KR950014207B1 - Tin(ñœ)stabilizer for hydrogen peroxide - Google Patents

Abstract

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Description

Tin (II) Stabilizer for Hydrogen Peroxide

The present invention relates to a stabilization method for the decomposition of hydrogen peroxide and to a stabilized hydrogen peroxide composition.

Pure hydrogen peroxide is a very stable compound, but in the presence of any number of transition metals such as iron and copper, it decomposes into oxygen gas and water. In production, hydrogen peroxide is rarely such a decomposition catalyst. However, there is a need to protect against unexpected contamination with stabilizers during shipping and storage of hydrogen peroxide.

Transparent colloidal tin sol formed from sodium stannate or other tin compounds have been known as an effective stabilizer for hydrogen peroxide, and the use of such tin sol is described in detail in Schumb et al. According to Schub et al., The optimum tin concentration for 85% hydrogen peroxide is 0.lmg / ferric iron. It is reported that SnO _{2 is} 0.83 mg / L.

It is well known that aluminum metal and aluminum ions do not catalytically decompose hydrogen peroxide. However, the presence of aluminum ions causes precipitation of tin sol from hydrogen peroxide. US Pat. No. 3,356,457 to Morris et al. Teaches that up to 0.2 mg / l of aluminum may be present in a tin stabilized hydrogen peroxide formulation. However, if phosphate stabilizers are present, tin stabilized hydrogen peroxide can tolerate up to 1 mg / l of aluminum ions without precipitation.

US Pat. No. 3,234,140 to lrani teaches that amino tris (methylenephosphonic acid) is a stabilizer for hydrogen peroxide solutions when phosphonic acid is present at a concentration of about 0.001 to about 5%. US Pat. No. 3,383,174 to Carnine et al teaches a synergistic mixture of 10-150 mg / l tin added as sodium stannate and 50-300 mg / l amino tris (methylenephosphonic acid). No. 3,861,022 to Kibel et al. Discloses a 35% hydrogen peroxide blend containing 300 mg / l tin in the form of a soluble alkali metal salt such as sodium stannate and dissolved with 1250 mg / l amino tris (methylenephosphonic acid). This is described.

In many fields, such as chemical reagents and semiconductors, it has been found that high concentrations of stabilizers taught by the prior art are not acceptable. For example, the ACS specification for hydrogen peroxide reagents requires a maximum residual concentration of 29.0 to 32.0% analyzed after evaporating hydrogen peroxide to 20 mg / l. Tin compounds used to stabilize hydrogen peroxide are widely known to be in the form of colloidal tin oxide particles that can coagulate and be neutralized by zwitterions such as calcium, magnesium and aluminum, and conventional decomposition catalysts.

Negative ions such as pyrophosphate, phosphate and sulfate are known to improve the stability of colloidal tin oxide. However, according to the prior art, the amount of these substances to be used at the minimum threshold cannot be used for ACS hydrogen peroxide reagents because up to 2 mg / l phosphorus and up to 5 mg / l sulfate are specified as phosphates.

Alkali metal ions such as sodium or potassium were not observed to adversely affect the stability of the hydrogen peroxide solution. Thus, tin stabilizers are commonly formulated into hydrogen peroxide solutions as sodium stannate or potassium stannate.

However, even alkali metal ions may be undesirable in applications, including semiconductors, so that hydrogen peroxide is generally preferred to be almost free of all metal compounds, including tin stabilizers.

The present invention relates to a transition metal, comprising incorporating a tin (II) salt of an acid selected from the group consisting of hydrofluoric acid, C ₆ to C ₁₇ saturated monocarboxylic acids and C ₂ to C ₆ saturated polycarboxylic acids, to hydrogen peroxide. By providing a stabilization method for the decomposition of hydrogen peroxide by means of the problem of the stabilizer of the prior art.

Typical saturated monobasic normal acid components of tin salts useful in the present invention include caproic acid, heptyl acid, caprylic acid, pelagonic acid, capric acid, undecylic acid, lauric acid, myristic acid, palmitic acid, stearic acid and C. Branched chain acids of less than ₁₀ , for example ethylhexanoic acid. Suitable polybasic acids include oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid, as well as hydroxy polybasic acids such as tartaric acid and citric acid.

It is surprising to discover that tin (II) salts can be blended into hydrogen peroxide as a stabilizer. In addition, although these compounds could be separated from aqueous hydrogen peroxide by centrifugation, decantation or filtration, it was unexpected to observe that some of these compounds were effective as stabilizers. Some of the stabilizing compositions that are free salts or salts of free acids, rather than tin salts or tin-containing compounds, are cloudy, cloudy or floc.

Preferably, the tin salt is first blended in a stock solution such as an aqueous slurry or solution and subsequently in aqueous hydrogen peroxide. The stock solutions may be prepared using water or aqueous hydrogen peroxide as a liquid, and may optionally contain other additives, such as acids, buffers, chelating compounds or agents, to the hydrogen peroxide to modify the viscosity, surface tension or shape of the hydrogen peroxide. . Preferably, the stock solution contains about 0.01 to 10%, more preferably about 1 to about 5% tin salt.

Particularly preferred tin (II) salts have the unexpected nature of forming a transparent sol or solution in hydrogen peroxide, but the first liquid portion and the initial liquid portion containing less than 1 mg / l tin when properly aged at 0 to l00 ° C. Tin added to the oxalic acid can be separated into a second non-fluidic part containing most of the tin. In general, it is sufficient to mature the stock solution at about 25 ° C. (room temperature) for about 10 days. However, the time required for aging can be reduced by keeping the stock solution at elevated temperature for a certain time. For example, maintaining the stock at about 100 ° C. for 15 minutes may reduce the time required for ripening to about 24 hours, while maintaining the stock at about 100 ° C. for 1 hour may result in about one to two hours or It can be reduced below that. One of ordinary skill in the art can most preferably easily select the temperature and time required to ripen the stock solution from the above description without unnecessary experimentation.

The hydrogen peroxide to be stabilized can be any convenient concentration. Preferably, the hydrogen peroxide has a concentration in the range of about 6 to about 75 weight percent, more preferably about 25 to about 70 weight percent. In this way, hydrogen peroxide can be stabilized at concentrations below 1%, but such solutions are too thin and are not suitable from an economical transport standpoint.

Those skilled in the art will readily appreciate that the most preferred amount of tin added to the solution varies depending on the concentration of hydrogen peroxide, the potential for contaminants in the hydrogen peroxide solution, and the intended use of the hydrogen peroxide. Typically, hydrogen peroxide is used in the electronics industry in amounts of 30-50%. It is desirable to combine sufficient stabilizer to provide from about 0.lmg / L to about 100 mg / L of tin, preferably from about 1 mg / L to about 20 mg / L of tin. Most preferably, the stock solution is prepared using tin oxalate (tin oxalate II), which is sufficiently mature to separate the non-fluid part from the first liquid, resulting in a product containing 1 mg / L of tin.

The present invention includes stabilized hydrogen peroxide compositions as well as methods for stabilizing hydrogen peroxide.

The invention is further illustrated by the following examples.

Unless otherwise noted, all concentration percentages are by weight.

Stabilized blends of 35% hydrogen peroxide were prepared using various tin salts, and optionally amino tris (methylenephosphonic acid) as chelating agents, as described in Table I. In some experiments the cracking catalyst was added as a dopant. The complete addition of dopant provides 1.2 mg / l of iron and aluminum, 0.24 mg / l of copper, 0.12 mg / l of manganese and 0.06 mg / l of hexavalent chromium in hydrogen peroxide, respectively. The high temperature stability of the hydrogen peroxide solution for 24 hours was measured, then several samples were decanted or filtered and the clear solution analyzed for tin.

For comparison, the stability to unstabilized hydrogen peroxide (control) was measured and the hydrogen peroxide stabilized at 1 mg / l tin as potassium stannate (standard).

As soon as hydrogen peroxide was prepared, the tin content was measured in experiments 74-1 to 74-4 and found to be 0.65, 0.64, 0.36 and 0.20 mg / l, respectively. In Experiment 74-2, the phosphate after hydrogen peroxide production was 0.75 mg / l and the phosphate after stabilization and filtration was 0.34 mg / l; Phosphates in Experiment 74-4 were 0.53 and 0.34, respectively.

Tin fluoride and tin tartaric acid did not dissolve completely. In addition, the tin fluoride and tin stearate samples had a clustered precipitate or solids added from the samples prepared using tin tartarate, 2-ethyl hexanoate, caproate and laurate while having visible haze.

Example 2

A sample of 35% hydrogen peroxide containing 2 mg / L tin tartarate was prepared as in Example 1 with or without doping with a decomposition catalyst at a ratio of 1/100. The sample was tested twice for stability before and after filtration through a 0.22 μm filter. The results are shown in Table II.

As this example removed most of the three insoluble stabilized tin salts, it was shown that the reproducibility of the sample stability was poor after filtration as expected.

Example 3

A series of experiments were planned to elucidate the reason for the incompatibility of tin analytes in samples made of tin oxalate. Samples of hydrogen peroxide containing lmg / l tin were prepared from stock solutions containing 0.5-2.0% tin oxalic acid and optionally additional oxalic acid. Freshly prepared filtered and unfiltered samples were aged for 10 days and the tin in the samples analyzed. Table III surprisingly shows that almost all tin can be filtered out of solution upon aging.

Oxalic acid tin stock solution was prepared by heating in a steam bath for about 15 minutes. The oxalic acid tin-tin oxalic acid mixture dissolved within 15 minutes at ambient temperature. Tin tartaric acid was not dissolved in 35% hydrogen peroxide even when heated overnight in a steam bath.

This example showed that tin can be filtered from H ₂ O ₂ by aging the stock solution.

Example 4

Table IV was planned to determine the time required to make the solution filterable. Samples were prepared from a 1% tin oxalic acid stock solution optionally containing 1% tin oxalate.

The stock solution was used daily to prepare a 35% hydrogen peroxide solution containing about 2 ppm of tin compound. The stabilization solution was filtered through a 0.22μ filter. The tin content in the filtered solution was measured.

Example 5

The stock solution was prepared as in Example 4 except that the stock solution was treated for 0, 2 and 3 hours in a steam bath. The stock solution was used to stabilize 35% or 70% hydrogen peroxide after 1 day. Hydrogen peroxide samples were filtered and analyzed for tin. The results are shown in Table V.

This example shows that the stabilized hydrogen peroxide can be produced even after the stock solution is aged at 100 ° C. for 1 hour, and tin in the hydrogen peroxide can be immediately removed by filtration or the like.

TABLE 1

Stability of 35% H ₂ O _{2 with} and without contaminants

Note: All annotations were analyzed after filtration through a 0.16μm filter with the exception of

*: 0. Filtered through 22 μm filter

**: solution was decanted from solids

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Claims (8)

A method for stabilization of decomposition of hydrogen peroxide by transition metal ions, characterized by blending tin (II) salts of C ₂ to C ₆ saturated polycarboxylic acids with hydrogen peroxide. The method of claim 1 wherein said acid is oxalic acid. The method of claim 1 wherein the acid is tartaric acid. The method according to claim 2, wherein (a) the amount of tin oxalate salt (II) is sufficient to provide a concentration of 0.01 to 10% by weight in the stock solution, (b), ... Aging for 5 minutes to 6 months at a temperature of, and (c) 1 to 20 mg / L of tin in hydrogen peroxide by sufficiently blending the stock solution aged from (b) to 6 to 70% aqueous hydrogen peroxide solution Providing a compound of tin (II) oxalate salt with hydrogen peroxide by providing. 5. The method of claim 4, wherein the hydrogen peroxide from step (c) is filtered to provide a first fluid portion of hydrogen peroxide containing less than 1 mg / l tin. The composition prepared by claim 4. A composition prepared according to claim 5. A method of centrifuging the stabilized hydrogen peroxide from step (c) of claim 4 into a first fluid portion and a second non-fluid portion containing 1 mg / l tin.