CAJ | 학술논문

采用连续流动超临界裂解装置，对正癸烷与环己烷在超临界状态下的热裂解进行实验研究和理论分析。同时，采用密度泛函方法在BH&HLYP／cc‐pVDZ水平上，对两者热裂解过程中起始反应关键步骤的速率常数进行计算。结果表明，相同条件下，正癸烷初始产气温度低于环己烷；低于923 K时，正癸烷更容易裂解，其产物主要是C1～C4小分子烃类及C5～C9的直链烯烃，1023 K时，两者的裂解程度相当，此时正癸烷裂解产物主要是C1～C4小分子烃类，而环己烷在低于973 K时裂解产物以甲基‐环戊烷为主，随着温度升高，裂解产物种类增多，当温度达到1023 K时裂解产物主要是芳香烃、环烯烃等结焦前驱体，积炭情况比正癸烷严重。相同温度时，正癸烷C—C键断键反应的速率常数比环己烷C—C键和C—H键断键反应速率常数都高，更容易发生裂解反应，理论结果很好地解释了温度低于923K时正癸烷比环己烷更容易裂解的实验现象。
채용련속류동초림계렬해장치，대정계완여배기완재초림계상태하적열렬해진행실험연구화이론분석。동시，채용밀도범함방법재BH&HLYP／cc‐pVDZ수평상，대량자열렬해과정중기시반응관건보취적속솔상수진행계산。결과표명，상동조건하，정계완초시산기온도저우배기완；저우923 K시，정계완경용역렬해，기산물주요시C1～C4소분자경류급C5～C9적직련희경，1023 K시，량자적렬해정도상당，차시정계완렬해산물주요시C1～C4소분자경류，이배기완재저우973 K시렬해산물이갑기‐배무완위주，수착온도승고，렬해산물충류증다，당온도체도1023 K시렬해산물주요시방향경、배희경등결초전구체，적탄정황비정계완엄중。상동온도시，정계완C—C건단건반응적속솔상수비배기완C—C건화C—H건단건반응속솔상수도고，경용역발생렬해반응，이론결과흔호지해석료온도저우923K시정계완비배기완경용역렬해적실험현상。
Pyrolysis of n‐decane and cyclohexane under supercritical pressure was investigated by utilizing self‐designed continuous flow reactor . To comparably analyze the cracking reactivity of these two model compounds , the cracking conversion , the gas yield , distribution of liquid and gaseous products were observed at the pressure of 4.5 MPa and in the temperature range of 823 -1023 K . To get the reaction rate constant for the initial key steps , theoretical calculation was performed by density functional theory method at BH&HLYP/cc‐pVDZ level .The results showed that under the same conditions ,the starting temperature for the gase production from n‐decane was lower than that from cyclohexane .When the temperature is below 923 K , n‐decane is easier to crack than cyclohexane ,and major C1 -C4 hydrocarbons and C5 -C9 straight‐chain olefins were produced .The similarly high cracking ratio can be achieved at 1023 K ,and major pyrolysis products of n‐decane were C1 -C4 hydrocarbons .Below 973 K ,cyclohexane mainly cracked to form methyl‐cyclopentane . Further , the components of cracking products become more complex with the temperature increasing . At 1023 K , coke precursors , for example , aromatic compounds and cyclones ,were generated in large amounts ,which lead to the more serious coking of cyclohexane than that of n‐decane .The reaction rate constant for C—C bond cleavage of n‐decane was larger than that for C—C bond and C— H bond cleavage of cyclohexane at the same temperature . Therefore ,n‐decane was more prone to cracking than cyclohexane . In general , the calculation results provided the good evidence for the experimental phenomena that n‐decane has larger cracking ratio than cyclohexane below 923 K .