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.     

B112催化剂上一氧化碳变换反应工业过程动力学研究

采用“沿程积分拟合法”,在某小合成氨厂变换工段引出的支线上,利用绝热固定床反应器,对B112催化剂上一氧化碳变换反应进行了常压及加压工业过程的动力学研究。通过对不同操作条件下的床层轴向温度分布进行积分拟合,得到了适用于工业条件的过程动力学方程。一氧化碳变换反应 CO+H_2~O(?)CO_2+H_2 是石油化工和煤化工重要的化学反应。国内外学者对许多种铁系催化剂上的该反应进行了动力学研究,推荐了各自的本征或宏观动力学方程。本文采用“沿程积分拟合法”对国产B112催化剂上的一氧化碳变换反应进行工业过程动力学研究。按照该法的要求,实验中需采用与工业实际反应器(绝热固定床反应器)型式相同的小型反应器,在工业条件下,测定不同进口条件的反应器轴向温度分布及出口浓度,通过积分拟合获得工业过程动力学方程。     

Gas-liquid and gas-liquid-solid reactors for the alkylation of benzene with propylene

This work deals with the mathematic models and improvement of four kinds of gas-liquid and gas-liquid-solid reactors for producing cumene by catalytic reaction, i.e., fixed-bed reactor, fixed-bed catalytic distillation (FCD) column, suspension catalytic distillation (SCD) column and ionic-liquid catalytic distillation (ICD) column. The fixed-bed reactor was improved by changing the particle diameter of catalyst and no extra equipment was needed. The FCD and SCD columns were, respectively, improved by carrying out alkylation and transalkylation simultaneously in a column, which also may hold for the ICD column, in which, however, the conductor-like screening model for real solvents (COSMO-RS) was used to take into account the influence of ionic liquid on vapor-liquid equilibrium (VLE).     

甲醇在耐高温磺酸树脂催化下的脱水反应动力学

为了开发反应精馏合成二甲醚新工艺,实验在2MPa(G)、120℃～155℃、初始甲醇摩尔分数100%～30%、液空速0.10mL/(min·g催化剂)～0.15mL/(min·g催化剂)条件下,以耐高温磺酸树脂作催化剂,在等温积分反应器内,系统地测定了甲醇脱水生成二甲醚的反应动力学数据。分别用L-H及E-R模型建立了反应动力学方程,并对实验数据进行了拟合。拟合结果表明:在实验范围内,按E-R模型拟合的反应动力学方程与实验结果更吻合。通过对动力学方程进行分析,发现随着反应温度的升高以及甲醇活度与水活度比值的增大,甲醇脱水反应速率都会增大。实验工作可为开发反应精馏合成二甲醚新工艺提供重要的反应动力学数据。     

Catalytic and kinetic study of methanol dehydration to dimethyl ether

Dimethyl ether (DME), as a solution to environmental pollution and diminishing energy supplies, can be synthesized more efficiently, compared to conventional methods, using a catalytic distillation column for methanol dehydration to DME over an active and selective catalyst. In this work, using an autoclave batch reactor, a variety of commercial catalysts are investigated to find a proper catalyst for this reaction at moderate temperature and pressure (110–135 °C and 900 kPa). Among the γ-alumina, zeolites (HY, HZSM-5 and HM) and ion exchange resins (Amberlyst 15, Amberlyst 35, Amberlyst 36 and Amberlyst 70), Amberlysts 35 and 36 demonstrate good activity for the studied reaction at the desired temperature and pressure. Then, the kinetics of the reaction over Amberlyst 35 is determined. The experimental data are described well by Langmuir–Hinshelwood kinetic expression, for which the surface reaction is the rate determining step. The calculated apparent activation energy for this study is 98 kJ/mol.     

ROLE OF WATER IN THE KINETIC MODELING OF METHANOL TRANSFORMATION INTO HYDROCARBONS ON HZSM-5 ZEOLITE

The attenuating effect of reaction-medium water (feed and/or reaction product) on the kinetics of the steps of methanol transformation into hydrocarbons on a HZSM-5 zeolite catalyst was studied by means of a kinetic model. In this model, the effect of water was quantified in all the steps of the kinetic scheme by means of a kinetic parameter, which is constant with temperature under the conditions of the MTG process. At low temperature, under conditions in which only methanol dehydration occurs, the kinetics of this reaction is attenuated by the presence of water, and the coefficient that quantifies the attenuation decreases as temperature is increased. In addition to considering the effect of water content in the reaction medium, another innovation of the kinetic model proposed, compared to those proposed in the literature consisting of lumps, is the fact that the higher reactivity of dimethyl ether over methanol is taken into account. A step of cracking of gasoline lump hydrocarbons to produce light olefins (ethene and propene) was also taken into account. The kinetic model proposed was verified by using the results obtained in an integral isothermal fixed bed reactor, in the 573-723 K range, for an ample range of space time values. The results revealed that the effect of water is due to its adsorption on the active sites by competition with the intermediate compounds of the kinetic scheme.     

ROLE OF WATER IN THE KINETIC MODELING OF METHANOL TRANSFORMATION INTO HYDROCARBONS ON HZSM-5 ZEOLITE

The attenuating effect of reaction-medium water (feed and/or reaction product) on the kinetics of the steps of methanol transformation into hydrocarbons on a HZSM-5 zeolite catalyst was studied by means of a kinetic model. In this model, the effect of water was quantified in all the steps of the kinetic scheme by means of a kinetic parameter, which is constant with temperature under the conditions of the MTG process. At low temperature, under conditions in which only methanol dehydration occurs, the kinetics of this reaction is attenuated by the presence of water, and the coefficient that quantifies the attenuation decreases as temperature is increased. In addition to considering the effect of water content in the reaction medium, another innovation of the kinetic model proposed, compared to those proposed in the literature consisting of lumps, is the fact that the higher reactivity of dimethyl ether over methanol is taken into account. A step of cracking of gasoline lump hydrocarbons to produce light olefins (ethene and propene) was also taken into account. The kinetic model proposed was verified by using the results obtained in an integral isothermal fixed bed reactor, in the 573–723 K range, for an ample range of space time values. The results revealed that the effect of water is due to its adsorption on the active sites by competition with the intermediate compounds of the kinetic scheme.     

完全液相法催化剂上甲醇脱水合成二甲醚的动力学及DFT研究

采用完全液相法制备AlOOH催化剂并进行了浆态床反应器中甲醇脱水制备二甲醚的反应动力学和DFT的研究。在3种甲醇脱水制备二甲醚的反应机理中,以表面反应即两个同时吸附的甲醇反应生成二甲醚作为速控步骤,所建立动力学模型的计算值和实验值吻合较好。采用DFT计算了液体石蜡环境中AlOOH(100)面的脱水反应,其反应过程和活化能结果与动力学模型结果基本一致,进一步表明采用该模型可以合理描述完全液相法制备的AlOOH催化剂表面甲醇脱水反应过程。     

绝热固定床反应器甲醇脱水合成二甲醚的实验和模型研究

One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether. Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor. The reactor was packed with 1.5 mm γ-Al2O3 pellets as dehydration catalyst and operated in a temperature range of 543-603 K at an atmospheric pressure. Also, the effects of weight hourly space velocity (WHSV) and temperature on methanol conversion were investigated. According to the results, the maximum conversion is obtained at 603.15 K with WHSV of 72.87 h－1.     

STUDY ON A CATALYTIC DISTILLATION COLUMN WITH A NOVEL INTERNAL

A novel internal for holding a catalyst in a catalytic distillation column was studied and its feasibility was verified by a model reaction, which is the alkylation of benzene with propylene over Hβ zeolite catalyst. The novel internal enlarges the void of the catalyst bed and provides the gas and liquid flow channels. It was proved that the catalytic distillation column with the novel internal has such advantages as simple structure, low operating cost, convenience for loading and unloading catalyst, and large catalyst loading fraction. It was found that the operational capability of the column with the novel internal whose volume fraction is about 30% is similar to that of a column filled with catalysts mixed with Cannon rings whose volume fraction is about 80%. It was also found that compared with the fixed-bed bubble reactor, the selectivity of cumene and the conversion of benzene are significantly improved in the CD (Catalytic Distillation) column with the internal.     

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.     

Study on a catalytic distillation column with a novel internal

A novel internal for holding a catalyst in a catalytic distillation column was studied and its feasibility was verified by a model reaction, which is the alkylation of benzene with propylene over Hβ zeolite catalyst. The novel internal enlarges the void of the catalyst bed and provides the gas and liquid flow channels. It was proved that the catalytic distillation column with the novel internal has such advantages as simple structure, low operating cost, convenience for loading and unloading catalyst, and large catalyst loading fraction. It was found that the operational capability of the column with the novel internal whose volume fraction is about 30% is similar to that of a column filled with catalysts mixed with Cannon rings whose volume fraction is about 80%. It was also found that compared with the fixed-bed bubble reactor, the selectivity of cumene and the conversion of benzene are significantly improved in the CD (Catalytic Distillation) column with the internal.     

C207铜基催化剂常压甲醇分解反应动力学(Ⅰ)本征动力学模型

在直流流动积分反应器中常压下研究了C207催化剂甲醇分解反应本征动力学。实验温度、气体组成与甲醇合成工业条件相接近。以实验測定数据应用改进高斯-牛顿法对动力学模型参数进行估值,获得甲醇分解反应本征动力学方程。     

Comparison of different reactor types for low temperature Fischer-Tropsch synthesis: A simulation study

The commercially established slurry bubble column and fixed-bed reactors for low temperature Fischer-Tropsch synthesis were compared with novel micro- and monolith-reactors by mathematical modeling. Special attention was paid to the influence of catalytic activity on the reactor efficiency and the losses by mass and heat transfer resistances. The simulation results show that a micro-structured reactor exhibits the highest productivity per unit of catalyst volume followed by slurry bubble column reactor and monolith reactor. The fixed-bed reactor that was assumed to operate in the trickle-flow regime has a particularly low catalyst specific productivity due to severe mass transfer resistances. However, caused by a very low ratio of catalyst and reactor volume the micro-reactor has only a similarly low productivity per unit of reactor volume as the fixed-bed reactor. In contrast, the reactor specific productivity of slurry bubble column reactor and monolith reactor is up to one order of magnitude higher.     

Modeling, simulation and control of dimethyl ether synthesis in an industrial fixed-bed reactor

Dimethyl ether (DME) as a clean fuel has attracted the interest of many researchers from both industrial communities and academia. The commercially proven process for large scale production of dimethyl ether consists of catalytic dehydration of methanol in an adiabatic fixed-bed reactor. In this study, the industrial reactor of DME synthesis with the accompanying feed preheater has been simulated and controlled in dynamic conditions. The proposed model, consisting of a set of algebraic and partial differential equations, is based on a heterogeneous one-dimensional unsteady state formulation. To verify the proposed model, the simulation results have been compared to available data from an industrial reactor at steady state conditions. A good agreement has been found between the simulation and plant data. A sensitivity analysis has been carried out to evaluate the influence of different possible disturbances on the process. Also, the controllability of the process has been investigated through dynamic simulation of the process under a conventional feedback PID controller. The responses of the system to disturbance and setpoint changes have shown that the control structure can maintain the process at the desired conditions with an appropriate dynamic behavior.     

反应与精馏耦合水解醋酸甲酯(英文)

A process composed of a fixed-bed and a distillation column with a side withdraw, mainly methanol, is developed to hydrolyze methyl acetate (MA) as a typical byproduct in polyvinyl alcohol (PVA) and pure terephthalic acid (PTA) factory. The process is simulated by employing the equilibrium stage model RadFrac and plug flow model Rplug in Aspen Plus. Experiments are also carried out in a lab-scale to evaluate the process. The results show that at the molar ratio of water to methyl acetate about 4.0-5.0 in the feed stream and the volume ratio of distillate to feed MA above a critical value, the side product contains more than 80% (by mass) (MeOH) and less than 2% (by mass) MA, while the bottom contains more than 46% (by mass) acetic acid (HAc) and less than 0.5% (by mass) methanol with almost complete conversion of MA. Compared with the old catalytic distillation process we proposed before, this process can cut down 47.6% energy consumption and a distillation column.     

异丁烯齐聚反应精馏的耦合工艺研究

针对异丁烯齐聚反应和产物提纯过程相分离的工业现状,在自行设计的实验装置上进行了异丁烯齐聚催化反应精馏耦合工艺的研究,分别考察了系统操作状态随时间的变化规律和影响反应精馏过程的主要因素。结果表明:为了得到较高的异丁烯转化率和二聚物选择性,采用全回流操作,进料位置宜设在反应段上方;回流温度过低和塔釜温度过高都对过程不利;添加适当的液相惰性组分,有利于改善填料层的分离效果。在转化率相同的情况下,该反应精馏过程的二聚物选择性大大高于固定床微分反应器和高压釜式反应器的实验结果。     

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg~(-1)·h~(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.     

乳酸的固定化细胞发酵及其在聚乙烯基吡啶树脂上的吸附研究

研究了以海藻酸为载体的固定化德氏乳酸杆菌在固定床反应柱中发酵生产乳酸,产生的乳酸通过吸附柱中的聚乙烯基吡啶树脂进行吸附分离的过程.建立了稳态时具有轴向近混的固定化细胞柱连续发酵模型,用线性推动力模型描述了乳酸通过吸附柱在聚乙烯基吡啶树脂上的吸附动态过程.结果是令人满意的.     

乳酸的固定化细胞发酵及其在聚乙烯基吡啶树脂上的吸附研究

研究了以海藻酸为载体的固定化德氏乳酸杆菌在固定床反应柱中发酵生产乳酸,产生的乳酸通过吸附柱中的聚乙烯基吡啶树脂进行吸附分离的过程.建立了稳态时具有轴向近混的固定化细胞柱连续发酵模型,用线性推动力模型描述了乳酸通过吸附柱在聚乙烯基吡啶树脂上的吸附动态过程.结果是令人满意的.