低浓度丙烯和苯催化精馏合成异丙苯过程非平衡级模拟

对苯与低浓度丙烯合成异丙苯的催化精馏过程建立非平衡级模型。针对模拟过程难以收敛的特点,在计算的开始阶段引入了模式搜索法（Hook-Jeeves method)求解。通过对变量的取值范围进行一定的约束,可比牛顿型法适用较宽的初值范围。计算中根据所用催化精馏塔的特点,对方程进行了一定程度的简化。得到了催化精馏塔内的温度及液相组成分布。模拟结果与试验数据吻合较好,可以为工艺设计提供参考。     

MnOx/颗粒活性炭催化臭氧氧化技术降解硝基苯效能研究

通过半动态实验,对MnOx/GAC(颗粒活性炭)催化臭氧氧化技术氧化硝基苯的降解效能与动力学规律进行了初步研究.结果表明MnOx/GAC催化臭氧氧化过程对硝基苯具有较高的催化活性,在相同的反应条件下,MnOx/GAC催化臭氧氧化技术对硝基苯的降解效率是单独臭氧氧化的2.4倍.催化剂对硝基苯有一定的吸附作用.MnOx/GAC催化剂的存在提高了臭氧的利用率.MnOx/GAC催化臭氧氧化过程存在着催化剂最佳投量,硝基苯初始浓度与反应速率常数有良好的线性相关性,水质本底对MnOx/GAC催化臭氧氧化效率也有影响.     

MnOx/颗粒活性炭催化臭氧氧化技术降解硝基苯效能研究

通过半动态实验,对MnOx/GAC(颗粒活性炭)催化臭氧氧化技术氧化硝基苯的降解效能与动力学规律进行了初步研究.结果表明MnOx/GAC催化臭氧氧化过程对硝基苯具有较高的催化活性,在相同的反应条件下,MnOx/GAC催化臭氧氧化技术对硝基苯的降解效率是单独臭氧氧化的2.4倍.催化剂对硝基苯有一定的吸附作用.MnOx/GAC催化剂的存在提高了臭氧的利用率.MnOx/GAC催化臭氧氧化过程存在着催化剂最佳投量,硝基苯初始浓度与反应速率常数有良好的线性相关性,水质本底对MnOx/GAC催化臭氧氧化效率也有影响.     

催化煤解聚产物分布特性研究

以课题组独创的催化剂添加方式,实现了对煤的催化解聚.研究了锌基催化剂对内蒙褐煤催化解聚产物分布的影响.结果表明:催化解聚对产物的分布影响显著.相比原煤热解,催化煤解聚焦油产率提高26.88%,煤气热值提高30.79%,半焦比表面积提高80.65%.催化煤解聚相比原煤热解显示出一定的潜在优越性.     

蜂窝陶瓷臭氧催化氧化工艺的生产性试验分析

臭氧催化氧化工艺能够强化臭氧氧化效果,北方某水厂引入蜂窝陶瓷臭氧催化氧化模块技术,并进行了生产性试验.试验结果表明,在原水水质较好的情况下,该技术在控制污染物浓度方面有一定的效果,臭氧催化氧化出水与单纯臭氧氧化出水相比TOC小10％,UV254和THMFP差值较小,而颗粒数增加,说明催化臭氧的氧化能力较强.由于催化模块空隙狭小,装填密集,臭氧长期停用时存在微生物滋长,造成模块堵塞的风险.     

21世纪能源资源转变对催化科学与技术发展的要求

介绍了21世纪催化科学与技术面临的挑战,能源资源转变对催化学科的发展所提出的要求,概述了生物质资源通过催化科学与技术的开发利用,指出了生物质加工的技术平台,对21世纪催化所面临的挑战、未来与方向进行了展望.     

催化裂解过程分子尺度反应动力学模型研究

以工业数据为基础,运用结构导向集总方法来构造烃分子,对催化裂解原料油进行了分子尺度上的Monte Carlo模拟.在深入研究催化裂解反应机理的基础上,以原料油模拟产生的分子矩阵作为反应物分子,将结构导向集总方法与Monte Carlo方法相结合,建立了催化裂解过程分子尺度的反应动力学模型.结果表明:Monte Carlo方法可以在分子尺度上实现对催化裂解原料较好的模拟,产品产率和汽油组成与实际值能较好地拟合.且随着虚拟分子数的增加,对原料油性质和反应结果的模拟计算精度提高;模型具有较好的适应性和外推性.     

几种氧化技术在污水深度处理中的对比研究

试验研究了Mn(II)催化KMnO4氧化、臭氧氧化、O3/UV组合工艺对城市二级处理水中有机物氧化分解的影响,并对它们的效果进行了对比.结果表明,适当的条件下Mn(II)催化KMnO4氧化、臭氧氧化、O3/UV组合工艺均可提高水的可生化性,并且对水中的UV254也有不同程度的去除效果.O3/UV组合工艺在提高可生化性和UV254去除中为最优.利用上述结果,选择适当的控制条件,为预氧化与不同工艺结合以实现城市污水的高效低耗再生利用提供一定的理论依据.     

催化精馏法合成乙二醇单甲醚的模拟研究

提出以环氧乙烷和甲醇为原料,应用催化精馏技术合成乙二醇单甲醚的工艺方法.采用基于非平衡级模型的模拟方法,考察关键操作参数对目的产物选择性和收率的影响,并得到优化的操作条件为400 kPa,377 K,甲醇和环氧乙烷流量均为0.078 mol/s,再沸比9,反应段高度1.8 m,提馏段高度3.2 m.建立了中试规模的催化精馏塔对模拟结果进行了验证.结果表明,采用催化精馏法合成乙二醇单甲醚,在优化条件下乙二醇单甲醚收率达到93%以上.实验结果与模拟结果吻合良好,表明模拟方法可靠.     

纳米金属粉及Fe2O3对高氯酸铵热分解的催化性能研究

用热分析法研究了纳米金属粉(Ni,Cu和Al)以及纳米Fe2O3对高氯酸铵(AP)热分解的催化性能.结果表明,质量分数为5%的纳米镍粉、铜粉和铝粉可以明显降低AP的高温分解温度,显示出对AP高温分解反应很好的催化活性;纳米铜粉对AP的低温分解也有很好的催化作用,而纳米镍粉和铝粉却表现出对AP低温分解反应具有一定的阻碍作用.微米级金属粉对AP高温分解反应的催化作用明显小于纳米金属粉.纳米Fe2O3对高氯酸铵的高温分解具有很好的催化效果,并且其催化效果明显优于微米Fe2O3.纳米Fe2O3与AP进行复合处理,可以提高纳米Fe2O3粒子对AP的催化性能.     

Determination of catalytic packing characteristics for reactive distillation

Catalytic distillation still expands its field of applications. New structured catalytic column internals have been developed in recent years and new studies have been reported. A modern structured catalytic packing MULTIPAK^® is a subject of the investigations presented in this paper.

Important parameters of MULTIPAK^® have been examined experimentally in a 250 mm ID laboratory column: pressure drop for dry, prewetted and irrigated packings, flooding line and mass transfer coefficients for the gas and liquid phases.

The correlations obtained have been incorporated into a software tool for the simulation of catalytic distillation processes and simulations have been performed assuming methyl acetate synthesis as a model process. The calculations have been verified using the experiments performed for the same synthesis in a 50 mm ID catalytic distillation column operating continuously and thus reflecting industrial applications. It is concluded that the model represents the real process with satisfactory accuracy, although some deviations can be observed, especially within the reactive zone.     

Activity evaluation of a catalytic distillation packing for MTBE production

The octane enhancer methyl tertiary butyl ether (MTBE) can be produced very efficiently from methanol and isobutene in a reactive distillation column where the heterogeneous catalyst also acts as distillation packing. Some mathematical models have been published for the simulation of such a process but they focus on the physical transport processes between the vapour and liquid phases. However, the aim of this paper is to analyze the importance of the internal and external multicomponent mass and heat transfer phenomena on the catalyst under boiling conditions. Therefore, experiments were carried out in a reactive distillation column at different compositions of feed, column pressures and reflux ratios using a Raschig ring shaped acidic ion exchange resin as the catalyst. The temperature and composition of the liquid phase entering and leaving the catalytic column section were measured. These data were used to evaluate the effectiveness factor of the catalyst with a rigorous macrokinetic model. It is shown that the effectiveness factor varies significantly along the column length. Under certain operating conditions, decomposition of MTBE can occur accompanied by boiling processes inside the catalyst macropores.     

Kinetics of acetic acid esterification over ion exchange catalysts

Computer simulation showed that catalytic distillation is an attractive process for the removal of dilute acetic acid from wastewater. Selection of catalysts and kinetic data have been obtained for the design of the catalytic distillation column. Kinetic measurements were conducted in a batch reactor. Methanol was added to the dilute acetic acid solutions and reacted with the acid in water to form methyl acetate and water. The reaction can be catalyzed by solid acid catalysts. It was found that Amberlyst 15 was an effective catalyst for this reaction. The effects of stirrer speed, reaction temperature, reactant concentration and catalyst loading on reaction rate were investigated. A complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed. This equation can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.     

非平衡级速率模型用于催化精馏过程的模拟计算

采用非平衡级速率模型对醋酸甲酯水解的催化精馏中试过程进行了模拟计算,反应精馏段催化剂填料层的气相和液相传质系数用自行测定的经验关联式计算,提馏段的填料层传质系数用Onta的关联式,反应速率根据所测定的宏观反应动力学方程结合催化剂包的效率因子进行计算,得到令人满意的结果．     

合成异丙苯的烷基化与烷基转移催化精馏

分别对苯与丙烯烷基化合成异丙苯的固定床和悬浮床精馏塔进行了模拟计算.结果表明,采用这两种催化精馏塔,均能在一个塔内同时实现烷基化与烷基转移反应.指出悬浮床催化精馏由于其独特的优点因而具有更强的竞争力.     

Investigations on the Synthesis of Methyl Acetate in a Heterogeneous Reactive Distillation Process

The production of methyl acetate in a reactive distillation process – prior art for 15 years – is often used as an example to study the basic phenomena of reactive distillation. The present paper deals with a theoretical and experimental analysis of methyl acetate synthesis in a reactive distillation column. A design method based on the interpretation of reactive distillation line diagrams is used to identify the main process parameters and to provide a foundation for experimental investigation. The significant influence of the reflux ratio on the conversion in the column is shown by mini plant experiments using supported ion exchanger in the form of Raschig rings as a heterogeneous catalyst. These experiments demonstrate the catalytic quality of this packing material. To simulate the reactive distillation column with a simple stage-to-stage method, the separation efficiency of the catalytic rings is investigated. Comparison of experimental and simulation results reveals that a simple model based on the assumption of simultaneous chemical and phase equilibrium describes the experimental data quite well over a wide range of reflux ratios. Furthermore, simulation results show that the conversion depends less on the number of reactive stages than on the use of two feed stages.     

2-Methylpropylacetate synthesis via catalytic distillation

The paper deals with a 2-methylpropylacetate synthesis process development. The process is based on esterification of acetic acid with 2-methylpropanol by the reactive distillation method. A column in which separation of the reaction products takes place together with esterification in catalytic active separation packing is utilized in this process. Computer simulation of catalytic distillation has been performed to study the process and to evaluate the pilot plant experimental data. KATAPAK^® S structural packing was used in the reaction zone, while stripping and rectifying sections of the column were packed by CY^® packing. A good agreement between the simulation results and pilot plant data has been achieved.     

Dehydration of Methanol to Dimethyl Ether by Catalytic Distillation

The kinetics of liquid catalytic dehydration of methanol over an ion exchange resin (Amberlyst 35) has been determined for the temperature range 343 to 403 K using a batch reactor. The experimental data are described well by an Eley‐Rideal type kinetic expression, for which the surface reaction is the rate‐determining step. A catalytic distillation process for methanol dehydration to dimethyl ether (DME) has been modeled using the experimentally determined kinetic data. The results were incorporated into the rate‐controlled reaction mode for RadFrac, a part of the commercial simulation program Aspen Plus. It was shown that synthesis of high purity DME can be achieved using a single catalytic distillation column. Thus there is significant potential for reduction of overall capital cost for a plant for methanol dehydration to DME when compared to conventional production facilities that involve separate reaction and distillation processes.     

Vapour- and liquid-side volumetric mass transfer coefficients measured in distillation column. Comparison with data calculated from absorption correlations

Volumetric mass transfer coefficients in liquid and vapour phases in distillation column were measured by the method consisting of a fitting of the concentration profile of liquid phase along the column obtained by the integration of a differential model to the experimental one. The mathematical model of distillation process includes mass and energy balances and the heat and mass transfer equations. The film model flux expressions with the convective transport contributions have been considered in the transfer equations. Vapour and liquid phases are supposed to be at their saturated temperatures along the column. Effect of changes of phase flows and physical properties of phases on the mass transfer coefficients along the column and non-ideal thermodynamic behaviour of the liquid phase have been taken into account. The concentration profiles of liquid phase are measured in the binary distillation of the ethanol-water and methanol-ethanol systems at total reflux on metal Pall Rings and Intalox saddles 25 mm in the column with diameter of 150 mm. The distillation mass transfer coefficients obtained by the fitting procedure are compared with those calculated from absorption data using Onda's, Billet's and Linek's correlations. The distillation heat transfer coefficients calculated from the model assuming saturated temperatures in both phases are compared with those calculated from the Chilton-Colburn and penetration model analogy between mass and heat transfer. The results have confirmed an agreement neither between distillation and from absorption correlations calculated mass transfer coefficients nor between analogy and from enthalpy balance calculated heat transfer coefficients. Also the concentration profiles obtained by the integration of the differential model of the distillation column using the coefficients from absorption correlation have differed from the experimental profiles considerably.