Thermal and Environmental Engineering Institute, School of Mechanical Engineering, Tongji University
Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization
Shanghai Municipal Engineering Design Institute (Group) Company Limited

生物质能的有效利用是实现“双碳”战略目标的重要途径。近年来,生物热解技术是研究热点之一,从分子尺度上理解热解过程和产物析出特性具有重要意义。基于反应分子动力学(ReaxFFMD)模拟结合热重(TG)分析和微型热解实验,研究了生物质三组分(纤维素、半纤维素和木质素)的共热解行为和气相产物析出特性。结果表明:ReaxFFMD模拟得到的三组分单独热解及共热解过程的热失重特性与TG实验结果基本吻合;基于一级反应动力学模型,共热解的活化能实际值比线性叠加的理论值降低约14.67%,表明共热解对化学键的断裂具有正向协同效应;在三组分共热解过程中,低温下析出气体主要为水蒸气(H2O)、二氧化碳(CO2)、甲酸乙酯(C3H6O2)和呋喃(C4H4O),来自纤维素和半纤维素的热解,而在高温下,主要析出气体变为甲烷(CH4)、一氧化碳(CO)和氢气(H2),源自木质素热解;纤维素和半纤维素单独热解时,无机气体按产率由大到小排序为:H2O,CO2,CO,H2,对于木质素热解,无机气体按产率排序则变为:H2O,CO,CO2,H2,三组分共热解时无机气体产率排序与纤维素和半纤维素热解时无机气体产率排序一致;纤维素和半纤维素可分别促进木质素热解产生CH4,三组分共热解则促进乙酸(C2H4O2)裂解和甲醛(CH2O)生成。

The effective utilization of biomass energy is an important way to achieve the “double carbon”. In recent years, bio-pyrolysis technology has become one of the research hotspots, and a comprehensive understanding of the pyrolysis process and the precipitation char- acteristics of products at the molecular level is of significant importance. Based on the reaction molecular dynamics (ReaxFF MD) simulation, thermogravimetric (TG) analysis, and micro- pyrolysis experiments, the co-pyrolysis behavior of three components (cellulose, hemicellulose, and lignin) and the precipitation characteristics of gaseous products were studied. The results show that the thermogravimetric characteristics of the separate pyrolysis and co-pyrolysis of the three components, as simulated by ReaxFF MD, are consistent with the results observed in the TG experiment. Based on the first-order kinetic model, the actual activation energy of co-pyroly- sis is about 14.67% lower than the theoretical value of linear superposition, indicating that co- pyrolysis has a positive synergistic effect on the fracture of chemical bonds. In the three-compo- nent co-pyrolysis process, the main gases precipitated at low temperatures are water (H2O), car- bon dioxide (CO2), ethyl formate (C3H6O2), and furan (C4H4O), which come from the pyroly- sis of cellulose and hemicellulose, while at high temperatures, the main gases precipitated into methane (CH4), carbon monoxide (CO), and hydrogen (H2), which come from the pyrolysis of lignin. When cellulose and hemicellulose are pyrolyzed separately, the order of inorganic gas according to the yield from large to small is H2O, CO2, CO, H2. When lignin is pyrolyzed sepa- rately, the order is H2O, CO, CO2, H2. The order during the co-pyrolysis of three components is consistent with that during the separate pyrolysis of cellulose and hemicellulose. Cellulose and hemicellulose promote the pyrolysis of lignin and result in higher CH4 production, while the co- pyrolysis of three components promotes the decomposition of acetic acid (C2H4O2) and the for- mation of formaldehyde (CH2O).

上海市科技计划国际合作项目(22230730300).

徐思佳,胡雨燕,胡维杰,等.基于 ReaxFF MD模拟的生物质三组分共热解气相产物析出特性研究[J].煤炭转化,2024,47(3):13-26

XU Sijia,HU Yuyan,HU Weijie,et al.Investigation on precipitation characteristics of gas products from three-component co-pyrolysis of bio-mass based on ReaxFF molecular dynamics simulation[J].Coal Conversion,2024,47(3):13-26