C_(2)链烃在热解/气化中的碳链裂解机理及速率常数计算研究  

Computational study on the chain cracking mechanisms and rate constants of C_(2)chain hydrocarbons during pyrolysis/gasification

作　　者：朱中旭 唐烽 金余其[1] 陈思雨 马家瑜 ZHU Zhong-xu;TANG Feng;JIN Yu-qi;CHEN Si-yu;MA Jia-yu(State Key Laboratory of Clean Energy Utilization,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]浙江大学能源清洁利用国家重点实验室,浙江杭州310027

出　　处：《燃料化学学报（中英文）》2023年第2期251-262,共12页Journal of Fuel Chemistry and Technology

基　　金：国家重点研发计划(2018YFD1100602)资助。

摘　　要：链烃裂解在热解/气化过程中大量存在,其中,轻质链烃反应时间短并且存在多种反应路径,难以通过实验的方式对单一演变路径进行准确的检测和分析。本研究选用Gaussian及其配套软件对C_(2)系列链烃(包括乙烷、乙烯和乙炔)的反应位点进行了预测,并对上述链烃在H/OH/O自由基及水分子作用下的碳链裂解机理进行研究。结果表明,自由基对乙烷的C原子及H原子均可发起进攻,而对于乙烯和乙炔的进攻则主要集中在C原子。在上述三种自由基中,OH自由基对不饱和烃的裂解效果最佳,而H自由基对于饱和烃的裂解效果更好,该结果反映了实际过程中水蒸气对于C_(2)系列链烃化合物的碳链断裂具有积极作用。此外,对比乙烯和乙炔与OH自由基作用的最优路径可以发现,CH_(2)CH_(2)OH在低于1200 K的环境中比CH_(2)CHO更容易裂解,而在高于1200 K的环境中则是CH_(2)CHO裂解更易,从中可以推断出醛类基团对于温度变化的响应速率优于醇类基团。Chain hydrocarbons cracking always occurs in pyrolysis/gasification.Among them,the reaction time of light chain hydrocarbons is short and they have many reaction paths,which make it difficult to accurately detect and analyze each evolution path by experiment.In this study,Gaussian and its related software were employed to predict the reaction sites and to study the chain cracking mechanism of C_(2)chain hydrocarbons(including ethane,ethylene and acetylene)under the action of H/OH/O radicals or H_(2)O.According to the results,radicals can both attack the C and H atoms of ethane,while the C atoms of ethylene and acetylene are the main attack sites.Among the above radicals,OH radical is the best for unsaturated hydrocarbons cracking,while H radical is the best for saturated hydrocarbons,showing that the steam is conducive to the cracking of C_(2)chain hydrocarbons in actual process.In addition,comparing the optimal path of the reaction of ethylene or acetylene with OH radical,it can be found that CH_(2)CH_(2)OH radicals are easier to crack than CH_(2)CHO radicals below 1200 K,while CH_(2)CHO radicals are easier to crack above 1200 K,inferring the better response speed of aldehyde groups for temperature than alcohol groups.

关 键 词：C_(2)烃 H_(2)O 自由基 反应位点预测 反应路径 反应速率常数 

分 类 号：O643.12[理学—物理化学]