JPS58210985A - Composition of aqueous solution of lithium bromide - Google Patents

Abstract

PURPOSE:A composition of an aqueous solution of lithium bromide, containing lithium hydroxide, prepared by adding a specific polyhydric phenol (derivative) and an alkali metallic nitrate (or nitrite) as corrosion inhibitors thereto, and capable of effectively suppressing the metal corrosiveness of absorption type refrigerators, etc. CONSTITUTION:A composition of an aqueous solution of lithium bromide, containing lithium hydroxide, and prepared by adding preferably 0.05-1.0wt% one or more selected from a polyhydric phenol of the formula (R is H, NH2 or halogen; 2<=n<=5), preferably resorcinol or pyrogallol, and derivatives thereof and preferably 0.01-0.1wt% alkali metallic nitrate (preferably to the aqueous solution of the lithium bromide containing the lithium sodium salt) or preferably 0.001-0.05wt% alkali metallic nitrite hydroxide, usually an aqueous solution consisting of 53-55wt% lithium bromide and 0.01-0.3wt% lithium hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an additive that effectively inhibits metal corrosion of lithium bromide aqueous solution compositions containing lithium hydroxide, particularly lithium bromide aqueous solutions containing lithium hydroxide used in absorption refrigerators, etc. and a lithium bromide aqueous solution containing lithium hydroxide.

It is well known that lithium bromide aqueous solution is corrosive to mild steel, copper, brass, etc., and when these metal materials are used in absorption refrigerators and lithium bromide aqueous solution is used as the absorption liquid, Various types of corrosion inhibitors have been proposed, some of which are in actual use.

For example, nitrates such as lithium molybdate, lithium chromate, lithium nitrate, lithium phosphate, lithium borate, lithium perchlorate, lithium tungstenate, lithium vanadate, lithium thioanate, lithium silicofluoride, lithium nitrite, In addition to diphenylguanidine, mercaptobenzothiazole, benzotriazole, mixtures of benzotriazole with molybdates, alkanolamine modules, or nitrates, lithium hydroxide, etc. are added to some of these, and lithium hydroxide. Examples include those in which only one of the following is added.

However, although these conventional additives are effective in preventing general corrosion of lithium bromide aqueous solutions, they have various drawbacks. For example chromates, molybdates, nitrates,
Lithium nitrite, etc. not only cause crevice corrosion, but they are also reduced and consumed rapidly, making management complicated.
Benzo) IJ azole has difficulty in dissolving into an aqueous lithium bromide solution, and when a mixture of benzotriazole or its derivative, molybdate, and lithium hydroxide is added, it lacks corrosion protection over a wide range. Addition of lithium hydroxide also provides insufficient corrosion protection.

As a result of the inventors' studies to solve these drawbacks,
Lithium bromide water containing lithium hydroxide? A composition comprising at least one selected from polyhydric phenols and derivatives thereof to be teared as liquid A and an alkali metal salt of nitric acid or an alkali metal salt of nitric acid is suitable;
Further, to the lithium bromide water bath solution containing lithium hydroxide, at least one selected from the polyhydric phenols and derivatives thereof is added to the alkali metal nitric acid.
□In the case of salt, 001 to O1 weight ratio is added, and in the case of alkali metal salt of nitrous acid, 0001 to 005 weight ratio is added.'
They discovered that the product was particularly excellent and completed the present invention.

The present invention will be explained in more detail below.

The lithium bromide bath solution containing lithium hydroxide constituting the composition according to the present invention is obtained by adding lithium hydroxide to a commonly used 53 to 55% by weight lithium bromide bath solution.
A lithium hydroxide concentration of 0.01 to 0.3% by weight is adjusted.

The other constituents are at least one selected from polyhydric phenols and their derivatives, representative examples being dihydric phenols such as sol 7nol, catechol, and hydroquinone, pyrogallol, and hydroquinone. , trihydric phenols such as phloroglu-7nol, and the like are preferably used.

In addition, these polyhydric phenols and their derivatives need only have solubility in the lithium bromide aqueous solution at around 6 to 40° C. in order to facilitate handling when the absorption liquid is distributed as a commercial product.

On the other hand, the degree of use of one or more types selected from 2-set polyhydric phenols and their derivatives is not particularly limited, but no effect can be expected if the amount is too small for a lithium bromide aqueous solution containing lithium hydroxide. However, it is preferable to add at least 0.005% by weight. On the other hand, if the amount is too large, there will be differences in water solubility depending on the species, and the effects of the present invention will not be as noticeable. It is sufficient to add

On the other hand, among other additives such as alkali metal salts of nitric acid and alkali metal salts of scolded nitric acid, Noda salt is superior in terms of ease of use. In addition, regarding the concentration, the effect is weak if the concentration is less than o, oi weight ratio for nitric acid, and less than 0001 weight ratio for nitrite; If it exceeds this, both tend to promote crevice corrosion.

The preferable ranges for each addition amount are as described above, but the particularly effective range in terms of the corrosion inhibiting effect of lithium bromide is 01 to 05 weight range for polyhydric phenols, and i for alkali metal salts of nitric acid. #i is 0.01 to 006% by weight, and in the case of alkali metal nitrite, it is 0002 to 002% by weight.

It has been known for a long time that the effect of containing lithium hydroxide as in the present invention is superior to that of containing lithium bromide alone; A lithium bromide aqueous solution containing lithium hydroxide having a weight ratio of 53 to 55 lithium and a 001 to 03 weight ratio of lithium hydroxide is used.

Next, examples using the composition according to the present invention will be described.

Examples 1 to 28 Comparative Examples 1 to 4 The effects of the implementation were determined by measuring the corrosion weight loss and the presence or absence of crevice corrosion.

These specific measurement methods will be explained. To measure the corrosion weight loss, add polyhydric phenol, etc. and an alkali metal salt of nitric acid or nitrous acid to an aqueous solution containing 01 parts by weight of lithium hydroxide and 55 parts by weight of lithium bromide, and place it in a steam condenser heating flask ( Vertical) 5.0
ffi+ × (horizontal) 30αX (thickness) 0.2Crn 88% of 232741. In an IJ, a flat plate with a hanging hole was thoroughly polished with emery paper, and the two degreased plates were separated and hung for 1,000 hours to undergo S% treatment, and the weight loss was judged.

To determine whether or not cracked crevice corrosion occurs, place an aqueous solution with the same composition as that used for corrosion attenuation measurement in a similar flask (upright).3. OcmX (horizontal) 2.
A 8811141 sand plate of Oc1n x (thickness) 0.2 cm was well polished with emery paper and degreased.
Rubber band made of silicone rubber (width 05 brocade, folded diameter 1.5cm)
) K Soak two rivers in the horizontal direction, 1.000
After boiling for a period of time, judgment was made based on the presence or absence of surface corrosion of the portion covered with rubber.

Table 1 shows the aqueous solution composition and the measured effects of the present invention.

Table 1 *l 55% by weight LiBr aqueous solution contains o,
i wt % added amount to the aqueous solution.

However, the comparative example shows that the composition of the present invention is very effective in preventing corrosion of a lithium bromide aqueous solution containing lithium hydroxide, as is clear from the results of the addition amount to a 55% by weight Li13r aqueous solution. .

Patent applicant: Showa Denko Co., Ltd.

Claims (4)

[Claims] (1) Brominated by adding at least one selected from hydroxide, polyhydric phenol and its derivatives produced in a lithium bromide aqueous solution, and an alkali metal salt of nitric acid or an alkali metal salt of nitrous acid. Lithium aqueous solution composition (2) At least one selected from the polyhydric phenols and their derivatives is added in an amount of 0.05 to 1.0% by weight to an aqueous solution of lithium bromide containing lithium hydroxide. Lithium bromide aqueous solution composition described in section (3) Lithium bromide water bath liquid according to claims 1 or 2, which is obtained by adding 0.01 to 0.1% by weight of an alkali metal salt of nitric acid to an aqueous lithium bromide solution containing lithium hydroxide. Composition (4) Lithium bromide aqueous solution composition according to claims 1 to 2, which is obtained by adding 0001 to 005% by weight of an alkali metal salt of nitrous acid to a lithium bromide aqueous solution containing lithium hydroxide.