WO2014040159A1

WO2014040159A1 - Carbon steel corrision inhibiting composition using mesoionic heterocyclic compounds dispersed in a micro-emulsion of saponified coconut oil

Info

Publication number: WO2014040159A1
Application number: PCT/BR2013/000409
Authority: WO
Inventors: Ruza Gabriela MADEIROS DE ARAÚJO MACEDO; Josealdo TONHOLO; Adriana SANTOS RIBEIRO; Maria APARECIDA MADEIROS MACIEL; Tereza NEUMA DE CASTRO DANTAS; Cátia GUARACIARA FERNANDES TEIXEIA ROSSI
Original assignee: Universidade Federal De Alagoas
Priority date: 2012-09-13
Filing date: 2013-09-13
Publication date: 2014-03-20
Also published as: BR102012024591A2

Abstract

The claimed invention proposes treating carbon steel and the like with nitrogenated substances (mesoionic heterocyclic compounds) solubilized in micro-emulsified systems, which substances act as corrosion inhibitors. The invention relates to a compound of the 1,3,4-triazole-2-thiol type, to a composition with mesoionic heterocyclic compounds in a micro-emulsion of saponified coconut oil, and to the uses thereof. These compounds exhibit anticorrosive properties for carbon steel and the like and synergistic properties when combined with the micro-emulsion.

Description

DESCRIPTION REPORT OF THE INVENTION: CARBON STEEL CORROSION INHIBITOR COMPOSITION USING MESOIONIC HETEROCYCLIC COMPOUNDS DISPOSED IN SAPONIFIED COCONUT OIL MICROEMULSION

Field of the Invention

The present invention has as its main field of operation industrial operations and processes that use carbon steel and analogs in their equipment, pipelines, reservoirs, etc., susceptible to chemical attack that causes corrosion. Proposes the treatment of carbon steel and similar with the use of nitrogenous substances (mesoionic heterocycles) solubilized in microemulsion systems, which act as corrosion inhibitors. The invention comprises a type 1,3,4-triazolium-2-thiol compound, the structure of which is below, a composition with mesoionic heterocyclic compounds in a saponified coconut oil microemulsion and their use. These compounds exhibit anti-corrosion properties for carbon steel and the like, having synergistic properties with microemulsion.

Background of the Invention and Prior Art

Despite the breadth of problems caused by the corrosion phenomenon, the search for corrosion inhibitors has, as a rule, resulted in very case-specific systems considering the complexities of the materials affected and the surrounding environments (usually wet). . Scientific literature and patent bases point to a large production of knowledge on the subject, with a significant focus on solving corrosion problems in the processes related to construction (more than 8,000 patents) and the oil industry (over 17,000 patents). Some collections are especially devoted to the study of corrosion, such as Shreir's Corrosion (Ed. TJA Richardson, Elsevier, 2010). Old patents already pointed to the advantages of using nitrogen heterocycles in the composition of corrosion inhibitors, such as Zisis et al., Who report the use of pyrazoles, imidazole and 1,2,4-triazoles (US 3553101). Bronze corrosion was also inhibited with the use of 3-azyl-1,2,4-triazole (CN101914772). Recently, there has been an increase in works and patents that make use of azo-type organic compounds for corrosion inhibition purposes in specific use compositions, such as Yoo et al., Who report the use of imidazoline-based inhibitors ( KR2011026199). Uskach et al. developed an acid corrosion inhibiting composition containing aromatic amines (RU2425858). Khusnitdinov and team produced an acid corrosion inhibiting composition of steel containing derivatives anilines (RU2415970). Another Russian patent (RU2383658-C1) describes the use of urotropin and polyethylene polyamine derivatives as a corrosion inhibitor in pipelines subjected to high temperatures and oil well pressure. Borisov (RU2379280) records the use of hydroxypropionate derivatives for use in carbon steel corrosion inhibition in saline solution. Protection against corrosion of copper by seawater has also been reported by Li et al. (CN102115471 and CN102115891) using triazole thiol compounds. Triazolic compounds have also been used in combination with sarcosines and their salts to inhibit corrosion of the mechanical part polishing process (KR2011037997). Other alkyl sarcosine derivatives, described as biodegradable, have also been labeled as anti-corrosion agents for addition to the acid rinsing mixture of oil and gas well drilling materials (US20110224111).

The use of microemulsions to prevent incompatibilities between extraction objects and drilling fluids has already been described, using 1 to 10 carbon chain species (US5762138). The removal of organic and mineral scale using esters / thiols microemulsions has already been reported (US20040092420). The use of propionate-based microemulsions, whether combined with coconut oil or polyglucosides, results in useful solutions for cleaning duct scale and other well drilling components (WO20061090 6). The use of eco-friendly microemulsions has a wide range of possibility of manufacture from diester derivatives and modified hydrocarbons, being indicated as special cleaning solutions for industrial processes (WO201 1 152872). The anticorrosive activity of the microemulsion coconut saponified oil was evidenced by the applicant group (Rossi CGFT, Scatena Jr, H, Maciel, MAM, Dantas, TNC STUDY ^'EFFICIENCY COMPARATIVE DIPHENYL CA RBAZIDA and coconut saponified microemulsion of oil in INHIBITION OF CARBON STEEL CORROSION, Quim. Nova, Vol. 30, No. 5, 1128-1132, 2007). The use of mesoionic heterocyclic compounds 1, 3,4-triazolium-2-thiol with the characteristics described in this application has not previously reported corrosion inhibition property in steels. Description of the Figures

Figure 1: (a) Polarization curves obtained with the saline medium AISI 1020 steel electrode with the different concentrations of the OCS-ME inhibitor. v = 1 mV / s. (b) Curve of corrosion potential as a function of OCS-ME concentration.

Figure 2: (a) OCS-ME-MI-1 polarization curves at different concentrations, v = 1 mV / s. (b) Curve of corrosion potential as a function of OCS-ME-MI-1 concentration.

Figure 3: Nyquist diagram of saline and OCS-ME at different concentrations.

Figure 4: Nyquist diagram for OCS-ME-MI-3 at different concentrations.

Figure 5: (a) Mesoionic compound MI-1 without ring replacement, (b) mesoionic compound MI-2 with the methoxy group and (c) mesoionic compound MI-3 with the nitro group.

Summary of the Invention

The present invention proposes the treatment of carbon steel and similar with the use of solubilized nitrogenous substances (mesoionic heterocycles) in microemulsion systems, which act as corrosion inhibitors. The invention comprises a compound of the type 1,4-triazolium-2-thiol, a composition with mesoionic heterocyclic compounds in a saponified coconut oil microemulsion and their use. These compounds have anti-corrosion properties for carbon steel and the like, presenting synergistic properties with microemulsion.

Detailed Description of the Invention

In this invention the synergistic behavior for corrosion inhibition between saponified coconut oil microemulsion and triazole-derived mesoionic heterocycles has been characterized. Three distinct mesoionic compounds (M1) were studied due to the presence of different functional groups, according to the structures of Figure 1. One of the mesoionic compounds, MI-1, has no substitution in its 6-membered ring, whereas the compound MI-2 has the methoxy group and compound MI-3 has the nitro group.

(A) PREPARATION OF MESOIONIC COMPOUNDS

The mesoionic compounds used in this patent were prepared according to the methodology described in Maciel (MACIEL, MAM; ECHEVARRIA, A .; RUMJANEK, VM Isolation and characterization of acylthiosemicarbazides as intermediates in the synthesis of mesoionic compounds. Química Nova, v. 21, p. 569-572, 1998). The chemical structures of the mesoionic compounds solubilized in the saponified coconut oil microemulsion are shown in figure 5.

(B) PREPARATION OF SAPONIFIED COCONUT OIL: The preparation of saponified coconut oil followed the methodology of Rossi et al (2007, op. Cit). Coconut oil was saponified by diluting 21.5 g NaOH in 80 mL distilled water; This solution was then added to coconut oil (100 g), followed by the addition of ethyl alcohol (300 mL). This reaction mixture was heated at reflux for 2 h. After removal of the alcohol, the soap obtained (100 g) was dried at 40 ° C.

(C) PREPARATION OF SAPONIFIED COCONUT OIL MICROEMULSION (OCS): The preparation of the microemulsion followed the methodology of Rossi et al (2007, op. Cit). A cohesive / surfactant ratio C / T = 1 (30%) was used, where OCS was the surfactant used (15%), butanol (15%, co-active), kerosene (10%, oil phase, FO). and NaCl solution (aqueous phase (FA), at the following concentrations: 0.5, 1, 5 and 2.5%), the Winsor IV working region ME system (base 2 g) was obtained. For this purpose, the active matter (C / T ratio) was titrated with the NaCI (FA) solution until it reached the turning point S (solubilization point), characterized by a change in the physical aspect of the system from turbid. to clear, or vice versa. Then we obtained a titration point (known as T) of known composition of the constituents of the mixture within the single phase region of the pseudoternary system. The T point is considered the titrant of the binary systems: FA + FO and C / T + FO. From a mass balance the limit points of the solubility curves of the four Winsor regions (I, II, III and IV) in the microemulsion system were determined.

(D) PREPARATION OF INHIBITOR COMPOSITIONS: Mesoionic compounds were dissolved in a 0.01 to 2% (vol: vol) proportion of saponified coconut oil microemulsion solution, allowing the preparation of concentrated inhibitor systems with varying composition. from 100 to 20,000 ppm.

(E) CHLORIDE CORROSION INHIBITION TEST: Working solutions of sodium chloride in distilled water at concentrations of 1000 to 50000 ppm in chloride were prepared. Portions of the inhibitor solutions prepared in (D) were added to the sodium chloride working solutions at concentrations ranging from 0.01 to 5.0% (vol.vol) over which the anti-corrosion power was evaluated. , comparing it with inhibitor-free solutions, both in the presence and absence of saponified coconut oil microemulsion. Electrochemical techniques such as linear polarization (pseudo-Tafel) and Electrochemical Impedance were used. Results revealed corrosion inhibition efficiencies greater than 80% at critical concentrations for each mesoionic compound. All tests were performed by both techniques. electrochemical studies, which revealed the evident synergism of inhibition of the M1 compounds and the saponified coconut oil microemulsion. Preferred Form of the Invention: Industrial / commercial application of corrosion inhibitors is through additives prepared as solid mixtures or in solution / suspension. In this case, it is suggested that the commercialization should be done through ready-to-use preparations as an anti-corrosive additive in the neutral cleaning processes (cases of organic or mineral fouling). It is also suggested the joint injection in drilling fluids or completion of oil wells and the use of geothermal energy, use in closed circulation systems of aqueous refrigerant solutions in industrial systems, among others.

To this end, it is suggested to prepare commercially available stock suspensions containing from 100 to 20,000 ppm inhibitor type I, 3,4-triazolium-2-thiol in saponified coconut oil microemulsion, respecting the maximum solubility limits. of each derivative. Depending on the end-user concentrations of interest, these stock suspensions may be diluted in the solution / working medium to an economically advantageous operating concentration for each case. These stock suspensions are stable at room temperature for several months, provided they are kept in the dark, and can be added directly to the system of interest. The material can be stored and marketed in dark plastic bags (larger volumes) or sturdy plastic bags (up to 2 liters). The material is non-toxic considering recommended end-use characteristics.

EXAMPLES

EXAMPLE 01: PROVEN EVALUATION OF CORROSION INHIBITION FOR MM INHIBITOR BY LINEAR POLARIZATION (PSEUDO-TAFEL).

An electrochemical cell of 3 electrodes was used, being an Ag / AgCI reference electrode, a platinum auxiliary electrode and a SAE1020 carbon steel working electrode (0.302 cm ² ) in a 10000 ppm chloride solution. The microemulsion concentration of saponified coconut oil (without inhibitor) was varied, and a sudden anodic displacement effect of the polarization curve was observed for more anodic potentials with the addition of microemulsion, as shown in Figure 1. Corrosion potential (Figure inset) was displaced by about 100 mV. Such displacement reveals the greatest protection of the electrode surface to corrosion.

Adding the mesoionic compound MI-1 at a constant ratio of 1/1000 to the microemulsion, but maintaining the same experimental conditions as described above, resulted in the progressive shift of the polarization curve to more anodic potentials with increasing concentration. microemulsion / mesoionic, and the corrosion potentials were displaced by more than 150 mV in the anodic direction at the highest concentration (Figure 2 and its inset). This result shows the significant increase in corrosion protection attributed to the Mesoionic MI-1 in synergy with microemulsion. The corrosion efficiency was calculated to be 42% for the lowest concentration microemulsion while for the highest concentration 1-1 / microemulsion the efficiency reached 97%.

EXAMPLE 2: PROOF OF INHIBIT EFFECTIVENESS

OF CORROSION FOR MI-3 INHIBITOR IMMEDIATELY

PHARADAIC

Using an experimental system analogous to that described in Example 1 on a frequency analysis module (FRA) potentiostat, faradaic impedance spectroscopy experiments were performed using frequencies from 10 KHz to 100 mHz and 10 mV amplitude on a logarithmic scale with 71 points per decade, in the region of the corrosion potential, making the real resistance with the imaginary deconvolution, in order to obtain the Nyquist diagrams. Figure 3 shows the Nyquist diagram for the various concentrations of coconut oil microemulsion in 10000 ppm sodium chloride. The radical change in behavior between the pure sodium chloride solution and the responses with the successive increase of the microemulsion concentration is observed. The relevant increase in the imaginary resistance at higher microemulsion concentrations shows a protection of the carbon steel electrode surface against corrosive chloride attack.

On the other hand, by adding the mesoionic compound MI-3 to the microemulsion, this effect was maximized, as can be seen in Figure 4. impedance was interpreted quantitatively through the Bode diagrams and proposition of an equivalent electronic circuit, which showed inhibition efficiency increase from 65% (0.1% microemulsion) to 92% (ΜΙ-3 / 0.4% microemulsion). . The data presented in Examples 1 and 2, as well as other experimental data available with the authors, show the effectiveness of chloride steel corrosion inhibition in the presence of coconut oil microemulsion, and this effect is substantially increased in the presence of inhibitors. mesoionic. Other experiments performed by the authors show that the three mesoionic compounds studied presented inhibition efficiencies ranging from 40 to 97%, depending on the critical micellar concentration of microemulsion and inhibitor. This study allows the extrapolation of inhibitory efficiency to other mesoionic derivatives of 1,4,4-triazolium-2-thiol and warns of the effective possibility of its preparation, since the method described by Maciel (Maciel, MAM; Echevarria, (Rmjanek, V. M, Isolation and Characterization of Acylthiosemicarbazides as Intermediates in Mesoionic Compound Synthesis, New Chemistry, 21 (5): 569-572, 1998) allows the preparation of a multitude of other analogous compounds.

The major novelty of this proposition is the evidence of the corrosion inhibitory effect presented by the investigated 1,3,4-triazolium-2-thiol compounds, with the addition of synergistic effect in relation to the inhibitory effect evidenced for the saponified coconut oil microemulsion system. Both the inhibitory effect and the effect synergists are considered unpublished. It should be noted that the corrosion inhibitory effect observed at critical concentrations is quite high, often reaching values above 90%, which denotes the potential for commercial application. Table 1 presents some critical inhibition concentrations (highest inhibitory effect evidenced), obtained by linear polarization (pseudo-tafel).

Table 1: Critical inhibition concentrations.

Inhibiting Efficiency Operation Concentration

Inhibitor

NaC1 inhibitor / microemulsion 10000 ppm

MI-1 5.0 ppm / 0.5% 96.7%

MI-2 3.0 ppm / 0.3% 90.3%

MI-3 4.0 ppm / 0.4% 89.5%

Claims

1- Heterocyclic compound characterized by the following structure:

Heterocyclic compound according to Claim 1, characterized in that X is Hydrogen.

Heterocyclic compound according to Claim 1, characterized in that X is a methoxy group (H ₃ CO);

Heterocyclic compound according to Claim 1, characterized in that X is a nitro group NO ₂ .

Heterocyclic compound according to Claims 1 to 4, characterized in that it is for use as a corrosion inhibitor.

6. Corrosion inhibiting composition comprising heterocyclic compounds dispersed in microemulsion.

Corrosion inhibiting composition according to claim 6, characterized in that it comprises a heterocyclic compound of claims 1 to 4.

8. Corrosion inhibiting composition comprising a saponified coconut oil microemulsion. 9- Corrosion inhibiting composition characterized for use on carbon steel and other metals.

10- Corrosion inhibiting composition characterized for use as addition to drilling fluids or completion of oil wells and other minerals and for the use of geothermal energy.

11 - Corrosion inhibiting composition characterized for being for use in closed circulation systems of aqueous refrigerant solutions in industrial systems.