RU1810333C - Method of aqueous acetonitrile hydrolysis inhibition - Google Patents

Abstract

Usage: in the process of separation of C4 - Cs hydrocarbons by the method of extractive distillation as an extractant. SUBSTANCE: method for inhibiting hydrolysis of aqueous acetonitrile. Reaction conditions: a base, an aqueous solution of sodium hydroxide mixed with ethylene glycol, is added to an aqueous solution of acetonitrile in a ratio of 1: 1, in an amount of 0.001-0.01% by weight of acetonitrile. The reaction temperature is 150 ° C. The ammonia content in the reaction mass is 0.002-0.00022 wt.%.

Description

The invention relates to a method of inhibiting the hydrolysis of aqueous acetonitrile during the separation of d-Cs hydrocarbons by extractive distillation.

An object of the invention is to reduce the rate of hydrolysis of acetonitrile. The goal is achieved by a method of inhibiting the hydrolysis of aqueous acetonitrile at elevated temperatures in separation processes by extractive distillation of hydrocarbons cVCs by introducing a base - an aqueous solution of sodium hydroxide mixed with ethylene glycol in a weight ratio of 1: 1, taken in the amount of 0.001-0.01 May. % - to the extractant The difference of this method is that an aqueous solution of sodium hydroxide mixed with ethylene glycol is used as the base in a ratio of 1: 1, taken in an amount of 0.001-0.01 wt.% to the extractant.

This inhibitory system is highly soluble in aqueous acetonitrile, strongly binds H + ions and thereby significantly slows down the autocatalytic hydrolysis process. To prepare it, a 15% alkali solution is taken and mixed with ethylene glycol at a ratio of 1: 1. A more concentrated alkali solution forms an insoluble precipitate with ethylene glycol.

Ethylene glycol is used as an alkali solvent for a better solution, neither in the extractant, it allows to exclude additional water, enhancing the hydrolysis of acetonitrile, and, as a result

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outside corrosion-enhancing equipment. Ethylene glycol additives do not worsen the process, they even slightly reduce the formation of ammonia in acetonitrile. The concentration of the inhibitory system in the extractant is 0.001-0.01% by weight. The concentration of alkali metal hydroxide is 0.0001-0.001 wt.%, The concentration of ethylene glycol is 0.0007-0.007 wt.%. An increase in alkali content in the extractant in excess of 0.001 wt.% Is undesirable, as it can lead to alkaline hydrolysis of acetonitrile.

Example (prototype) Acetonitrile containing b wt.% Water, 0.03 wt.% Tri-ethanolamine (TEA), was loaded into a metal reactor and thermostated at a temperature of 150 ° C for 24 hours. After cooling, it was determined Using cytometric titration, the ammonia content was 0.003 wt.%.

PRI me R 2. Acetonitrile containing 6 wt.% Water. 0.00008 wt.%. NaOH, 0.0003 wt.% Ethylene glycol (the content of the inhibitory system in the extractant was 0.0006 wt.%, The ratio of a 15% NaOH solution and ethylene glycol 1: 1) was tested under the conditions described in Example 1.

The ammonia content in the reaction mixture is 0.002 May. %

PRI me R 3 Acetonitrile containing 6 wt.% Water, 0.0001 wt.% NaOH, 0.0607 wt.% Ethylene glycol (inhibitory content of 0.0015 wt.%, The ratio of a 15% solution of NaOH and ethylene glycol 1 : 1), was tested under the conditions described in example 1,

Ammonia content 0.00043 wt.%.

PRI me R 4. Acetonitrile; containing 6 wt.% water, O. Oobb wt.% NaOH, 0.003 wt.% ethylene glycol (inhibitory content of 0.006 May.% ratio of 15% NaOH and ethylene glycol 1: 1), was tested under the conditions described in example 1.

The ammonia content in the reaction mixture is 0,00022 wt.%.

Example 5. Acetonitrile containing 6 wt.% Water, 0.001 wt.% NaOH, 0.007 wt.% Ethylene glycol (inhibitory content of 0.015 May.%, Ratio of 15% NaOH and ethylene glycol 1: 1), was tested under the conditions described in example 1.

The ammonia content in the mixture was 0,00058 wt.%.

PRI me R 6. Acetonitrile containing bmes.% Water, 0.01 wt.% NaOH, 0.07 wt.% Ethylene glycol (inhibitory system content of 0.15 wt.%, The ratio of 15%

NaOH solution and ethylene glycol 1: 1) were tested under the conditions described in Example 1.

The ammonia content was 0.003 wt.%.

Example (Comparative) Acetonitrile containing 6 wt.% Water, 0.001 wt.% NaOH was tested under the conditions described in Example 1.

The ammonia content was 0.0009

wt.%.

PRI me R 8, Acetonitrile containing 6 wt.% Water, 0.00007 wt.% NaOH, 0.0046 wt.% Ethylene glycol (inhibitory system content of 0.001 may.%; Ratio

A 15% solution of NaOH and ethylene glycol 1: 1) were tested under the conditions described in Example 1.

The ammonia content in the reaction mixture is 0,00027 wt.%.

PRI me R 9. Acetonitrile containing 6 wt.% Water, 0.0007 wt.% NaOH 0.0046 wt.% Ethylene glycol (inhibitory system content of 0.01 wt.%, The ratio of a 15% solution of NaOH and ethylene glycol 1: 1),

tested under the conditions described in Example 1.

The ammonia content in the reaction mixture is 0.00035 wt.%. Thus, the use of an inhibitory system (7.5 wt.% NaOH, 42.5 wt.% And 50 wt.% Ethylene glycol) leads to a decrease in the amount of ammonia in the reaction mixture by 7 , 5 times and slows down the hydrolysis of acetonitrile. This allows one to obtain an economic effect by reducing acetonitrile losses, reducing the formation of a by-product and increasing the mileage of the equipment.

Claims (1)

SUMMARY OF THE INVENTION A method of inhibiting the hydrolysis of aqueous acetonitrile at elevated temperatures during the separation by extractive distillation of C4-Cd hydrocarbons by introducing a base, and the like, in order to reduce the rate of hydrolysis, use an aqueous hydroxide solution as the base sodium in a mixture of d ethylene glycol in a ratio of 1: 1, in an amount of 0.001-0.01 wt.% to the extractant,