催化精馏与固定床联合工艺用于乙酸甲酯水解

在原乙酸甲酯催化精馏水解技术工业化应用成功基础上,为进一步提高乙酸甲酯水解率,利用聚乙烯醇厂已具备的固定床设备,建立了乙酸甲酯水解催化精馏与固定床联合的工艺.通过系统的实验考察了进料位置、水酯比、回流进料比和空速对乙酸甲酯水解率和酸水比的影响,得出了满足厂家要求的适宜工艺条件,并与原催化精馏单塔工艺进行了比较.研究表明...     

乙酸甲酯与甲醇共沸物催化精馏水解工艺

以乙酸甲酯与甲醇共沸物为原料,采用阳离子交换树脂为催化剂,研究了乙酸甲酯催化精馏水解工艺。在实验中以捆扎包作为催化剂的装填方式,系统地研究了催化精馏段和提馏段的高度、进料位置、进料中含甲醇、水酯物质的量比、回流进料比和空速等对酯分解率的影响,获得了最佳的工艺条件。分析了传统的水解分离工艺,提出了可行的新工艺。在最佳工艺条件下,新工艺系统的能耗比传统的固定床工艺降低39.99%。     

“背包式”反应精馏水解乙酸甲酯的工艺

采用“背包式”反应精馏深度水解乙酸甲酯,考察了工艺条件对水解率和酸水比的影响,并与传统的单塔催化精馏工艺进行了对比。结果表明：提高水酯比可以显著提高乙酸甲酯的水解率;回流进料比的增加有利于提高水解率但会增加能耗,较佳回流比为3.0左右;乙酸甲酯水解率随空速的增加而降低的速度较慢,可以适当提高空速以增加处理能力;增加固定床体积有利于酯的预水解,但是不一定有利于酯的总转化率。采用“背包式”催化精馏工艺可以实现乙酸甲酯的深度水解,且优于传统的单塔催化精馏工艺。     

带侧采的醋酸甲酯催化精馏水解新工艺

本文建立了带侧线采出的醋酸甲酯催化精馏水解新工艺,通过实验研究了进料中水酯摩尔比、回流进料体积比、空速等对醋酸甲酯水解率的影响。与不带侧线采出的催化精馏工艺进行了比较,在同样工艺条件回流比较大情况下,带侧采的催化精馏水解工艺醋酸甲酯水解率明显提高。     

醋酸甲酯水解工艺的技术进展

本文介绍了醋酸甲酯水解催化精馏新工艺，并将其与传统的固定床工艺进行了比较，结果表明，催化精馏新工艺比传统的固定床工艺能耗低、分解率高、且处理量大。     

精对苯二甲酸生产中副产物醋酸甲酯催化精馏水解研究

在间歇搅拌釜反应器中考察了不同强酸性阳离子交换树脂催化醋酸甲酯水解效果的影响,选择Amberlyst 35型阳离子交换树脂为水解催化剂.建立了催化精馏实验装置,反应段采用捆扎包装填方式,考察了塔结构、进料水酯比、回流进料比和空速对催化精馏效果的影响.结果表明,催化精馏水解合适的条件为醋酸甲酯从反应段底部进料,水从反应段顶部进料,反应段6块理论板,提馏段5块理论板,空速0.36 h-1,进料水酯物质的量比5,回流进料体积比3,醋酸甲酯的水解率可以达到61.6%.使用Aspen Plus软件对醋酸甲酯催化精馏水解过程进行模拟,模拟值和实验值吻合较好.     

醋酸甲酯水解工艺研究

在聚乙烯醇(PVA)生产过程中,会产生大量的醋酸甲酯副产品,需水解回收甲醇。现在普遍使用的离子交换树酯固定床工艺存在很多缺点,如:单程转化率低,大量未反应的醋酸甲酯需回收循环,设备庞大,能耗高等。本研究采用催化精馏工艺,阳离子交换树脂为催化剂,考察空速、进料水酯比(摩尔比)和回流进料比(体积比)对反应精馏过程的影响;通过实验,提出适宜的操作条件。     

醋酸甲酯水解新工艺过程模拟计算

本文利用已有的热力学、水解反应动力学模型以及现有催化填料的基础数据,提出了醋酸甲酯水解工艺新流程,采用催化精馏塔代替老工艺中的固定床水解反应器,分析新工艺中各塔的进料位置、回流比等灵敏度参数确定了新工艺的优化操作参数。通过全流程模拟优化,得到了各塔较佳的操作参数,在优化操作条件下醋酸甲酯总水解率达到100%,甲醇和醋酸质量浓度分别为99.97%与95.00%,为醋酸甲酯催化精馏水解新工艺的工业应用提供了基础数据。     

用催化精馏技术水解乙酸甲酯的实验研究

用填料催化反应精馏塔对乙酸甲酯的水解过程进行了系统的研究,测定了不同条件下的水解转化率数据及沿塔各组分的浓度分布。与传统的固定床反应器的极限转化率相比,其水解转化率有了大幅度的提高。对所测数据的分析表明,进料组成中是否含有甲醇不影响催化精馏水解过程。     

醋酸甲酯催化精馏水解技术的工业应用

醋酸甲醇精馏水解工艺在水酯比＝2．0，回流进料＝1．8－2．53，空速＝0．43的范围内，酯的分解率大于57％，水解产物中酸水比大于1．3。与传统的固定床水解工艺相比具有明显优势。     

Hydrolysis of methyl acetate via catalytic distillation: Simulation and design of new technological process

An equilibrium stage model was developed for the simulation of the catalytic distillation process of methyl acetate (MeOAc) hydrolysis. In the model, the influences of the reactive kinetics, residence-time, liquid holdup, and separation efficiency of the catalytic packing were considered. The model predicted the conversion of MeOAc and the mass ratio of acetic acid to water in the hydrolysis mixture. The predictions were in good agreement with experimental data. A novel process was designed based on the results of theoretic analysis and the simulation research. This new process had a higher conversion of MeOAc compared with the results in previous research and was found to be energy efficient. Optimal effect parameters and design factors of new technology on energy consumption and conversion were also determined and summarized as the following: the position of side draw is 18th to 19th stages, the catalytic distillation (CD) column pressure is at 350 kPa, the volume ratio of reflux to feed is 6–8, mole ratio of feed water to MeOAc is 3.5–4.5, and the mass ratio of side withdrawal to feed is 0.32–0.34.     

Simulation study on a reactive distillation process of methyl acetate hydrolysis intensified by reaction of methanol dehydration

Methyl acetate (MeOAc) recovery from the polyvinyl alcohol (PVA) production is a difficult and heavy energy consuming process. In this work, a reactive distillation (RD) process of MeOAc hydrolysis intensified by methanol (MeOH) dehydration, as an auxiliary reaction, was proposed. Two different feeds with the mole ratio of MeOAc to MeOH at 1:1 and 1:9 were studied, and the effect of the operating pressure, the feed location and the reflux ratio on the RD column was analyzed. The simulations of reactive distillation were performed using a three phase non-equilibrium model implemented by gPROMS. As the limit of the reaction rate of MeOH dehydration, it is impossible to get 100% conversion of MeOAc and MeOH by a single RD column. Therefore, two novel processes for recovery of methyl acetate in PVA production were developed. The simulation results show that the high purity of dimethyl ether (DME) could be achieved with a complete conversion of MeOAc, and a large amount of energy demand and equipment costs can be reduced.     

流化床串联多段冷激式绝热固定床HCl氧化反应模拟优化

提出了由流化床与多段冷激式绝热固定床串联的新型HCl氧化制氯反应工艺. 通过物料、能量、动量衡算建立了绝热反应器一维数学模型,对绝热固定床反应器段间冷激气种类、流率、流化床反应器进口处HCl与O2摩尔配比及催化剂用量等工艺参数进行了优化计算. 结果表明,液态氧为较适宜的冷激气,流化床反应器入口处最佳HCl与O2摩尔配比为1:0.7,流化床和绝热床中最佳催化剂用量分别为4.3与8.6 t,在该条件下,HCl转化率可达85%.     

醋酸甲酯水解的新工艺

提出醋酸甲酯水解的新工艺，并进行了处理量、进料分水比及回流比等操作因素对醋酸甲酯转化率影响规律的研究。醋酸甲酯的转化率随处理量的增加而降低，随回流比的增加而增大。当小于０．７，进料分水比对醋酸甲酯转化率的影响较为显著，并存在最佳操作值     

PREPARATION OF ULTRAPURE PIVALIC ACID BY RECTIFICATION

A rectification method was developed for the purification of pivalic acid (PVA) on an experimental scale. Ultrapure PVA with a purity of 99.993% was prepared at a rate of 250 mL a week by multistep rectifications, a more convenient and much faster method than the traditional zone refining method. Typical operational conditions were: head pressure around 1 kPa, reboiler temperature 85°C, head vapor temperature 55°C, condenser temperature 36.5°C, and reflux ratio of 6:1. A formula was given to determine the purity of PVA based on the relationship of freezing point and purity. The freezing point of ultrapure PVA, which was obtained by measuring solidification temperature curve using an inner sheath method, is 35.912 ± 0.001°C.     

模拟移动床反应器中合成乙酸甲酯过程的多目标优化

采用非支配基因算法(Non-dominated Sorting Genetic Algorithm, NSGA-II)对模拟移动床反应器(Simulated Moving Bed Reactor, SMBR)中合成乙酸甲酯(MeOAc)过程进行了多目标优化.所考虑的优化问题包括:(a) MeOAc产率和纯度同时最大化;(b)产率最大化和洗脱剂用量最小化;(c)产率、纯度的最大化和洗脱剂用量最小化.以MeOAc产率和纯度最大化为目标,确定了5柱SMBR最优的各区柱数分布和乙酸进料摩尔分率.此外,还研究了转化率限制和洗脱液流量对多目标优化非劣解(Pareto optimal solutions)的影响.提出并验证了一种SMBR设计和优化的通用方法.     

Design of immobilised glucoamylase reactors using a simple kinetic model for the hydrolysis of starch

A comparative study is reported of the three main types of continuous reactors, continuous feed stirred tank reactor (CFSTR), packed bed reactor (PBR) and fluidised bed reactor (FBR), for the conversion at 50°C of a 30% (w/w) corn syrup 40 DE using glucoamylase (exo-1,4-D-glucosidase, EC 3.2.1.3) immobilised on carbonyl derivatives of titanium(IV)-activated porous silica by a method developed previously.^1–3 The hydrolysis of starch in these reactors is described by a simple kinetic model⁴ which involves the intrinsic kinetic constants as well as mass transfer and dispersion effects, and allows the computation of enzyme activity values under continuous operation. FBR appears to be more effective for the hydrolysis of starch. This reactor also confers a better operational stability (t_1/2=775h) on the immobilised enzyme than the other immobilised glucoamylase reactors (PBR, t_1/2=629h; CFSTR, t_1/2=239h).     

2,3-丁二醇分离纯化中反应精馏工艺

乙醛-环己烷反应萃取体系能够有效分离发酵液中的2,3-丁二醇。文章重点研究了2,3-丁二醇-乙醛反应萃取液的连续水解精馏工艺,为工业化生产提供理论基础。水解精馏使用阳离子交换树脂HZ732为水解催化剂,以2,4,5-三甲基-1,3-二氧戊环(2,3-丁二醇-乙醛缩醛)水解率为指标,考察了反应段温度、反应段级数、进料速度、进料油水比(2,4,5-三甲基-1,3-二氧戊环和水摩尔比)和回流比的影响。通过实验得到优化水解精馏工艺条件为:反应段平均温度90℃,反应段理论板数为20,进料油水比为0.6,进料速度0.2 h-1。在该条件下2,4,5-三甲基-1,3-二氧戊环水解率为73%,未水解2,4,5-三甲基-1,3-二氧戊环被回收。水解液经精馏得到2,3-丁二醇产品,纯度(质量分数)>96%,总收率≥93%。开发了连续水解精馏工艺,为整个工艺工业化实践提供了参考。     

Concentration and residence time effects in packed bed membrane reactors

A fixed bed reactor (FBR) and a packed bed membrane reactor (PBMR) were compared with respect to their performance in the oxidative dehydrogenation of ethane over VO_x/γ-Al₂O₃ catalyst. The experiments were carried out at high space velocities and under oxygen excess conditions. In the PBMR, the oxidant air was distributed from the shell side of the membrane.

At similar overall feed configurations, the conversion of ethane was found to be higher in the PBMR. This effect was most pronounced at the highest space velocity. Mostly ethylene yield was higher in the PBMR than in the FBR. However, the yield of carbon oxides increased more. Thus, an improvement of olefin selectivity was not observed. There were even sets of experimental conditions, where the ethylene yield in the PBMR fell below the corresponding value for the FBR. In the PBMR under oxygen excess conditions, the consecutive oxidation of ethylene is more favoured than in the FBR.

Two essential reasons for the observed differences in the reactor performances are discussed. At first, there are different local reactant concentrations. Secondly, there are essential differences in the residence time behaviour of the reactants in the FBR and PBMR. In order to exemplify the latter aspect additional experiments have been carried out using a cascade of three identical PBMRs. Varying the specific oxygen flow rates over the individual membrane segment walls different dosing profiles were implemented. The results obtained in this study emphasise the general potential, but also the limits of membrane reactors compared to the FBR.