HDPE/PP共混热裂解特性

Thermal Cracking of HDPE/PP Mixtures

利用热重分析聚烯烃HDPE、PP的单独热裂解特性及HDPE/PP共混热裂解特性,研究了HDPE与PP共混裂解过程中的相互作用。以HDPE和PP为裂解原料,在间歇裂解反应釜中,考查了不同裂解温度、停留时间、起始压力及原料中PP比例对裂解产物收率及性能的影响。通过模拟蒸馏得到裂解产物油各馏分组成分布,采用FT-IR对产物油进行表征,并对轻质组分进行GC-MS分析。最后,采用密度泛函理论计算分析了聚烯烃以及链烷烃的化学键断裂能。结果表明:PP可降低HDPE的裂解温度,PP/HDPE共混裂解过程中存在明显的相互作用。经过正交实验得到:PP比例对混合聚烯烃裂解产油率的影响最为显著;影响轻质馏分收率的因素由主到次依次为:停留时间,裂解温度,PP比例,起始压力。FT-IR、GC-MS分析和理论计算都表明:裂解产物油的主要成分为链烷烃,其中直链烷烃含量较高,所得产物油是良好的乙烯裂解原料。

Thermal cracking of HDPE, PP and HDPE/PP mixtures and the interaction between the polymers were investigated with TGA （thermogravimetric analysis）. The effects of cracking temperature, residence time, initial pressure and PP content on the yield and properties of the products were discussed, and the oil products were analyzed with simulated distillation, FT-IR and GC-MS. In addition, the chemical bond breaking energies of HDPE and PP were calculated and analyzed using Density Functional Theory. It was found that PP can decrease cracking temperature of HDPE and there presents significant interactions between HDPE and PP in the cracking process. Orthogonal experimental design reveales that the most important factor on oil yield is PP content, and factors affecting the light oil yield are in the order of residence time, cracking temperature, content of PP and initial pressure. The analysis results of FT-IR, GC-MS and theoretical calculation show that the oils obtained from thermal cracking of HDPE/PP are mainly aliphatic and can be used as feedstock to produce ethylene.