【作者】 郭文瑶；

【导师】 肖文德；

【作者基本信息】 上海交通大学 ， 应用化学， 2013， 博士

【摘要】 甲醇制丙烯（Methanol to Propylene，MTP）技术相当于煤或天然气制丙烯，是最有希望以煤（或天然气）替代石油的能源化工新工艺。本论文围绕基于ZSM-5催化剂的固定床MTP工艺的条件优选和过程强化展开了深入研究。鉴于目前MTP固定床工艺大多采用烯烃循环的方法增加丙烯收率，论文研究了甲醇与烯烃的耦合反应，并首次对带有烯烃循环和甲醇分段进料的多段MTP过程进行了实验研究，针对工业粒度催化剂中的内扩散影响，提出了适合于MTP过程的整体式催化剂和反应器。论文主要研究内容如下：首先进行了甲醇单独反应的实验研究。考察了反应温度、甲醇空时、甲醇分压、醇水比等反应条件对MTP反应的影响。结果表明，升高温度、增大空时或增大甲醇分压，甲醇转化率和丙烯选择性明显增加，但副产物烷烃和芳烃的选择性也随之增加；水含量增加有利于丙烯的生成，但降低甲醇的转化率。其次，进行了甲醇与烯烃共反应的实验研究。甲醇和丁烯或戊烯的耦合反应规律相似，温度的升高有利于提高甲醇转化率和C2-C4烯烃选择性，并减少C5-C7烯烃和副产物烷烃和芳烃的生成。较低的甲醇空时可有效减少副产物烷烃和芳烃的生成并提高丙烯/乙烯比。与甲醇单独反应相比，丁烯或戊烯的加入可以明显减少副产物烷烃和芳烃的生成。第三，进行了三段甲醇制丙烯过程的实验研究。甲醇制丙烯催化剂使用满650小时后，甲醇转化率仍然保持98%以上，催化剂再生周期达到600小时，三段模拟反应的丙烯选择性均超过75%，说明所设计的工艺条件和选配的催化剂满足工业MTP过程要求。第四，建立了单颗粒催化剂上的MTP反应-扩散模型。采用工业粒度ZSM-5催化剂在内循环无梯度反应器中进行了宏观反应速率实验，内扩散效率因子的模型计算值与实验值吻合良好，所建立的反应-扩散模型适用于后续MTP反应器设计和工业计算。第五，对多段绝热固定床反应器进行了模拟研究，采用一维非均相反应器模型计算了反应器进口温度、甲醇空速、进料组成等主要操作条件对反应器性能的影响，揭示了反应器内甲醇转化率、床层温度和烃类产物分布的规律，为MTP反应器的工业放大、操作调优和设计优化提供了理论依据。第六、对蜂窝状规整结构催化剂及反应器进行了模拟研究，建立的二维反应器模型包括气相流体的质量传递和热量传递、催化剂内部的扩散和反应和气固两相界面的传递。计算了催化剂结构对甲醇转化率、丙烯选择性、热点温度和副产物生成的影响，提出规整结构反应器的设计方法，与催化剂散堆的传统固定床反应器相比，规整结构反应器在MTP过程中具有明显优越性。同样甲醇转化率下，催化剂可节省80%，丙烯选择性可提高7%。更多还原

【Abstract】 Methanol to propylene (MTP) technology, which enables thetransformation of coal or natural gas to propylene via methanolsynthesis, is an alternative route to produce petrochemicals and gasolinefrom coal other than crude oil with great potential. The operatingcondition and process intensification of MTP process in a fixed bedreactor over ZSM-5catalysts have been investigated in this work. In atypical MTP process, several olefin-containing streams are sent back tothe main synthesis loop as the additional propylene sources. Therefore,the coupled reaction of C4/C5olefin with methanol, and the multi-stageMTP process with olefins co-feeding were studied in a fixed bed reactor.Considering the intra-particle mass transfer restriction in industrialcatalyst pellets, a monolith catalyst and reactor has been proposed andmodelled for the MTP process.The main contents and results in this work are as follows:First of all, effects of operational conditions on methanol conversionto propylene were investigated in an isothermal fixed bed reactor, suchas reaction temperature, space time, methanol partial pressure andwater/methanol molar ratio. The results indicated that methanolconversion and propylene selectivity increased with increase in reactiontemperature, the methanol space time or methanol partial pressure andso did selectivities of alkanes and aromatics. Increasing water content inthe feed mixture is conducive to forming propylene, but harmful to themethanol conversion.Secondly, the coupled reaction of butene and pentene with methanolhave been investigated, respectively. Both two co-reaction systemsobtained similar results that increasing reaction temperature increasesmethanol conversion and light olefins selectivity, but decreases the formation of C5-C7olefins,alkans and aromatics. The formation ofalkanes and aromatics is inhibited and propylene/ethylene ratioenhanced by lower methanol space time. Compared with the reaction ofmethanol alone, co-feeding butene or pentene with methanol resulted inmuch less alkanes and aromatics. The selectivity of propylene increaseswith increasing methanol/olefin molar ratio.Thirdly, the three-stage methanol to propylene reaction process hasbeen simulated experimentally based on a high silicon ZSM-5catalyst.The catalyst life time was long up to650hours, and the selectivity ofpropylene was above75%in all three stages.Fourthly, a reaction-diffusion model for MTP reaction system hasbeen proposed and validated by comparing with the experimental resultsobtained in a berty type reactor. The calculated intraparticle diffusionefficiency factors are in good agreement with the experimental results,which indicates that the proposed model is appropriated for MTPreaction system and qualified for further reactor design and industrialsimulation.Fifthly, a multi-stage adiabatic fixed-bed reactor has been simulatedby a one-dimensional heterogeneous reactor model. The effects ofreactor inlet temperature, methanol space velocity and feed compositionon methanol conversion, reactor temperature and product distributionwere calculated and analyzed, to provide a theoretical basis for furtherscale-up, optimization and intensification of MTP process.Finally, a monolith reactor has been proposed for MTP reaction andcalculated based on a two-dimensional adiabatic heterogeneous reactormodel including the interactions of mass and heat transfer and chemicalreactions between the gas and catalyst phases and inside the catalystphase. Concentration and temperature profiles in both radial and axialdirection were calculated with special focus to influence of monolithchannel geometries on methanol conversion, propylene and by-productselectivity. Hints for monolithic catalyst design were derived. Thecalculation results showed that the monolith catalyst intensifies thereactor efficiency significantly. Compared with the randomly packed catalyst, for a complete methanol conversion, the monolithic catalystamount is80%less than the randomly packed reactor, and propyleneselectivity is increased by7%.更多还原