The influence of nitrogen-containing polycyclic aromatic hydrocarbons(NC-PAH)on the formation of carbonaceous mesophase remains enigmatic,despite extensive research on the production of carbonaceous materials from aro...The influence of nitrogen-containing polycyclic aromatic hydrocarbons(NC-PAH)on the formation of carbonaceous mesophase remains enigmatic,despite extensive research on the production of carbonaceous materials from aromatic-rich oils.Molecular dynamics simulation was used to investigate the variations in pyrolysis behavior between PAH and NC-PAH based on the composition analysis.Through adjusting the content of NC-PAH,the influence of NC-PAH on the thermal stability of slurry oils(SOs)was evaluated by thermogravimetry,viscosity,coke value,and quinoline insoluble(QI).The morphology and structure of mesocarbon microbeads(MCMBs)prepared with SOs were measured by a polarized-light microscope,SEM,XRD,and Raman.Simulation results indicate that NC-PAH possesses much higher reactivity and tends to produce highly condensed solid and coke products.It corresponds to the QI and high viscosity in thermal stability experiments.Therefore,high concentrations of NC-PAH result in nonuniform morphology and disordered structures.In a system with low viscosity and few QIs,SO,which has a low nitrogen content(475 ppm),reacts gently to produce MCMBs with a uniform particle size(10-40μm)and an excellent spherical shape.As NC-PAH content decreases,the crystalline size of graphitization elevates,as evidenced by parallel layers(10.472-11.764)and stack height(3.269-3.701 nm).The graphitization degree becomes worse and nonuniform with the increase of the content of NC-PAH,and the best is 20.58%evaluated by Raman spectra area ratio(AG/Aall).Overall,this work suggests a nitrogen content reference and a controlling technology of nitrogen for the preparation of superior MCMB.展开更多
B-COPNA resin,synthesized from the light fraction of ethylene tar(ETLF),is a superior precursor of the carbon materials.An in-depth understanding of the COPNA resin preparation process and strict control of crosslinki...B-COPNA resin,synthesized from the light fraction of ethylene tar(ETLF),is a superior precursor of the carbon materials.An in-depth understanding of the COPNA resin preparation process and strict control of crosslinking degree are crucial for controlling carbon materials performance.Therefore,the synthesis kinetics of B-COPNA resin prepared from ETLF was investigated using in-situ FTIR in this work.The synthesis kinetic models of B-COPNA resin were established for the first time.To express the kinetic model,the concentration changes of C-H in aromatic rings and O-H in PXG monitored by in-situ FTIR were selected as two indicators to calculate concentration of other compounds and describe the synthesis kinetics.Then confirmatory experiments were conducted,and the ρ^(2)(>0.9900),F-values(>10F_(0.05))and parameter errors(below 3%)of kinetic models verify that concentration changes of C-H and O-H can be used to describe synthesis kinetics of B-COPNA resin.Based on the results of confirmatory experiments,the synthesis kinetic model of B-COPNA resin in the ETLF system is established successfully using concentration changes of O-H as an indicator,whose appropriateness and feasibility are proved by the ρ^(2)(0.9960)and F-values(>10F_(0.05)).These models could accurately describe the synthesis rate of B-COPNA resin.展开更多
基金support of National Natural Science Foundation of P.R.China(22308104).
文摘The influence of nitrogen-containing polycyclic aromatic hydrocarbons(NC-PAH)on the formation of carbonaceous mesophase remains enigmatic,despite extensive research on the production of carbonaceous materials from aromatic-rich oils.Molecular dynamics simulation was used to investigate the variations in pyrolysis behavior between PAH and NC-PAH based on the composition analysis.Through adjusting the content of NC-PAH,the influence of NC-PAH on the thermal stability of slurry oils(SOs)was evaluated by thermogravimetry,viscosity,coke value,and quinoline insoluble(QI).The morphology and structure of mesocarbon microbeads(MCMBs)prepared with SOs were measured by a polarized-light microscope,SEM,XRD,and Raman.Simulation results indicate that NC-PAH possesses much higher reactivity and tends to produce highly condensed solid and coke products.It corresponds to the QI and high viscosity in thermal stability experiments.Therefore,high concentrations of NC-PAH result in nonuniform morphology and disordered structures.In a system with low viscosity and few QIs,SO,which has a low nitrogen content(475 ppm),reacts gently to produce MCMBs with a uniform particle size(10-40μm)and an excellent spherical shape.As NC-PAH content decreases,the crystalline size of graphitization elevates,as evidenced by parallel layers(10.472-11.764)and stack height(3.269-3.701 nm).The graphitization degree becomes worse and nonuniform with the increase of the content of NC-PAH,and the best is 20.58%evaluated by Raman spectra area ratio(AG/Aall).Overall,this work suggests a nitrogen content reference and a controlling technology of nitrogen for the preparation of superior MCMB.
基金financially supported by the National Natural Science Foundation of China(52174023)National Natural Science Foundation of P.R.China(22308104)China Petroleum Engineering Corp.,Ltd.(CPEC)(2021ZYGC-01-01)。
文摘B-COPNA resin,synthesized from the light fraction of ethylene tar(ETLF),is a superior precursor of the carbon materials.An in-depth understanding of the COPNA resin preparation process and strict control of crosslinking degree are crucial for controlling carbon materials performance.Therefore,the synthesis kinetics of B-COPNA resin prepared from ETLF was investigated using in-situ FTIR in this work.The synthesis kinetic models of B-COPNA resin were established for the first time.To express the kinetic model,the concentration changes of C-H in aromatic rings and O-H in PXG monitored by in-situ FTIR were selected as two indicators to calculate concentration of other compounds and describe the synthesis kinetics.Then confirmatory experiments were conducted,and the ρ^(2)(>0.9900),F-values(>10F_(0.05))and parameter errors(below 3%)of kinetic models verify that concentration changes of C-H and O-H can be used to describe synthesis kinetics of B-COPNA resin.Based on the results of confirmatory experiments,the synthesis kinetic model of B-COPNA resin in the ETLF system is established successfully using concentration changes of O-H as an indicator,whose appropriateness and feasibility are proved by the ρ^(2)(0.9960)and F-values(>10F_(0.05)).These models could accurately describe the synthesis rate of B-COPNA resin.
