DMF溶剂回收中降低焦油塔进料酸度的探索

<正> 二甲基甲酰胺(DMF)是化纤生产中重要溶剂,在现有DMF溶剂回收流程中,普遍存在的问题是:焦油塔进料中甲酸的含量高达0.6％～1.5％(6000～15000ppm),甲酸与DMF能形成共沸混合物,使DMF的损失量增加;同时进一步加剧了DMF的水解,继续生产甲酸,使焦油塔塔顶回收的溶剂酸值达到200ppm以上,超过了生产上限值90ppm;而且含较高甲酸的DMF溶剂在循环使用中会对设备造成严重腐蚀。 在DMF回收中焦油塔的作用是从DMF精馏塔塔底及稀进料蒸发器排出的残液中除去高沸点物质和甲酸。为了解决焦油塔进料中甲酸含量偏高的难题,经过研究,我们拟采取以下两项改造措施:     

(DMF法)丁二烯抽提装置降低溶剂精制塔塔顶损失措施

通过分析抚顺石化公司乙烯厂丁二烯装置开车以来溶剂精制塔塔顶DMF损失较大的原因,结合本装置工艺技术特点,通过局部改造和优化操作调整,降低了塔顶DMF损失.     

DMF回收系统焦油塔操作条件的实验研究

实验测定了不同压力温度条件下DMF水溶液的水解度，分析总结了DMF水溶液的酸度及DMF的水解度随压力温度的下降而下降的变化规律，为DMF焦油塔的减压操作改造方案研究提供了实验依据：研究了二甲胺含量对焦油塔喂料酸度及DMF水解度的影响，归纳了焦油塔喂料酸度随二甲胺加入比例的增加而减小的变化规律，为焦油塔的常压优化改造方案研究提供了新思路。     

雾化喷淋技术在淋洗塔改造中的应用

采用雾化喷淋技术对干法腈纶生产中回收二甲基甲酰胺(DMF)的填料式淋洗塔进行了改造。改造过程不很复杂,投入较小,改造后的淋洗塔不仅运行费用大大降低,操作简便,运行中的故障率极低,而且对DMF的吸收率也有较大提高,在节能减排方面效果明显。     

甲胺/DMF装置蒸汽系统节能改造小结

安阳九天精细化工有限责任公司60 kt/a甲胺装置采用甲醇与液氨气相催化胺化和四塔精馏工艺,60 kt/a DMF装置采用CO一步法和三塔精馏工艺,各精馏塔塔釜物料需使用蒸汽进行加热。为节能降耗及解决系统存在的问题,对甲胺/DMF装置蒸汽系统进行节能技改——增设Syclonic汽旋隆装置等。简介甲胺/DMF装置蒸汽系统流程及存在的问题,详细介绍蒸汽节能装置(即汽旋隆装置)的工作原理、操作规程及注意事项。改造后的实际运行情况表明,蒸汽节能装置节汽效果明显,具有良好的经济效益与社会效益。     

PTA老装置溶剂脱水塔HT-701优化改造

对PTA二装置HT701塔的改造方案进行了分析和比较,提出了合适的改造方案,通过改造,HT701塔完全满足装置的需要,同时,为类似PTA装置溶剂脱水塔的改造提供了参考。     

一种基于微谱技术分析溶剂型涂料的方法

利用超声离心方法快速高效分离出A、B组分中主要物质,并结合傅里叶红外光谱法、热裂解气相色谱-质谱联用法、X射线衍射等微谱方法完成了对未知溶剂型涂料重要组分（成膜剂、固化剂、溶剂、填料）的定性分析。实验证明,未知样品的成膜剂为双酚A型环氧树脂,固化剂为聚酰胺固化剂,溶剂剂体系为二甲苯、乙苯、乙酸戊酯和丙酸丁酯,填料为铁红、铁灰、滑石粉和长石粉。     

镍系顺丁橡胶溶剂及丁二烯回收装置过程模拟

溶剂及丁二烯回收装置是镍系顺丁橡胶生产工艺中的重要组成部分,其能耗占整个装置的40%左右,是顺丁橡胶生产过程中节能降耗的关键工序。某企业原本采用抽余油为溶剂,回收工艺采用六塔流程,后为降低能耗,将抽余油更换为己烷溶剂,并对原有工艺进行了相应改造,如降低溶剂脱重塔的回流量,并对回收油脱水塔塔底产物进行直采。本文结合其生产工艺改造前后的生产情况和实际生产操作数据,应用Aspen Hysys软件分别对改造前和改造后的溶剂回收流程进行建模和模拟,并与实际结果进行对比以验证模拟的准确性。在产品质量符合生产指标的情况下,对比分离要求和能耗,模拟结果表明改造后的流程总能耗降低15.25%,节能效果十分显著,其中回收油脱水塔和溶剂脱重塔的能耗降低最为明显。     

间歇萃取精馏分离环己烷-正丙醇的研究

首次研究了间歇萃取精馏方法分离环己烷-正丙醇二元共沸物。通过溶剂选择原理选出DMF作为分离此共沸物系的溶剂,采用UNIFAC模型对常压下环己烷-正丙醇物系和加入溶剂DMF后的物系进行气液平衡模拟,并进行了实验验证,其中模拟结果与实验数据吻合较好。通过间歇萃取精馏分离此共沸物的实验研究来进一步考察所选萃取剂的效果。结果表明,DMF能够消除环己烷-正丙醇共沸物系的共沸点,采用有30块理论板的填料塔,萃取剂进料位置为第4块板,溶剂质量比为1∶1,回流比为3∶1时,塔顶环己烷产品质量分数为96.2%,回收率为72.2%。     

板式塔在FCC液化气脱硫溶剂再生塔的应用

介绍FCC液化气脱硫溶剂再生塔的工艺流程,对溶剂再生过程中存在的问题进行分析。通过对溶剂再生塔进行改造,将填料塔改为板式塔,提高溶剂再生效果。装置改造使用CTST立体传质塔盘后,溶剂循环量增大23%,贫液再生效果变好,贫液中H2S浓度降至0.5 mg/L,装置运行更加安全平稳。     

溶剂的性质对聚砜／磺化聚砜合金膜性能的影响

介绍了溶剂的性质对聚砜 /磺化聚砜 (PSF/SPSF)合金分离膜膜性能的影响     

Diffusion coefficient of DMF in acrylic fiber formation

A H₂O/dimethyl formamide (DMF) mixture was used as the coagulation bath of wet‐spun process for acrylic fibers. Diffusion coefficient of DMF in the protofibers prepared by acrylonitrile/acrylamide copolymers was determined. It has been found that diffusion coefficient of DMF outflow of the protofibers prepared by acrylonitrile/acrylamide copolymers synthesized by solution polymerization is highest compared with those of acrylonitrile/acrylamide copolymers synthesized by H₂O/DMF mixture suspension polymerization and aqueous suspension polymerization. With an increase of copolymer concentration in the dope, diffusion coefficient of DMF decreases continuously. Diffusion coefficient of DMF increases along with the bath temperature, but the changes in diffusion coefficient values are less prominent as temperature goes beyond 55°C. When DMF concentration in the coagulation bath was 50%, the value of the diffusion coefficient of DMF was minimal. Diffusion coefficient of DMF increases along with jet stretch minus ratio increase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3616–3619, 2006     

Effect of dimethyl formamide in the synthesis of linear low density polyethylene on branched and molecular structure

In this research work, effect of dimethyl formamide (DMF) as an external electron donor in gas phase ethylene/1‐butene copolymerization process in the presence of Ziegler–Natta catalyst has been investigated. Different experiments were performed using TiCl₄/MgCl₂ as catalyst, triethyl aluminum as cocatalyst and in the presence of various amounts of DMF as an external electron donor. Then, effect of DMF on various parameters such as catalyst activity, molecular weight, and short chain branching content of the samples has been studied. The results showed that the more the ratio of DMF/Ti, the lower the catalyst activity. Moreover, the curves relating molecular weight and short chain branching content of the samples to the ratio of DMF/Ti passed through an extremum point at about DMF/Ti = 0.25. A justification for the occurrence of the extremum point has been proposed in this research work, and some analysis methods are adopted to confirm the suggested justification. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1267–1272, 2012     

非均相催化剂催化5-羟甲基糠醛氢解制备2,5-二甲基呋喃研究进展

随着化石能源的日益短缺,清洁可再生生物质资源的利用,尤其是制备高品质生物燃料逐渐成为研究热点。2,5-二甲基呋喃（DMF）具有优良的物理化学性质,被认为是最有前途的液体生物燃料之一,可通过生物质平台分子5-羟甲基糠醛（HMF）选择性氢解制备。HMF化学性质非常活泼,可以转化成多种下游产品,因此设计制备高选择性催化剂对于靶向合成DMF至关重要。本文依据贵金属和非贵金属对催化剂进行分类,详细综述了非均相催化剂在HMF氢解制备DMF反应中的研究新进展;针对目前研究中存在的局限性和问题,提出了催化剂和反应体系的研究方向。此外,指出以生物质为原料直接制备DMF及建立有效的分离技术是实现DMF工业化生产的重要途径。     

Influence of solvent on degree of acylation in the formation of sucrose esters

Sucrose palmitates were prepared by the interesterification of sucrose and methyl palmitate in different solvents. The ratio of methyl palmitate to sucrose in dimethylformamide (DMF) solution was varied so that the effect on yield and ester composition could be evaluated. When sucrose esters were prepared in DMF, the palmitoyl groups approximated a random distribution when only penta- and lower esters were formed. When the proportion of palmitoyl groups was increased, hexa- through octaesters were formed, but the yield was less than that calculated for a random distribution. The interesterification of sucrose and methyl palmitate in solvents other than DMF, but under otherwise identical reaction conditions, yielded different reaction products. Only traces of sucrose esters were produced in hexamethylphosphoramide and formylmorpholine. Reactions in dimethylsulfoxide and N-methyl-2-pyrrolidinone yielded larger percentages of higher esters than were obtained in DMF. However the distribution was far from random. Presented at the AOCS Meeting, New Orleans, April 1970. S. Market. Nutr. Res. Div., ARS, USDA.     

生物质液体燃料2,5-二甲基呋喃的催化合成进展

2,5-二甲基呋喃（DMF）是一种可替代化石能源的新型液体生物质燃料,对于缓解当今能源危机具有重要意义。鉴于其优良的性质和广阔的应用前景,以生物质资源为原料通过绿色、经济的方法制备DMF逐渐成为科学研究的热点。本文归纳和总结了近年来国内外由生物质糖类化合物出发制备DMF的一些催化技术研究新进展,着重从活性中心和载体的构效关系出发对比了不同金属催化剂的催化效果,讨论了影响多相反应体系的关键因素,分析了不同反应路线和制备方法。对进一步研究和开发从生物质糖类化合物“一锅法”转化成DMF的催化新技术提出了一些建议和展望,为探索高效、经济、绿色、可持续的DMF合成途径提供科学依据和创新思路,促进生物质制DMF的工业技术发展。     

Effect of addition of surfactants on the rheology of gels from methylcellulose in N,N‐dimethylformamide

The effect of highly substituted cationic cetyl trimethyl ammonium bromide (CTAB), less substituted cationic hexadodecyl ammonium bromide (HDAB), CTAB‐ and HDAB‐modified montmorillonite (CTABMONT and HDABMONT), and nonionic surfactants on the rheological properties of methylcellulose (MC) N,N‐dimethylformamide (DMF) gels have been studied. The storage modulus of the MC‐MDF gels increases with an increase in frequency. During the frequency scan, the storage and loss modulus of MC‐DMF gel crosses over each other at two different frequencies. At the crossover points, the loss tangent is found to be unity. The addition of CTAB‐ and HDAB‐modified nanofiller increases in the gel strength of MC‐DMF gel. The storage modulus of MC‐DMF gel in the presence of CTABMONT is found to be higher than that of CTAB‐modified MC‐DMF gel. Whereas, the storage modulus of MC‐DMF gel in the presence of HDABMONT is lower than that of HDAB‐modified MC‐DMF gel. On the other hand, the addition of nonionic surfactant (Brij78) decreases the gel strength. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

分光光度法测定海水中叶绿素含量的研究

近年来,海洋污染日益成为世界各国严重关切的问题。叶绿素a是环保部门监测水质状况的重要指标之一,可通过海水中叶绿素a浓度来估算海洋初级生产力。文章系统比较了三种常用有机萃取溶剂:90%丙酮、90%热乙醇,N,N-二甲基甲酰胺(DMF)以及不同萃取时间对叶绿素a的萃取效果,结果显示DMF做萃取剂萃取较为完全,且所用时间短,其中测定的变异系数RSD-DMF为2.9%,满足叶绿素a含量检测的要求。     

四丁基氟化铵在DMF中的活度系数测定

采用电导法测定了298.15~343.15 K下四丁基氟化铵（TBAF）在DMF中的电导率,计算出TBAF在DMF中的摩尔电导率;根据Kohlrausch规则,采用外推法求出TBAF在DMF中的无限稀释摩尔电导率;采用DebyeHücker和Osager-Falkenhangen公式计算出TBAF在DMF中的平均活度系数,并讨论了TBAF电解质溶液活度系数的影响因素。结果表明,其活度系数随溶液浓度的增大和温度的升高而减小。