RU2324727C1 - Process of obtaining mixture of higher fatty acids - Google Patents

Abstract

FIELD: chemistry, organic, fatty acids.

SUBSTANCE: invention relates to process of obtaining mixture of higher fatty acids that are widely used in chemical, petrochemical, varnish-and-paint, tyre and other industry branches. The process involves isolation of fatty acids from the fat raw material with their subsequent distillation. Fatty acids, at that, will be released from sunflower oil by means of its distillation at the temperature 230-260°C and residual pressure 0.13-0.8 kPa, the distillate thus obtained will be repeatedly subjected to distillation at the temperature 210-220°C and residual pressure 0.67-1.33 kPa. The process enables one to reduce 2.5-5-fold unit discharge of the oil for production of distilled fatty acids, to simplify technology of obtaining distilled fatty acids and improve quality of the distilled fatty acids.

EFFECT: simplification of technology of obtaining and improvement of quality of distilled fatty acids.

2 cl, 2 tbl, 2 ex

Description

The invention relates to the oil and fat industry, and in particular to methods of processing oil and fat raw materials in order to obtain a mixture of higher fatty acids, which are widely used in chemical, petrochemical, paint, varnish, tire and other industries.

A known method of producing a mixture of higher fatty acids in the process of alkaline refining of vegetable oils to obtain an oily sludge (soap stock), saponification of the latter, treatment with mineral acid (usually sulfuric acid) to isolate free fatty acids, washing the obtained acids, drying and subsequent distillation. ("Guide to the technology for the production and processing of vegetable oils and fats", L., publishing house of VNIIZh, pp. 75-101, v.4, 1975).

The disadvantage of this method is the need to use mineral (sulfuric) acid, the presence of acidic effluents to be neutralized, which leads to the formation of a significant amount of wastewater containing sulfate salts, the treatment of which is difficult and requires large material costs.

A known method of obtaining a mixture of higher fatty acids by non-reactive hydrolysis of a composition of vegetable oils, consisting of 70-80% of the mass. high oleic sunflower oil and 20-30% mustard or rapeseed oils or mixtures thereof, followed by distillation of the obtained fatty acids (A.S. No. 1373724 "Method for producing a mixture of unsaturated higher fatty acids", С11C 1/04, С07С 57/02, 1988 g.).

The disadvantage of this method is the need for spending 100% edible vegetable oils and 2-stage splitting of oils in batch autoclaves using high-pressure steam (2.5 MPa).

The closest in technical essence and properties of the obtained product to the proposed method is a method for producing a mixture of higher fatty acids by non-reactive hydrolysis in two periods of a composition of vegetable oils in the presence of free fatty acids isolated from co-stocks of vegetable oils used in the formulation, and subsequent distillation of the resulting fatty acids. (AS No. 1664825 "Method for the production of a mixture of higher unsaturated acids", С11С 1/04, С07С 57/12, 1991)

This method is adopted as a prototype.

The disadvantage of this method is the significant consumption of edible oils - up to 80 wt.% And the need to use high pressure steam (2.5 MPa) during hydrolysis, which necessitates the use of metal-intensive autoclaves and high energy costs. In addition, up to 30 wt.% Of fatty acids isolated from the stocks of vegetable oils are used in the splittable composition, the production technology of which, as shown above, is not faulty from an environmental point of view.

The objective of the invention is to reduce the consumption of edible vegetable oils used, simplifying the method by eliminating two periods of non-reactive hydrolysis, improving the quality of distilled fatty acids.

The problem is solved in that in the method of obtaining a mixture of higher fatty acids from fatty raw materials with their subsequent distillation, moreover, fatty acids are isolated from vegetable oil by distillation at a temperature of 230-260 ° C and a residual pressure of 0.13-0.8 kPa, and the obtained distillate is further subjected to distillation at a temperature of 210-220 ° C and a residual pressure of 0.67-1.33 kPa. Sunflower oil can be used as a vegetable oil, and primary distillate with an acid number of 140-160 mg KOH / g is fed for re-distillation.

In the process of distillation of sunflower oil at low residual pressure and high temperature, the evaporation of free fatty acids, odorizing substances and other volatile compounds is ensured, their separation from the oil stream and subsequent condensation from the gas mixture.

Since during the distillation process mechanical losses of oil occur due to drop entrainment with the vapor phase, the obtained distillate is a mixture of predominantly fatty acids and a neutral oil with a mass fraction of fatty acids of 70-80%.

It should be noted that vegetable oil, subjected to high-temperature distillation, is purified from impurities, acquiring additional nutritional value, and is not completely split, as in the method adopted for the prototype. Re-distillation of the distillate extracted from sunflower oil with an acid number of 140-160 mg KOH / g is carried out in mild conditions at a temperature of 210-220 ° C and a residual pressure of 0.67-1.33 kPa, which allows to increase the acid number of the obtained fatty acids to 193 , 6 mg KOH / g and reduce the unsaponifiable content in the product to 2.7 wt.%.

When the applicant conducted the analysis of the prior art, an analogue was not found that was characterized by all the features of the claimed invention, and the definition of the prototype as the closest in terms of the totality of the features of the analogue made it possible to identify the totality of the essential distinguishing features in the claimed object set forth in the claims.

We give examples of the proposed method and the method adopted as a prototype.

Example 1 (prototype).

A composition consisting of 75% sunflower oil and 25% fatty acids isolated from the stocks of sunflower oil with an acid number of 60 mg KOH / g is subjected to non-reactive hydrolysis at a temperature of 225 ° C and a pressure of 2.5 MPa in two periods with a change of water with a total the ratio of reacting components 1: 0.75.

The split composition with an acid number of 184 mg KOH / g is distilled at a temperature of 230 ° C. and a residual pressure of 1.33 kPa. After distillation, fatty acids with an acid number of 192 mg KOH / g and an unsaponifiable content of 3.4 wt.% Were obtained.

Example 2

Sunflower oil with an acid number of 2.25 mg KOH / g is distilled at a temperature of 230 ° C and a residual pressure of 0.13 kPa. The isolated distillate with an acid number of 140 mg KOH / g is subjected to repeated distillation at a temperature of 210 ° C and a residual pressure of 0.67 kPa.

After secondary distillation, fatty acids were obtained with an acid value of 192.6 mg KOH / g and an unsaponifiable content of 3.2 wt.%.

Examples 2, 3, 4 of the implementation of the proposed method in comparison with the prototype (example 1) are shown in tables 1 and 2.

Moreover, examples 2, 3, 4 confirm the possibility of implementing the proposed method, which is reflected in the claims.

The transcendental values of the parameters of the oil distillation process at a residual pressure of less than 0.13 kPa are impractical due to the sharply increasing costs of providing a vacuum; increasing the distillation temperature above 260 ° C is inappropriate to avoid undesirable side reactions - polymerization, thermal decomposition, oxidation, etc., leading to poor quality and lower yield of the resulting products.

Beyond the parameters of the secondary distillation process of the distillate extracted from oil at a distillation temperature above 220 ° C and at a residual pressure below 0.67 kPa, undesirable impurities pass from the tar to the distillate, which increases the unsaponifiable content and reduces the acid number of the resulting fatty acids.

A decrease in the temperature of secondary distillation below 210 ° C and an increase in residual pressure above 1.33 kPa leads to an unjustified loss of marketable fatty acids remaining in the tar.

Thus, the proposed method for producing a mixture of higher fatty acids in comparison with the prototype allows you to:

- reduce the specific consumption of vegetable oil for the production of distilled fatty acids by 2.5-5 times;

- to simplify the technology for producing distilled fatty acids by eliminating two periods of non-reactive hydrolysis and reducing the total number of stages from 3 to 2;

- to improve the quality of distilled fatty acids by increasing the acid number to 193.6 mg KOH / g and reducing the unsaponifiable content to 2.7 wt.%.

Table 1
Technological parameters of the methods No. p / p The composition of the raw material composition, wt.% The acid number of the raw material composition, mg KOH / g Enumeration of technological operations. Isolation of Fatty Acids from Raw Compositions Distillation Non-reactive hydrolysis Oil distillation Fatty acid distillation after hydrolysis Distillation of distillate recovered from oil t, ° С R, MPa Number of periods t, ° С P, MPa t, ° С P, kPa t, ° С P, kPa one. Sunflower oil - 75
Soap stock fatty acids of sunflower oil - 25 (prototype) 60.0 Reactive oil hydrolysis. Distillation of crude fatty acids. 225 2,5 2 - - 230 1.33 - - 2. Sunflower oil - 100 2.25 Oil distillation. Distillation of fatty acids of a vegetable oil distillate. - - - 230 0.13 - - 210 0.67 3. Sunflower oil - 100 4.3 - - - 240 0.4 - - 215 0.95 four. Sunflower oil - 100 5.9 - - - 260 0.8 - - 220 1.33

table 2
Quality indicators of commercial and intermediate products No. p / p The composition of the raw material composition, wt.% The acid number of the raw material composition, mg KOH / g The acid number of hydrolysis products, mg KOH / g Acid number after distillation of hydrolysis products, mg KOH / g The acid number after the primary distillation of the oil, mg KOH / g Acid number after repeated distillation of the distillate recovered from the oil, mg KOH / g Number of process steps The consumption of edible oil per 1 ton of fatty acids, kg / t The content of unsaponifiable, wt.% one. Sunflower oil - 75 Fatty acids of stocks of sunflower oil - 25 (prototype) 60.0 184 190 - - 3 850 3.4 2. Sunflower oil - 100 2.25 - - 140.0 192.6 2 330 3.2 3. Sunflower oil - 100 4.1 - 150,4 193.2 2 240 2.9 four. Sunflower oil - 100 5.9 - - 160,0 193.6 2 160 2.7

Claims (2)

1. A method of obtaining a mixture of higher fatty acids, including the selection of fatty acids from fatty raw materials with their subsequent distillation, characterized in that fatty acids are isolated from sunflower oil by distillation at a temperature of 230-260 ° C and a residual pressure of 0.13-0, 8 kPa, the obtained distillate is again subjected to distillation at a temperature of 210-220 ° C and a residual pressure of 0.67-1.33 kPa. 2. The method according to claim 1, characterized in that the primary distillate with an acid number of 140-160 mg KOH / g is fed for re-distillation.