【作者】 朱宁；

【导师】 陈丰秋； 程党国；

【作者基本信息】 浙江大学 ， 化学工程， 2010， 博士

【摘要】 轻质烯烃,如乙烯、丙烯等,作为石化工业下游产品的重要原料,通常来自于石脑油的热裂解工艺(蒸气热裂解)。其反应温度高,消耗了炼油工业中40%的能量。而新兴的催化裂解技术不仅可以比热裂解温度降低50-200℃,而且相对于热裂解较为固定的产物组成,能对各种产物的选择性进行灵活的调整。为了缓解日益严峻的环境问题以及能源枯竭的威胁,达到节能减排的目的,以及实现对产物分布的控制,轻烃催化裂解就得到了越来越多的关注,成为了项很有前景的课题,而裂解催化剂的开发与研究则是这项课题的关键。本文对上海石化院提供的两代催化裂解催化剂H0108以及P57进行了全面的分析。纯分子筛型H0108催化剂活性较高,其水热稳定性是关键问题。本文通过原位漫反射红外光谱等表征手段对于正庚烷在水热处理前后的H0108催化剂上的反应机理进行了研究,分析了水热处理前后催化剂活性中心以及孔道结构的变化,并且建立了微孔与介孔内单分子以及双分子反应的机理模型。分子筛与氧化铝混合型催化剂P57的水热稳定性较高,其催化性能则成为关键问题。本文对不同反应物在P57催化剂上的活性以及产物分布进行了考察,分析了不同反应物在低酸密度P57催化剂上所遵从的反应路径,并建立了反应机理模型。此外,通过P57与H0108的活性稳定性对比,说明了催化剂结构、酸性位差异对催化裂解反应路径、催化剂活性以及催化剂水热稳定性的影响。除了催化反应机理以及催化剂的活性,本文还对催化剂的失活机制与再生过程进行了研究。通过对比P57与H0108催化剂失活速率与再生性能以及表征失活催化剂的结构与酸性位,发现P57主要失活方式为积炭失活,而H0108则不仅存在积炭失活,还存在分子筛骨架脱铝的结构性失活。进一步利用原位红外技术对H0108骨架脱铝失活过程进行了机理研究,并建立起骨架脱铝过程的动力学模型。最后,通过TG-DTG对两种催化剂上的积炭进行考察,分别建立起了无水蒸气存在和有水蒸气存在两种反应条件下的烧炭再生动力学模型,其中无水反应条件下失活的H0108催化剂存在两种积炭,对应两段反应动力学模型。有水反应条件下失活的H0108催化剂、有水以及无水反应条件下失活的P57催化剂都只对应一段再生动力学模型。更多还原

【Abstract】 The petrochemical industry is the foundation of the modern society. Basic chemicals such as ethylene, propylene, and other light olefins are currently manufactured mainly by thermal cracking of naphtha, i.e., so-called steam cracking or steam pyrolysis. However, the current steam pyrolysis process, taking place at the high temperature, consumes as much as 40% of the energy needed by the entire petrochemical industry. Global increasing environmental issues and the drying fossil fuel energy have stimulated the development of processes of energy saving and emission reduction. For this purpose, the research on the catalytic cracking to replace the steam cracking of light hydrocarbons has attracted more and more scientific interests. The catalytic cracking can not only reduce the reaction temperature about 50～200℃but also control the products distribution of light olefins easily. Hence, the R&D of proper catalyst plays the key role in the catalytic cracking.The present work compared H0108 and P57 catalysts which represent two generations of the catalytic cracking catalysts synthesized and provided by Shanghai Research Institute of Petro-chemical Technology. The pure zeolites catalyst H0108, corresponding to the first catalyst generation, showed high catalytic activity but low hydrothermal stability in the reaction. The hydrothermal treatment can easily change the active sites and porous channel structures of H0108. The in-situ Diffuse Reflectance Infrared Fourier transform Spectroscopy (DRIFTS) was used to analyze the cracking mechanisms of fresh and the hydrothermal treated H0108. And a brief model of the catalytic cracking of n-heptane in micropores and mesopores was proposed.The composite catalyst P57 constitutes of the equal amount of zeolites and Al2O3, which exhitied high hydrothermal stability and mild catalytic activity. The phase pattern, activity, products distribution, acidity and stability were analyzed by various characteristic methods. Different feedstocks were employed to study the catalytic mechanisms and reaction pathways at different temperatures. Comparisons of the structures and natures between H0108 and P57 were also studied. Besides, the mechanisms of the catalytic cracking of n-heptane over H0108 and P57 were discussed.Besides the activity and the reaction mechanism, the deactivation and the regeneration of these two catalysts were studied. The coke was the main cause of the deactivation over P57. For H0108, its deactivation is not only due to the coke but also the framework dealumination. Moreover, in situ FTIR was employed to construct the mechanistic model and the kinetic model of the freamework dealumination of H0108. Finally, the types of coke and the kinetic models of the regeneration by the coke combustion over the deactivated H0108 and P57 were studied by TG-DTG.更多还原