MXPA03011658A - Composition for inhibiting corrosion based on bisimidazoline 2,2'-naphthenic. - Google Patents

Abstract

The present invention refers to a composition for inhibiting corrosion based on bisimidazoline 2,2'nephthenic, which is a bicyclic compound presenting two imidazole rings linked by an ethyl bridge and having in the C2 of the first ring two cyclohexyl groups. Said cyclohexyl groups and the two imidazoline rings are linked with an ethyl by tertiary nitrogen atoms. The bisimidazoline 2,2'nephthenic is useful as an active principle for preparing said corrosion inhibiting composition, the same comprising 5% of isopropanol and xylene or naphtha, so as to be applied in concentrations (from about 10 to about 20ppm) lower than those used in further compounds that have been used in the corrosion inhibition of atmospheric distillation towers containing heavy crudes, which are highly corrosive due to the high content of salts and heavy metals such as vanadium and nickel.

Description

CORROSION INHIBITORY COMPOSITION BASED ON BISI IDAZOLINE 2,2'-NAPHTHENIC DESCRIPTION TECHNICAL FIELD The present invention relates to an effective corrosion inhibiting composition having as an active principle one of the new molecules of mixed bisimidazolines having in the imidazoline ring two identical naphtenyl substituent groups and having superior properties to inhibit corrosion with greater efficiency in the bitter waters resulting from industrial oil refining plants.

BACKGROUND OF THE INVENTION Heavy crude brings a higher cot of water and salts dissolved in it such as sodium chloride, calcium chloride, magnesium chloride, ionic sulphides of the same cations, hydrogen sulphide, sulfides and organic disulphides as well as coordinated vanadium and nickel compounds, which are highly corrosive, which is why it is necessary to use substances called corrosion inhibitors which, when added to the workflow, extend the useful life of the equipment.

For reasons of cost it is desirable that a compound can fulfill more than one function in the refining process, such as, neutralizing and de-emulsifying, as well as inhibiting corrosion.

The greater corrosive capacity of heavy crude oils makes it necessary to design more efficient corrosion inhibitors with an improved rheological behavior, that is, they do not form emulsions or suspensions with the chemical products used in the refining of crude oil, besides complying with the protection and neutralization functions.

In the Mexican patent MX 133364 of publication date of September 11, 1976, imidazolines substituted with a hydrocarbon chain of 16 to 18 carbon atoms are present in the C2 atoms and a 1-H-imidazole protonated in N2 of the imidazoline, that is, that the structure has an imidazoline ring and an imidazole ring.

US Pat. No. 4,482,724, dated November 13, 1984 assigned to Hoechst Aktiengesellschaft, mentions the use of bisimidazolines with dimerized fatty acid chains of 22 to 42 carbons and with substitutes of hydrogen, methyl, ethyl, benzyl and polyethoxylated radicals that are used as demulsifiers and corrosion inhibitors. This American patent represents the closest prior art in terms of the state of the art to the present invention, however, the substituents and raw materials from which they are made are different so that the radicals protected by it are also different .

The Mexican patent application with File No. PA / a / 2003/011620 of presentation date on December 15, 2003, the inventors of which we are the undersigned, refers to mixed bisimidazolines as active principles of corrosion inhibiting compositions that present in the structure of the imidazoline ring is identical or different substituents which may be hydrogen, oleyl, naphtenyl, dodecylbenzenesulfonyl, abieyl or dehydroabieyl. Preferably, protection of the active ingredients with new chemical structures, such as 2,2'-oleic bisimidazolines, and a bisimidazoline - [(1-aminoethyl) -imidazoline] -1,6-hexanoic which is abbreviated (bis- , 6-hex).

The present invention relates to the preparation of a composition having 2,2'-naphthenic bisimidazoline as the active principle. This new composition has a greater character dispersible in water to guara that the inhibitor acts in both phases, both with the gasoline and turbosine fractions and in the bitter waters in diesel and gasoline media and that solves the problems of formation of emulsions and / or suspensions at the water-gasoline and water-turbosin iface.

Therefore, an object of the present invention is to prepare a suitable composition so that the new 2,2'-naphthenic bisimidazoline optimizes its corrosion inhibiting properties by using it at lower concentrations (10 to 20 ppm) than those used in other compounds reported in corrosion inhibition in atmospheric distillation towers with heavy crudes that are highly corrosive due to their high cot of salts and heavy metals such as vanadium and nickel.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corrosion inhibiting composition for optimizing the application of the new 2,2'-naphthenic bisimidazoline which belongs to the family of imidazolines and is a new bicyclic compound linked by an ethyl bridge between the nitrogens 1 and V of the imidazoline rings which in turn have a naphthenyl group in C2 and in C2 '.

The composition of the present invention is prepared with 2,2'-naphthenic bisimidazoline with xylene and isopropanol to be used at lower concentrations (10 to 20 ppm) than those used in other compounds reported in the inhibition of corrosion in towers of atmospheric distillation with heavy crude oils for diesel and gasoline streams.

Also, the composition of the present invention has the property of inhibiting corrosion in primary distillation plants with gasoline and turbosine streams, with greater efficiency than the imidazoline-based commercial inhibitors currently used. It also has a higher protective capacity as a corrosion inhibitor, a better dispersibility, both in the phase of hydrocarbons and in the phase of the bitter waters of the process that work with gasoline and turbosine. This behavior of better miscibility in the aqueous and organic phase, solves the problems of formation of hydrocarbon-water-inhibitor emulsions.

Additionally, percentages greater than 90% of the corrosion protection efficiency of the synthesized inhibitors were obtained, with a concentration 20 times lower than that on average used with commercial inhibitors.

The active principle of the composition of the present invention, 2,2'-naphthenic bisimidazoline, was the result of theoretical studies of molecular modeling with programs of theoretical chemistry that allow to predict its reactivity and with it the way in which they have to adhere to the surface of stainless steel that they have to protect with greater efficiency. The new 2,2'-naphthenic bisimidazoline, with structure 1, has two imidazoline rings linked by an ethyl bridge and has on the C2 of one of the imidazoline rings two cyclohexyl groups, as shown below: General procedure for the preparation of 2,2'-naphthenic bisimidazoline which will be the active principle of the composition of the present invention. 2 mole gram (the equivalent to the molecular weight considered in grams) of naphthenic acid are heated, with one gram mole triethylenetetramine in xylene contained in a reaction equipment with water separator until 2 grams mole of water have been removed. The xylene is then removed by distillation and the obtained bisimidazoline is stored in a hermetically sealed container until it is used in the preparation of the formulation of the inhibitory composition, object of the present invention.

The 2,2'-naphthenic bisimidazoline obtained with the general procedure indicated above must be stored in a container with a hermetic seal to protect its functionality.

The inhibiting composition of the present invention is prepared in the range between 0.5 and 3% by weight in xylene or naphtha, depending on what is reported from the crude in the refinery, regarding the activity in corrosion. At 1% good results are obtained with heavy crude oils with specific gravity lower than 32 ° API and a content of recovered distillates @ 538 ° C lower than 80% by volume. Additionally, 5% by weight of isopropanol is used to prepare the formulation to be applied to the internal parts of the equipment to be protected from corrosion.

Bisimidazoline 2.2'-naphthenic 1.0% Isopropanol 5.0% Xylene complete at 100 g The percentages are by weight of each of the components.

With respect to the industrial application of inhibitory composition of the present invention, the following considerations are taken: Corrosion is the reaction of the metal with oxygen, hydrogen, acids, salts, which gives rise to the formation of corrosion mechanisms. The problem occurs with greater severity in three specific locations in a primary distillation plant: 1. - Where water exists as in dew or condensation points. 2. - Where there is a change of direction that affects the speed, erosion and corrosion factor. 3. - Where there are dirt deposits. 4. - Formation of emulsions and / or suspensions in water-hydrocarbon.

On the other hand, it is known that high concentrations of chloride ions give rise to the following diagnosis: 1. - Increase water conductivity. 2 - . 2 - Increase the solubility of the iron sulfide film at pH less than 5. 3. - Decrease in the initial pH of the condensate associated with the hydrogen ion. 4. - Causes corrosion points in the places where chloride salts are deposited.

All these problems make it necessary to use additives that act as efficient corrosion inhibitors and also as neutralizers when the nitrogens of the imidazoline ring have the capacity to accept protons from an acidic medium, antifouling agents and demulsifiers by having improved rheological properties that prevent the formation of emulsions or suspensions in the inferióase water-hydrocarbon. For a good application of these chemicals, certain parameters must be taken into account and in this case the parameters that were analyzed for the injection of the inhibitor composition of the present invention based on 2,2'-naphthenic bisimidazoline were: • The type of heavy crude oil has a specific gravity lower than 32 ° API and a recovered distillate content @ 538 ° C lower than 80% in volume that is fed to the columns, dents, primary and vacuum fractionation and especially with currents from . gasoline and turbosine.

• The pH of the bitter waters from each of the condenser banks of the trimmer, fractionator and vacuum columns of the plant (5.5 to 7.5).

• The temperature of the dome (130-160 ° C).

For the inhibiting composition of the present invention it was found to work well in laboratory tests at up to pH = 4 and does not form emulsions or suspensions at the water-diesel or water-gasoline interface.

Tests of inhibition of corrosion and demulsifying activity.

To quantify the ability to inhibit corrosion of the composition of the present invention, NACE? 0? 72, ASTM-D-1094 and NACE ID182 evaluation methods are applied.

The NACE TM0172 method evaluates the corrosive properties of distillate fuels and in preparation for transport through pipelines. It uses a steel cylinder that is subjected to a mixture of corrosive hydrocarbon and water. Concentrations are tested from 10 ppm to higher to determine the minimum concentration of maximum efficiency. This test is also called a rust test.

The ASTM-D-1094 test quantifies the efficiency in the protection against corrosion and allows confirming the results obtained with the NACE TM0172 test. Additionally, the methodology of the NACE ID 82 test allows determining the demulsifying capacity.

Table 1 shows the results of these tests for the inhibitory composition of the present invention based on 2,2'-naphthenic bisimidazoline.

Comparison of the results obtained with the corrosion inhibiting composition of the present invention and two commercial corrosion inhibiting compositions.

Principle Active tolerance of No.%% to water 10ppm Rust composition Test inhibitor efficiency 10 ppm 10 ppm corrosion interface Separation Imidazoine- 1 40 65 1 3 imidazole cyclohexy sheet 2 50 63 1 3 Bisimidazoline 3 0 94.43 2 2 2,2'-naphthenic

Claims (4)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the content of the following clauses is claimed as property:

1. A corrosion inhibiting composition based on 2,2'-naphthenic bisimidazoline characterized in that it comprises the following weight percentage composition: 1.0% 2,2'-naphthenic bisimidazoline, 5% isopropanol, and the amount needed to complete 100 g of solution with xylene or naphtha.

2. A corrosion inhibiting composition based on 2,2'-naphthenic bisimidazoline, according to clause 1, characterized in that structure 1 of the active principle is: wherein the imidazoline rings are linked by an ethyl bridge and has on the C2 of one of the imidazoline rings two cyclohexyl groups.

3. A corrosion inhibiting composition according to clauses 1 and 2, which when dosed between 5 and 18 ppm in the output of the dome of a primary distillation plant with gasoline and diesel streams, is characterized by an efficiency of 90 98% as a corrosion inhibitor, and a 0% rust value according to the method according to the ASTM-D-1094 test. A corrosion-inhibiting composition, in accordance with clauses 1 to 3, which when dosed between 5 and 18 ppm at the water-hydrocarbon interface at the exit from the dome of a primary distillation plant, with gasoline and turbosine streams, is characterized by minimizing the rust with one to a value of 0 according to the method NACE ?? 0? 72. A corrosion inhibiting composition, in accordance with clauses 1 to 4, which when dosed between 5 and 18 ppm at the water-hydrocarbon interface at the outlet of the dome of a primary distillation plant, with gasoline and turbosine streams, is characterized because it has a water tolerance of 2 according to the NACE ID182 test methodology. A corrosion inhibiting composition, in accordance with clauses 1 to 5, characterized in that it resists acidic media up to a pH = 4. A corrosion inhibiting composition, in accordance with clauses 1 to 6, characterized in that it does not form emulsions or suspensions at the water-diesel or water-gasoline interface.