JPS58164767A - Container holding solution containing heteropolyacid ion - Google Patents

Abstract

PURPOSE:To obtain a container preventing stress corrosion cracking, by using a specified stainless steel as the material of the surface of a container which is in contact with a soln. contg. heteropolyacid ions and other specified stainless steel as the material of the weld zone. CONSTITUTION:The surface of a container which is in contact with a soln. contg. heteropolyacid ions is made of a Cr-Ni stainless steel plate consisting of, by weight, 2-7% Ni, 19-27% Cr, <=0.05% C, <=3% Mo, <=3% Cu and the balance Fe with inevitably contained elements. The weld zone of the container is made of an austenitic stainless steel consisting of, by weight, 9-16% Ni, 16-21% Cr, <=0.03% C, <=3% Mo and the balance Fe with inevitably contained elements. Thus, a container having superior general corrosion resistance and preventing stress corrosion cracking due to welding is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a container for containing a solution containing heteropolyacid ions. Specifically, there is a method in which stress corrosion cracking of the container is prevented by constructing at least the surface of the container that comes into contact with a solution containing heteropolyacid ions from a specific stainless steel.

In general, heteropolymonomers or their salts are used for various purposes, e.g.
For example, surface treatment agents for metals: chelating agents for dyes, lake agents: Widely used as catalysts in various organic synthesis reactions.

Conventionally, it has been known that in solutions containing heteropolyacid ions, the coexistence of ridge ions causes iron ions to act catalytically, promoting decomposition. In particular, the decomposition effect of heteropolyacid ions by iron increases as the pressure increases, so it is generally considered that iron or stainless steel cannot be used as the container.
A reaction vessel under high pressure used for the production of alcohols or carboxylic acid esters by hydration of olefins catalyzing heteropolyacid ions described in 2544 is lined with a noble metal such as gold, platinum, or silver. They were made of expensive materials such as nickel, chromium, zirconium, tantalum, or titanium.

However, it has been found that the use of such an expensive material is not only economically undesirable, but also causes component metals such as titanium to become embrittled due to the special action of heteropolyacid ions. Although such hydrogen embrittlement occurs even at relatively low temperatures, it becomes extremely noticeable at high temperatures of, for example, 200° C. or higher and under high pressure. In view of the above-mentioned problems, the present inventors have studied materials that are relatively inexpensive, have corrosion resistance, and do not have properties that promote hydrogen embrittlement or decomposition of heteropolyacid ions.
It was proposed as No. 254. In other words, the cough member provides a reaction IFW etc. suitable for producing alcohol by the hydration reaction of olefin using heteropolyacid ions as a catalyst. When a container for an aqueous solution or the like is manufactured and actually used in the above environment, it will corrode to some extent in the initial stage of use in terms of overall corrosion resistance, but after a certain period of use, the corrosion will almost completely stop. It is resistant to stress corrosion cracking and exhibits excellent properties as an industrial container. However, if the shape of the container is complex and the heat from processing such as welding during manufacturing is severe, stress corrosion cracking may occur due to the heat effects from welding and residual stress during extremely long-term use. However, since it requires skill to prepare the parts, such as the risk of causing damage, there is a lack of versatility.

31 In view of the above problems, the present inventors have developed a product with excellent general corrosion resistance,
Further, as a result of investigating a reaction vessel for preventing stress corrosion cracking due to welding, the inventors discovered that the conventional problems could be solved by using stainless steel having specific properties in combination, and came to provide the present invention.

That is, in the present invention, the surface that comes into contact with a solution containing at least heteropolyacid ions contains 2 to 7% by weight of nickel and 2 to 7% by weight of chromium.
19 to 27% by weight, carbon: O, OS weight % or less, molybdenum and copper: 3Ii weight% or less each, and the balance is made of chromium-nickel stainless steel steel plate made of unavoidably mixed elements and iron, and welded. Part is nickel = 9 to 16
Weight%, chromium: 16 to 20 parts by weight, carbon 0.03% by weight or less, molybdenum: 3% by weight or less, and the balance is composed of austenitic sterless steel consisting of unavoidably mixed elements and iron. This is a storage container for a solution containing characteristic heteropolyacid ions.

Incidentally, in the present invention, the magazine welded portion is a general term that includes not only the welding Depo but also the caul plate portion.

The container in the present invention is not only a container for transporting or storing a solution containing a heteropolyacid ion, but also a container for transporting or storing a solution containing a heteropolyacid ion.
i4- Refers to any container for receiving heteropolyacid ions, such as a container for producing teropolyacid or its salts, a reaction vessel for carrying out a reaction involving heteropolyacid ion, and particularly at a high temperature, e.g. It is suitable for the above-mentioned coal production and/or for storing a solution containing heteropolyacid ions under high pressure, for example, 10 atmospheres or more.

As generally recognized by chemical engineers, the heteropolyacid in the present invention refers to an acid composed of two or more metals among polyacids formed by a combination of inorganic acids, and generally one metal. The central atom is a polyacid group of other metals, which are coordinated with other metals.
'04o'), polytungstic acid: e.g. Hi(B
W+x 046), phosphotungsten II: e.g. Ha(PWII 04#), HA(Px WyO
ty=>, silicomolybdic acid di, e.g. H4 (S i
Mo+2040) phosphomolybdic acid: H3(PMO
s2LO+o>, etc., and the polyacid is V, MO or W, and the central atom is 8% Qu N 8,
A#, C, Si, Ge, Sn, Ti, Zr, Ce,
Th, N% P, As, Sb, V, Nb.

Ta, Cr, Mo, W%U
, Ss Se , Te , Mn
s summer, 5-Fe5Co, Ni, Rh, Os, Ir, Pt, etc.

Among these, heteropolyacid ions which are particularly suitable for the present invention are tungsten and molybdenum as polyacids, and heteropolyacid ions whose central core is silicon, phosphorus and boron, for example (S i Wlz O46') ',
(BW+:LO4o)-'ノ(PWlz 04a) and (SIM o +
l o#) etc., and as compounds, these -
, acid salts, neutral salts, etc.

(□The chromium-Ninkel stetholess steel used for the surface that comes into contact with the solution containing heteropolyacid ions of the present invention is a known one, but 'generally SUS 329Jl (J I
s standard) is used. The Ni, Cr, and C content chains of the chromium-nickel stainless steel used in the present invention are in a specific range, that is, Ni: 2 to 7 m%, Cr: 19 to 27
- Maximum %, %, C: 0.05% by weight or less If it deviates from this range, the heteropolyacid ion will be decomposed and it cannot be used as the container material of the present invention.

The mechanism by which the chromium-nickel stainless steel exhibits particular corrosion resistance in solutions containing heteropolyacid ions is thought to be due to the formation of a protective film 7 on the material surface due to the reaction between heteropolyacid ions and iron.

6- Also, the austenitic stainless steel used for the welding part of the present invention contains 9 to 16% by weight of nickel and 16 to 20% of chromium.
General-purpose austenitic stainless steel can be used as long as it is within the range of @% by weight, charcoal j1003% by weight or less, molybdenum: 3% by weight or less.

Materials other than the above EIS cannot be used in the method of the present invention from the viewpoint of corrosion resistance. In particular, since the purpose of the present invention is to prevent stress corrosion cracking in welded parts, it is essential that the carbon content be 0.03% or less.
If these requirements are not met, intergranular corrosion may occur due to the thermal effects of welding, etc., and there is a risk of cracking in areas where tensile stress is applied, so it cannot be used. Incidentally, the lower the carbon content of the chromium-nickel stainless steel and austenitic stainless steel used in the present invention, the better, as long as it is equal to or less than the above aS. Further, in addition to these components, the contamination of silica, manganese, phosphorus, etc. entrained from the raw materials, or the contamination of molybdenum, nitrogen, copper, etc. added for the purpose of improving properties, has almost no influence. Therefore, these unavoidably mixed materials may be present, and depending on the situation, they may be mixed and used as necessary. For example, according to research by the present inventors, MO and Cu of 3% or less do not impair the properties of the stainless steel, and the addition of MO is a preferable component for preventing pitting corrosion. be.

The most important point in the present invention is that when a specific chromium-nickel stainless steel is brought into contact with an environment containing heteropolyacid ions for a long period of time, it has excellent general corrosion resistance, but stress corrosion cracking is observed in the welded parts. In addition, when a low carbon content austenitic stainless steel is brought into contact with a hexacyclic mass containing heteropolyacid ions, corrosion cracking does not occur at the welded part, but the general corrosion resistance is poor, and iron ions eluted from the stainless steel However, by using the method of the present invention, all the disadvantages of using both alone can be eliminated, and the advantages of both, namely, heteropolyacid ion, can be eliminated. Fully corrosion resistant to ions,
It has excellent stress corrosion cracking resistance and excellent properties that can almost prevent the decomposition of heteropolyacid ions.

Especially conventional Auste! ';7 It was difficult to use r-stainless steel in a heteropolyacid ion for the reasons stated above.

The welding method used in the present invention includes welding a welded part of chromium-nickel stainless steel with an austenitic stainless steel welding rod, or applying the austenitic stainless steel to a partially repaired part of chromium-nickel stainless steel. Possible methods include welding with an austenitic stainless steel welding rod. During this welding, the area of the welded portion is usually extremely small compared to the area of the entire surface. In the present invention, the general corrosion resistance of austenitic stainless steel itself against heteropolyacid ions is lower than that of chromium-nickel stainless steel, so the area where the austenitic stainless steel and chromium φ nickel stainless steel are used is mainly the latter. It must be as follows.

That is, the area of the portion in contact with the solution of heteropolyacid ions is preferably 10 times or more, more preferably 50 times or more.

In addition, known methods can be used for welding conditions such as welding current density, welding speed, and blade edge shape when welding both stainless steels.

In order to explain the present invention in more detail, Examples are given below.
- However, the present invention is not limited to these examples.

Table 1 shows the chemical composition of the stainless steel used as the test piece and welding rod in the examples.

In addition, in the following examples, the corrosion rate of the test piece was determined by mechanically removing corrosion products from the test piece using crude baking soda or a nylon brush, washing it with water, and washing it with methanol, and then weighing it to determine the amount of corrosion. It was calculated using the following formula.

Corrosion rate (1 (j/d$/day) 10- JP-A-58-164767 (4) Example 1 A stainless steel plate and a welding rod (
Welded joint specimens were prepared using a rod (2,6-/I) in the combinations shown in Table 2.

Next, place this with the weld bead in the middle and make it 15-m (width)
It was cut into a shape of 60-(length) x 21-(thickness).

In all cases, the area of the portion other than the welded portion was 50 times or more that of the welded portion. After that, straight 1140g
An aqueous solution containing 39/12 phosphomolybdic acid at a ratio of 3 ko/Hr per 1 C of reactor volume was suspended from the top with a Teflon string in a silver-lined back pressure reactor with a height of 1201 m and an internal volume of 1,212 m. was supplied and heated to 300℃ while blowing propylene from the bottom at a rate of 0.2kMHr.
A continuous hydration reaction was carried out under the reaction conditions of , 200ko 10/G, and the corrosion weight loss of the bales shown in Table 2 was determined. The corrosion rates are summarized in Table 2.

In addition, stress corrosion cracking susceptibility was also investigated. The shape of the test piece is 15m5 (width:') x 70111 (length) x 21m (thickness), 0-shaped bend (R'-3t, where R is the radius of the U-shaped bend, and t is the thickness of the test piece. The test was conducted in exactly the same manner as described above, except that stress was applied to the test piece. 112- The presence or absence of cracks in the specimen after the test was confirmed visually and with an optical metal chain mirror. The results are summarized in Table 193.

The numbers in parentheses in the results column of Table 3 indicate the number of cracked samples relative to the number of test materials.

13- Table 2 14- Example 2 A heteropolyacid ion-containing aqueous solution was mixed with borotungstic acid,
The stress corrosion cracking susceptibility of the welded test pieces shown in Table 2 was examined in exactly the same manner as in Example 1, except that silicomolybdic acid, silicotungstic acid, and sodium dihydrogen silicomolybdate were used. The results are summarized in Table 4.

17- Example 3 A high-pressure reactor (300 kg/c) for producing isopropyl alcohol from propylene using a heteropolyacid as a catalyst.
sG.

The side of the channel cover in contact with the reaction liquid (300°C) is lined with chromium nickel stainless steel (material A) shown in Table 1, and then the A part corresponding to the seam weld is lined with 2
An austenitic stainless steel plate (material D in Table 1) having a thickness of ms+ was applied, and the welded portion was welded using an austenitic stainless steel welding rod (welding rod d in Table 1).

After approximately one year of commercial operation, we removed it and checked for cracks using the color check method, etc., and found that the lining side (material A), patch plate side (@material 0), and welded Qepo part were all damaged. It was healthy with no problems.

patent applicant Tokuyama Soda Co., Ltd. 18-

Claims (1)

[Claims] 1) The surface in contact with IIw, which contains at least a heteropoly-ion, is made of 2 to 7% nickel nickel and 19 to 19% chromeco.
21% by weight, carbon: 4), less than 05% by weight, molybdenum and steel: less than 3% by weight each, and the remainder is from chromium and nickel stainless steel plate consisting of unavoidably mixed elements and iron and the welded part is nickel 20~16-
% by weight, chromium = 16-21% by weight, carbon: O, OA % by weight or less, molybdenum: 3% by weight or less, and the remainder is composed of austenitic stainless steel consisting of elemental wheat flour that is mixed in impossibly. Storage container for solutions containing heteropolyacid ions