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OA北大核心CSTPCD

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).