SU819078A1 - Method of hydrocarbon purification from cyclopentadiene - Google Patents

Description

The invention relates to the petrochemical industry, in particular to the prevention of thermopolymerization of styrene in the process of its production.

The production of styrene from ethylbenzene includes the steps of dehydrogenation of ethylbenzene and the separation of styrene from the products of dehydrogenation by distillation. The rectification process is significantly complicated due to the tendency of styrene to spontaneous polymerization at high temperatures (90-120 ° C), supported in the columns.

The most common styrene thermopolymerization inhibitor used in industry is a mixture of p-quinondioxime and hydroquinone [lj.

There is also a method of inhibiting the polymerization of styrene at elevated temperatures with a mixture of / g-quinondixime with nitrophenol [2]. However, p-quinondioxime is insoluble in styrene and is deposited on the plates of distillation columns during operation, resulting in a decrease in their productivity. This especially affects valve plates, which are used in industry. In addition, work experience at styrene-producing enterprises showed that the use of n-quinondioxime is undesirable when using film ki2 pyatilnikov, since α-quinondioxime clogs the distribution grid and thereby reduces the efficiency of the equipment.

There is also a method of inhibiting the thermopolymerization of vinyl aromatic hydrocarbons, for example methyl vinyl pyridine, in which 3,5-dialkyl- (aryl) -4-okch-N, N10-dimethylbenzylamine or its mixture with sulfur 131 is used as an inhibitor. This method is sufficiently reliable for methyl vinylpyridine and relatively well protects equipment from clogging with a thermopolymer. However, in the case of styrene 15, the inhibitory ability of Zb-di-tert-butyl-4-hydroxy-K, Y-dimethyl benzyl amine or its mixture with sulfur is insufficient, and a very high inhibitor consumption is required to achieve the desired result.

The aim of the invention is to increase the efficiency of inhibition by reducing the consumption of inhibitor, ensuring high performance equipment.

This goal is achieved by the proposed method of inhibiting styrene by introducing a preheated solution of a mixture of 3,5-di-7 ^, ret-butyl-4-hydroxy-Ν, Ν-dimethylbenzylamine and aliphatic carboxylic acids Су — С ₂ о with a weight ratio of 30 of components 1 —20: 1 in aroma 819078 with a sand solvent taken in an amount of 0.05-0.22 weight. % of styrene.

The inhibitor is preferably used in the form of a 2-20% solution in an aromatic solvent.

Preheating the inhibitor mixture solution is carried out for 1–48 hours at 35–85 ° С.

The following examples show weight percent on styrene.

P r'imer 1 (prototype).

In a vial purged with nitrogen, 20 g of styrene are charged and 3,5-ditret-butyl-4-hydroxy-I, N-dimethylbenzylamine as an inhibitor. The ampoule is sealed and then thermostated at 120 ° C for 6 hours. After cooling, the ampoule is opened, the resulting polymer is planted and dried to constant weight. The results are presented below.

Dosage of 3,5-di-tert-butyl-4-hydroxy-K ^ -dimethylbeisylamine,% 0.075 0.100 0.500

The yield of thermopolymer,% 46.0 34.2 2.00

Example 2 (prototype). Under the conditions of Example 1, a mixture of 3,5-di-772et-butyl-4-hydroxy-L [, M-dimethylbenzylamine with sulfur is used as an inhibitor. The results are given below.

Dosage of 3,5-di-tert-butyl-4 · hydroxy-M.M-dimethylbepzilamine,%

Sulfur dosage,% Thermopolymer yield,%

Example 3 In the conditions of example 1, 0.22% of a mixture of 3,5-di-7'ret-butyl-4-hydroxy-I, I-dmethylbenzylamine and stearic acid (GOST 64-84-64), taken in a weight ratio of 10: 1, in the form of a 20% benzene solution, preheated at 35 ° C for 48 hours. The yield of the thermopolymer is 0.00% (the polymer did not form).

Example 4. Under the conditions of Example 1, 0.082% of a mixture of 3,5-di-tert-butyl-4-hydroxy-X ^ -dimethylbenzylamine and stearic acid is used as an inhibitor,

0,200

0,200

7.5

0,200 0,100

0.020 0.010

4.6 19.7 taken in a weight ratio of 10: 1 components in the form of a 10% toluene solution, preheated at 85 ° C for 1 h. The yield of the thermopolymer is 0.45%.

Example 5. Under the conditions of Example 1, 0.050% of a mixture of 3,5-di-treg-butyl-4-hydroxy-I, C-dimethylbenzylamine and synthetic fatty acid (aliphatic carboxylic acids Siu-Ci6 OST 38-7-25 are used as an inhibitor -73), taken in a weight ratio of 10: 1, in the form of a 10% egilbenzene solution, preheated for 5 hours at 55-60 ° C. The yield of thermopolymer is 0.65%.

Example 6. In the conditions of example 1, 0.22% of a mixture of 3,5-di-tert-butyl-4-hydroxy-No, P-dimethylbenzylamine and synthetic fatty acid C17 — C ₂ about (OST 38-7- 25-73) taken in weight Order 239S

Ed. No. 278 in a 20: 1 ratio, in the form of a 10% ethylbenzene solution, heated at 55-60 ° C for 2 hours. The polymer yield was 0.40%.

Example 7. Under conditions of example 1 to ₅ is used as an inhibitor 0.22% of a mixture of ^3,5-di-t ret-butyl-4-hydroxy-I, I-dimethylbenzylamine and synthetic fatty acid in the weight ratio 2: 1 , in the form of a 20% xylene solution, preheated at 55-60 ° С for 2 hours. The polymer yield is 0.55%.

Example 8. Under the conditions of Example 1, 0.22% of a mixture of 3,5-di-treg-butyl-4-hydroxy-I, I-dimethylben15 zylamine and stearic acid, taken in a weight ratio of 1: 1 in the form of 10, is used as an inhibitor. % ethylbenzene solution, preheated at 55-60 ° C for 2 hours. The polymer yield of 0.16%.

EXAMPLE 9 A 10% ethylbenzene inhibitor solution in an amount of 0.082% per styrene is preheated for 2 hours with stirring at a temperature of 55-60 ° C in the styrene rectification system.

₂₅ The mixture is used as an inhibitor

3,5 - di-tert-butyl-4-OKCH-N, N-dimethylbenzylamine and stearic acid in a weight ratio of 10: 1. The amount of thermopolymer in the cube of the rectification column of styrene 30 is 0.1-0.3 weight. %

The proposed method, in comparison with the known method, allows to increase the efficiency of inhibition, reduce the consumption of an inhibitor, avoid clogging equipment _{35 with a} thermopolymer due to a decrease in its formation, and therefore increase the yield of marketable styrene.

Claims (3)

Claim 1. A method of inhibiting the thermopolymerization of styrene by introducing a polymerization inhibitor, characterized in that, in order to increase the efficiency of inhibition, a preheated solution of mixture is used as an inhibitor 4§ Cu 3,5-di-tert-butyl-4-hydroxy-S, C-dimethylbenzylamine and aliphatic carboxylic acids Сю — С ₂₀ at a weight ratio of components of 1-20: 1 in an aromatic solvent, taken in an amount of 0.05— 50 0.22 weight. % of styrene. 2. The method according to π. 1, characterized in that the inhibitor is used in the form of a 2-20% solution in an aromatic solvent. 55 'Sources of information taken into account in the examination 1. USSR Copyright Certificate No. 257496, cl. C 07 C 7/18, 1968. 2. USSR copyright certificate _f6fl No. 441263, cl. C 07 C 7/18, 1972. 3. / USSR Copyright Certificate No. 504787, cl. C 08 F 2/40, 1974 (prototype). Circulation 448 Subscription Zagorsk Printing House of Uprpoligrafizdat Mosoblispolkoma