萃取精馏技术与工业应用进展

萃取精馏是近沸点混合物分离的主要方法,而萃取精馏性能受选取的溶剂、工艺流程及设备结构影响。结合国内外萃取精馏技术中溶剂选取方法、萃取工艺及设备改进方面取得的研究进展,介绍了近年来萃取精馏技术的应用新情况,特别是石化行业为了达到生产产品的升级,采用萃取精馏技术解决油品脱硫、芳烃工艺改进、裂解汽油中副产品的分离等生产难题,为石油化工、炼油行业带来了明显的经济效益。     

混合溶剂萃取精馏分离邻二甲苯-苯乙烯的流程模拟与参数分析

通过气液相平衡实验,确定了萃取精馏分离邻二甲苯-苯乙烯物系的单一萃取剂(环丁砜)和混合溶剂(环丁砜和N-甲基吡咯烷酮)及其适宜的质量配比.在此基础上,用Aspen plus流程模拟软件,对萃取精馏过程进行模拟分析,考察了溶剂比、回流比、理论板数对分离效果的影响,得到了萃取精馏塔适宜的操作工艺条件,为工艺设计开发提供了基础数据.     

基于能量目标的芳烃萃取精馏溶剂评价模型

以NRTL活度系数模型为基础,利用Aspen Plus对不同单组分萃取剂回收芳烃的萃取精馏装置进行了全流程模拟和工艺操作参数优化。综合考虑各操作变量及其关联,提出了基于局部耦合参数迭代优化的整体协同优化策略,在保证分离要求的条件下,以能耗为目标,对萃取精馏塔(EDC)、溶剂回收塔(ERC)的进料位置、ERC回流比等关键操作参数进行优化,建立过程能耗的物性关联模型。通过分析不同溶剂对芳烃萃取精馏过程能耗和分离效果的影响,提出了基于能耗目标的芳烃萃取精馏溶剂评价模型,结果表明影响芳烃萃取精馏过程能耗的关键物性为溶剂的分子量及常压沸点,所建立的过程能耗关联模型具有较高的关联性,其R2均大于0.9,可有效指导萃取精馏溶剂选择,为计算机辅助分子设计提供简化的目标函数。     

基于能量目标的芳烃萃取精馏溶剂评价模型

以NRTL活度系数模型为基础，利用Aspen Plus对不同单组分萃取剂回收芳烃的萃取精馏装置进行了全流程模拟和工艺操作参数优化。综合考虑各操作变量及其关联，提出了基于局部耦合参数迭代优化的整体协同优化策略，在保证分离要求的条件下，以能耗为目标，对萃取精馏塔（EDC）、溶剂回收塔（ERC）的进料位置、ERC回流比等关键操作参数进行优化，建立过程能耗的物性关联模型。通过分析不同溶剂对芳烃萃取精馏过程能耗和分离效果的影响，提出了基于能耗目标的芳烃萃取精馏溶剂评价模型，结果表明影响芳烃萃取精馏过程能耗的关键物性为溶剂的分子量及常压沸点，所建立的过程能耗关联模型具有较高的关联性，其R ²均大于0.9，可有效指导萃取精馏溶剂选择，为计算机辅助分子设计提供简化的目标函数。     

碳五装置溶剂分离提纯方法分析

碳五分离是利用乙烯裂解生产的副产品碳五馏分为原料,用DMF(N、N-二甲基甲酰胺)为溶剂,采用萃取精馏和精密精馏得到异戊二烯、间戊二烯和双环戊二烯3种产品。其中采用萃取精馏仅是为得到纯度为99.5%以上的异戊二烯产品,循环溶剂的分离与提纯成为影响产品质量的关键因素。简要介绍了溶剂分离提纯的工艺流程,详细分析了溶剂在萃取系统进行分离与提纯的工艺流程和操作关键。     

碳五工艺分离过程模拟与参数优化

利用Aspen Plus软件,建立了碳五工艺分离第一萃取精馏单元的过程模拟,考查了萃取精馏塔主要操作参数如溶剂比、回流比对分离过程的影响,确定了萃取精馏塔的最佳工艺操作条件。     

武汉乙烯碳五原料组成对碳五产品质量的影响

碳五馏分可以利用各种烃类沸点的不同或在溶剂中相对挥发度相异,而进行精馏、萃取精馏、共沸精馏,生产异戊二烯(聚合级)、间戊二烯和双环戊二烯、抽余碳五等产品。在实际生产过程中,武汉乙烯C5原料组成与设计指标偏差较大,导致间戊二烯产品质量与设计指标存在偏差。比较了碳五分离工艺与裂解汽油加氢工艺优化方案,根据市场需求,选择不同的方案可获得更好的经济效益。     

轻质芳烃 BTX 的分离

本文在查阅国内外文献的基础上,对现有的芳烃分离方法逐一进行了比较,并着重阐述了萃取精馏方法。先分析了典型的萃取精馏,继而评述了溶剂的选择,并介绍了几种常用的溶剂,最后列出几种具有特点的国外萃取精馏工艺。     

重汽油萃取精馏制溶剂油工艺设计与模拟

提出了以汽油加氢装置的切轻重汽油为原料产重芳烃溶剂油新工艺,从而提高资源利用效率。采用萃取精馏的方法,首先确定环丁砜作为重芳烃与非芳组分分离的基础溶剂,并通过复配萘的方法降低萃取溶剂的沸点,解决了萃取溶剂高温分解的问题,实现了重芳烃分离过程的平稳运行。随后利用Aspen Plus软件模拟计算并设计加氢重汽油制重芳烃溶剂油产品工艺流程,确定了萃取剂配比及用量,并优化萃取精馏塔和溶剂回收塔工艺参数,最终获得满足溶剂油产品指标的重芳烃产品。     

萃取精馏提取高纯度三甲苯的模拟研究

采用单级汽液平衡釜测定加氢裂解C9芳烃与溶剂之间的汽液平衡数据,计算各组分与茚满的相对挥发度,筛选出邻苯二甲酸二甲酯(DMP)为最佳溶剂。采用Aspen P lus流程模拟软件模拟加氢裂解C9芳烃萃取分离结果,模拟结果与实验结果相对误差小于1%。考察了萃取段理论板数、溶剂比(原料与溶剂的质量比)、回流比等因素对分离效果的影响。模拟结果表明,萃取精馏塔的最佳工艺条件:萃取段理论塔板数35,溶剂比0.5,回流比5。此时,三甲苯质量分数和收率分别达到99.87%和96.20%。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.