
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.