聚乙烯与水反应的高温高压实验及热力学探讨

EXPERIMENTS ON REACTION OF POLYETHYLENE AND WATER UNDER HIGH PRESSURE AND HIGH TEMPERATURE

在金刚石压腔设备中进行聚乙烯的高温高压裂解实验研究。实验分含水和不含水两种情况。在显微镜下观察反应过程中的变化并显微照相记录有关现象 ,在高压下就位测定反应过程中荧光的变化。用气相色谱方法测定气相产物组成。含水实验中CH4 占烃类气体产物的 92 %并有CO2 生成 ,固体残余物非常少 ,表明水直接参与了化学反应 ,为烃类气体的形成提供氢源 ,为CO2的形成提供氧源。不含水实验中烃类气体的产率相对较低并有较多的固相残余物存在。用热力学理论探讨了实验中有关反应的机制。根据聚乙烯与干酪根结构的可比性 ,推测在水参与条件下有利于提高有机质裂解成烃的产率。

Hydrous and anhydrous pyrolysis of polyethylene under high temperature and high pressure was conducted in diamond anvil cell (DAC) apparatus. Reaction phenomena can be observed by microscope and be recorded by micrography during the experimental processes. At the meantime, in situ fluorescence change can be determined under high pressure. Compositions of gas products were analyzed by gas chromatographic technique. It shows that CH4 made up about 92% of the total gas hydrocarbon products, CO2 and very little solid residue were existed in the hydrous pyrolysis experiment. The results indicate that H2O participates in the chemical reaction directly, offering H to hydrocarbons and O to CO2. Anhydrous pyrolysis of polyethylene generates less gas hydrocarbons and much more solid residue than hydrous run. Thermodynamic theory was used to discuss reaction mechanism in the experiments. Compared polyethylene structure with kerogen, we infer that the ration of hydrocarbons generation would be increased while H2O exists in the organic matters pyrolysis processes.