CN101172928B - Method for salt extraction separation of benzol-cyclohexane normal heptane - Google Patents
Method for salt extraction separation of benzol-cyclohexane normal heptane Download PDFInfo
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- CN101172928B CN101172928B CN2007101445619A CN200710144561A CN101172928B CN 101172928 B CN101172928 B CN 101172928B CN 2007101445619 A CN2007101445619 A CN 2007101445619A CN 200710144561 A CN200710144561 A CN 200710144561A CN 101172928 B CN101172928 B CN 101172928B
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- normal heptane
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- cyclohexane
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Abstract
The invention provides a method for leaching and separating benzene-cyclohexane or normal heptane saliferously. Inorganic slat extraction agent is dissolved in main organic leaching agent to form saliferous organic solvent with certain concentration so as to obtain composite extraction agent. The invention is characterize in that the composite extraction agent is added according to the volume ratio of 0.5 to 2:1 of the composite extraction agent and the benzene-cyclohexane or normal heptane to form a benzene-cyclohexane or normal heptane compound system; the benzene-cyclohexane or normal heptane compound system is saliferously leached through multiple cross-flows and counter-flows so as to obtain cyclohexane with the mol concentration being larger than 96 percent, or the normal heptane with the mol concentration being larger than 73 percent; and the leaching liquid which is rich in benzene is rectified so as to obtain the benzene with the mol concentration being larger than 98 percentand the organic main extraction agent with the concentration being larger than 96 percent. The invention has the advantages that a method of adding the saliferous assistant component into the organicsolvent is adopted, so that the obtained composite leaching agent has repulsive interaction on the cyclohexane or normal heptane among the raw material components, thereby decreasing the mutual solubility and mixing the liquid layers.
Description
(1) technical field
What the present invention relates to is a kind of extraction, separation method, the method for specifically a kind of Separation of Benzene, hexanaphthene or normal heptane.
(2) background technology
Benzene is important Organic Chemicals, from the seventies in 20th century so far, be growing on and on to the demand of purified petroleum benzin in the domestic and international market always.Non-aromatics impurity in the crude benzol is mainly hexanaphthene, normal heptane and methylcyclohexane, because the relative volatility of benzene and hexanaphthene is all very low and formation azeotrope in full compositing range, this makes and levels off to benzene and separating of they a both ancient and difficult problem that the method for existing Separation of Benzene and hexanaphthene mainly is azeotropic distillation, extracting rectifying and pervaporation.Azeotropic distillation flow process complexity not only needs entrainer but also need extraction agent, and operation is difficulty comparatively; Extracting rectifying process solvent ratio is too high, and energy consumption is big; The pervaporation method, though solved energy consumption problem, the industrial production feasibility is relatively poor, technology is not mature enough.The method of existing Separation of Benzene and normal heptane mainly is extracting rectifying and extractive distillation with salt, exists energy consumption big equally, shortcomings such as complicated operation.Adopt extraction process separation of benzol-cyclohexane normal heptane system not appear in the newspapers as yet.Because benzene is excellent solvent, with many organic solvents such as N, dinethylformamide (being called for short DMF) waits and dissolves each other, and is difficult to layering, so utilizes DMF etc. can't realize for extraction agent extraction separation of benzol-cyclohexane normal heptane system.
(3) summary of the invention
The object of the present invention is to provide a kind of energy consumption low, simple to operate, have the method for the salt extraction separation of benzol-cyclohexane normal heptane of good and economic and commercial viability.
The object of the present invention is achieved like this:
1, the preparation of composite extractant: help extraction agent to be dissolved in organic main extraction agent inorganic salts, form certain density saliferous organic solvent, make composite extractant;
2, multistage cross flow or adverse current saline extraction: be 0.5～2: 1 ratio according to the volume ratio of composite extractant and benzol-cyclohexane normal heptane, add composite extractant and form the benzol-cyclohexane normal heptane mixed system, the benzol-cyclohexane normal heptane mixed system is carried out multistage cross flow or adverse current saline extraction, obtain volumetric molar concentration greater than 96% hexanaphthene or greater than 73% normal heptane and the extraction liquid that is rich in benzene;
3, conventional rectification: the extraction liquid that will be rich in benzene carries out rectifying, obtain volumetric molar concentration greater than 98% benzene and concentration greater than 96% organic main extraction agent.
The present invention can also comprise:
1, to help extraction agent be inorganic salt KSCN to described inorganic salts, and described organic main extraction agent is N, the dinethylformamide one-part solvent, and the add-on of KSCN is 7%～25% of a double solvents total mass.
2, described benzol-cyclohexane normal heptane saline extraction sepn process is operating as normal temperature and pressure intermittence or successive processes.
3, the add-on of KSCN is 15% of a double solvents total mass.
After innovation of the present invention is to add salt in DMF, the layering of benzol-cyclohexane normal heptane-DMF (saliferous) mixing solutions, and partition ratio is very high with the selection coefficient, makes extracting and separating become possibility, has obtained gratifying separating effect.The present invention utilizes the method Separation of Benzene and the cyclohexane normal heptane of saline extraction and conventional distillation associating, reclaims volumetric molar concentration in greater than 96% hexanaphthene (or normal heptane) greater than 96% DMF greater than 98% benzene and volumetric molar concentration obtaining volumetric molar concentration respectively.This method energy consumption is low, and is simple to operate, and technology maturation has good and economic and commercial viability.
(the hexanaphthene mole contains and shows 45%), single-stage extraction hexanaphthene molar content in raffinate can reach 62.5% when stock liquid is benzene and hexanaphthene azeotropic composition; The Pyatyi cross current solvent extraction, the molar content of hexanaphthene can reach 86.4% in the extracting phase; Seven grades of cross current solvent extractions, the hexanaphthene volumetric molar concentration can reach 96.4% in its raffinate.When stock liquid is benzene and normal heptane mixed system, can get the normal heptane molar content behind the Pyatyi cross current solvent extraction greater than 96% raffinate.When stock liquid was benzene and cyclohexane normal heptane mixed solution, behind the Pyatyi cross current solvent extraction, the molar content of benzene can reach 85.7% (desolventizing content) in the extraction liquid.Adopt conventional batch fractionating to handle the extraction liquid that is rich in benzene, benzene mole content can reach more than 98.2% in the distillate, and the volumetric molar concentration of DMF is greater than 96% in the tower still.
The present invention adopts the method that adds the salt auxiliary component in the organic solvent, because salt effect, this process changes the free energy of system thereby has changed the activity quotient of each component, make prepared composite extractant play repulsive interaction to the cyclohexane normal heptane in the feed composition, reduced mutual solubility, the mixed solution layering has produced the novel method of salt extraction separation of benzol and cyclohexane normal heptane.
(4) embodiment
For example the present invention is done in more detail below and describes:
Embodiment one: single-stage extraction Separation of Benzene and hexanaphthene azeotrope
Add a certain amount of N in beaker, dinethylformamide adds the thiocyanic acid sylvite after drying when stirring with motor stirrer, makes adding potassium sulfocyanate amount account for 25% of the two total mass; In Erlenmeyer flask, add 22.5ml hexanaphthene, 22.5ml benzene (azeotropic is formed benzene mole content 55%) and 45ml composite extractant, adopt constant temperature blender with magnetic force to carry out thorough mixing at normal temperatures and stirred one hour; Separatory, weighing obtains raffinate 30ml, extraction liquid 60ml; Use the gas chromatographic analysis solution composition, the molar ratio of hexanaphthene and benzene is in the raffinate: 1.77: 1.00; The molar ratio of hexanaphthene and benzene is 0.21: 1.00 in the extraction liquid.The partition ratio of hexanaphthene is 9.4, and the partition ratio of benzene is that 1.12 selection coefficients reach 8.43.
The contrast experiment: with 22.5ml hexanaphthene, 22.5ml benzene and 45mlN, dinethylformamide mixes, and mixing solutions is transparent evenly not stratified, can't carry out extracting and separating.
Experimental result shows: at N, can adopt extracting operation separation of benzol-cyclohexane azeotrope behind the adding potassium sulfocyanate in the dinethylformamide; Utilize single-stage saline extraction method separation of benzol-cyclohexane azeotrope effect obvious, the hexanaphthene separation rate reaches 83.3%.
Embodiment two: multistage cross flow extraction benzol-cyclohexane-normal heptane mixture
Add a certain amount of N in beaker, dinethylformamide adds the thiocyanic acid sylvite after drying when stirring with motor stirrer, add the potassium sulfocyanate amount and account for 15% of total mass; In separating funnel, add 10ml hexanaphthene, 10ml normal heptane, 20ml benzene and 40ml composite extractant, vibration mixes; Standing demix, get extraction liquid in beaker, by volume 1: 1 new composite extractant of adding of throughput ratio mixes in raffinate, repeat above-mentioned steps, carry out the Pyatyi cross current solvent extraction, utilize the gas chromatographic analysis solution composition, the molar content of benzene is 0.63% in the extracting phase, and the molar content of benzene is 85.7% (desolventizing content) in the extraction phase.
As can be seen, utilize the N that contains potassium sulfocyanate, dinethylformamide solution can obtain good separating effect as extraction agent multistage cross flow extraction separation of benzol-cyclohexane-normal heptane mixture, and the benzene separation rate reaches 88.2%.
Embodiment three: multi-stage counter current extraction benzene and hexanaphthene azeotrope
Utilize three separating funnel simulation Pyatyi counter-current extraction processes.Get three separating funnel numberings, add 20ml hexanaphthene, 20ml benzene (azeotropic is formed benzene mole content 55%) and 40ml composite extractant in No. 1 separating funnel, vibration mixes, standing demix; Separating funnel is put in lower floor's extraction liquid taking-up No. 2, and by volume throughput ratio adds fresh feed liquid and double solvents respectively in 1, No. 2 separating funnel, shake up the back standing demix respectively; No. 3 separating funnel lower floor extraction liquids are discharged, No. 2 separating funnel lower floor extraction liquids are prevented that No. 1 separating funnel lower floor extraction liquid places separating funnel No. 2 in No. 3 separating funnels, No. 1 separating funnel upper strata extracting phase is discharged; By volume throughput ratio adds solvent and fresh feed liquid respectively, standing demix in No. 1 separating funnel and No. 3 separating funnels.Repeat above step, can realize the operation of Pyatyi counter-current extraction, with gas-chromatography test experiments result, as shown in table 1.
Table 1 counter-current extraction experimental result
| Hexanaphthene molar content % | Benzene mole content % | DMF molar content % | |
| Material liquid | 45.5 | 54.5 | - |
| The upper strata extraction phase | 73.35 | 23.90 | 2.76 |
| Lower floor's extracting phase | 7.94 | 54.16 | 37.91 |
By table as can be seen, after counter-current extraction separated, the content of benzol-cyclohexane in extraction phase and extracting phase all had obvious variation, and away from the azeotropic composition.
Claims (1)
1. the method for a salt extraction separation of benzol-cyclohexane normal heptane is characterized in that:
(1), the preparation of composite extractant: help extraction agent to be dissolved in organic main extraction agent inorganic salts, form certain density saliferous organic solvent, make composite extractant, it is inorganic salt KSCN that described inorganic salts helps extraction agent, described organic main extraction agent is N, dinethylformamide one-part solvent, the add-on of KSCN are 7%～25% of double solvents total mass;
(2), multistage cross flow or adverse current saline extraction: be 0.5～2: 1 ratio according to the volume ratio of composite extractant and benzol-cyclohexane normal heptane, add composite extractant and form the benzol-cyclohexane normal heptane mixed system, the benzol-cyclohexane normal heptane mixed system is carried out multistage cross flow or adverse current saline extraction, obtain volumetric molar concentration greater than 96% hexanaphthene or greater than 73% normal heptane and the extraction liquid that is rich in benzene;
(3), conventional rectification: the extraction liquid that will be rich in benzene carries out rectifying, obtain volumetric molar concentration greater than 98% benzene and concentration greater than 96% organic main extraction agent.
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| CN2007101445619A CN101172928B (en) | 2007-11-06 | 2007-11-06 | Method for salt extraction separation of benzol-cyclohexane normal heptane |
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| CN101654392A (en) * | 2009-09-09 | 2010-02-24 | 哈尔滨工程大学 | Extracting agent for extracting and separating benzene-cyclohexane mixture by adding salt and preparation method thereof |
| CN103073383B (en) * | 2013-02-07 | 2015-07-01 | 天津大学 | Method and device for separating isohexane, n-hexane and benzene |
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Non-Patent Citations (6)
| Title |
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| 张志刚,徐世民.常规间歇萃取精馏分离苯-环己烷的研究.化学工程 4.2006,(6),全文. |
| 张志刚,徐世民.常规间歇萃取精馏分离苯-环己烷的研究.化学工程 4.2006,(6),全文. * |
| 董红星, 刘剑.含盐二甲基甲酰胺溶液萃取精馏分离苯-正庚烷的研究.石油化工34 4.2005,34(4),第360页左栏第3行-第363页左栏第1行. |
| 董红星, 刘剑.含盐二甲基甲酰胺溶液萃取精馏分离苯-正庚烷的研究.石油化工34 4.2005,34(4),第360页左栏第3行-第363页左栏第1行. * |
| 董红星,刘剑.加盐萃取精馏分离苯中低含量正庚烷的实验研究.哈尔滨工程大学学报 6.2004,(6),全文. |
| 董红星,刘剑.加盐萃取精馏分离苯中低含量正庚烷的实验研究.哈尔滨工程大学学报 6.2004,(6),全文. * |
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