费托合成催化剂失活动力学模型的研究进展

费托合成催化剂由于自身的化学性质在反应中不可避免会发生失活，为了保证生产的连续稳定，需要建立费托合成催化剂失活的动力学模型来预测催化剂的活性变化，并及时对失活的催化剂进行置换和再生。本文论述了费托合成失活动力学模型的研究进展，讨论了通用型失活动力学模型，根据机理建立的失活动力学模型的特点。通用型失活动力学模型与催化剂种类和失活原因没有直接关联，包括线性模型、简单幂律模型、通用幂律模型、韦伯分布模型、S型分布模型。根据机理建立的失活动力学模型则与催化剂种类和失活发生的机理相关，包括硫中毒失活模型、烧结失活模型、表面氧化失活模型等。通用型失活动力学模型准确性好、容易建立，但比较粗略，适用于费托合成的生产管理、过程模拟。根据机理建立的失活动力学模型建立过程复杂，只适用于特定催化剂，但能够从中研究催化剂的失活机理。费托合成失活动力学模型未来的发展趋势是融合两类模型，从失活机理的角度理解通用型失活动力学模型里参数的含义。     

废水催化湿式氧化处理中的催化剂失活问题

活性组分流失和催化剂表面积炭是导致废水催化湿式氧化处理中催化剂失活的主要原因。介绍了催化湿式氧化中催化剂失活的机理和影响其失活的原因。催化剂组分和制备方法、反应条件以及反应器类型会影响催化剂的失活。对提高催化剂稳定性的方法也作了论述。     

MODELLING THE DEACTIVATION KINETICS OF CYCLOHEXANE DEHYDROGENATION ON PLATINUM/ALUMINA CATALYST

Two reaction deactivation kinetic models of the deactivation of cyclohexane on platinum/alumina catalyst have been proposed based on the coking mechanism of Corella and Asua and the reaction mechanism of Susu el al. The difference in the models was in the number of active sites participating in the coking reaction represented by h with h = 1 in model 1 and h ≠ 1 in model 2. The models were dynamic models and parameter estimates were carried out by a method that did not require decoupling of the main from the coking reaction. The model formulation has made possible the estimation of the level of residual activity by the incorporation of a factor, ƒ, that represents incomplete deactivation. For the deactivation kinetic data studied, a high value of ƒ; was obtained indicating a low residual activity. The models were found to give a good fit with the data. The standard deviation of the models from experimental were 10.21 % for model 1 (h ≠ 1) and 12.63% for model 2 (h ≠ 1), None of the models is superior to the other, though for having a lower standard deviation model I is better. It is therefore appropriate to propose that deactivation by coking in this work occurred preferably by a single site mechanism of the rate controlling step of the coking reaction.     

EFFECT OF PORE DIFFUSION ON DEACTIVATING RATES OF SECOND ORDER REACTION

The research and development of catalysts, the design and operation of catalytic reactors are complicated by the phenomenon of catalyst deactivation which is affected by various factors. In this paper, the effect of internal mass transfer resistance in the second order catalytic reaction system of uniform independent deactivation on both reaction and deactivation rates of straight cylindrical pore model has been discussed. In addition, the quantitative relations between effectiveness factor and Thiele modulus in second order reaction and first order deactivation system have been correlated     

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.     

Deactivation disguised kinetics in high-velocity dilute-phase transport reactors

For a chemical reaction carried out with a fast-decaying catalyst in an isothermal high-velocity dilute-phase transport reactor, the apparent kinetics of the primary chemical reaction may be disguised by the presence of the catalyst deactivation. With a given reaction system of power-law type expressions for both the chemical reaction and catalyst deactivation rates, investigated are the existence conditions of its disguised kinetic system which is also of power-law type formulations.     

Alkylation of benzene with isopropanol over SAPO‐5: A kinetic study

The kinetics of benzene alkylation with isopropanol has been studied in vapour phase over SAPO‐5 catalyst. On the basis of the product distribution pattern obtained over this large pore molecular sieve, a reaction mechanism has been proposed. Based on this reaction network, suitable phenomenological models have been derived and fitted to the kinetic data. A Langmuir‐Hinshelwood model with surface reaction involving single site mechanism fitted the data better than the other models. The deactivation kinetics has also been investigated in the low temperature chosen. The activation energy for the deactivation reaction in this range is found to be lower than that for the main reaction.     

ON THE INFLUENCE OF EXTERNAL DIFFUSIONAL LIMITATIONS ON OPTIMUM TEMPERATURE OPERATIONS POLICIES IN DEACTIVATING FIXED-BED REACTORS

The influence of external mass transfer limitations on optimum temperature operations policies, and on the reaction and deactivation parameters is determined for a first-order primary reaction and first-and d^th-order reactant-independent deactivation kinetics occurring in a fixed-bed reactor. This is now done using the correct optimum temperature operations criterion. The rate of temperature rise is lower when external mass transfer limitations are present compared to the diffusion-free condition. The apparent activation energy for reaction is not only different from its intrinsic value but it is also time-variant along the optimum temperature operations policy.     

ZSM-5分子筛在MTP反应中积炭失活原因探讨

讨论了分子筛积炭失活的机理,以及影响ZSM-5在MTP反应中积炭失活的主要因素,包括孔结构、酸度、晶粒尺寸、反应温度和空速等。ZSM-5在MTP反应中积炭是一个具有酸催化反应和分子择形反应的复杂的物理化学过程,对其积炭反应和失活机理的研究是十分重要的工作。     

Simulation of methanol-to-olefin reaction over SAPO-34 catalysts with different particle sizes: Formation of active sites and deactivation

Conversion profiles of methanol-to-olefin (MTO) reaction over SAPO-34 catalysts with different particle sizes were simulated using two kinetic models. The MTO reaction was assumed to consist of three steps: the formation of hexamethylbenzene (HMB), the production of lower olefins over HMB and the further condensation of HMB to polyaromatic hydrocarbons. To reflect the effect of particle size on the MTO reaction, only the space near the external particle surface was considered to be available for HMB formation in Model I, whereas an effectiveness factor and a deactivation function were introduced in Model II. The simulated conversion profiles of the MTO reaction by both models successfully confirmed the presence of an induction period and deactivation, but Model II showed a better agreement between the experimental and simulated results because of its inclusion of the deactivation function and its consideration for the gradient of methanol concentration.     

Kinetics, acid sites and deactivation of H-mordenite during the SCR of NOx with CH4

H-mordenites are active for the SCR reaction but they suffer irreversible partial deactivation after being on stream for one hour at 650°C. The reaction orders and activation energies are not significantly affected by deactivation. This indicates that deactivation originates in a decrease in the number of active sites due to dealumination and possible pore blockage. The NO disappearance rate correlates with TPD NH₃ between 300 and 700°C; FTIR confirms these results. ¹²⁹Xe NMR of adsorbed xenon shows that pore blockage occurs and is due to the presence of aluminum species in the main zeolite channels. The overall deactivation process and the role of acid sites is discussed in terms of the current literature. This revised version was published online in July 2006 with corrections to the Cover Date.     

甲烷无氧芳构化的催化研究进展

综述了甲烷在MoO3/HZSM - 5催化剂上无氧芳构化的反应机理 ,以及催化剂活性态、催化剂的改性剂、反应条件等对无氧芳构化反应活性的影响 ,并讨论了可能的失活机理     

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。     

甲烷在活性炭上催化裂解制氢的研究进展

甲烷的热催化裂解是一种制取富氢气体的有效方法,活性炭作为一种经济、高效的催化剂而被广泛研究。本文简要阐述了甲烷在活性炭上的裂解机理,着重介绍了活性炭作为催化剂时的影响因素,包括表面物化特性、反应条件、制备工艺及预处理方法、加热方式、反应装置的影响,并分别对活性炭的失活原因及再生手段进行了详细叙述。提出活性炭作为催化剂在进一步应用中所遇到的主要问题是最佳的活性炭制备工艺及预处理手段、最佳反应条件的控制以及活性炭的快速失活特性。     

Five-lump kinetic model with selective catalyst deactivation for the prediction of the product selectivity in the fluid catalytic cracking process

The effective simulation of the fluid catalytic cracking (FCC) operation requires a good understanding of many factors such as, reaction kinetics, fluid dynamics, and feed and catalyst effects. The different product slates that can be obtained are the consequence of a complex reaction scheme including cracking, isomerization, hydrogen transfer, oligomerization, etc. Furthermore, the catalyst deactivation may affect each one of the reactions in different ways, which creates an additional reason for different variation with time-on-stream of the yield to each product. On the basis of the experimental data of the FCC pilot plant operated in Chemical Process Engineering Research Institute (CPERI, Thessaloniki, Greece), a lumping model was developed for the prediction of the FCC product distribution. The lumped reaction network involved five general lumps (gas oil, gasoline, coke, liquefied product gas, and dry gas) to simulate the cracking reactions and to predict the gas oil conversion and the product distribution. The paths of catalyst deactivation were studied and a selective deactivation model was adopted that enhances the fundamentality and accuracy of the lumping scheme. The hypothesis of selective catalyst deactivation was found to improve the product slates prediction. Models with different assumptions were examined, regarding the behavior of the catalyst, as deactivated, and its effect on the reactions of the lumping scheme. A large database of experiments, performed in the FCC pilot plant of CPERI was used to verify the performance of the models in steady state unit operation. The simulation results depict the importance of incorporating selective catalyst deactivation functions in FCC lumping models.     

整装催化转化器数学模型研究进展

对用于控制汽车尾气排放的整装催化转化器的模型研究进行了论述。讨论了催化转化器中主要的物理和化学过程,包括传热传质、气流分布、化学动力学、储氧和催化剂中毒。对已有的一些模型作了描述和分析。最后分析了转化器模型的应用。     

Simultaneous Reaction-Deactivation Kinetics in N-octane and Methylcyclopentane Reforming Reactions on Platinum-Containing Catalysts

The deactivation data obtained from the multiple regeneration of platinum-containing catalysts were utilized to explore the efficiency of reforming catalyst utilization. The data were collected in a CSTR at a total pressure of 101.325 kPa and W/F values up to 0.33 g min/cm³. The reactive system investigated was the re-forming and coking of n-octane and methylcyclopentane on the monometallic Pt/Al₂O₃ and the bimetallic Pt-Re/Al₂O₃ catalysts. The deactivation models combined the kinetic equation with the coking equation; both of these equations were derived from mechanistic models. The kinetic expressions were based on the models of Susu et al. for n-octane reaction and Dartingues et al. for methylcyclopentane reaction. The coking mechanism of Corella and Asua was used for the coking reaction. The coupling of the two models resulted in a dynamic expression, and the parameter estimates were carried out without decoupling the main reaction from the coking reaction. The model formulation affords the estimation of the level of residual activity by the incorporation of a factor, f, representing incomplete deactivation. A high value of f was obtained for all deactivation-kinetic data indicating high utilization efficiency for the catalysts for the two reactants, regardless of the large difference in the coking ability of the hydrocarbon species.     

从反应温降波动分析重整催化剂活性变化

介绍了所用催化剂以及工艺流程的概况。详细讨论了正在运行的第八周期中重整反应器的有关情况。对重整反应器1在2002年初发生的催化剂失活，从失活的现象、可能的原因以及采取的措施进行了详细的分析。从生产效益考虑，应整体更换催化剂。     

ON SOME KINETIC PROBLEMS OF CATALYST DEACTIVATION AND REGENERATION

Kinetic problems of catalyst deactivation and regeneration have been discussed for dehydrogenation of isopentenes and higher alkanes and catalytic transformation of 5-methyl furfurol. Common kinetic models have been obtained for each process in both stationary and nonstationary regions with stability function being introduced into these models to describe deactivation.     

催化裂化装置模拟研究与进展

分析和介绍了国内外催化裂化装置建模和稳态模拟方面的研究和进展。对催化裂化反应集总方法及相应的反应网络进行归纳,并讨论其优缺点;推导了动力学模型方程并着重探讨方程求解算法以及模型中动力学参数、催化剂失活因子和装置因素的估计方法。