CS247294B1 - A method of increasing the corrosion resistance of a medium - Google Patents

Abstract

The method solves the problem of increasing the corrosion resistance of copper to the action of sulfuric acid, phosphoric acid), organic acids, their mixtures and their aqueous solutions. To the liquid containing acids that come into contact with copper, approximately a single substance from the group of tin, aluminum, lead, iron and/or their oxides is added at once or in parts, in a preferred amount of 0.01 to 0.5% by weight per acid contained in the liquid, preferably tin in the form of powder.

Description

247294

The invention relates to increasing the corrosion resistance of the medium to the sulfuric acid, phosphoric acid, and organic acids.

It is known that copper and its alloys also have one or two orders of magnitude less corrosion than steel in very aggressive atmospheres. The most reactive atmosphere for copper is hydrogen sulphide. For good electrical and thermal conductivity and good corrosion resistance, strength, formability is advantageously used for z-arming in the food industry, in the distillery and in the chemical industry ( R. Dorundorfa collective: Werikstoffeiinsatz und Koirrosioms-schutz in der Chemischen Industrie, VEBDeutscher Verlag für Grundstoffindustrie, Leipzig 1980).

Honey is relatively good to non-oxidizing acids and alkalis. The oxidizing agents (oxygen, air, FeCl3, KMnO / J, in the presence of acids, the corrosion increases by a factor of several. For example, while at 20 DEG C. in 50% acetic acid without air access) a loss of 0.09 mm / year, under the same conditions in the presence of air, increased to 2.1 mm / yr, at a temperature of 100 ° C, linear corrosion increased in 50% acid to 0.2 mm / yr.

The same is true for other acids. In sulfuric acid at 6% at 20 ° C in a hydrogen atmosphere, corrosion is 0.08 mm / year and in the presence of oxygen 3.8 mm / year. At 50 ° C, corrosion in hydrogen is 0.32mm / year , in oxygen 11.0 mm / year. As the sulfuric acid concentration increases, the corrosion decreases slightly. Stages of the Corrosion Proceedings (Collective of Authors of the Research Institute of Protection of Materials: Corrosion Proceedings, Industrial Development, Prague '1952), according to the mass-weight unit per unit of surface, they read as follows: J-'? · '1 to 0 , 1 g. m-2. h-1, practically standing "0" 0.1 to 1 g. nr 2. h-1, quite stable "1" 1 to 3 g. m-2. hr1, not particularly "2" more than 3 g.m_2.h_1, non-volatile "3"

According to the aforementioned assessment, for benzenesulfonic acid, copper class "3", for citric acid 50% class "1", pre-phosphoric class "2" (40% at 90 ° C) for chloroacetic acid class "3" corrosion 6 gm-2. tr1, lactic acid, " 3 "

For the sake of reducing the corrosion losses of the medium as well as increasing the possibility of use. in a broader range of temperatures than hitherto, we have sought to find a solution that would increase the resistance of the medium to both inorganic and organic acids, which is the subject of the present invention.

According to the present invention, increasing the corrosion resistance of the medium to the action of sulfuric acid, phosphoric acid, organic acids, mixtures thereof, and aqueous solutions thereof is effected by dispersing the liquid containing acids in contact with one another or at least one substance from the group of tin, aluminum, lead, iron and / or their oxides is added in portions, in an amount of 0.01 to 0.5% by weight. to the acid-containing liquid preferably tin in the powder. An advantage of the process of the present invention is the technically unpretentious yet significant increase in the corrosion resistance of the medium to the araganic and organic acids as well as the elevated temperatures, which several times prolongs the life of the device of this metal. In this way, the working time pool and thus the plant's production capacity are also reduced, thereby reducing the operating costs of the replacement or the plant. repair of equipment, as well as safety of work and stratysuriny resulting from the crash of corroded equipment.

The method of the present invention is extremely difficult, as it can be carried out directly in the manufacturing process, even in built-up production facilities, i.e., no additional investment is required. The addition of inhibitors, especially tin, to the acidic liquid medium creates a compact buildup on the copper material, which effectively prevents corrosion. In this case, the coating process can be carried out either before the application of the corrosive medium or directly with the acids. The application of tin is preferably carried out in a powdered state by dosing, e.g., in the form of a suspension of the device to be protected by pre-corrosion. In this case, it is necessary that the portion of the metallic tin remains in the form of suspensions, which guarantees its excess in the environment.

Particularly suitable is an increase in corrosion resistance by the medium, e.g., in an esterification apparatus, to produce esters such as butyl acetate. In this case, by using a mixture of an organic acid, an alcohol and an esterification catalyst such as sulfuric acid, it is possible to continuously feed the reacting mixture into the varnish esterification apparatus. The azeotrope formed with water is distilled and condensed at the top of the column. In such cases, the most corrosion-stressed collar snake is in contact with the corrosive acids. In this case, the catalyst and the inhibitor need only be fed to the apparatus at the start of the cycle and only during the continuous feed dosing, control the contents of the apparatus in the apparatus. Further dosing is sufficient only to bring the inhibitor content down below the desired target. As a result, the corrosion inhibition of the corrosion inhibitor is greatly reduced in practical corrosion prevention.

Control of a sufficient amount of inhibitor can be done visually on the basis of the color of the device in the appearance of the device, but based on the color of the solution, which must not reach the media with the compound, which can be quantitatively quantified, it is also not possible to assess it visually. solution color (water salts are mostly blue). In doing so, a few microns of tin do not reduce the heat of the device.

The method of enhancing the corrosive stability of the present invention can be used in both discontinuous and continual cold and hot acid storage systems for reboiler and boiler distillation devices, heat exchangers, and the like.

Embodiments of the present invention as well as the corrosive properties of the medium against red acids illustrate examples which do not exhaust all possible combinations of its use. An example of a meter of 65 x 15 x 2 mm is rotated in a 250 cm 3 flask equipped with a thermometer and a heat sink. 4 flasks are placed in a 120 degree centigrade silica-oil bath and weighed copper sheets and an appropriate liquid whose coarse properties are absorbed. After 7 hours of thermal stress at 100 ° C (in a flask), the solution is allowed to cool freely and after 16 hours of standing in the solution the rinsed plate is rinsed with distilled water, acetone, allowed to dry and weighed. The procedure is repeated at least three times to determine the uniformity of the material effect and the loss in g is calculated from the loss and surface of the pad. m ~ 2. h_1. Corrosion test results are included in Table 1.

Copper Lung Corrosion

Table 1

Medium corrosion in an aqueous solution containing 1 wt. % sulfuric acid and 40 wt. acetic acid in the presence of additions at 100 ± 1 ° C. (% by weight of addition refers to the weight of solution). Test Number Test Time. (h) Addition of Decay (g. m ~ 2 .h-i) Corrosion. Class Note Type Qty. (% w / w) 1 22 without addition 0,0 1,048 2 2 22 CuSO4 0,5 2,33 2 3 20 Fe2 (S04) 3 0,5 4,82 3 4 20 ZnSO4 0,5 1,067 2 5 20 p- methoxyphenol 0,5 1,703 2 6 20 formaldehyde 0,5 1,672 2 7 20 As2O3 0,5 1,115 2 8 20 Na2S2O3 0,5 9,217 3 9 20 HCOOH 0,5 3,621 3 10 20 MnSO4 0,5 1,062 2 11 20 Cr2 ( SO4) 3 0,5 5,936 3 12 20 NčigSO ^ 0,5 4,436 3 13 14 without addition 1,86 2 6% H2SO4 14 22,5 without addition 1,25 2 15 14 Zn powder 0,5 1,12 2 6 % H3SO4 16 22.5 Zn powder 0.5 1.25 2 17 14 AI powder 0.5 0.47 1 6% H2SO4 18 22.5 Al powder 0.5 0.15 1 19 14 Pb (CH3COO) 2 0 , 5 1.31 2 20 22.5 Pb (CH3COO) 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% H2SO4 23 15.5 Pb powder 0.5 0.26 1 24 7.5 Pb powder 0.5 0.27 1 6% H2SO4 25 15.5 Co (CH3COO) 0.5 0.54 1 26 7.5 Co (CH3COO) 2 0.5 1.60 2 6% H2SO4 27 15.5 Sb2O3 0.5 0.59 1 28 7.5 Sb2O3 0.5 0.81 1 6% H2SO4 2-27 Sn powder 0.5 0 , 00 0 Sn coating on the tested plate 247294

As a result of the results summarized in Table 1, in the sulfuric acid mixture 1% by weight, acetic acid 40% by weight. and 59% by weight of water at boiling point (100 ° C), the honey without addition exhibits corrosion stability of 2, some oxidation reducing additives increase the corrosion of the medium with the transversal class 3 and other than aluminum; In addition, cobalt acetate and iron powder reduce the corrosion class to 1, even by using tin addition, corrosion is not observed and, on the other hand, the sheet is covered with a tin layer. In some cases, in tests Nos. 13 to 27, the corrosion tests are performed at 15.5 to 22.5 h in a solution as shown in the table and after this time the solution is added with 5% w / w. Sulfuric acid is again treated with 7.5 to 22.5 hrs. The corrosion with tin is followed by the use of a liquid amount of liquid addition in the test. The test results are included in Table n.

Table 2

Medium corrosion in aqueous solution containing 1 wt. % sulfuric acid and 40 wt. acetic acid at a boiling point of 100 +1 ° C with the addition of tin in wt. naroztok. Test Number Test Period. (h) Addition of quantity (° / o w / w) Loss of media (g. m 2. hl_1) Corrosion 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% H2SO4 5 28 Sn 0.05 0 , 21 1 6 22 Sn 0.05 0.04 0 6% H2SO4 7 28 Sn 0.015 1.26 2 8 22 Sn 0.015 0.284 1 6% H2SO4 9 28 Sn 0.005 0.83 1 10 22 Sn 0.005 0.42 1 6 EXAMPLE 2 that after 28 hours the solution was replaced with a fresh one, with the sulfuric acid concentration in the apparatus of Example 1 being monitored in solution increased to 6% by weight. with new corrosion of copper plates using a tin sheet as a corrosion inhibitor of the medium. In comparison with the corrosion of the solution, the corrosion of the organic and inorganic streams is significantly reduced by the exchange of the solution, due to the further passivation of the measured surface by the addition of tin.

Formulated acids and with addition of corrosion inhibitor. The results are presented in Table 3.

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.