RU2525552C1 - Additive for increase of cetane number of diesel fuel and method of its obtaining - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to an additive for the increase of the cetane number of Diesel fuel based on alkylnitrate, characterised by the fact, that the additive represents an alkylnitrite-containing product of nitration of the fraction IBP-195°C, separated from the bottom residue of production of butyl alcohols and which contains isopentanol from 0 to 5.0 wt %, isoheptanols from 5.0 to 10.0 wt %, dimethylcyclohexanols from 5.0 to 10.0 wt %, isooctanols from 10.0 to 40.0 wt %, polybutoxybutanes from 0 to 15.0 wt %, dibutoxybutanes - the remaining part. The invention also relates to a method of obtaining the additive for the increase of the cetane number of Diesel fuel by nitration of the fraction IBP-195°C, separated from the bottom residue of production of butyl alcohols, by a mixture of sulphuric acid in the range of temperatures of 0-8°C for 1.0-1.5 hours.

EFFECT: application of the said fraction makes it possible to extend resources of the raw material for the production of the cetane-increasing additive, excludes the necessity of the said fraction separation, reduces expenditures for the additive obtaining, the application of the additive makes it possible to increase the cetane number of Diesel fuel.

3 cl, 1 tbl, 2 ex

Description

The invention relates to the field of oil refining and petrochemicals, and in particular to the composition and method of producing additives that increase the cetane number of diesel fuel.

Known methods for producing cyclohexyl nitrate using flooded nitrating mixtures of acids at a temperature not exceeding 0-5 ° C. The nitration process is carried out in an environment of solvents - methylene chloride, hexane, the presence of which facilitates heat removal from the reaction mixture (Piterkin RN, Chesalov AM Nitration of cyclohexanol in a solvent environment. / Chemical industry, No. 9, 2000, p. 483-486 )

The disadvantages of these methods are the use of solvents, scarce expensive raw materials cyclohexanol, which leads to an increase in the cost of additives.

Also known is a method of producing a cetane-enhancing additive - 2-ethylhexyl nitrate by nitration of 2-ethylhexanol with a basic substance content of at least 99.0 wt.% Nitrating mixture of nitric and sulfuric acids with the addition of urea, with the separation of waste acids from the target product - 2-ethylhexyl nitrate and the subsequent washing it successively twice twice with a 10 wt.% aqueous solution of sodium sulfate and then once with a 10 wt.% solution of a mixture of sulfate and sodium carbonate taken in a 1: 1 ratio, using 2 parts of 2-ethylhexyl nitrate each time and 1 part of a solution of salts (U.S. Patent №5162568, S07S 203/04, 1992 YG).

The disadvantages of this invention are:

- the use of expensive and scarce raw materials - 2-ethylhexanol to obtain a cetane-raising additive;

- requires a large consumption of reagents for washing 2-ethylhexyl nitrate;

- low stability and stability of the nitration process, which is due to the supply of nitratable substances - 2-ethylhexanol in the nitrating mixture.

These shortcomings complicate the process, reduce production efficiency, increase the cost of additives.

The closest in technical essence and the achieved effect is a method for producing a cetane-raising additive, in which a fraction boiling off at a temperature of 166-190 ° C, isolated from the bottom residue of the production of butyl alcohols obtained by oxosynthesis, is used as a raw material. The nitration process of a fraction with a boiling range of 166-190 ° C, containing 2-ethylhexanol as the main component for nitration, is carried out using a mixture of nitric and sulfuric acids at a temperature of 8-18 ° C for 1.5-2.5 hours. Obtained by nitration, the products are separated from spent in the process of nitration of acids. The separated organic layer (target product) is washed twice with a 10 wt.% Salt solution obtained by neutralizing the spent acids and once with the same solution with the addition of a 10 wt.% Sodium hydroxide solution, 3 wt. parts of a solution of salts are added per 10 wt. parts of the target product (RF patent No. 2235118 C10L 1/22, C07C 203/04, 2002).

The disadvantages of this method are:

1) as a raw material, a fraction of the bottoms residue of butyl alcohols, limited to the boiling point, is used, which significantly reduces the resources of the raw materials for the synthesis of additives and requires additional technological equipment for the separation of raw materials, which leads to an increase in the cost of additives;

2) the irrational use of the fraction NK-166 ° C isolated during fractionation of the bottom residue of butyl alcohols;

3) the process at a longer time for 1.5-2.5 hours reduces the performance of the installation.

The technical objective of the invention is to expand the raw material base, simplify the technology for the production of cetane-raising additives, reduce the consumption of reagents for the production of additives, increase the efficiency of its use in diesel fuel, as well as the qualified use of bottoms production of butyl alcohols and acid spent in the nitration process.

The task is achieved in that the additive for increasing the cetane number of diesel fuel based on alkyl nitrate is an alkyl nitrate-containing product of nitration of the NK-195 ° C fraction isolated from the bottom residue from the production of butyl alcohols. As a raw material for the additive use fraction NK-195 ° C of the following component composition, wt.%:

isopentanol from 0 to 5.0 isoheptanols from 5.0 to 10.0 dimethylcyclohexanols from 5.0 to 10.0 isooctanol from 10.0 to 40.0 polybutoxybutanes from 0 to 15.0 dibutoxybutanes rest

The task in terms of the method of producing additives to increase the cetane number of diesel fuel by nitration of the fraction extracted from the bottoms of the production of butyl alcohols is solved by nitration of the NK-195 ° C fraction at a temperature from 0 to 8 ° C for 1.0 -1.5 hours.

The method of producing additives to increase the cetane number of diesel fuel is as follows: carbamide, which prevents oxidation processes, is loaded into a cooled reactor, then, with constant cooling and stirring, (4-5 ml / min) a previously prepared nitrating mixture of sulfuric and nitric acids is dosed, then at a speed of 4-5 ml / min, the NK-195 ° C fraction, carefully controlling the temperature that is maintained in the reactor from 0 to 8 ° C. Upon completion of loading the nitrating mixture and the NK-195 ° C fraction into the reactor, the reaction mass is maintained at a temperature of 0 to 8 ° C for 1.0-1.5 hours. Next, the resulting reaction mixture is subjected to separation, where the spent acid is separated from the organic layer of the nitration product. After separation, the organic layer is washed twice with a 10 wt.% Solution of salts (sulfate and sodium nitrate) obtained by neutralizing the acids worked out in the nitration process (acidity is neutral); and carry out a single wash with the same solution with the addition of 10 wt.% aqueous sodium hydroxide solution (alkaline acidity). When washing with 10 wt. parts of the nitration product use 3 wt. parts of a 10 wt.% salt solution.

A distinctive feature of the invention is:

- use as a raw material for the additive fraction, boiling within the limits of NK-195 ° C, isolated from the bottom residue of the production of butyl alcohols;

- use as a raw material for the additive of the NK-195 ° C fraction of the following component composition, wt.%:

isopentanol from 0 to 5.0 isoheptanols from 5.0 to 10.0 dimethylcyclohexanols from 5.0 to 10.0 isooctanol from 10.0 to 40.0 polybutoxybutanes from 0 to 15.0 dibutoxybutanes rest

- simplification of the technological scheme of obtaining additives to increase the cetane number due to the elimination of the need to isolate fractions NK-166 ° C;

- the nitration process is carried out at lower temperatures (in the temperature range from 0 to 8 ° C) and a shorter nitration process;

- reduced concentration of nitric acid in the nitrating mixture by 10 wt.%, which reduces the corrosion of the equipment.

The solution of this problem allows you to increase the efficiency of the additive and expand the raw material base for its production.

The invention is illustrated by the following examples:

Example 1. In a reactor equipped with a stirrer and a cooling bath, 1.6 g of urea are charged in the temperature range from 0 to 8 ° C, then, with constant cooling and stirring, the nitrating mixture obtained by mixing is dosed at a speed of 4-5 ml / min , 0 ml of nitric acid at a concentration of 58.8 wt.% And 20.0 ml of sulfuric acid at a concentration of 93.3 wt.%. As a raw material for nitration, the NK-195 ° C fraction was used, which was supplied to the reactor at a rate of 4-5 ml / min in an amount of 26.0 ml. After the introduction of the entire amount, the reaction mixture with continuous stirring is kept in the temperature range from 0 to 8 ° C for 1.0-1.5 hours. At the end of the nitration process and the separation of the reaction mixture, the spent acid is separated from the organic layer of the nitration product.

For the treatment of the organic layer, a 10 wt.% Solution of a mixture of sodium sulfate and sodium nitrate salts is used, obtained by neutralizing the sodium hydroxide spent in the nitration process (medium acidity is neutral), in an amount of 10 cm ³ for double treatment and a third time in an amount of 10 cm ³ salt solution with the addition of 4 cm ³ 10 wt.% sodium hydroxide solution (alkaline acidity). Each treatment is carried out with stirring for 15 minutes.

Example 2. (Prototype) Data on cetane numbers are taken from the table of the prototype.

The additives obtained are added to diesel fuel and the cetane characteristics of diesel fuel are determined. The test results are shown in table 1.

Table 1 The additive obtained by example The amount of additives added to diesel fuel, wt.% Cetane number of diesel fuel, cetane units Change in cetane number of diesel fuel source after adding additives one 0.2 46.0 52,2 6.2 0.5 55.0 9.0 2 0.2 48.0 52.0 4.0 0.5 52.0 59.0 7.0

From table 1 it follows that with the addition of 0.2-0.5 wt.% Additives obtained according to the claimed invention, the cetane number increases by 6-9 units in diesel fuel. The use of the NK-195 ° C fraction allows expanding the resources of the raw materials for the production of a cetane-raising additive, eliminates the need to isolate the NK-166 ° C fraction, and reduces the cost of obtaining the additive.

Claims (3)

1. Additive to increase the cetane number of diesel fuel based on alkyl nitrate, characterized in that the additive is an alkyl nitrate-containing nitration product of the NK-195 ° C fraction isolated from the bottom residue of the production of butyl alcohols of the following composition, wt.%:
isopentanol from 0 to 5.0 isoheptanols from 5.0 to 10.0 dimethylcyclohexanols from 5.0 to 10.0 isooctanol from 10.0 to 40.0 polybutoxybutanes from 0 to 15.0 dibutoxybutanes rest 2. The method of producing additives to increase the cetane number of diesel fuel by nitration of the fraction isolated from the bottom residue of the production of butyl alcohols, characterized in that the fraction NK-195 ° C of the composition according to claim 1 is used as raw material for the additive. 3. The method according to claim 2, characterized in that the nitration process is carried out at a temperature of from 0 to 8 ° C for 1.0-1.5 hours