CS247294B1 - Copper corrosion resistance increase method - Google Patents

Abstract

The method solves the increase in corrosion resistance sulfuric acid, phosphoric acid), organic acids and mixtures thereof; their aqueous solutions. In a liquid containing acids that come in contact with it is added once or in portions asiploň the only substance from · Groups tin, aluminum, lead, iron and / or oxides thereof, preferably 0.01 to 0.5 wt. on the an acid drawn in the liquid, preferably tin in powder form.

Description

The invention is concerned with increasing the compositional resistance of the medium to the deposition of sulfuric acid, phosphoric organic acids and mixtures thereof.

It is known that copper and its alloys, even in very aggressive atmospheres, have one to two orders of magnitude less corrosion than steel. The most aggressive atmosphere for honey is hydrogen sulfide. For good tramway and in particular thermal conductivity and good corrosion resistance, strength, moldability, it is advantageously used for food, distillery and chemical industries in general (R. Dorundorf et al. Grundstoffindustrie, Leipzig 1980).

The honey is relatively good against non-oxidizing acids and alkalis. In the presence of acids, corrosion is several times higher in the presence of oxidizing substances (oxygen, air, FeCl ₃ , KMnO / J) in the presence of acids, for example, while at a temperature of 20 ° C in 50% acetic acid without air The corrosion increased to 2.1 mm / year under the same conditions in the presence of air, and at 100 ° C linear corrosion increased to 0.2 mm / year in 50% acid.

It is similar with other acids. Thus, in sulfuric acid 6% at 20 ° C in a hydrogen atmosphere, the corrosion is 0.08 mm / year and in the presence of oxygen 3.8 mm / year. At 50 ° C the corrosion in hydrogen is 0.32 mm / year, in oxygen 11.0 mm / year. As the concentration of sulfuric acid increases, the corrosion decreases slightly.

According to the Corrosion Proceedings (Collective of Researchers of the Material-on-In Research Institute: Corrosion Proceedings, Friemysiloivé Publishing House, Prague-1952), the weight loss per unit surface area is assessed as follows:

¹ to 0.1 g. m ^-2 . h ^-1 , practically stable "0"

0.1 to 1 g. nr ² . h ^-1 , fairly stable "1" to 3 g. m ^-2 . br ¹ , not particularly stable "2" more than 3 gm ^_2 .h ^_1 , unstable corrosion class "3"

According to the above assessment, for benzenesulfonic acid, honey complies with class' 3 ', for citric acid 50% class'1', for phosphoric acid class' 2 '(40% at 90 ° Cj for chloroacetic acid class'3' corrosion loss 6 gm ' ^{2 1} , acid and lactic acid "3" hot.

In order to reduce corrosion side of the media, as well as increasing the possibility of using in- wider range of temperature ako- ¹ so far we tried to find a solution that would increase the resistance to copper inorganic and organic acids, which is the object of the present invention.

According to the present invention, increasing the corrosion resistance of the medium to the action of sulfuric, phosphoric, organic acids, mixtures thereof and aqueous solutions thereof is accomplished by adding at least one or more portions to the copper-containing liquids in contact with the copper. tin, aluminum, lead, iron and / or oxides thereof, in an amount of 0.01 to 0.5 wt. to the acid contained in the liquid, preferably tin in powder form.

An advantage of the process according to the invention is the technically undemanding yet significant increase in the corrosion resistance of the medium to the inorganic and organic acids even at elevated temperatures, which will prolong the life of the metal device several times. This also increases the working time fund and hence the production capacity of the plant, reducing the operating costs of replacing or replacing the machine. equipment repairs, as well as safety of work and loss of raw materials - resulting from accidentally corroded equipment.

The process according to the invention is very simple, since it can be carried out directly in the production process, even in built-in production facilities, i. j. does not require additional investment. The addition of inhibitors, in particular tin, to the acidic liquid environment causes the formation of a compact deposit on the copper material, which practically prevents corrosion. The plating can then be carried out either before the application of the corrosive acid medium or directly with the acids. Application of tin is advantageously carried out in powder form by dosing e.g. in the form of suspensions into a device to be protected from corrosion.

At the same time, it is necessary for some of the metal tin to remain in the form of suspensions, which ensures a sufficient excess thereof in the environment.

It is particularly suitable to increase the corrosion stability of the media e.g. in an esterification apparatus in the manufacture of esters e.g. butyl acetate. In this case, using a mixture of an organic acid, an alcohol and an esterification catalyst e.g. sulfuric acid, it is possible to continuously feed the reacting mixture into the reboiler and esterification apparatus. The resulting ester with water in the form of an azeotrope distills and condenses on the top of the column. In such cases, the snake and column digestor coming into contact with the corrosive acids are most stressed. At the same time, it is sufficient to feed the catalyst and inhibitor into the apparatus only at the beginning of the cycle and during the continuous feeding of the raw materials only to check their contents in the boiler boiler.

Subsequent dosing is sufficient only when the inhibitor content is lowered to the required required amount. Thereby, the consumption of the corrosion inhibitor is reduced many times while practically preventing corrosion.

A sufficient amount of inhibitor can be checked visually based on the color of the device in the device window or on the color of the solution which must not be ob247294 (compounds of the medium, which can be quantitatively quantified but can also be assessed visually solution (the salts of the media in water are mostly blue), while the gentle micron coating of tin does not reduce the heat transfer through the device.

The method of increasing the corrosive stability of the media of the present invention can be used in discontinuous and continuous cold and hot acid storage devices to protect the digester and boiler of distillation equipment, heat exchangers, and the like.

The embodiments of the process according to the invention as well as the corrosion properties of the medium to various acids are illustrated by the examples, which, however, do not exhaust all possible combinations of its use.

Example 1 measured 65 x 15 x 2 mm in a 250 cm ³ flask equipped with a thermometer and a reflux condenser. 4 flasks are placed in a silicone oil bath heated to 120 degrees Celsius and labeled with the weighed copper plates and the appropriate liquid, whose corrosion properties are examined. After 7 hours, the heat stress at · 100 ^Q C (in a bank), the solution is self-cooled and, after 16 hours of standing the solution of the reference plate of the rinsed with distilled water, acetone, allowed to dry and liberally weighed. Repeat the procedure at least 3 times to determine the uniformity of material loss and calculate the loss in g from the drop and the surface of the flask. m ~ ² . h · ^-1 .

The results of the corrosion tests are presented in Table 1.

Corrosion tests of copper plates rozTabufka 1

The corrosion of the medium in an aqueous solution containing 1 wt. % sulfuric acid and 40 wt. of acetic acid in the presence of various additions at a temperature of 100 + 1 ° C. (% by weight of the addition refers to the weight of the solution).

Number test time exam. (H) addition Medium loss (g. M ~ ² .hi) Koroz. the class remark Kind of Qty. (% by weight) 1 22 without addition 0.0 1,048 2 2 22 CuSO ₄ 0.5 2.33 2 3 20 Fe ₂ (SO ₄ ) ₃ 0.5 4.82 3 4 20 ZnSO ₄ 0.5 1,067 2 5 20 p-methoxyphenol 0.5 1,703 2 6 20 formaldehyde 0.5 1,672 2 7 20 As ₂ O ₃ 0.5 1,115 2 8 20 Na ₂ S ₂ O ₃ 0.5 9,217 3 9 20 HCOOH 0.5 3,621 3 10 20 MnSO ₄ 0.5 1,062 2 11 20 Cr ₂ (SO ₄ ) ₃ 0.5 5,936 3 12 20 NčigSO ^ 0.5 4,436 3 13 14 without addition 1.86 2 6% H ₂ SO ₄ 14 22.5 without addition 1.25 2 15 14 Zn powder 0.5 1.12 2 6% H ₃ SO ₄ 16 22.5 Zn powder 0.5 1.25 2 17 14 AI powder 0.5 0.47 1 6% H ₂ SO ₄ 18 22.5 AI powder 0.5 0.15 1 19 14 Pb (CH ₃ COO) ₂ 0.5 1.31 2 20 22.5 Pb (CH ₃ COO) ₃ 0.5 1.28 2 21 15.5 Fe powder 0.5 0.41 1 22 7.5 Fe powder 0.5 1.58 2 6% H ₂ SO ₄ 23 15.5 Pb powder 0.5 0.26 1 24 7.5 Pb powder 0.5 0.27 1 6% H ₂ SO ₄ 25 15.5 What (CH ₃ COO)? 0.5 0.54 1 26 7.5 Co (CH ₃ COO) ₂ 0.5 1.60 2 6% H ₂ SO ₄ 27 15.5 Sb ₂ O ₃ 0.5 0.59 1 28 7.5 Sb ₂ O ₃ 0.5 0.81 1 6% H ₂ SO ₄ 2Θ 27 Sn powder 0.5 0.00 0 Sn coating on test plate

As can be seen from the results summarized in Table 1, sulfuric acid 1 wt.%, Acetic acid 40 wt. and 59 wt. water at boiling point (100 ° C) honey without addition shows corrosion stability 2, some additions with oxidizing and reducing character increase the corrosion of the intermediate grade 3 media and other than aluminum, lead, partly cobalt acetate and iron powder reduce the corrosion class to 1, when using the addition of tin, even corrosion is not observed and, on the contrary, the sheet is covered with a tin layer.

In some cases, in tests 13 to 27, the corrosion tests are carried out for 15.5 to 22.5 hours in solution as indicated in the table, after which time 5% w / w is added to the solution. sulfuric acid and again monitored for 7.5 to 22.5 h. Since corrosion using tin is detected in the pirosities of interest, a different amount of liquid addition is used. The test results are listed in Table n

Table 2

The corrosion of the medium in an aqueous solution containing 1 wt. % sulfuric acid and 40 wt. of acetic acid at a boiling point of 100 +1 ° C with the addition of tin in wt. per solution.

Number test time Try. (H) Quantity addition (° / w / w) ^Medium loss (g m ² h ^-1 ) corrosion the class I know. 1 36.5 without addition 1.48 2 2 27 Sn 0.5 0.00 0 3 28 Sn 0.15 0.14 1 4 22 Sn 0.15 0.12 1 6% H ₂ SO ₄ 5 28 Sn 0.05 0.21 1 6 22 Sn 0.05 0.04 0 6% H ₂ SO ₄ 7 28 Sn 0.015 1.26 2 8 22 Sn 0.015 0,284 1 6% H ₂ SO ₄ 9 28 Sn 0.005 0.83  1 10 22 Sn 0.005 0.42 1 6% H ₂ SO ₄ During the tests are it proceeds the way Example 2 that after 28 hours the solution is replaced with with that the concentration of sulfuric acid On device according to Example 1 is monitored % in solution increases to 6 wt. with a new one Corrosion of copper plates using the backfill tin as corrosion inhibitor media. different organic and inorganic flows

Compared to the original corrosion, the exchange of solution, the corrosion is substantially reduced, which can be caused by further passivation of the copper surface by the addition of tin.

Acids without preparation and with addition of tin as corrosion inhibitor. The results are listed in Table 3.

171 9 4

Table 3

Effect of various inorganic acids in the form of aqueous solutions on corrosion of the medium at 100 + 1 ° C without addition of inhibitor and with 0.5 wt. for the use of tin as an inhibitor.

Number time acid addition decrease corrosion test test Kind of Concentration sn médi the class in Tracy. (% by weight) (gm ~ ² . .h-i) 1 2 3 4 5 6 7

1 21.5 CH ₃ COOH 2 21.5 h ₂ š ₄ 3 21.5 oxalic acid 4 21.5 lactic acid 5 22 formic acid 6 22 formic acid 7 13 p-toluenesulfonic acid 8 13 hno ₃ 9 13.5 chloroacetic acid 10 21.5 HC1 11 33.5 h ₃ Mon ₄ 12 21.5 CH3COOH 13 21.5 H ₂ SO ₄ 14 21.5 oxalic acid 15 21.5 lactic acid 16 22.0 formic acid 17 22.0 formic acid 18 13.0 p-toluenesulfonic acid 19 13 HNO3 20 13.5 chloroacetic acid 21 21.5 HC1 22 33.5 H ₃ PO ₄

The results summarized in Table 3 ¹ seen that in the case of organic acids and sulfuric acid, and phosphoric acid, the effect of the addition of tin to retard corrosion clear. When hydrochloric and nitric acids are used, the corrosion is even greater. In the case of trials 5, 6 and 16, 17, ie with formic acid of different concentrations with or without addition of tin, after 22 hours of testing (3 days of testing 7 to 8 hours per day at boiling time remaining 16 to 17 hours under self-cooling) to room temperature) exchange the solutions with:

40 not 0,579 1 5.0 not 1,900 2 5.0 not 0,195 1 10 not 0,302 1 10 not 0,443 1 40 not 0,779 1 2.5 not 1,158 2 5.0 not 16.13 3 10.0 not 9.26 3 10.0 not 1.81 2 10.0 not 0.36 1 40 0.5 0,000 0 5.0 0.5 0,000 0 5.0 0.5 0,000 0 10.0 0.5 0,000 0 10.0 0.5 0,000 0 40.0 0.5 0,000 0 2.5 0.5 0,000 ' 0 5.0 0.5 13.9 3 10.0 0.5 0,000 0 10.0 0.5 6.43 3 10.0 0.5 0,000 0 does not add after 7 hours coating

tin from the test specimen dissolves to the flood mass of the specimen and for another 21 hours the corrodes corroded equally whether or not the flood tin is present in the solution. The loss in all four cases is 1.21 + 0.1 g · m -1 h ^-1 .

This implies that a certain concentration of tin must always be present in the environment for sufficient corrosion protection of the material. Tin is consumed during the tests and needs to be replenished to prevent corrosion.

Claims (1)

9 10 2 17 2, 4 Table 3 Effect of various inorganic acids in the form of aqueous solutions on corrosion at 100 + 1 ° C without the addition of an inhibitor and with the addition of 0.5% by weight. as an inhibitor. Number Time Acid Addition Residential Corrosion Tests Test Type Conc. (% by weight) (gm-2. .hi) 1 2 3 4 5 6 7 1 21.5 CH3COOH 2 21.5 h2šo4 3 21.5 oxalic acid 4 21.5 lactic acid 5 22 formic acid 6 22 formic acid 7 13 p-toluenesulfonic acid 8 13 hno 3 9 13,5 chloroacetic acid 10 21,5 HCl 11 33,5 h3po4 12 21,5 CH3COOH 13 21,5 H2SO4 14 21,5 oxalic acid 15 21,5 lactic acid 16 22,0 formic acid 17 22.0 formic acid 18 13.0 p-toluenesulfonic acid 19 13 HNO3 20 13.5 chloroacetic acid 21 21.5 HCl 22 33.5 H3PO4 Based on the results summarized in Table 3, in the case of organic acids and sulfuric acid and phosphoric acid, the effect of the addition of tin on the retardation of corrosion is unambiguous. When using hydrochloric acid and nitric acid, the corrosion is increased. In the case of experiments 5, 6 and 16, 17, ie with acidic formulations of varying concentrations, with and without addition of additions, after 22 hours of testing (3 days of testing of 8 to 8 hours at the boiling point of the remaining 16 to 17 hours) in the case of spontaneous cooling at the temperature of the laboratory, the solutions are exchanged with 40 not 0.579 1 5.0 no 1.900 2 5.0 no 0.195 1 10 no 0.302 1 10 no 0.443 1 40 no 0.779 1 2.5 no 1.158 2 5, 0 no 16.13 3 10.0 no 9.26 3 10.0 no 1.81 2 10.0 no 0.36 1 40 0.5 0.000 0 5.0 0.5 0.000 0 5.0 0.5 0.000 0 10.0 0.5 0.000 0 10.0 0.5 0.000 0 40.0 0.5 0.000 0 2.5 0.5 0.000 '0 5.0 0.5 13.9 3 10.0 0 5 0.000 0 10.0 0.5 6.43 3 10.0 0.5 0.000 0 not added after 7 hours the tin coating of the test specimen is dissolved to the body weight and corroded for the next 21 hours as well, but or the flood is not present in the solution. The residual in all four cases is 1.21 + 0.1 gm-3.h_1. There is always a certain concentration of tin present in the material to protect the material. Tin is consumed during testing and needs to be replenished to prevent corrosion. SUBJECT OF THE METHOD OF IMPROVING CORRESSIVE RESISTANCE OF MEDIUM TO SURFACE OF SULFURIC, PHOSPHORIC, ORGANIC ACIDS, THEIR COMPOUNDS AND ANIMAL SOLUTIONS, characterized in that the liquids containing acids that come into contact with the copper are added to the composition in one or more portions. at least one of tin, aluminum, lead, iron and / or oxides in an amount of 0.01 to 0.5% by weight; to the acid contained in the liquid, preferably tin in powder form.