D E A R O M A T I Z A T I O N OF E X T R A C T I O N B E N Z I N E D I S T I L L A T E

W I T H DIME T H Y L F O R M A M I D E

G. E. L e d y a s h o v a a n d A. Z . D o r o g o c h i n s k i i UDC 665.521.2:665.52.061.5:542.52

Benzine which is used in the food industry to extract fats and oils should not contain more than 4% of aro- matic hydrocarbons.

In connection with a study of dimethylformamide as a selective solvent for the aromatic hydrocarbons which are contained in benzine fractions [1], the authors of this article have also checked out the possibility of dearomat- izing extraction benzine distillate.

The extraction of aromatic hydrocarbons from extraction benzine distillate with dimethylformamide was car- ried out using a disk rotary extractor. Extraction conditions were selected as a result of experience in dearomatiz- ing "Galosh" benzine with this solvent [1]. The sample of extraction benzine distillate was withdrawn from one of the units of the Groznyi petroleum refinery, The aromatic hydrocarbon content in it was 4.7% by weight (density, p~0 0.709; refractive index, n~ 1.3994; aniline point, 51.5~

In Table 1 we give the results of extracting aromatic hydrocarbons from the extraction benzine distillate with dimethylformamide. In Fig. 1~ for comparison with the results of extracting aromatic hydrocarbons from extraction benzine distillate with dimethylformamlde, we give results of dearomatlzing a similar feedstock with diethylene glycol obtained on a laboratory extractor [2].

~r80

o ~ /

( , 0 l , t , , j

2

I I I 3

�9 N !

�9 I I I I I

"~ ~ / $ 5 7 .9 1t Solvent to feed ratio (by wt.)

Fig. 1. Effect of solvent ratio on characteristics of extraction of aromatic hydrocarbons from ex- traction benzine distillate with dimethylformamtde or with diethylene glycol: l) for dimethylformamide (10%o water) at 40-45~ 2) for diethylene glycol (8% water) at 140-150~

Groznyi Scientific Research Institute. Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 8, pp. 9 to 10, August, 1968.

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TABLE 1. Results of Dearomatizing Extraction Benzine Distillate with Dimethylformamide (10% water) in a Laboratory Rotary Disk Extractor

Conditions and characteristics of dearomatization

Extraction temperature, deg C Aromatic hydrocarbons extracted, wt. % Yield of rafftnate, wt. % of distillate Properties of raffinate;

density, O z0 4 refractive index, n~ aniline point, deg C % by wt. (OST-17872-40, M.I. 20K-40

Yield of extract, wt. % of distillate Properties of extract:

density, 042~ refractive index, n~ aromatic hydrocarbon content,

wt. % (GOST-6994-54)

;olvent to feedstock ratio (by weight)

I:I

40-45 41.8 97.0

0.706

1.3966

54.2

3.1

3.0

0.813 1.4593

65.6

2 . 2 . 1

40-45 94.6 91.7

0.703

1.3942

56.6

0.7

8.3

0.783

1.4411

48.0

2 . 7 : 1

40-45 95.0 87.8

0.702

1.3938

57.6

0.2

12.2

0.764 1.4292

36.6

From the data shown, it is evident that aqueous dimethylformamide (10% water) at extraction temperatures of 40-45~ possesses higher dearomatizing ability and selectivity than diethylene glycol (8% water) at 140-150~

An aromatic hydrocarbon extraction of 95% of the theoretically possible is attained at a solvent to feedstock (d[stiilate) ratio of 2.2. The raffinates obtained as a result of the extraction (0.2-0.7% aromatic hydrocarbons) can be used as solvents in the food industry and also in polymerization of low-molecular-weight olefins.

C O N C L U S I O N S

1. Dimethylformamide is a highly effective solvent for the aromatic hydrocarbons contained in extraction benzine distillate.

2. An aromatic hydrocarbon extraction of 95% of the theoretically possible is attained with dimethylform- amide (10% water) at a solvent to feedstock (distillate) ratio of 2.2 and an extraction temperature of 40-45~

1~

2.

L I T E R A T U R E C I T E D

G. E. Ledyashova and A. Z. Dorogochinskii, Khim. i Tekhnol. Topliv i Masel, No, 3 (1966). M, G. Mitrofanov, O. A. Artem'eva, and G. E. Ledyashova, in: Production of Benzine [in Russian], Goskhi- mizdat (1962).

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