共查询到17条相似文献,搜索用时 109 毫秒
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加盐萃取精馏分离苯-环己烷 总被引:1,自引:1,他引:0
测定不同萃取剂和盐对苯-环己烷共沸物相对挥发度的影响,研究不同质量分数的盐和萃取剂与原料液体积比对苯-环己烷体系相对挥发度的影响以及萃取剂加入速率和回流比对加盐萃取精馏的影响,按实验确定的最佳工艺条件进行重复实验。结果表明:采用N,N-二甲基甲酰胺(DMF)作为萃取剂,加入质量分数为15%的KAc,萃取剂与原料液体积比为0.75,萃取剂加入速率为6 mL/min,回流比为3,可得到纯度大于98%的环己烷。与常规萃取精馏相比,加盐萃取精馏所需萃取剂与原料液体积比小,所得环己烷的纯度较高。塔底釜液经减压精馏,可得质量分数大于99.5%的苯和苯质量分数小于0.15%的加盐萃取剂。 相似文献
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离子液体萃取精馏分离乙醇-环己烷共沸物 总被引:3,自引:0,他引:3
在0.101 MPa压力下,测定了不同离子液体对乙醇-环己烷共沸物相对挥发度的影响,研究了溶剂比(萃取剂与原料液体积比)对体系相对挥发度、离子液体加入速率和回流比对萃取精馏的影响,按实验确定的最佳工艺条件进行了重复实验. 结果表明,离子液体作为萃取剂可以消除乙醇-环己烷物系的共沸点,提高该物系的相对挥发度. 采用[bmim]PF6作为萃取剂,溶剂比为0.5,离子液体加入速率为6 mL/min,回流比为3,可得到纯度大于99.8%的环己烷. 釜液采用闪蒸分离回收乙醇和离子液体,乙醇的回收率达99.9%以上. 离子液体的循环使用不影响分离性能. 相似文献
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萃取精馏中用脱溶剂方法计算萃取剂用量十分繁杂,计算误差大。主要原因是:萃取剂的挥发度小,用数值小的数据关联数值较大的萃取剂用量,可能产生计算误差;在计算过程中脱溶剂的数据与不脱溶剂的数据混用;脱溶剂计算方法没有考虑液气比对分离效果的影响。建立了萃取精馏在三角相图中的几何意义,用浓度杠杆规则可以计算萃取剂的用量。计算结果合理,且符合精馏的各种规律。 相似文献
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基于改进的UNIFAC模型,以MATLAB语言开发了萃取精馏过程相对挥发度的计算程序。依据萃取精馏溶剂选择的基本原则、溶解性能评价、相对挥发度比较和溶剂再生性能等,对乙二胺和N-乙基乙二胺共沸体系萃取精馏溶剂进行筛选。研究结果表明:较为合适的萃取精馏溶剂为丙三醇和乙二醇,其中丙三醇更好,此时N-乙基乙二胺成为易挥发组分;溶剂比是重要的影响因素之一,溶剂比越大,被分离体系的相对挥发度越大,且溶剂比的影响主要集中在溶剂比15以下;原料组成对相对挥发度的影响较弱。 相似文献
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加盐萃取精馏分离邻二甲苯-苯乙烯的研究 总被引:1,自引:0,他引:1
测定了不同萃取剂和盐对邻二甲苯-苯乙烯近沸程物系相对挥发度的影响,研究了盐质量浓度、萃取剂加入速率和回流比对加盐萃取精馏的影响,并建立了反映塔顶馏出液中邻二甲苯质量分数与各因素关系的回归模型。研究结果表明,环丁砜(DMSO)-水(质量分数3%)-硫氰酸钾(KCNS,0.03 g/mL)可作为加盐萃取精馏分离邻二甲苯和苯乙烯体系的最佳加盐萃取剂。 相似文献
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苯乙炔存在下萃取精馏回收苯乙烯的溶剂评选 总被引:1,自引:0,他引:1
提出了一种有效用于苯乙烯阻聚的复配阻聚剂,由2,2,6,6-四甲基-4-羟基-哌啶氧自由基(TMHPO.)和对叔丁基邻苯二酚(TBC)按质量比1∶1复配而成。恒压25 kPa下测定了C8馏分中各组分对苯乙烯的相对挥发度,并在苯乙炔存在下以邻二甲苯对苯乙烯的相对挥发度为指标,通过汽液平衡实验考察了不同单一萃取剂和混合溶剂在苯乙烯萃取精馏分离过程中的影响。结果表明,N,N-二甲基甲酰胺为最优单一萃取剂,质量比为3∶7的二甲基亚砜和N-甲基吡咯烷酮混合溶剂也能起到明显效果。 相似文献
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萃取精馏分离丙醇-水-乙酸丙酯混合物 总被引:1,自引:0,他引:1
为挑选萃取精馏分离丙醇-水-乙酸丙酯混合物较好的溶剂,采用基于UNIFAC模型的动态法对待选溶剂进行了计算机高通量筛选。根据加入溶剂后体系互溶性和相对挥发度大小的预测结果,经综合考虑选出较好的萃取剂为丁醇和甲醇。选取丁醇为溶剂做实验验证,测定了丙醇-水-乙酸丙酯-丁醇体系的部分汽液平衡实验数据;泡点温度tb、加入溶剂后的相对挥发度α和平衡气相组成yi的计算值与实验值吻合良好,这表明采用基于UNIFAC模型的动态法筛选萃取精馏的溶剂具有良好的可靠性和适用性。 相似文献
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提出按溶剂之间复配形成氢键的情况和修正的UNIFAC模型相结合的方法选择分离共沸体系的萃取精馏复合溶剂。准确测量了共沸体系与萃取精馏单溶剂和复合溶剂的汽液平衡数据,结果表明采用的萃取精馏单溶剂和复合溶剂的选择方法具有较好的准确度,模拟值与实验值比较,相对偏差均小于9%。通过综合比较得到分离乙酸乙酯-乙醇、乙醇-水和环己烷-苯3个共沸体系的最佳复合溶剂及配比。在最佳复合溶剂组成下,原共沸体系的相对挥发度达到最大值,该值优于组成复合溶剂的单溶剂所达到的分离效果。在最佳复合溶剂组成下,改变原料体系组成,复合溶剂组成对原料体系相对挥发度的影响趋势基本相同,这表明复合溶剂在萃取精馏塔内不同原料组成下均能较好地增加体系的相对挥发度,为工业上在萃取精馏过程中使用复合溶剂提供了理论依据。 相似文献
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《分离科学与技术》2012,47(11):769-807
Abstract An improved strategy for the selection of solvents for recovery of chemicals from dilute solution is presented. Low solvent losses and a high solute distribution coefficient are primary goals for solvent selection. High relative volatility of the solvent also is an important property if the solute is to be recovered from the extract by distillation. Low solvent losses will ensure adequate selectivity and the formation of two phases. High solute-solvent boiling point difference will increase the relative volatility and reduce the chance of azeotrope formation. The dependence of these properties on solvent structure is examined in some detail, and this indicates guidelines for the selection of solvents with the desired properties. The strategy is illustrated with the example of 1-butanol recovery. 相似文献
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引 言乙烯 /乙烷的分离是乙烯生产过程中非常重要的一步 .长期以来 ,低温精馏在烷烃 /烯烃分离中占主导地位[1] .尽管精馏是一种非常成熟的工艺 ,并且近期内不易被其他方法取代 ,但低温精馏一直存在着压缩功耗高 ,冷耗大 ,板数多的缺点 .例如 ,在一个 10 0多块塔板的精馏塔内分离乙烷 /乙烯 ,需要在 - 2 5℃的低温和 2 .30 6MPa的高压下操作[1] .所以研究人员一直致力于寻求一种高效、节能、低成本的方法 ,以取代低温精馏分离烷烃 /烯烃 .目前 ,文献报道[2~ 5] 中有关轻烃分离的方法主要有膜分离、吸附、吸收和萃取精馏等 .膜分离法具… 相似文献
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The selection of a desirable solvent or solvent system as the carrier of a particular polymer is fundamental for the optimisation of electrospinning. Solvent selection is pivotal in determining the critical minimum solution concentration to allow the transition from electrospraying to electrospinning, thereby significantly affecting solution spinnability and the morphology of the electrospun fibres. 28 solvents diversely positioned on the Teas graph were studied for their solubility and electrospinnability for making polymethylsilsesquioxane (PMSQ) solutions. The results are combined and mapped on the Teas graph using different colour codes. Based on this new spinnability-solubility map, various solvent systems for PMSQ are methodically developed. Solvents are selected to produce binary solvent systems that have solvent parameters close to a good single solvent for electrospinning of the polymer solution. This work shows that solvents of high solubility do not necessarily produce solutions good for electrospinning. Polymethylsilsesquioxane solutions of the same concentration in solvents of partial solubility showed better spinnability than solutions in solvents of high solubility. A methanol-propanol binary solvent system produced electrospun fibres with high surface porosity, showing that high volatility and high vapour pressure difference among solvents mixed can induce phase separation in electrospinning. It is noteworthy that the binary solvent system mixing 2-nitropropane (high solubility) and dimethylsulphoxide (non-solvent), neither of which exhibited high volatility, also produced highly porous electrospun fibres. This demonstrates that phase separation can be induced by solubility difference in the electrospun polymer solution. 相似文献
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Zhaoyou Zhu Guoxuan Li Yao Dai Peizhe Cui Dongmei Xu Yinglong Wang 《Frontiers of Chemical Science and Engineering》2020,14(5):824
The traditional approach to solvent selection in the extractive distillation process strictly focuses on the change in the relative volatility of light-heavy components induced by the solvent. However, the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility. This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost. The functional relationship between the relative volatility and the total annual cost is established, where the main factors, such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent, are taken into account. Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model. The results show that using the solvent with the minimal two-column extractive distillation index, the process achieves a minimal total annual cost. The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification. 相似文献