Abstract:

In this study, molecular dynamics simulation method was used to study the mechanism of hydrogen production by catalytic fast pyrolysis of tire rubber over Ni, ZSM-5 and Ni/ZSM-5. At the same time, it was compared with the previous experimental studies to verify the simulation calculation. The model was established by Material Studio, the transition state of the hydrogen generation path was searched by DMol3 module, and the catalytic pyrolysis process of adding Ni was simulated by CULP module. The simulation results indicated that the energy barrier of hydrogen generation path decreased with the addition of three catalysts, and the order of catalytic effect was Ni>Ni/ZSM-5>ZSM-5. The catalytic fast processing was divided into two stages:①the low temperature stage was the long chains released monomer compounds, which was mainly isoprene, styrene and 1,3-butadiene; and ②the high temperature stage was that free radical attacked monomer compounds to form small molecular structure. The addition of the catalyst in the low temperature stage was mainly manifested in speeding up the pyrolysis process and increasing the number of monomers in the low temperature stage. The pyrolysis temperature was reduced and the proportion of H₂ increased with the addition of Ni catalyst.

Key words: tire rubber, molecular dynamics, catalytic pyrolysis, hydrogen production

摘要：

采用分子动力学模拟方法，选取Ni、ZSM-5以及Ni/ZSM-5催化剂，对轮胎橡胶热解制氢的机理进行探究，并同时与前人做过的实验研究进行对比验证模拟计算。文中利用Material Studio建立轮胎橡胶模型，DMol3模块对生成氢气路径进行过渡态搜索，CULP模块对其加入Ni催化剂的热解过程进行模拟。模拟结果表明，制氢催化效果顺序为Ni>Ni/ZSM-5>ZSM-5。催化热解大致分为两个阶段：①低温阶段长链裂解成单体化合物，单体主要是异戊二烯、苯乙烯以及1,3-丁二烯；②高温阶段自由基攻击单体生成小分子物质。加入Ni催化剂后降低了热解终止温度。催化剂的加入在低温阶段主要表现在加快热解进程，增加低温阶段时单体数量。在高温阶段主要表现在改变了气体产物分布，Ni的加入降低了轮胎热解温度，并且使氢比例增加。

关键词: 轮胎橡胶, 分子动力学, 催化热解, 制氢