JPS5926620B2 - Concentration separation method for naphthalene-1,3,6-trisulfonic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for removing excess sulfuric acid by evaporation in a naphthalene trisulfonation reaction mixture containing naphthalene-1,3,6-trisulfonic acid as a main component.

More specifically, the excess sulfuric acid in the trisulfonation mixture is
When removing and recovering by evaporation at a temperature of 50 to 3000C,
This is a method for concentrating and separating naphthalene-1,3,6-trisulfonic acid, which is characterized by using a distillation apparatus using an austenite-ferritic two-phase stainless steel alloy as the distillation apparatus material. Conventionally, H acid (1-amino-8-naphthol-3,6-disulfonic acid), which is important as an intermediate for azo dyes, is industrially usually obtained by trisulfonating naphthalene with about 7 times the mole of sulfuric acid.・3
・By nitration and reduction of a trisulfonation reaction mixture containing 6-trisulfonic acid as a main component, 1-aminonaphthalene-3,6,8-trisulfonic acid is derived, and then alkali melting is performed. It is manufactured by Yotsu.

By the way, the naphthalene trisulfonation reaction mixture contains by-products and a large amount (approximately 50% by weight) of excess sulfuric acid in addition to the target naphthalene-1,3,6-trisulfonic acid. When using this method, a large amount of excess sulfuric acid is discharged as waste sulfuric acid, and wastewater treatment requires a large amount of expense. Therefore, it is necessary to remove excess sulfuric acid from the trisulfonation reaction mixture from the viewpoint of pollution prevention and economical reasons. , collect,
At the same time, separating naphthalene-1,3,6-trisulfonic acid has become an important issue.

In order to solve such problems, the present inventors previously proposed in Japanese Patent Application No. 51-80734 that the content of naphthalene-1,3,6-trisulfonic acid in the trisulfonation reaction mixture can be substantially reduced. We have found a method to evaporate and recover excess sulfuric acid without causing any deterioration. The sulfuric acid recovered by this method is high purity sulfuric acid with a concentration of 98-99%,
It can be recycled and used to sulfonate naphthalene. The main purpose of the present invention is to
The object of the present invention is to provide a distillation apparatus useful for industrially carrying out the method of No. 80734.

The composition of the naphthalene trisulfonation reaction mixture that is the subject of the present invention is illustrated in Table 1, but is not limited thereto.

The naphthalene trisulfonation reaction mixture exemplified in Table 1 is usually 150-300°C, preferably 180-200°C.
It is necessary to evaporate and recover excess sulfuric acid by heating to 60° C. under reduced pressure in a short residence time, and as a distillation device, for example, a liquid film distillation device is suitable for this purpose.

By the way, the inventors have discovered that the trisulfonation reaction mixture of naphthalene at 150-300°C is a highly corrosive medium, and that the 20 alloys Carbender 20, Dulymet 20
Even corrosion-resistant high-grade stainless steel materials such as , wawsite, Hastelloy C, which is generally known to have excellent acid resistance, and high-nickel alloys such as Inconel 600 and Monel, are insufficient for practical use due to their high corrosion rates. Knowing that it is, it has corrosion resistance, weldability, and workability such as bending that can withstand this severe corrosion condition, and furthermore, it has a combination of good mechanical properties that are essential for manufacturing distillation equipment. As a result of various studies on device materials that meet these requirements, we have discovered that a commercially available austenite-ferritic duplex stainless steel alloy specifically satisfies these requirements, and have completed the present invention.

The results of corrosion resistance experiments will be explained below. 1. Corrosion Conditions The test liquid used was a naphthalene trisulfonation reaction mixture whose liquid composition was shown in Table 1, and the test was conducted at 200°C for 100 hours.

Since the test liquid is relatively unstable with respect to heat, an overflow type stirring tank type continuous flow container is used, and in order to substantially prevent thermal deterioration of the test liquid, the test liquid is heated within an average residence time of 1 hour. was continuously supplied.

The test results are shown in Table 2. Regarding the average corrosion rate, the maximum corrosion rate that is practically allowed is 0.4 mm/year, and the lower the value, the better.This result shows that the austenite-ferritic duplex stainless steel alloy has practically sufficient corrosion resistance. There is.

Although it is not clear why only austenite-ferrite two-phase stainless steel is uniquely superior in combination with naphthalene-1,3,6-trisulfonic acid,
It is thought that the naphthalene sulfonic acids mixed therein make some contribution to the corrosion resistance. Conventionally, high-silicon cast iron (Vesilon, Dulyron, etc.) has been used in such highly corrosive media because of its good corrosion resistance, but its mechanical properties are hard and brittle, resulting in poor castability.
It has the disadvantage that it cannot be used in parts that require dynamic strength.

On the other hand, the austenitic-ferritic duplex stainless steel alloy used in the present invention has almost the same machining properties as SUS3l6, and does not have the same machining limitations as high-silicon cast iron.

For comparison, mechanical properties are listed in Table 3.

The austenite-ferritic duplex stainless steel alloy used in the present invention is mainly composed of 20 to 28% Cr and 3 to 8% Ni, with a ferrite phase (approximately 70%) and an austenite phase (approximately 70%) containing 1 to 3% MO. 30%) is an alloy with a finely mixed structure, more specifically NAR-F (
(manufactured by Nippon Stainless Steel KK), NTK-R4 (manufactured by Nippon Metal Industries KK), NTK-C1 (manufactured by Nippon Metal Industries KK), NAS-
45M (manufactured by Nippon Yakin KK), YUS329Jl (manufactured by Nippon Steel Hei), SANDVIK-3RE60, URANUS5
Commercially available steel grades such as O are equivalent.

The present invention will be explained below with reference to Examples. Example 1 The naphthalene trisulfonation reaction mixture shown in Table 1 was heated to 150°C and dissolved to form an austenitic resin.
Excess sulfuric acid in the reaction mixture was continuously removed using a G-light two-phase stainless steel rising film evaporator.

Distillation conditions are as follows.

Equipment Double-tube heat exchange type rising type liquid film evaporator Material: NARF (made by Nippon Stainless), diameter 27 mm, length 1.37 m Tube cross-sectional area 0.00057 d, heat transfer area 0.1162 d Double tube heat exchange type rising type After the liquid film evaporator was tested, it was cut and visually observed, and no corrosion was observed.

Claims (1)

[Claims] 1. In removing and recovering excess sulfuric acid in the naphthalene trisulfonation reaction mixture containing naphthalene-1,3,6-trisulfonic acid as a main component by evaporation at a temperature range of 150 to 300°C, distillation is performed. Naphthalene-1 characterized by using a distillation device using an austenite-ferritic duplex stainless steel alloy as the device material
- Concentration and separation method for 3,6-trisulfonic acid.