摘要
采用基于反应力场的分子动力学模拟方法研究了钙对煤与塑料(聚乙烯和聚苯乙烯)共热解反应的影响,结合核磁共振和XPS等表征技术构建了掺钙的煤模型。结果表明:钙能促进高温下焦油的二次反应,提高焦炭产量,降低焦油产量。加钙后,相较于煤与聚苯乙烯反应,煤与聚乙烯反应中焦炭含量的大幅增加及焦油含量的大幅降低反映出钙对煤与聚乙烯共热解过程中煤分解的影响更大,且煤与聚苯乙烯共热解过程中煤释放的CO_(2)受到抑制。钙对聚乙烯的影响是促进聚乙烯热解产物链接入煤的热解产物中,并通过产生大量的H自由基的途径造成煤焦油大幅下降。钙对聚苯乙烯的影响是促进聚苯乙烯的裂解,有利于打破聚苯乙烯中的芳香环结构。根据一级反应动力学模拟,钙显著降低了煤与塑料共热解反应的活化能,且钙对煤与聚乙烯共热解的影响更大。
The effect of calcium on the co-pyrolysis reaction between coal and plastics(polyethylene and polystyrene)was investigated using molecular dynamics simulations based on reaction force fields(ReaxFF),and a modified coal model was developed for calcium doping conditions by combining NMR,XPS,and other characterization techniques.The results show that the presence of calcium promotes the secondary reaction of tar at high temperatures,increases char yield,and reduces tar yield.The addition of calcium leads to a significant increase in char yield and a dramatic decrease in tar yield of coal in the coal and polyethylene reaction compared to the coal and polystyrene reaction,reflecting the more significant influence of calcium on coal decomposition during coal and polyethylene co-pyrolysis process.Additionally,the CO_(2) release from coal is inhibited in the coal and polystyrene co-pyrolysis.The effect of calcium on polyethylene is to promote the linking of polyethylene pyrolysis products into the pyrolysis products of coal and to greatly decrease the coal tar by generating large amounts of H radicals.The effect of calcium on polystyrene is to promote the cleavage of polystyrene and facilitate the breaking of the aromatic ring structure in polystyrene.According to the first-order reaction kinetics simulation,the existence of calcium significantly reduces the activation energy of the coal and plastic co-pyrolysis reaction,and the effect of calcium on coal and polyethylene co-pyrolysis is larger.
作者
吴棒
郭欣
洪迪昆
WU Bang;GUO Xin;HONG Dikun(State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, China;Department of Power Engineering, North China Electric Power University, 071003 Baoding, China)
出处
《煤炭转化》
CAS
CSCD
北大核心
2022年第3期26-33,共8页
Coal Conversion
基金
国家自然科学基金资助项目(51876073).
