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Method for salt extraction separation of benzol-cyclohexane normal heptane

A cyclohexane and n-heptane technology, applied in the field of separation and extraction, can solve problems such as difficult stratification and unrealization, and achieve the effects of simple operation, good economy, industrial feasibility, and mature technology

Inactive Publication Date: 2008-05-07
HARBIN ENG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because benzene is an excellent solvent, it is miscible with many organic solvents such as N,N-dimethylformamide (DMF for short), and it is difficult to separate layers. Therefore, DMF is used as an extraction agent to extract and separate benzene-cyclohexane / n-heptane system is impossible

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment one: single-stage extraction separation of benzene and cyclohexane azeotrope

[0016] Add a certain amount of N,N-dimethylformamide into the beaker, and add the dried potassium thiocyanate while stirring with an electric stirrer, so that the amount of potassium thiocyanate added accounts for 25% of the total mass of the two ; In the conical flask, add 22.5ml hexanaphthene, 22.5ml benzene (the azeotropic composition benzene molar content 55%) and 45ml composite extraction agent, adopt constant temperature magnetic stirrer to fully mix and stir one hour at normal temperature; , weighing, obtain raffinate 30ml, extract 60ml; Analyze solution composition with gas chromatography, the mol ratio of cyclohexane and benzene in the raffinate is: 1.77: 1.00; The molar ratio of cyclohexane and benzene in the extract is 0.21 : 1.00. The distribution coefficient of cyclohexane is 9.4, the distribution coefficient of benzene is 1.12 and the selectivity coefficient reaches ...

Embodiment 2

[0019] Embodiment 2: Multistage cross-flow extraction of benzene-cyclohexane-n-heptane mixture

[0020] Add a certain amount of N,N-dimethylformamide in a beaker, add the dried potassium thiocyanate while stirring with an electric stirrer, the amount of potassium thiocyanate added accounts for 15% of the total mass; In the liquid funnel, add 10ml cyclohexane, 10ml n-heptane, 20ml benzene and 40ml compound extractant, oscillate and mix evenly; let the layers stand, take the extract in a beaker, and add new compound extractant according to the volume flow ratio of 1:1. Extractant is mixed in raffinate, repeats above-mentioned steps, carries out five-stage cross-flow extraction, utilizes gas chromatography analysis solution to form, and the molar content of benzene in the raffinate phase is 0.63%, and the molar content of benzene in the extract phase is 85.7% (desolvation content ).

[0021] It can be seen that the separation of benzene-cyclohexane-n-heptane mixture by using N,N...

Embodiment 3

[0022] Embodiment three: Multistage countercurrent extraction of benzene and cyclohexane azeotrope

[0023] The five-stage countercurrent extraction process was simulated by using three separating funnels. Get three separatory funnel numbers, add 20ml cyclohexane, 20ml benzene (azeotropic composition benzene molar content 55%) and 40ml composite extractant in No. Take out the extract and put it into the No. 2 separatory funnel, and add fresh material liquid and compound solvent into the No. 1 and No. 2 separatory funnels according to the volume flow ratio, shake them up separately, and let them stand for stratification; put the lower layer of the No. 3 separatory funnel The extract is discharged, the extract from the lower layer of the No. 2 separatory funnel is placed in the No. 3 separatory funnel, the lower layer extract of the No. 1 separatory funnel is placed in the No. 2 separatory funnel, and the raffinate phase from the upper layer of the No. 1 separatory funnel is dis...

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Abstract

The invention provides a method for extracting and separating benzene-cyclohexane / n-heptane by adding salt. Dissolve the inorganic salt co-extractant in the organic main extractant to form a certain concentration of salt-containing organic solvent to obtain a composite extractant; The ratio of 2:1, adding a composite extractant to form a benzene-cyclohexane / n-heptane mixed system, the benzene-cyclohexane / n-heptane mixed system is subjected to multi-stage cross-current or countercurrent salt extraction to obtain a molar concentration greater than 96% cyclohexane or greater than 73% n-heptane and benzene-rich extract; rectify the benzene-rich extract to obtain benzene with a molar concentration greater than 98% and an organic main extract with a concentration greater than 96% agent. The invention adopts the method of adding salt auxiliary components into the organic solvent, so that the prepared composite extractant can repel the cyclohexane / n-heptane in the raw material components, reduce the mutual solubility and separate the mixed liquid.

Description

(1) Technical field [0001] What the present invention relates to is a kind of extraction, separation method, specifically a kind of method of separation benzene, cyclohexane or n-heptane. (2) Background technology [0002] Benzene is an important organic chemical raw material. Since the 1970s, the demand for pure benzene in domestic and foreign markets has been increasing. The non-aromatic impurities in crude benzene are mainly cyclohexane, n-heptane and methylcyclohexane. Since the relative volatility of benzene and cyclohexane is very low in the whole composition range and form an azeotrope, this makes benzene Their separation is approaching an old and difficult subject. The existing methods for separating benzene and cyclohexane are mainly azeotropic distillation, extractive distillation and pervaporation. The azeotropic distillation process is complex, requiring both an entrainer and an extractant, and the operation is relatively difficult; the solvent ratio in the extr...

Claims

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Application Information

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IPC IPC(8): C07C7/10C07C7/04C07C15/04C07C11/02C07C13/18
Inventor 董红星杨晓光王晓宇姚春艳
Owner HARBIN ENG UNIV
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