聚丙烯及聚苯乙烯催化共热解的产物分布规律

Product Distribution and Composition of Catalytic Co⁃Pyrolysis of Polypropylene and Polystyrene

将聚丙烯与聚苯乙烯等质量混合物在小型固定流化床内进行催化共热解,选用废FCC催化剂,分析了温度、催化剂比例、载气流速(停留时间)对热解产物分布及组成的影响。在480~560℃下进行实验,将水蒸气作为载气,催化剂与反应物的比例为2:6、载气流速为0.5~2.0 mL水/min。液体与气体产物组成分别采用气相色谱质谱联用(GC⁃MS)及气相色谱(GC)进行分析。结果表明,催化共热解产物主要由油、气及积碳组成,三者的最高收率分别为75.65%、15.77%及5.55%。温度与催化剂比例的提高促进了裂解反应的发生,而随着停留时间的增加,发生二次反应数量增加,例如聚合、环化及异构化等。共热解油以芳烃为主,收率可达到69.16%,烷烃及烯烃含量较低,热解气以C_(1)~C_(4)为主,其中,与烷烃相比,烯烃总收率较高,可达到62.87%。在所有气态烃中,丙烯的含量最大,其值为37.83%。

The catalytic co⁃pyrolysis of polypropylene and polystyrene was carried out in a small fixed⁃fluidized bed,and the effects of temperature,catalyst proportion and carrier gas velocity(residence time)on the distribution and composition of the cracking products were investigated using spent FCC catalysts.The experiments were conducted at temperatures ranging from 480℃to 560℃,with water vapor as the carrier gas,while the carrier gas flow rate ranged from 0.5 mLH2O/min to 2.0 mLH2O/min.The compositions of oil and gaseous products were analyzed by gas chromatography⁃mass spectrometry(GC⁃MS)and gas chromatography(GC),respectively.The results indicate that the main products of catalytic co⁃pyrolysis products were mainly composed of oil,gas,and carbon deposition,with maximum yields of 75.65%,15.77%,and 5.55%,respectively.The increase in temperature and catalyst ratio promoted the cracking reactions,while the increase of residence time resulted in more secondary reactions such as polymerization,cyclization,and isomerization.Besides,the pyrolysis oil was mainly composed of aromatics,with a yield of 69.16%,while the contents of alkanes and olefins were relatively low.The pyrolysis gas was predominantly composed of C_(1)~C_(4) hydrocarbons,with an overall yield of olefins exceeding that of alkanes,reaching 62.87%.Among all gaseous hydrocarbons,propylene exhibited the highest content,accounting for 37.83%.