PORE-MOUTH POISONING OF NON-UNIFORM CATALYSTS

Impurity poisoning of a catalyst particle having a non-uniform activity distribution is analyzed. Equations that relate the position of the poison-front with time for different activity profiles are derived. It is shown that the effect of the activity distribution on the poisoning rate is apparent in the case of intraparticle-diffusion control. The performance of a non-uniform bifunctional catalyst in such conditions is also studied.     

QDB-03型耐硫变换催化剂失活的原因分析

结合QDB-03型耐硫变换催化剂的使用情况和废催化剂/过滤剂的分析数据,对该催化剂失活的原因进行分析,初步判定催化剂活性快速衰退的原因。     

CATALYST DEACTIVATION IN THE HYDROLYSIS OF ACRYLONITRILE TO ACRYLAMIDE OVER RANEY COPPER

Two possible processes for deactivation in the catalytic hydrolysis of acrytonitriie over Raney copper have been examined at temperatures in the range 40 to 100°C. The first of these is the diffusion limited oxidation of the catalyst surface which produces oxides of copper. The other, more dominant, effect is thought to result from fouling of the catalyst pores by thermally polymerized acrylamide. This mechanism of catalyst poisoning which is independent of both reactant and product concentrations is evidenced by changes in specific surface areas and pore sizes of the catalyst used.     

转化催化剂中毒事故分析

就１９９５年元月我二制氢装置发生的转化催化剂中毒事故进行分析，并介绍事发后采取的紧急处理措施和实施效果。     

ON THE SOLUTION OF A MODEL CASE F DEACTIVATION BY SITE POISONING ND PORE BLOCKAGE

The problem of deactivation by active site poisoning and pore blockage is analyzed. A solution technique is presented which considerably simplifies the numerical effort involved in the analysis of the problem. For problems with slab geometry, in particular, closed form solutions are developed which can be conveniently utilized in reactor design problems.

Numerical examples are presented which show that the effect of pore blockage can be quite detrimental to the life of the catalyst, sometimes even more so than the effect of site coverage by a poison.     

一段转化催化剂硫中毒及处理

介绍脱硫分子筛在大型氨厂脱硫工序中的应用、一段转化催化剂硫中毒的过程分析及硫中毒后的放硫操作，提出了脱硫工序优化操作和一段转化催化剂硫中毒的预防措施。     

有效反应区概念在催化剂颗粒级设计中的应用

将有效反应区概念引入催化剂颗粒级设计中,用来分析由于反应与传递交互作用所引起的一类问题——在实际体系中,催化剂颗粒内可能存在有效反应区和死区的情形。数值模拟的结果表明,在许多情况下,尤其对扩散控制的体系,催化剂颗粒内存在有效反应区和死区的情形。在这种情况下,采用不同的活性分布形式是避免死区扩大有效反应区的一个重要方法,尤其对放热反应,用适当的活性分布形式制成的催化剂有可能既满足反应器系统对颗粒尺寸的要求,又能得到很好的催化剂效率。     

HYDRODEMETALLATION CATALYST DEACTIVATION—EFFECT OF METALS ACCUMULATION ON HYDROGENATION AND HYDROGENOLYSIS ACTIVITIES

The deactivation of hydrodemetallation catalyst was investigated in diffusion-free conditions using a model oil system. The hydrodemetallation activity of a CoMo/γ-alumina catalyst was studied using nickel or vanadyl etioporphyrins as model compounds and the hydrodesulfurization and hydrogenation activity using dibenzothiophene and naphthalene. The experiments were carried out over sulfided catalysts at 320°C and 4.83 MPa total pressure. The catalyst activity for nickel etioporphyrin hydrodemetallation was maintained at least up to 50% metal loading. The hydrogenolysis activity decreased with increasing nickel and vanadium on the catalyst but the hydrogenation activity increased. The changes in activity were attributed to the different activities of the various sulfide phases present in the catalyst system.     

MICRODEVICE-BASED SYSTEM FOR CATALYST DEVELOPMENT

Catalytic chemical reaction processes have played a major role in the growth of today's international economy. Because of this impact, technologies that reduce the development time of new catalyst materials are highly sought. We describe a new experimental system for the characterization of candidate catalysts that exploits the many advantages of microfabricated chemical devices. The core component of the system is a silicon microreactor in which the reaction of study is executed under highly controlled conditions. The system was used to acquire data on a model hydrocarbon hydrogenation reaction over platinum catalyst. The measured values of turnover frequency and reaction probability compare well with the literature and illustrate the value of the system as a tool for rapid and efficient catalyst development.     

甲醇合成铜基催化剂硫化氢中毒研究(Ⅰ)——硫化氢中毒本征失活动力学

研究了甲醇合成C207铜基催化剂硫化氢中毒本征失活动力学.研究表明,硫化氢分压增加,失活速率加快;温度升高,失活速率加快.本征失活速率方程为r_d=-da/dr=0.1474×10~(12)exp(-81128/R_gT)P_(H_2s~a)     

甲醇合成铜基催化剂硫化氢中毒研究(Ⅰ)——硫化氢中毒本征失活动力学

研究了甲醇合成C207铜基催化剂硫化氢中毒本征失活动力学.研究表明,硫化氢分压增加,失活速率加快;温度升高,失活速率加快.本征失活速率方程为r_d=-da/dr=0.1474×10~(12)exp(-81128/R_gT)P_(H_2s~a)     

MODELING OF COMPETITIVE ADSORPTION OF NITROGEN SPECIES IN HYDRODESULFURIZATION

Previously, we developed a simple, one-parameter model reproducing the observed inhibiting effect of nitrogen species in the hydrodesulfurization (HDS) of hindered sulfur heterocycles. The model owes its simplicity to some nontrivial assumptions. Here we develop a full model by relaxing these assumptions, which gives a more quantitative picture of how sulfur, nitrogen, and catalyst surface interact on many widely disparate time scales. Computational results build a strong case for the accuracy of the previous one-parameter theory. As such, the theory should be applicable to reaction systems in which catalyst poisoning is driven by nonequilibrium adsorption. Some of the complexities and subtleties in modeling the competitive adsorption effects in distillate HDS are discussed, giving special attention to the design of robust catalyst-deactivation-compensation operating strategies.     

催化剂失活的控制及长寿命催化剂的开发

针对工业催化剂在生产中都存在着程度不同的失活问题，剖析了失活与反应物或反应中间体的毒化，催化剂的烧结或积炭及相等因素的关连，总结了抑制失活的对策并展望长寿命催化剂的开发方向。     

催化剂孔结构参数的设计及对宏观活性的影响

催化剂孔结构对其宏观活性是至关重要的,而孔结构的设计与优化是反应工程与催化剂工程的交叉。本文着重就前人对某一特定催化反应内扩散对宏观反应速率(效率因子)影响的工作进行了评述,并指出以反应工程理论指导催化剂设计将对催化剂制造有很重要的作用和指导意义。     

OPTIMAL CATALYST DISTRIBUTION AND DILUTION IN NONISOTHERMAL PACKED BED REACTORS

The problem of the optimal distribution of two different catalysts in a nonisothermal packed bed reactor is analyzed. State variable constraints, such as maximum allowable temperature, may be incorporated through a penalty function approach into the steepest ascent solution of this problem.

Loading a wall-cooled reactor with two chemically different catalysts is compared to dilution of a single catalyst with inerts for temperature moderation. A criterion is presented for estimating whether catalyst dilution may be necessary in order to keep reactor temperature below some maximum allowable value.

Conditions for optimal loading with a two-dimensional reactor model are presented and applied to catalyst dilution in a butane oxidation reactor. Suboptimal catalyst loadings are compared with the optimal loading.     

载体SIAL对丙烷氨氧化催化剂的影响

详细研究了丙烷氨氧化催化剂载体SIAL的组成及其相对合且对反应结果的影响。实验发现：载体中Al2O3与SiO2的重量比存在一个最佳值，当Al2O3／SiO2在2．0～2．5时，丙烯腈的收率取得最大值；随着催化剂中载体相对含量的增大，其反应效果得到明显的改观：丙烷的转化率随载体含量的增加而增大，而丙烯腈的选择性在载体／活性组分（重量比）在三1．5附近达到最大，此时COx的选择性最小，当该比例在1．5～2．5时丙烯腈的收率达到最大值。     

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.     

MATHEMATICAL MODEL OF FCC CATALYST DEACTIVATION

A model is proposed that explains both lab-scale and commercial unit FCC catalyst deactivation, taking vanadium mobility between particles into account. Equilibrium catalyst density fractionation is also simulated, helping in the interpretation of the commercial unit results.     

单颗粒催化剂多定态特性的理论分析

借助于奇异理论和突变理论,本文对单颗粒催化剂的多定态特性进行了分析。得到了反应为一级不可逆放热反应时系统定态模型方程解的结构以及可能具有的歧化图型式;对非一级反应系统,利用区域搜索算法得到了其系统定态模型方程突变集合在操作参数平面上的投影图,分析了反应动力学表达式及动力学参数的变化对体系多定态特性的影响。