AF—5分子筛催化剂上苯气相乙基化反应的失活动力学研究…

在绝热固定床实验反应器中对苯和乙烯在ＡＦ－５分子筛催化剂上进行的烷基化反应的失活动力学作了研究。初步考察表明乙烯和苯都会引起失活，但乙烯引起的失活是主要的。在和工业反应器类似的操作条件下系统测定了由催化剂失活引起的乙烯转化率随操作时间的变化，所得数据将用于建立失活动力学模型。     

乙炔法气相合成醋酸乙烯工业固定床反应器优化操作的研究Ⅱ乙炔醋酸在Zn（AC）_2—活性炭催化剂上合成醋酸乙烯反应的失活动力学

在该反应的宏观反应动力学研究的基础上，对新型Ｚｎ（ＡＣ）２—活性炭催化剂上合成醋酸乙烯的失活动力学进行了实验研究，对催化剂失活的原因进行了分析探讨。对实验数据进行计算机模拟的结果表明，在实验条件范围内催化剂的失活符合独立失活的机理，即催化剂的失活速率与反应物的浓度无关，只与反应的温度和时间，以及催化剂本身的活性高低有关。由此导出了有关的失活动力学方程，为工业固定床反应器的优化操作提供了有关的基础方程和数据。     

AF-5分子筛催化剂上苯气相乙基化反应的失活动力学研究——(Ⅰ)实验研究

在绝热固定床实验反应器中对苯和乙烯在 AF-5分子筛催化剂上进行的烷基化反应的失活动力学作了研究。初步考察表明乙烯和苯都会引起失活,但乙烯引起的失活是主要的。在和工业反应器类似的操作条件下系统测定了由催化剂失活引起的乙烯转化率随操作时间的变化。所得数据将用于建立失活动力学模型。     

乙炔法气相合成醋酸乙烯工业固定床反应器优化操作的研究

在该反应的宏观反应动力学研究的基础上，对新型Ｚｎ（ＡＣ）２－活性炭催化剂上合成醋酸乙烯的失活学进行了实验研究，对催化剂失活的原因进行了分析探讨。地实验数据进行计算机模拟的结果表明，在实验条件范围内催化剂的失活符合独立的失活的机理，即催化剂的的失活速率与反应物的浓度无关，只与反应的温度和时间，以及催化剂本身的活性高低有关。由此导出了有关的失活动力学方程，为工业固定床反应器的优化操作提供了有关的基础方     

AF－5分子筛催化剂上苯气相乙基化反应失活动力学研究（Ⅱ）数学模型的建立和验证

根据前文的实验结果，提出了苯和乙烯在ＡＦ－５分子筛催化剂上进行烷基化反应的失活动力学模型，乙烯引起的失活属平行失活，芳烃引起的失活可按独立失活处理。通过理论分析和数据拟合确定了动力学参数和失活参数，得到了如下失活动力学模型动力学方程活性方程     

甲烷无氧芳构化反应器及催化剂积炭的研究进展

综述了甲烷无氧芳构化反应的研究进展,对甲烷无氧芳构化反应机理、反应器的选择、催化剂的选择、催化剂积炭失活与再生等方面做了讨论,对甲烷无氧芳构化的工艺开发、对能源利用、催化科学均具有重大意义。     

Fe-ZSM-5分子筛上N_2O一步氧化苯制苯酚反应失活动力学研究

根据实验现象和对积炭物组成进行的GC-MS分析结果,提出了N2O和苯在Fe-ZSM-5分子筛催化剂上进行催化氧化反应的的失活动力学模型,即产物苯酚引起的连串失活。采用固定床积分反应器系统测定了由催化剂失活引起的N2O转化率随运行时间的变化,所得实验数据用于失活动力学模型参数估值。模型表明:较低反应温度和苯相对N2O过量都可减缓催化剂的失活速率。模型统计检验表明:所得失活动力学方程在显著性水平α=0.05下有较高的拟合精度和可信度。该模型对深入了解N2O一步氧化苯制苯酚反应及指导反应器和再生器设计均具有重要的意义。     

SAPO-34催化剂上甲醇制烯烃反应——催化反应失活动力学

甲醇制烯烃(MTO)催化剂SAPO-34在反应过程中存在失活现象,为了合理设计MTO反应器,需要了解该反应的本征动力学以及催化剂的失活规律,为此在固定床等温积分反应器内进行了甲醇制烯烃反应失活动力学的研究。通过测定不同催化反应时间下反应物和各产物的浓度,考察了催化剂不同使用时间后的催化活性,研究了SAPO-34催化剂的失活规律,建立了5集总反应和失活动力学模型,该模型充分考虑到水和积炭对反应过程的影响。根据实验测定的动力学数据拟合得到了失活反应的动力学常数,该动力学模型预测得到的SAPO-34催化剂上MTO反应产物组成随反应时间的变化规律与实验值吻合很好,说明了获得的动力学模型的可靠性。     

吡啶氯化反应中催化剂失活动力学的研究

采用积分反应器,研究了吡啶氯化反应中催化剂失活动力学。在常压下测定了在350-390℃,氯气与吡啶摩尔比8～12时的反应速度,建立了失活动力学方程,估算出主反应级数、活化能,以及失活级数和失活因子。统计检验结果表明,该失活动力学方程能很好地拟合实验数据。由所得模型,催化剂失活不受反应物浓度影响,但反应物和产物均能积炭而引起催化剂失活,因而推测催化剂的失活机理为平行连串失活。     

多孔催化剂颗粒的内扩散效应对伴有失活的二级反应动力学的影响

采用正交配置等数学方法,研究在均匀独立失活的催化反应系统中,内扩散效应对等温球形催化剂失活速率的影响,建立适用于任何内扩散区域的二级反应、m级失活系统的失活有效因子和失活西勒模数的定量关系,对n级反应、m级失活系统也作了相应地推广.运用加压微反-色谱-数据处理机联合装置,通过分析在原颗粒丝光沸石催化剂上进行的临氢甲苯歧化反应的失活数据,研究了内扩散对二级反应失活动力学的影响规律.同时,在实验范围内,建立了一套内扩散存在下的甲苯歧化失活动力学模型.     

Application of kinetics and computational fluid dynamics in pinene isomerization

A reliable kinetic model to describe the effects of various factors on the reaction rate and selectivity of pinene isomerization is developed. Furthermore, computational fluid dynamics (CFD) is applied to simulate the solid- liquid dispersion in reactor. The catalyst TiM is obtained by improving the composition and structure of hydrated titanium dioxide. The kinetic equation of pinene isomerization is deduced based on reaction mechanism and catalyst deactivation model. The kinetic equation of pinene isomerization reaction is fitted, and the results show that the fitted equation is correlated with the experimental data. The rate and selectivity of pinene isomerization reaction are affected by the amount of catalyst, deactivation of catalyst, structure of catalyst, reaction temperature and water content of catalyst. The solid-liquid distribution of the reactor is calculated by computational fluid dynamics numerical simulation, and the solid-liquid dispersion in commercial scale reactor is more uniform than that in lab-scale reactor.     

Application of kinetics and computational fluid dynamics in pinene isomerization

A reliable kinetic model to describe the effects of various factors on the reaction rate and selectivity of pinene isomerization is developed. Furthermore, computational fluid dynamics(CFD) is applied to simulate the solid–liquid dispersion in reactor. The catalyst Ti M is obtained by improving the composition and structure of hydrated titanium dioxide. The kinetic equation of pinene isomerization is deduced based on reaction mechanism and catalyst deactivation model. The kinetic equation of pinene isomerization reaction is fitted, and the results show that the fitted equation is correlated with the experimental data. The rate and selectivity of pinene isomerization reaction are affected by the amount of catalyst, deactivation of catalyst, structure of catalyst, reaction temperature and water content of catalyst. The solid–liquid distribution of the reactor is calculated by computational fluid dynamics numerical simulation, and the solid–liquid dispersion in commercial scale reactor is more uniform than that in lab-scale reactor.     

Kinetic study of propane dehydrogenation and side reactions over Pt–Sn/Al2O3 catalyst

The kinetics of reactions involved in dehydrogenation of propane to propylene over Pt–Sn/Al₂O₃ catalyst was studied. The simultaneous deactivation of individual dehydrogenation, hydrogenolysis and cracking sites was also studied. A model was developed to obtain the transient conversion of propane, product selectivity and catalytic site activity. The dehydrogenation reaction was considered as the main reaction governing propane and hydrogen concentrations along the reactor. Catalytic test runs were performed in a fixed-bed quartz reactor. The kinetic expressions developed for the main and side reactions were verified by integral and a combination of integral–differential analysis of reactor data, respectively, and the kinetic parameters were obtained. The deactivation of the active sites for the three reactions was found to follow a first-order independent decay law. The rate constants of deactivation were found to decrease in the order of dehydrogenation, hydrogenolysis and cracking. Noncatalytic thermal cracking was found to be comparable to the catalytic route resulting in a very low apparent deactivation rate constant for cracking reaction.     

环氧乙烷合成银催化剂宏观动力学及失活分析

在工业生产的条件下用无梯度反应器研究了工业颗粒银催化剂上乙烯氧化合成环氧乙烷宏观动力学 ,得到了能反映该系统主副反应特性的双速率方程 .建立了二维非均相反应器模型 ,模拟并比较了工业生产操作数据 ,获得了该种催化剂的活性校正因子随使用时间变化的经验关联式和主副反应失活速率方程     

Kinetic investigations of the deactivation by coking of a noble metal catalyst in the catalytic hydrogenation of nitrobenzene using a catalytic wall reactor

The vapour phase hydrogenation of nitrobenzene to aniline is a highly exothermic reaction deactivated by coking of the palladium catalyst supported on -alumina carrier. For studying the deactivation of the catalyst a catalytic wall reactor was used in order to ensure isothermal reaction conditions for the kinetic measurements. Furthermore, the catalytic wall reactor allowed the determination of axial coke profiles by total carbon analysis of different wall segments. On the assumption that the main reaction and the deactivation of the catalyst can be assumed separable both the steady state and the unsteady state kinetics were studied. Nitrobenzene was identified as the relevant coke precursor whereas aniline has neither an influence on the main reaction nor on the deactivation. It could be shown that the hydrogenation of nitrobenzene to aniline follows a Langmuir–Hinshelwood mechanism considering the surface reaction of the adsorbed nitrobenzene molecule and one adsorbed hydrogen atom as the rate determining step. The differentiation of coke on the active sites and coke on the support must be taken into account to model the kinetics of coke formation with sufficient accuracy.     

Kinetic studies on catalytic methanation by means of a concentration-controlled recycle reactor

The rate behaviour of multi-step reaction systems is difficult to model. Concentration-controlled investigations in a recycle reactor provide new tools for this purpose, e.g. the possibility to decompose a network into single reaction steps. Methanation of carbon monoxide over a supported Ni catalyst could be shown to be accompanied to a considerable extent by the shift reaction, and to a lesser extent by direct hydrogenation of carbon dioxide. Deactivation of the catalyst was measured at definite gas compositions. The two main steps show different responses to deactivation: Separable kinetics was found only for the methanation step. Power law rate equations were fitted to the rate data of the individual reaction steps to represent the main features of their kinetic behaviour. Some aspects of deactivation kinetics are also discussed.     

Kinetic study of olefin polymerization with a supported metallocene catalyst. I. Ethylene/propylene copolymerization in gas phase

A kinetic study of ethylene homopolymerization and copolymerization is conducted with a supported metallocene catalyst in a gas‐phase reactor. An experimental procedure is developed that minimizes the effect of impurities in the reactor and simultaneously yields consistent and reproducible reaction‐rate data. The effects of operational parameters such as reaction temperature, pressure, and comonomer concentration on the kinetics of both homopolymerization and copolymerization are investigated. Online perturbation techniques are implemented to determine key kinetic parameters such as the activation energies for ethylene propagation and catalyst deactivation. A reaction‐rate order close to 2 is obtained for ethylene homopolymerization from pressure perturbations, while near to first‐order dependency is observed in the presence of propylene. To quantify the effects of the operational parameters, a one‐site kinetic model for homopolymerization and a two‐site kinetic model for copolymerization are proposed. The necessary kinetic parameters in the model are estimated using the POLYRED™ package. The resulting kinetic model represents the kinetic data over a wide range of conditions for this supported metallocene catalyst. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 81–114, 2001     

Kinetic model and simulation for catalyst deactivation during dehydrogenation of methylcyclohexane over commercial Pt-, PtRe- and presulfided PtRe-Al2O3 catalysts

The catalyst deactivation kinetics for the dehydrogenation of methylcyclohexane were studied with Pt-, PtRe-, and presulfided Presulfided PtRe-Al₂O₃ Catalysts in a fixed-bed differential reactor. The kinetic analysis was made based on a Langmuir-Hinshelwood model assuming that the dehydrogenation of methylcyclohexene into methylcyclohexadiene was the rate-controlling step for the main reaction, and the polymerization of adjacently adsorbed methylcyclohexadiene as coke precursor molecules was the rate-controlling step for the deactivation reaction. The experimental data for the three catalysts at varying partial pressures of methylcyclohexane and hydrogen were well correlated by the hyperbolic deactivation function derived. The number of active sites involved in the rate-controlling step of the deactivation was evaluated to be 2.7 in average. The enhanced activity maintenance by the addition of Re as well as sulfur was attributed to a reduction in the concentration of multiple sites occupied by coke precursors adjacently adsorbed, leading to a decrease in the rate constant of the deactivation reaction.     

Détermination de constantes cinétiques du craquage catalytique par la modélisation du test de microactivité (MAT)

The microactivity test (MAT) for cracking catalyst test works with an approximately plug flow isothermal reactor. The yields at the outlet of such a reactor is numerically computed in the case of lumped kinetic with large molecular expansion and rapid catalyst deactivation expressed versus poison concentration. The poison (coke in cracking reaction) is considered as a product formed by several reaction routes. The results are applied to catalytic cracking kinetic with a four lump model (feedstock, gasoline, gas, coke). The comparison between experimental and computed yields, permits the adjustment of kinetic constants with a set of experimental results obtained from a laboratory scale reactor derived from the MAT. The simulation of concentration profile in the reactor permits a better understanding of the reaction courses.     

糠醛液相加氢制糠醇骨架钴催化剂反应动力学研究

采用合金架钴催化剂在间隙高压反应釜中进行了糠醛液相加氢反应动力学及失活动力学的研究。提出了该反应的动力学及失活动力学的数学模型，并求得了该反应的反应级数、反应活化能值、反应速率常数及失活速率常数值，还测得了钴催化剂的使用寿命。