The method of extraction of aromatic hydrocarbons from mixtures with non-aromatic hydrocarbons

 

(57) Abstract:

Describes a better way of extracting aromatic hydrocarbons. As extractants of aromatic hydrocarbons from mixtures with non-aromatic hydrocarbons, in particular from catalization reforming proposed to use a mixture of diethylene glycol with N-formylmorpholine or triethylene glycol with sulfolane containing 5-6 wt.% water. This will reduce the ratio of extractant: raw materials 35-30% compared to di - and triethylene glycol, the temperature of the process straccia from 150 to 100 - 120oWith consumption of risaykl with 80-90 30-60 wt.%. The components are mixed extractants - deg and N-formylmorpholine, TAG and sulfolan have practically the same boiling point, which allows to maintain a constant composition of the extractants in the process of regeneration. The technical effect is to increase the efficiency of the allocation process of aromatic hydrocarbons. table 2.

The invention relates to the refining industry and can be used for the recovery of benzene, toluene and xylenes from catalization reforming of gasoline fractions of oil 62-105oC and 62-140oC.

Known method of extraction of the aromatics from the containing a series of 7 - Mas.% water (Sulimova A. D. "the Production of aromatic hydrocarbons from petroleum sources", M.: Chemistry, 1975, S. 304). The disadvantages of the method of extraction arenes mixtures of glycols with water is insufficient selectivity and low solvent capacity of the extractants according to the ratio of glycols is the low quality aromatic hydrocarbons by high concentration of impurities of saturated hydrocarbons, in particular, Methylcyclopentane in benzene.

The consequences of low dissolving ability of mixtures of glycols with water are the high ratio of extractant to raw materials (8-15:1 wt.), high temperature extraction process (150oC), high consumption of acute water vapor in the distillation arenes from the extract phase.

Closest to the technical essence and the achieved effect of the present invention method for separating aromatic hydrocarbons from mixtures thereof with non-aromatic using as extractant mixtures of di - and triethylene glycol with tetrahydrofurfuryl alcohol (TGFS) in a ratio of 70/30 (wt.) (SU 833938, C 07 C 7/10, 30.05.81).

The disadvantage of this method is not only insufficient selectivity of mixtures of glycols with tetrahydrofurfuryl alcohol, n the basics by distillation, due to significant differences in the boiling points tetrahydrofurfurylamine of alcohol and diethylene glycol (T = 67oC) and triethylene glycol (T = 110oC). At boiling point TGPS the ratio of the pressure of saturated steam TGFS and the TAG is 31.4 and TGFS and deg - 5.9.

With the purpose of increase of efficiency of process of separating aromatic hydrocarbons from mixtures thereof with saturated hydrocarbon liquid extraction as a selective solvent is proposed to use a mixture of diethylene glycol with N-formylmorpholine and triethylene glycol with sulfolane when the content of the glycol in a mixture of 70 wt.%, and second component 30 wt.%.

A mixture of diethylene glycol with N-formylmorpholine outperforms extraction properties as diethylene glycol and a mixture of diethylene glycol with tetrahydrofurfuryl alcohol (PL. 1).

Unlike in opposition to the invention, the components of the proposed mixed extractants have similar boiling point: TAG (287.4oC) and sulfolane (287.8oC), DEG (245oC) and N-formylmorpholine (244oC). The ratio of the pressure of saturated steam system components TAG - sulfolan - 1.008, and N-formylmorpholine - deg 1.004, i.e. these compounds ablauts leads to the increase of the coefficient of distribution and the degree of extraction of toluene, however, this reduces the concentration of toluene in the extract and the separation factor of hydrocarbons, because of lower selectivity TGFS compared with glycols.

The addition of 30 wt.% sulfolane to TAG leads to an increase of all indicators of the extraction process as compared with the TAG (in the greatest degree increases the degree of extraction and the distribution coefficient of toluene), and with a mixture of TAG - TGFS (especially on the content of the toluene extract and partition coefficient). The results obtained with the proposed mixed extractant TAG - sulfolan due to the fact that he beats the TAG, and a mixture of TAG - TGFS both selectivity and solvent's ability to aromatic hydrocarbons.

The pressure of 30 wt.% - formylmorpholine to DAG increases the degree of extraction and distribution coefficient of toluene compared to deg and increase all extraction parameters in comparison with a mixture of deg - TGFS proposed in opposition to the invention.

The smaller the viscosity of the mixture DAG - N-formylmorpholine compared to the MONEY (for example, at 60oWith a dynamic viscosity of MONEY with 5 wt.% water 8.0 centipoise, and the viscosity of the mixture MONEY with 30 wt.% N-formylmorpholine, the temperature. Moreover, the extractant is superior to the watered at 150 degoC on all parameters of the extraction process.

In table. 2 presents the results of a single-stage extraction of organs offered mixed extractants, as well as DAG and TAG from catalyzate reforming install LH-35-8/300B JSC "Kirishinefteorgsintez". When the extraction arenes TAG and a mixture of TAG - sulfolan used stable can produce the following composition, wt. %: benzene - 15.55, toluene - 17.25, arena C8- 1.90, saturated hydrocarbons - 65.3. When the extraction arenes deg and a mixture of deg - N-formylmorpholine used sample catalyzate with a higher content of arenes, wt.%: benzene - 19.6, toluene - 18.2, arena C8- 1.4, saturated hydrocarbons - 60.8.

High dissolving ability of the proposed mixed extractants and lower viscosity compared to deg and TEG allows to reduce the temperature of the extraction process mixtures TAG - sulfolan and DAG - N-formylmorpholine from 150 to 70oC. thus, as shown in table. 2 results offer mixed extractants exceed watered DAG and TAG on all parameters of the extraction process - the distribution coefficients and the degree of extraction of arenes to as solving ability, and selectivity adding sulfolane to TAG and N-formylmorpholine to deg.

In table. 3 presents the main parameters and results of a six-speed countercurrent extraction arenes from catalyzate reforming using TEG, deg, and the proposed mixed extractants. Adding to the TAG 30 wt.% sulfolane reduces the ratio of extractant to raw materials at 25 wt.% and temperature of the extraction process, and significantly reduce the consumption of risaykl. In this case, loss of arenes with rafinate phase decreases and the degree of their extraction, in particular toluene and arenes C8is raised.

Adding to deg 30 wt.% N-formylmorpholine the ratio of the extractant to the raw material, the temperature of the extraction and consumption of risaykl can also be significantly reduced while increasing the degree of extraction of arenes.

An important advantage of the process of extraction of the proposed mixed extractants is also in the reduction of specific energy consumption, due to the low process temperature, the ratio of extractant: raw materials, heats of vaporization, viscosity and specific heat capacities of mixtures TAG - sulfolan and DAG - N-formylmorpholine compared to TEG and deg. So, share the Olin - water at 100oC Cp= 2.51 j/goC. the Specific heat of the TAG with 8 wt. % water at 150oC Cp= 2.85 j/goC, and offer a mixture of TAG - sulfolan - water at 120oC Cp= 2.35 j/goC.

Example 1.

In a sealed vessel with a magnetic stirrer load of 50 g of material containing 35 wt.% toluene and 65 wt.% heptane and 100 g of solvent of the following composition: TAG - sulfolan (70/30 wt.). The mixture thermostatic for 30 min at 50oC under vigorous stirring. After sedimentation of the upper and lower layers separated. The top layer (rafinate phase) was washed with water, dried over calcium chloride, filtered off and weighed. Get 42.62 g of raffinate containing 26.8% toluene and 73,2% heptane. From the lower layer (extract phase) by distillation with water vapor is separated 7.25 g of extract containing 82.4% toluene and 17.6% heptane.

Removing the toluene is 34.1% of the potential content in the initial mixture.

Example 2.

In a sealed vessel with a magnetic stirrer load of 50 g of material containing 35% of toluene and 65% heptane and 100 g/extractant of the following composition: DAG - N-formylmorpholine (70/30 wt.%). The mixture thermostatic for 30 min at 50oC when intensive phase allocate 7.45 g of extract, containing 78.6% of toluene. Removing toluene amounted to 33.5% of the content in raw materials.

Example 3.

In an airtight container with a stirrer load of 50 g catalyzate reforming containing 34.8% of aromatic hydrocarbons, and 100 g of solvent of the following composition, wt.%: triethylene glycol - 65,8, sulfolan - 28.2, water - 6.0.

After stirring at a temperature of 70oC for 30 min and sedimentation of the upper and lower layers separated. By distillation with water vapor from the extract phase allocate 7.2 g of extract containing 77.6% aromatic hydrocarbons. The extraction of aromatic hydrocarbons totaled 32.0% of the content in the catalyzate reforming.

Example 4.

In an airtight container with a stirrer load of 50 g catalyzate reforming containing 39.2% of aromatic hydrocarbons, and 100 g of solvent of the following composition, wt.%: diethylene glycol - 66,5, N-formylmorpholine - 28.5, water is 5.0.

After stirring and settling at a temperature of 70oC the upper and lower layers separated. By distillation with water vapor from the extract phase allocate 10.55 g of extract containing 74,7% aromatic hydrocarbons. Removing arenes 40.2% of the content in raw materials.

Example 5.

oC at a temperature of 70oC (consumption of 100 g/hour) containing 40.4% of arenes, including: benzene - 20,2%, toluene 18,8%, arenes C8to 1.4%. In the upper part of the extraction column at a temperature of 120oC with a speed of 600 g/h is the extractant composition of triethylene glycol - sulfolan (70/30) containing 6% of water. In the bottom of the extractor additionally served risaykl containing 60% arenes in the amount of 31% for raw materials extraction.

In the multistage countercurrent extraction after stable mode is selected raffinata phase, washed with water from the traces of solvent, dried and analyzed. The content of arenes in the raffinate is 1.12%. The carrying amount of the extract phase is sent to a distillation column for distillation of risaykl and extract with water vapor. Risaykl is returned to the bottom of the extractor, and the extract is washed with water, dried and analyzed. The content of aromatic hydrocarbons in the extract was 99.25%.

The degree of extraction arenes from catalyzate reforming amounted, %: benzene - 99,8, toluene - 97,3, arenes C8- 89,0.

Example 6.

In the lower part of the extractor serves reforming catalysate composition described in the temperature 100oC is fed into the upper part of the extractor in the amount of 800% on raw materials extraction. In the bottom of the extractor additionally served risaykl containing 71% of arenes in the amount of 60% of raw materials extraction.

After processing (for example 5) products extraction are analyzed. The raffinate contains 1.78% arenes.

The degree of extraction arenes from catalyzate reforming amounted, %: benzene is 98.8, toluene - 96,4, arenes C8- 88,6.

Sources of information

1. Sulimov, A. D. Production of aromatic hydrocarbons from petroleum sources. - M.: Chemistry, 1975 - 304 S.

2. Hrušov E. I., Shcherbina E. I. A. S. 833938, C 07 C 7/10, 1981. BI N 20, 1981.

The method of extraction of aromatic hydrocarbons from mixtures with non-aromatic by liquid extraction with a selective solvent-based di - and triethylene glycol, characterized in that as the selective solvent used inseparable boiling mixture of diethylene glycol with N-formylmorpholine or triethylene glycol with sulfolane containing 5 to 6 wt.% water.

 

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