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典型废塑料PE/PP/PS共热解初期反应特性的ReaxFF研究

贺兴处 陈德珍

贺兴处, 陈德珍. 典型废塑料PE/PP/PS共热解初期反应特性的ReaxFF研究[J]. 燃料化学学报. doi: 10.1016/S1872-5813(21)60161-5
引用本文: 贺兴处, 陈德珍. 典型废塑料PE/PP/PS共热解初期反应特性的ReaxFF研究[J]. 燃料化学学报. doi: 10.1016/S1872-5813(21)60161-5
HE Xing-chu, CHEN De-zhen. ReaxFF study on reaction characteristics of mixed PE/PP/PS in the earlier co-pyrolysis stage[J]. Journal of Fuel Chemistry and Technology. doi: 10.1016/S1872-5813(21)60161-5
Citation: HE Xing-chu, CHEN De-zhen. ReaxFF study on reaction characteristics of mixed PE/PP/PS in the earlier co-pyrolysis stage[J]. Journal of Fuel Chemistry and Technology. doi: 10.1016/S1872-5813(21)60161-5

典型废塑料PE/PP/PS共热解初期反应特性的ReaxFF研究

doi: 10.1016/S1872-5813(21)60161-5
基金项目: 国家自然科学基金(51776141)和上海市科委国际合作项目(20230712900)
详细信息
    作者简介:

    贺兴处(1994—),男,硕士研究生,hexingchu@126.com

    通讯作者:

    陈德珍(1969—),女,博士,教授,chendezhen@tongji.edu.cn

  • 中图分类号: O63

ReaxFF study on reaction characteristics of mixed PE/PP/PS in the earlier co-pyrolysis stage

Funds: National Natural Science Foundation of China (51776141) and Shanghai Science and Technology Commission Project for International Cooperation and Exchanges (20230712900)
  • 摘要: 利用ReaxFF结合AutoRMA分析工具从动力学、热解产物及热解反应过程三方面探究了典型废塑料PE/PP/PS共热解原子层面的反应机理。研究表明,PE/PP/PS共热解的动力学参数可通过C–C键和C–H键断裂的活化能加权求和(即Char Bonds方法) 获得,其活化能与实验值的误差仅为 ± 3.86%,因此C–C键和C–H键断裂可以表征反应进程。针对三种塑料的混合热解体系即PP-PE,PP-PS和PE-PP-PS的研究表明,增加PP-PE中PP的含量可以提高油和可燃气的产率,增加PP-PS中PS的含量可以提高炭和油产率;在PE-PP-PS体系中,高温有利于重油裂解为轻油,轻油相对含量从2400 K的44.77 wt%升高到3000 K的56.18 wt%,同时高温也会促使烃类小分子进一步裂解生成更小分子产物,随热解温度升高,H2和CH4的产率明显上升,但C2H4和C3H6的产率先上升后降低。相比单独热解,混合热解体系开始反应时间有所延迟,但达到第一次平衡的总反应时间缩短,并且更倾向于生成较小分子产物。PE和PP单独热解时,首先生成其单体,继而生成烷烃和小分子气体,但在共热解过程中,首先生成烷烃和小分子气体,而后生成其单体。PS在共热解体系中更倾向于提供·H自由基从而与PE和PP生成的自由基结合,形成小分子烷烃或H2
  • 图  1  PE-PP-PS体系初始构象

    Figure  1  Initial snapshot of PE-PP-PS model system

    图  2  不同温度下PE-PP-PS体系共热解过程C–C键和C–H键数量变化、固体转换率及动力学计算(a.体系中总C–C键,b. 体系中总C–H键,c. 固体转换率,d. 固相产物中C–C键,e. 固相产物中C–H键,f. 动力学计算)

    Figure  2  The number change of C–C bond and C–H bond in the pyrolysis system at different temperatures, solid conversion rate and kinetics calculation (a. C–C bond number in system, b. C–H bond number in system, c. solid conversion rate, d. C–H bond number in solid products, e. C–C bond number in solid products, f. kinetics calculation)

    图  3  不同温度下PE/PP/PS单独热解及PE/PP和PP/PS共热解过程C–C键和C–H键数量变化

    Figure  3  The number changes in C–C bond and C–H bond during isothermal pyrolysis of PE/PP/PS and binary mixture of PE/PP and PP/PS at different temperatures

    图  4  3000 K下PE/PP混合热解过程三项产物产率变化

    Figure  4  Changes of product yields during PE/PP co-pyrolysis at 3000 K

    图  5  3000 K下PE/PP不同比例混合热解80 ps油产品比率

    Figure  5  Heavy oil and light oil ratio from PE/PP co-pyrolysis for 80 ps at 3000 K

    图  6  3000 K下PE/PP不同比例共热解80 ps主要气体组分

    Figure  6  Main gas components from PE/PP co-pyrolysis for 80 ps at 3000 K

    图  7  3000 K下PP/PS共热解过程三项产物产率变化

    Figure  7  Changes of product yields during PP/PS co-pyrolysis at 3000 K

    图  8  3000 K下PP/PS不同比例共热解80 ps后油产品比率

    Figure  8  Heavy oil and light oil ratio from PP/PS co-pyrolysis for 80 ps at 3000 K

    图  9  3000 K下PP/PS在不同比例下共热解80 ps后主要气体组分

    Figure  9  Main gas components from PP/PS co-pyrolysis for 80 ps at 3000 K

    图  10  2400−3000 K下PE-PP-PS体系热解主要产品产率及转化率

    Figure  10  Yield and conversion rate of main products from PE-PP-PS co-pyrolysis system at 2400−3000 K

    图  11  不同温度下PE-PP-PS体系热解气主要组分

    Figure  11  Main components of gas from PE-PP-PS co-pyrolysis at different temperatures

    表  1  废塑料典型组分主要来源及其热解产品分布

    Table  1  Main sources of typical components and distribution of pyrolysis products of waste plastics

    ComponentsSourceLow temperature productsHigh temperature products
    PEhousehold, industrial packaging, agricultural filmwax, oil[5, 6]gas, light oil[6, 7]
    PPhousehold, industrial packaging, automotive industrywax, oil[5, 6]gas, light oil[6, 7]
    PShousehold, industrial packaging, construction, WEEEtoluene, styrene and
    its oligomers [8]
    styrene and its oligomers, PAH[8]
    下载: 导出CSV

    表  2  模拟体系分子构成

    Table  2  Molecular composition of simulation system

    System modelPE(C300H602) chain numberPP(C300H602) chain numberPS(C304H306) chain number
    PE9//
    PP/9/
    PS//14
    PE-PP-8-383/
    PE-PP-1-155/
    PE-PP-3-838/
    PP-PS-9-8/66
    PP-PS-3-1/62
    PP-PS-1-3/26
    PE-PP-PS622
    下载: 导出CSV

    表  3  PE/PP/PS废塑料单独热解及共热解过程动力学参数

    Table  3  Pyrolysis kinetic parameters of PE/PP/PS and mixtures of PE-PP, PP-PS and PE-PP-PS

    System modelSimulation time(t/ps)Activation energy(Ea/kJ·mol−1)Preexponential factor (A/s−1)Correlation coefficient
    ExperimentalSimulatedExperimentalSimulatedExperimentalSimulated
    PE 20 362.9 367.89a 4.09 × 1023 1.17 × 1022 0.978 0.973
    PP 7 332.3 332.28b 1.38 × 1022 2.55 × 1022 0.996 0.897
    PS 12 257.4 252.27b 2.61 × 1016 9.87 × 1020 0.997 0.983
    PE-PP-8-3 9 338.4 337.75b 6.71 × 1022 7.37 × 1022 0.979 0.990
    PP-PS-9-8 17 300.4 302.60b 1.65 × 1019 1.44 × 1022 0.999 0.997
    PE-PP-PS 16 314.7 310.85b 9.24 × 1019 2.74 × 1022 0.998 0.995
    a: Calculated by Bonds method; b: Calculated by Char Bonds method.
    下载: 导出CSV

    表  4  3000 K下PE/PP/PS在等温混合热解化学反应进程

    Table  4  Chemical reaction process during isothermal co-pyrolysis of PE/PP/PS at 3000 K

    PE/PP/PSSystem modelChemical reaction process
    PEPE
    PE-PP-8-3
    PE-PP-PS
    PPPP
    PE/PP/PS体系化学反应进程
    PPPE-PP-8-3
    PP-PS-9-8
    PE-PP-PS
    PSPS
    PP-PS-9-8
    PE-PP-PS
    下载: 导出CSV
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出版历程
  • 收稿日期:  2021-07-20
  • 修回日期:  2021-08-31
  • 网络出版日期:  2021-09-18

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