{"title":"Breaking the temperature limit of hydrothermal carbonization of lignocellulosic biomass by decoupling temperature and pressure","authors":"Shijie Yu, Xiaoxiao Yang, Qinghai Li, Yanguo Zhang, Hui Zhou","doi":"10.1016/j.gee.2023.01.001","DOIUrl":null,"url":null,"abstract":"<div><p>Hydrothermal carbonization (HTC) of lignocellulosic biomass is a promising technology for the production of carbon materials with negative carbon emissions. However, the high reaction temperature and energy consumption have limited the development of HTC technology. In conventional batch reactors, the temperature and pressure are typically coupled at saturated states. In this study, a decoupled temperature and pressure hydrothermal (DTPH) reaction system was developed to decrease the temperature of the HTC reaction of lignocellulosic biomass (rice straw and poplar leaves). The properties of hydrochars were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analyzer (TGA), etc. to propose the reaction mechanism. The results showed that the HTC reaction of lignocellulosic biomass could be realized at a low temperature of 200 °C in the DTPH process, breaking the temperature limit (230 °C) in the conventional process. The DTPH method could break the barrier of the crystalline structure of cellulose in the lignocellulosic biomass with high cellulose content, realizing the carbonization of cellulose and hemicellulose with the dehydration, unsaturated bond formation, and aromatization. The produced hydrochar had an appearance of carbon microspheres, with high calorific values, abundant oxygen-containing functional groups, a certain degree of graphitization, and good thermal stability. Cellulose acts not only as a barrier to protect itself and hemicellulose from decomposition, but also as a key precursor for the formation of carbon microspheres. This study shows a promising method for synthesizing carbon materials from lignocellulosic biomass with a carbon-negative effect.</p></div>","PeriodicalId":12744,"journal":{"name":"Green Energy & Environment","volume":null,"pages":null},"PeriodicalIF":10.7000,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"16","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Green Energy & Environment","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2468025723000018","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 16
Abstract
Hydrothermal carbonization (HTC) of lignocellulosic biomass is a promising technology for the production of carbon materials with negative carbon emissions. However, the high reaction temperature and energy consumption have limited the development of HTC technology. In conventional batch reactors, the temperature and pressure are typically coupled at saturated states. In this study, a decoupled temperature and pressure hydrothermal (DTPH) reaction system was developed to decrease the temperature of the HTC reaction of lignocellulosic biomass (rice straw and poplar leaves). The properties of hydrochars were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analyzer (TGA), etc. to propose the reaction mechanism. The results showed that the HTC reaction of lignocellulosic biomass could be realized at a low temperature of 200 °C in the DTPH process, breaking the temperature limit (230 °C) in the conventional process. The DTPH method could break the barrier of the crystalline structure of cellulose in the lignocellulosic biomass with high cellulose content, realizing the carbonization of cellulose and hemicellulose with the dehydration, unsaturated bond formation, and aromatization. The produced hydrochar had an appearance of carbon microspheres, with high calorific values, abundant oxygen-containing functional groups, a certain degree of graphitization, and good thermal stability. Cellulose acts not only as a barrier to protect itself and hemicellulose from decomposition, but also as a key precursor for the formation of carbon microspheres. This study shows a promising method for synthesizing carbon materials from lignocellulosic biomass with a carbon-negative effect.
期刊介绍:
Green Energy & Environment (GEE) is an internationally recognized journal that undergoes a rigorous peer-review process. It focuses on interdisciplinary research related to green energy and the environment, covering a wide range of topics including biofuel and bioenergy, energy storage and networks, catalysis for sustainable processes, and materials for energy and the environment. GEE has a broad scope and encourages the submission of original and innovative research in both fundamental and engineering fields. Additionally, GEE serves as a platform for discussions, summaries, reviews, and previews of the impact of green energy on the eco-environment.