连续流化催化精馏与间歇精馏制备乳酸乙酯的对比研究

乳酸乙酯具有无毒、溶解性好、不易挥发、有果香气味等特点,是极具开发价值和应用前景的"绿色溶剂"。由于乳酸乙酯的特性,国内外学者渐渐致力于开发更高效更环保的制备方法。连续流化催化精馏是利用乳酸和乙醇酯化、粉末状大孔强酸性交换树脂作为催化剂,随反应物流动的连续催化精馏方式,是一种更优的高效而环保的乳酸乙酯生产方式。首次利用连续流化催化精馏制备乳酸乙酯,并旨在研究连续流化催化精馏与间歇精馏制备乳酸乙酯的对比来突出前者的优势,对连续流化催化精馏的产物进行精馏提纯,得到更高纯度的乳酸乙酯,为连续流化催化精馏制备乳酸乙酯的优势提供了可靠的理论依据,并在食品工业等高纯度要求的工业中的运用起到了推进作用。     

固定床反应器催化酯化制备乳酸乙酯工艺研究

以乳酸和乙醇为原料,采用经金属离子改性的阳离子交换树脂为催化剂,填装在列管式固定床反应器中.原料经固定床反应器催化酯化,再经精馏纯化制备出乳酸乙酯.具有反应条件温和,催化剂活性稳定且循环使用,利于工业化清洁生产等优势.试验研究了乳酸和乙醇酯化过程中,原料醇酸物质的量比、酯化反应温度和进料体积空速对乳酸转化率的影响.结果...     

精馏法合成乳酸乙酯的研究

采用带分水器的精馏装置,使乳酸酯化的原有脱水－酯化两步过程,能在该装置上一步进行。通过正交试验, 考察了乙醇的用量、催化剂的用量、带水剂的用量三个因素对乳酸乙酯收率的影响。确定了最佳的配比,并由验证实验得到证明,脱水－酯化反应在2h基本完成,乳酸乙酯的收率可达到96％以上。     

用粉末树脂催化合成顺丁烯二酸二乙酯

由于在无机酸催化酯化反应中存在副反应较多，后处理复杂、产率不高且容易造成对机器设备的腐蚀等不利因素，利用强酸性离子交换树脂代替无机酸，催化酯化反应，可以减少副反应，提高产率、产量，避免设备腐蚀，降低成本。     

乳酸乙酯工艺研究

乳酸乙酯为无色透明液体,具有酯类物质特有的香味,无毒。在工业上用作溶剂,在饮食业中用来配制酒用香精,可作为啤酒、饮料的添加剂。     

精馏法合成乳酸乙酯的研究

采用带分水器的精馏装置 ,使乳酸酯化的原有脱水 -酯化两步过程 ,能在该装置上一步进行。通过正交试验 ,考察了乙醇的用量、催化剂的用量、带水剂的用量三个因素对乳酸乙酯收率的影响。确定了最佳的配比 ,并由验证实验得到证明 ,脱水 -酯化反应在 2h基本完成 ,乳酸乙酯的收率可达到 96 %以上     

浆料催化精馏制备醋酸甲酯

在内径为76 mm的常压玻璃塔内,精馏段填充θ环,反应段为筛板,以甲醇与醋酸酯化反应合成醋酸甲酯为模型反应,采用平均粒径为4μm的强酸性大孔型离子交换树脂为催化剂,对浆料催化精馏工艺制备醋酸甲酯进行了试验研究。考察了催化剂浓度、进料比、进料总流量和回流比等因素对该过程的影响。在选定的试验条件下,醋酸甲酯收率可达86.4%,塔顶酯的纯度可达92.95%(质量分数)。     

NKC-9酸性树脂催化合成乳酸乙酯活性研究

研究NKC-9酸性树脂催化合成乳酸乙酯的新工艺。一定量的乳酸与一定量的乙醇,在NKC-9催化作用下以环己烷为脱水剂,采用回流脱水合成工艺。乳酸0.2mol,催化剂0.7g,环己烷25mL,反应时间为3h,当酸醇摩尔比为1:3时,乳酸转化率达49.5%。NKC-9酸性树脂催化合成乳酸乙酯工艺是快速、节能、环境友好的绿色合成新工艺。     

脱水法合成乳酸乙酯

以乳酸和乙醇为原料 ,在对甲苯磺酸的催化下以氧化钙或 3A分子筛或MgSO3 为脱水剂 ,采用自制的索氏提取器进行回流脱水合成乳酸乙酯。对影响乳酸乙酯产率的诸因素进行了考察。实验结果表明 :加入脱水剂和带水剂可以显著提高乳酸乙酯的产率 ,酯的产率随催化剂用量的增加、醇酸物质的量比的增大、反应时间的延长先增加到最高点后略有降低。当乳酸 0 1mol、乙醇 0 3mol、对甲苯磺酸 1 0g、带水剂环己烷 5 0mL、脱水剂CaO 18 7g和反应 2h时 ,乳酸乙酯的产率达 84 5 %。     

催化反应精馏技术连续制备乙酸乙酯

在直径３０ｍｍ的催化反应精馏塔中进行合成乙酸乙酯的研究，考察了酸醇比、进料流量、回流比、进料位置等因素对过程的影响，在本实验最优条件下，塔顶可获得酯含量大于９４％的产品。     

催化精馏合成醋酸甲酯的研究

以强酸型阳离子交换树脂为催化剂,在直径为40 mm的填料塔内对催化精馏合成醋酸甲酯进行了研究。实验塔的三段填料高度分别为810、270、450 mm,填料段之间放置直径为60 mm、高度为175 mm的2节催化剂床层,并在塔釜放置催化剂。采用连续操作,着重考察了醇酸进料摩尔比、醋酸进料位置、甲醇进料位置和回流比对催化精馏合成醋酸甲酯的影响。在选定实验条件下,塔顶醋酸甲酯的质量分数可达到98.43%,醋酸的转化率达到99.13%。     

催化精馏合成乙酸乙酯

以乙酸、乙醇为原料,阳离子交换树脂为催化剂,在自制精馏塔内催化精馏酯化合成乙酸乙酯.以捆扎包作为催化剂装填方式,并考察了催化剂布包材料、乙醇进料位置、空速、回流比、进料酸醇物质的量之比对乙醇转化率和塔顶产品中乙酸乙酯含量的影响.结果表明,合适的条件为催化剂布包采用尼龙布材料,乙醇进料位置在催化段底部,空速为0.213 h-1,进料酸醇物质的量之比3:1,回流比1.0.该工艺条件下,乙醇转化率为97.16%,塔顶乙酸乙酯的质量分数为95.44%.     

Synthesis of methylal by catalytic distillation

Methylal is an important raw material and an excellent solvent in industry. The conventional methods for the synthesis of methylal have drawbacks such as corrosion to the equipments, catalyst isolation, high molar ratio of methanol to formaldehyde and high cost of equipments. To overcome these drawbacks, the synthesis of methylal was investigated in a pilot scale catalytic distillation column using Sulzer BX and the structured catalytic packing Katapak-SP 12 in the present study. The reaction was catalyzed by polystyrene based macroporous cation exchange resin (D72) which was filled in the catalystic layers of the structured packings. The effects of operating parameters such as reflux ratio, total feed rate, molar ratio of methanol to formaldehyde, catalyst weight, aqueous formaldehyde concentration were studied experimentally. The appropriate operating parameters obtained in the present study include: reflux ratio is 5; total feed rate is 3.10 kg/h; molar ratio of methanol to formaldehyde is 2.5, catalyst weight is 0.51 kg, aqueous formaldehyde concentration is 35.3%. Under the above operating conditions the average conversion of formaldehyde is 99.6% while the average methylal purity is 92.1%. In order to achieve higher purity of methylal at the top of the column, two different configurations: feeding aqueous formaldehyde and feeding water at mid-way of rectifying section, was tried in the experiments. The experimental results show that the former configuration surpasses the latter, under which the average conversion of formaldehyde is 99.8% and the average methylal purity is 99.1%.     

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%。     

催化精馏合成乙酸乙酯的工业试验

以固体酸为催化剂,在中试催化精馏塔中进行了乙酸与乙醇反应制备乙酸乙酯的工业试验,试验塔的精馏段塔径为600 mm,内装陶瓷规整填料,反应精馏段塔径为1 000mm,内装7层立体催化精馏塔板.采用连续操作,考察了不同的回流比、釜酸质量分数、进料流量对反应和分离过程的影响,同时测定了塔板上气液相质量分数的分布.通过试验得到...     

Recovery of lactic acid by batch reactive distillation

Lactic acid, being virtually a non‐boiling compound, is difficult to separate from its aqueous solution by conventional methods such as distillation. It is necessary to convert it to the relatively volatile ester and the separation of the ester, followed by hydrolysis, is recommended as an appropriate method of recovery. In the present work, we explore and investigate a novel reactive distillation strategy to perform esterification, distillation and hydrolysis in a single unit. The experiments were performed in a batch reactive distillation set‐up and the results have been explained with the help of an appropriate model. An unsteady state mathematical model based on an equilibrium stage concept was developed for batch reactive distillation. A pseudo‐homogeneous model was used for the determination of reaction kinetics. The effect of operating parameters such as feed concentration, mole ratio, catalyst loading, boil‐up rate, etc. on the recovery of lactic acid was studied with the help of simulation and experimental results. The feasibility issue of reactive distillation has been discussed based on the results obtained. Copyright © 2006 Society of Chemical Industry     

离子液体催化合成食用香料乳酸乙酯的研究

以离子液体[HSO3-pmim]HSO4为催化剂,乳酸和乙醇为原料合成乳酸乙酯。通过正交实验考察了影响酯化反应的主要因素,确定最佳合成条件为:[HSO3-pmim]HSO4用量10mL,酸醇摩尔比1.0∶1.5,反应温度110℃,反应时间2.0h,酯化率达96.7%。离子液体易分离回收,可重复使用。     

硫酸氢钠催化合成乳酸乙酯的研究

采用硫酸氢钠为催化剂合成乳酸乙酯。研究表明该催化剂具备价廉易得，催化活性高，能有效提高原料利用率，流程简单，操作方便，减少废液排放等优势。产品总收率达88．3％。     

A continuous process for the recovery of lactic acid by reactive distillation

Separation and purification of lactic acid from the fermentation broth are difficult because of its non‐volatile nature and the presence of other organic acids. Esterification of lactic acid with methanol followed by hydrolysis of the separated methyl lactate is an effective technique for this purpose. A continuous process for recovery is proposed and various aspects are evaluated through simulation and experiments. In the proposed route, a vapor stream containing methyl lactate is removed from a two‐phase CSTR, used for esterification, operated under boiling conditions. The ester thus separated from the aqueous solution is further hydrolyzed in a reactive distillation column. Continuous removal of the volatile component (i.e. methanol) from the reaction zone increases conversion, thus pure lactic acid is obtained from the bottom of reactive distillation column. The results obtained in the experiments are compared with the simulation results. Further simulation studies were performed to obtain the suitable operating conditions for higher conversion and concentration of lactic acid. Copyright © 2006 Society of Chemical Industry