JPS5879590A - Removing method for dissolved oxygen - Google Patents

Abstract

PURPOSE:To remove the dissolved oxygen in liquid to be treated efficiently, by bringing liquid to be treated contg. dissolved oxygen into contact with a palladium catalyst in the presence of a water soluble hydrogen occluding compd. CONSTITUTION:A palladium catalyst and liquid to be treated contg. dissolved oxygen are brought into contact with each other in the presence of a water soluble hydrogen occluding compd. (e.g., NaBH4). The quantity of addition of said water soluble hydrogen occluding compd. is sufficient at about equimol of the quantity of dissolved oxygen in the liquid to be treated or about 1.8 times mole. Catalysts deposited with Pd on carriers of ion exchange resins, alumina, etc., other than Pd compds. such as metallic Pd, Pd oxide, and Pd hydroxide are usable for said palladium catalyst. It is possible to deposit Pd on anion exchange resins simply by packing the anion exchange resins in a column and passing an acidic soln. of Pd chloride through the column.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for removing dissolved oxygen in water.

Today, large amounts of water are used as boiler water and cooling water. However, if dissolved oxygen exists in these waters, corrosion problems due to dissolved oxygen will occur in the boiler water system and cooling water system. Therefore, before use, dissolved oxygen in water must be removed by chemical or physical methods. Conventionally, chemical methods such as adding hydrazine or sulfite to these liquids have been used. Dear friend. but,
This method has drawbacks such as slow derlI removal rate and a large amount of non-evaporable solids being introduced into the liquid to be treated, which can cause problems in boiler operation when water is being fed to the boiler. .

The present invention has been developed to overcome these drawbacks of the prior art and provides a method that can efficiently remove dissolved oxygen from a liquid to be treated.

That is, the present invention is a method for removing dissolved hydrogen, which is characterized by bringing a palladium catalyst into contact with a liquid to be treated containing dissolved hydrogen in the presence of a water-soluble hydrogen storage compound.

Water-soluble hydrogen storage compound 1, when added to water, 2- A compound that can generate hydrogen.

For example, Na BH4, Li BH4, KBH4, C
a (B H4)! #CCHs) aNBH4m A#
(BH4)3pS r (BHa )g, NaZn(
BH4)s, (C5kk) me e BHJ' risef
f') Rel 2>", jThey do not generate hydrogen when stored as concentrated liquids, but pat
When it is changed or diluted to 9V, it quickly generates hydrogen. Among them, -NaBH is a water-soluble material used in the invention because it is relatively inexpensive, the concentrated stock solution is extremely easy to handle, and it can quickly generate the theoretical amount of hydrogen just by adding it to the liquid to be treated. This is a preferred example of a hydrogen storage compound.

Hydrazine hardly generates hydrogen as it is, but when a suitable catalyst, such as a palladium compound, coexists with it,
Occurs on hydrogen.

In addition, when NaBH4 and hydrazine are used in combination,
More excellent effects can be obtained with a small amount added.

Since these water-soluble hydrogen storage compounds are uniformly dissolved in water, hydrogen is also generated uniformly, and as a result, contact with dissolved steel occurs quickly, and it is converted to water by the palladium catalyst.
As a result, dissolved oxygen is removed from the liquid to be treated.

Since the contact reaction between dissolved oxygen and hydrogen in the presence of a palladium catalyst is extremely rapid, the evolution of hydrogen from water-soluble hydrogen storage compounds is usually invisible and the reaction with dissolved oxygen is completed immediately after hydrogen generation. .

It is sufficient that the amount of the water-soluble hydrogen storage compound added is about 1 molar to 1.7 times the amount of dissolved oxygen in the liquid to be treated. Irile comes true/tsubo ← Rira Wabi 1-・工 ψ〜tO ← Ut・shii ≠ Yafuga.

Palladium catalysts include palladium compounds such as metallic palladium, palladium II, and aqueous palladium, as well as
Ion exchange resin, alumina, activated vertical.

A catalyst in which palladium is supported on a carrier such as zeolite can also be used. The loading t is usually 0.1 to te11!
degree. In particular, it is preferable to use an anion exchange resin because excellent effects can be achieved with a small amount of palladium supported.

In order to support palladium on an anion exchange resin, it is sufficient to apply the anion exchange resin to a t-column and then pass water through an acidic solution of palladium chloride. If it is to be supported on a metal plate, formalin or the like may be further added to the above for reduction.

The palladium catalyst can be used in any shape, such as a powder, a single grain, or a pellet. When using all of the powder, a reaction tank is provided and an appropriate amount is added to the reaction tank. Granules and pellets are advantageous when packed in a column or the like and the liquid to be treated is continuously passed therethrough. of course,
Even if it is in powder form, it can be packed into a column and operated in a fluidized bed.

In the method of filling a column and passing the liquid, the liquid passing speed company 50~
It can be about 50017br. The liquid to be treated in this invention is boiler feed water.

Can be used for industrial water such as cooling water. It can also be applied to waters with high salt production, such as seawater.

When the pH of the liquid to be treated is about 4 to 12, special pretreatment such as pH adjustment is not necessary, and the method of the present invention is directly applied. Normal industrial water is within this pH range and is preferred. Please do not take any precautions, especially such as heating.

As mentioned above, by bringing the water to be treated and the water-soluble hydrogen storage compound into contact in the presence of a palladium catalyst, the hydrogen generated from the water-soluble hydrogen storage compound and dissolved oxygen are rapidly reacted to remove oxygen. However, if hydrogen gas is used directly instead of the water-soluble hydrogen storage compound used in this invention, first of all, hydrogen gas is explosive and is extremely difficult to handle as a salt. It is extremely difficult to dissolve it in the liquid to be treated, and it is necessary to add it in a large excess amount, which is more than necessary, and furthermore, the hydrogen gas in the water must be separated before it can be used as water.
A tedious operation is required.

As mentioned above, this invention utilizes a very simple method of reacting an extremely easy water-soluble hydrogen compound with dissolved hydrogen in the coexistence of a palladium catalyst. It can be removed safely and efficiently (in addition, since the reaction speed is fast, the contact time is short, and a large amount of liquid to be treated can be treated in a short time.In addition, the equipment itself It can be made smaller.In particular,
When a palladium catalyst packed column is used, an appropriate amount of a water-soluble water bulk storage compound is added to the liquid to be treated, and after death, the water is simply passed through the packed column, and dissolved II. Treated water with extremely low elemental content can be obtained.

Example 1 After adding a predetermined amount of various WR removal additives shown in Table 1 to demineralized water containing dissolved A12 tl-8/l, a palladium catalyst (an acidic solution of palladium chloride was passed through anionic water, and anion was added to the demineralized water at the column outlet. The amount of dissolved I in the treated water was determined.

The results are shown in Table-1.

Table 1 In addition, as a comparative example, the results of adding a predetermined amount of hydrazine hydrate or sodium sulfite, stirring roughly, and then determining the dissolved oxygen vm in the treated water are also shown.

As you will see, in the case of sodium borohydride, by simply adding 1.1 to 1.6 times the theoretical amount, 5v
The amount of dissolved oxygen in the treated water is 0.1 to 0.5 ■/! It became.

On the other hand, in the case of hydrated hydrazine, hydrated hydrazine alone without coexistence with a palladium catalyst tube has almost no effect, whereas in the case of this invention, the amount added is 40% of the theoretical amount.
．． Although the amount of dissolved oxygen is 8 to 97 times, the amount of dissolved oxygen is 0.4 to 0.1, and the reaction is completed instantly, making it sufficiently practical (hydrazine is volatile, so even if a large amount is added, it will not form as a solid substance. (no residue).

To obtain 0.1 da/, e of dissolved oxygen in the treated water obtained with sodium borohydride using sodium sulfite, sodium sulfite f65η/! It was necessary to add some amount. The entire amount added becomes a non-evaporable solid and remains in the aqueous system.

Example 2 Example 1 except that a combination of sodium borohydride and hydrazine hydrate was used as the water-soluble hydrogen storage compound.
The deoxygenation reaction was carried out in the same manner.

The results are shown in Table-2.

Table-2 Comparing Table-1 and Table-21, they are the same gys.

However, how to set the amount of dissolved oxygen in the treated water to t-0,1■/1? 'JIBHa alone is 6 da/! , N Snow H4 alone is almost impossible, but when both are combined, N! IBH4 can be reduced by over 20%, and -NIH
The amount of addition of 4 is only 7.8■/! It's done.

In this way, it is preferable to mix both of them because the amount added can be greatly reduced.

Patent applicant Kurita Industries Co., Ltd.

Claims (1)

[Claims] 1. Palladium catalyst and dissolved in the presence of a water-soluble hydrogen storage compound! [Including subject! Patented method for removing dissolved oxygen L The water-soluble hydrogen storage compound is sodium borohydride (lJIBHa) Claim 1 Method for removing dissolved oxygen Claim 1 [11!] The water-soluble hydrogen storage compound is hydrazine or hydrated hydrazine. Dissolved oxygen removal method 4 according to I. The method for removing dissolved oxygen according to any one of claims 1 to 3, wherein the palladium catalyst is an anion exchange resin tube carrier.