反应精馏回收糠醛生产中产生的甲酸和醋酸

二步法甲酸/醋酸催化玉米芯生产糠醛工艺的水解过程会产生少量的醋酸和甲酸,因此水解液中醋酸和甲酸的质量分数不断增加。为了使糠醛生产中甲酸和醋酸质量分数适合工艺条件,文中采用反应精馏法回收该工艺中过量的醋酸和甲酸。分别考察了回流比、酸水进料流量、甲醇与醋酸进料摩尔比、醋酸质量分数和甲酸质量分数等因素对反应精馏回收甲酸和醋酸效果的影响。通过实验得出了适宜的工艺条件:对甲酸质量分数在0.5%以上、醋酸质量分数20%以下的水解液,酸水进料流量在9.0 mL/min、甲醇醋酸进料摩尔比为3∶1和回流比为5等条件下的处理效果最佳。最佳反应条件下对于醋酸质量分数为20%的水解液,醋酸转化率为50.4%,同时甲酸质量分数降低到0.5%。实验证明此方法在满足二步法生产糠醛工艺对水解液甲酸和醋酸质量分数的要求的同时,可回收过量的甲酸和醋酸。     

Thermodynamische Grundlagen der Reaktivdestillation

Thermodynamic Fundamentals of Reactive Distillation Reactive distillation means the simultaneous implementation of reaction and distillation in a counter-current column. The effective phase equilibrium is very complex since the chemical equilibrium is superimposed on the vapor liquid equilibrium. The paper focuses on the calculation and presentation of this equilibrium using so called reactive distillation lines. This leads to a clear explanation for the existence of reactive azeotropes and to a simple method for the determination of the concentration of these azeotropes. The effectiveness of this method is demonstrated on several mixtures with different reaction mechanisms.     

Thermodynamic Fundamentals of Reactive Distillation

Reactive distillation means the simultaneous implementation of reaction and distillation in a counter currently operated column. The effective phase equilibrium is very complex since the chemical equilibrium is superimposed on the vapor liquid equilibrium. The paper focuses on the calculation and presentation of this equilibrium using so called reactive distillation lines. This leads to a clear explanation for the existence of reactive azeotropes and to a simple method for the determination of the concentration of these azeotropes. The effectiveness of this method is demonstrated on several mixtures with different reaction mechanisms.     

Prozesse der Reaktivdestillation

Reactive Distillation Processes Reactive distillation, i.e. the simultaneous implementation of reaction and distillation in a counter–current column, is a promising alternative to the conventional sequential processes. In a preceding paper the effective phase equilibrium of a reactive distillation was studied with a special focus on the determination of so–called reactive azeotropes. In this contribution, a knowledge of these thermodynamic fundamentals is applied to the conceptual design of reactive distillation processes. Furthermore, some process examples of technically important processes are presented.     

离子色谱法同时测定环境样品中的甲酸、乙酸、氯乙酸

采用离子色谱法同时测定环境样品中的甲酸、乙酸、氯乙酸,简便快速,准确性较好,灵敏度较高。甲酸、乙酸、氯乙酸的检出限依次为0.030,0.096,0.574μg/mL(S/N=3),在1~20μg/mL浓度范围内均呈现良好的线性关系,相关系数(r)均大于0.998。将三种目标物定量加入到空白水样中,甲酸、乙酸、氯乙酸加标回收率均在95.04%~105.46%范围内,其RSD值均在1.65%~3.12%之间。结果表明,该法可应用于雨水、地下水、地表水等环境样品中甲酸、乙酸和氯乙酸的测定。     

醋酸废水回收利用技术研究

从稀醋酸水溶液中回收醋酸是酸性工业废水处理中一项很重要的问题,对于资源再利用和环境污染控制等方面都具有重要意义。作为废水处理和资源回收相结合的过程,现在通常采用的方法是:共沸精馏;简单蒸馏;溶剂萃取,然后精馏回收溶剂;超临界流体萃取或氧化;吸附。本文针对先行方法存在的不足,提出并详细介绍SO42-/Al2O3-Al催化剂条件下的催化精馏反应回收醋酸的原理及意义。     

Systematic design of an extractive distillation for maximum‐boiling azeotropes with heavy entrainers

Extractive distillation is one of the most attractive approaches for separating azeotropic mixtures. Few contributions have been reported to design an extractive distillation for separating maximum‐boiling azeotropes and no systematic approaches for entrainer screening have been presented. A systematic approach to design of two‐column extractive distillation for separating azeotropes with heavy entrainers has been proposed. A thermodynamic feasibility analysis for azeotropes with potential heavy entrainers was first conducted. Then, five important properties are selected for entrainer evaluation. Fuzzy logic and develop membership functions to calculate attribute values of selected properties have been used. An overall indicator for entrainer evaluation is proposed and a ranking list is generated. Finally, the top five entrainers from the ranking list have been selected and use process optimization techniques to further evaluate selected entrainers and generate an optimal design. The capability of the proposed method is illustrated using the separation of acetone–chloroform azeotropes with five potential entrainers. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3898–3910, 2015     

NMP萃取精馏分离醋酸和水的过程模拟

利用化工模拟软件Aspen Plus采用萃取精馏法,以N-甲基吡咯烷酮(NMP)为萃取剂,对生产中醋酸和水分离进行了模拟计算,并与普通精馏法进行比较。结果表明,NMP是一种良好的萃取剂,能够很好的实现醋酸和水的分离;与普通精馏法相比,同样分离指标下萃取精馏法的能耗降低了69.8%,每吨醋酸蒸汽消耗量由10.5 t降低至3.2 t,表明萃取精馏分离醋酸和水,节能显著,优于普通精馏,为醋酸和水分离的优化操作和设计提供依据。     

糠醛废水中的醋酸回收工艺

使用自制络合萃取剂,采用脉冲填料塔通过络合萃取回收糠醛废水中的醋酸,萃取效率可达到97％～99％。测定了该物系的液液平衡数据,试验考察了影响萃取效率的因素。以醋酸的精制可利用减压精馏蒸出和共沸精馏脱水来实现。萃取液中醋酸蒸出率接近100％,脱水效果良好,得到合格的工业级醋酸。     

Solubilities of Isophthalic Acid in Acetic Acid + Water Solvent Mixtures

The solubilities of isophthalic acid (1) in binary acetic acid (2)+water (3) solvent mixtures were determined in a pressurized vessel. The temperature range was from 373.2 to 473.2K and the range of the mole fraction of acetic acid in the solvent mixtures was from x₂ 0 to 1. A new method to measure the solubility was developed, which solved the problem of sampling at high temperature. The experimental results indicated that within the temperature range studied, the solubilities of isophthalic acid in all mixtures showed an increasing trend with increasing temperature. The experimental solubilities were correlated by the Buchowski equation, and the calculate results showed good agreement with the experimental solubilities. Furthermore, the mixed solvent systems were found to exhibit a maximum solubility effect on the solubility, which may be attributed to the intermolecular association between the solute and the solvent mixture. The maximum solubility effect was well modeled by the modified Wilson equation.     

萃取、共沸精馏技术联用回收废液中的醋酸

针对化工生产过程中产生的稀醋酸溶液难以回收高纯度醋酸的问题,首先采用乙酸乙酯和苯的混合溶剂萃取浓缩稀醋酸溶液;再通过精馏蒸出溶液中的萃取剂和部分水;最后采用乙酸丁酯作为挟带剂,用共沸精馏法分离得到醋酸。得到的醋酸质量分数达96.84%,回收率达84.97%。对工业化回收稀醋酸溶液中的醋酸有一定的实用价值。     

On the dynamics of distillation processes—III: The topological structure of ternary residue curve maps

The differential equations describing the simple distillation of azeotropic ternary mixtures place a physically meaningful structure (tangent vector field) on ternary phase diagrams. By recognizing that such structures are subject to the Poincaré-Hopf index theorem it has been possible to obtain a topological relationship between the azeotropes and pure components occurring in a ternary mixture. This relationship gives useful information about the distillation behavior of ternary mixtures and also predicts situations in which ternary azeotropes cannot occur.     

Synthesis,experiments and simulation of heterogeneous batch distillation processes

The presence of azeotropes in multicomponent mixtures complicates the design of batch distillation separation processes widely used in pharmaceutical and speciality chemical industries. Most of those processes include the use of a homogeneous entrainer to ease the separation. We describe novel methods to break azeotropes using an entrainer that is partially miscible with one of the initial binary mixture components. We depict some of the advantages of heterogeneous batch distillation processes: more design alternatives for the separation of an azeotropic binary mixture than with homogeneous batch distillation, batch distillation boundary crossing thanks to a controlled reflux of the entrainer-rich phase, simplified distillation sequences as a consequence of less distillation tasks. Three examples based on the separation of non-ideal azeotropic or close boiling point binary mixtures through heterogeneous batch distillation are simulated using a commercial batch distillation package. Experiments validate the simulated separation of a minimum boiling azeotropic mixture.     

Acid Extraction from Liquid Phase Pyrolysis Oil Using Cyanex®923 and Subsequent Solvent Regeneration

Liquid phase pyrolysis (LPP) oil, an intermediate from biofuel production using second‐generation biomass, is a promising source of biobased platform chemicals like acetic acid, however, displaying a complex, multicomponent mixture. Reactive extraction with Cyanex®923 was investigated for selective recovery of acids and subsequent solvent regeneration in distillation at 200 mbar. In a three‐stage extraction 81 % of acids were removed from the LPP oil without loss of Cyanex®923 to the raffinate. Solvent regeneration efficiency of acids was up to 99.7 % with mainly acids and water in the distillate.     

副产醋酸水溶液回收利用工艺研究进展

化工生产副产大量的醋酸水溶液,将其中的醋酸分离并回收利用,是涉及化工资源利用和环境保护的重要课题。醋酸水溶液分离方法包括精馏、萃取、吸附法、膜分离等物理方法和直接酯化、反应精馏等化学方法,在对已见报道的分离方法进行综述的基础上,提出利用烯烃水合反应脱水将醋酸提浓的新思路,并简要介绍初步研究结果。     

The amplified distillation of methyl esters of fatty acids

Summary Amplified distillation is a useful technique for the quantitative analysis of mixtures of fatty acid esters, especially for the detection and estimation of minor components and for the analysis of small samples. The amplified distillation of free fatty acids is largely limited to qualitative work on account of the formation of azeotropes with mineral oils. Presented before the 1945 Fall Meeting of the American Oil Chemists' Society, Chicago, Ill.     

Separation of tert‐Butyl Alcohol‐Water Mixtures by a Heterogeneous Azeotropic Batch Distillation Process

Tert‐butyl alcohol and water form an azeotrope at normal pressure. Simple distillation cannot be used to separate these two components. In this article, a systematic study of the separation of tert‐butyl alcohol–water mixtures with an entrainer by heterogeneous azeotropic batch distillation was performed. Based upon the thermodynamic behavior of the ternary mixtures, cyclohexane was chosen as the entrainer. It formed ternary and binary heterogeneous azeotropes with the original components. The process feasibility analysis was validated by using rigorous simulation with chemical process simulation software – HYSYS Plant 2.2 and DISTIL 4.1. Simulation results were then corroborated in a batch experimental column for the selected entrainer.     

Aspen Plus在醋酸精馏塔中的应用

采用Aspen数据库软件对醋酸回收工艺进行模拟,建立醋酸精馏的稳态模型,对精馏塔的操作温度、热负荷、回流量、产品质量等操作变量进行分析,为旧塔改造和生产实际提供理论依据,通过投产后的对比分析,模拟值与操作值基本吻合。     

醋酸浓度对钛在共沸溶液中的腐蚀行为影响

钛盘的腐蚀是醋酸精馏塔安全稳定生产过程中亟待解决的一个问题,然而,影响钛材腐蚀的因素较多,很多腐蚀规律还不清楚。基于某化工厂钛材醋酸精馏塔的实际腐蚀工况,采用电化学阻抗谱和动电位极化法原位研究了钛材在不同模拟共沸醋酸溶液中的腐蚀行为,用金相显微镜观察了腐蚀前后的形貌变化,对极化曲线和阻抗谱曲线进行了模拟计算得到腐蚀动力学参数,探讨了腐蚀溶液浓度和腐蚀时间对钛板腐蚀行为的影响规律,分析了腐蚀机理,发现醋酸浓度和腐蚀时间对钛板的腐蚀影响较大,高浓度醋酸共沸体系中钛有利于钝化,当醋酸浓度由60％增大至97．5％时,钝化膜阻抗AK486．7Q增大至16000Q,腐蚀速率从5．80×10-10g／（m2-a）降低至5．66×10-11g／（m2．a）,但是腐蚀时间延长会破坏钝化膜,97．5％醋酸的共沸溶液中,当腐蚀时间由30min增大至60min时,钝化膜阻抗从16000Q降低至14600Q,腐蚀速率Ak5．66×10-11g／（m2．a）增大至2．97×10-10g／（m2．a）。实验结果为工业醋酸精馏塔中钛的防护提供了重要参考价值。     

乳酸还原浸出低品位软锰矿

用乳酸还原浸出低品位软锰矿,采用单因素实验考察乳酸用量、反应时间、温度、硫酸用量等因素对锰浸出率的影响,用响应面法对反应条件进行了优化,用高效液相色谱测定了反应中的有机物,对还原浸出产物进行了研究. 结果表明,在锰矿粉加入量10.0 g、乳酸用量1.2 mL、反应时间3.47 h、温度90℃、硫酸用量12%、搅拌速率200 r/min、液固比10 mL/g条件下,锰的浸出率可达93.99%. 还原产物为丙烯酸、甲酸和乙酸;还原浸出60 min后乳酸反应基本完全,210 min内丙烯酸含量降低不明显,甲酸和乙酸含量缓慢增加.