JPS6330323A - Production method of β-manganese dioxide - Google Patents

Abstract

PURPOSE:To produce high-purity beta-MnO2 wherein the crushing of the product is facilitated by adding nitric acid or Mn(NO3)2 to MnOOH and heat-treating the mixture. CONSTITUTION:beta-MnO2 is produced by adding nitric acid or Mn(NO3)2 to MnOOH and heat-treating the mixture (preferably at 100-400 deg.C). By this method, high-purity beta-MnO2 can be produced. Furthermore since the temp. of heat-treatment is low as shown in the above-mentioned temp. in comparison with the conventional technique, the obtained product is spongy or powdery and the structure of crystal is rodlike and therefore the crushing thereof can be easily performed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing β-manganese dioxide (hereinafter referred to as β-MnO2) useful for solid capacitors, catalysts, etc. The present invention relates to a method for manufacturing.

(Prior Art and Problems to be Solved by the Present Invention) One of the generally known methods for producing β-Mn02 is a method of thermally decomposing manganese nitrate (Mn (NO3)2-6H20).

However, this manufacturing method has the problem that manganese trioxide (Mn203), which is a lower manganese oxide, is produced as an impurity from a macroscopic perspective, and from a microscopic perspective, it produces nitrate radicals (hereinafter referred to as NO3-). is β-M n O
Since there is a problem that NO3- remains even if it is rolled up into two particles and washed with hot water, highly pure β-MnO
It was difficult to obtain 2.

Furthermore, the β-MnO2 obtained by this method was a sintered hard lump and was not easy to crush.

The present invention solves the above problems and provides highly pure β-MnO
The purpose of the present invention is to provide a method for producing β-Mn02 capable of obtaining β-Mn02.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors used hydrated manganese oxide (hereinafter referred to as Mn0OH) as a raw material and nitric acid as an oxidizing agent. Alternatively, the present invention was completed based on the knowledge that highly pure β-MnO2 can be obtained by using manganese nitrate.

That is, the present invention provides β-MnOz, which is characterized by adding nitric acid or manganese nitrate to Mn0OH and heat-treating it.
This relates to a manufacturing method.

The standard of nitric acid or manganese nitrate used in the present invention is Mn0
10 with concentrated nitric acid or manganese nitrate hexahydrate for OH
~ioo weight % is preferred. If the amount is more than this, the content of N O3- in the product becomes high, which is not preferable.

The thermal decomposition temperature is not particularly limited as long as it is between 100°C and 400°C, but preferably between 150°C and 400°C.
It is ℃.

(Example) The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 Commercially available Mn0OH (manganite manufactured by Toyo Soda) 100Q and concentrated nitric acid (specific gravity 1.3) 1011r1 were placed in a porcelain evaporating dish and heated in an electric furnace at 200°C for 8 hours, resulting in a spongy shape. of product was obtained.

For this purpose, this product was crushed in an agate mortar and washed with hot water.

The results of the chemical analysis of this product are shown in Table 1, at a magnification of 10
An electron micrograph at a magnification of 1,000 times is shown in FIG. 1, and an X-ray diffraction diagram is shown in FIG. 2(b).

In FIG. 2(b), commercially available Mn shown in FIG. 2(a)
The diffraction lines based on the X-ray diffraction diagram of 0OH have disappeared. In addition, as shown in Figure 2(b), ASTM card 24-73
It is clear that β-Mn02 corresponding to 5 is produced with high purity.

Furthermore, it is clear from the results of chemical analysis that β-MnOz is produced with high purity.

Example 2 Commercially available Mn0OH10C1 and concentrated nitric acid 60-
was heated in an electric furnace at 380° C. for 8 hours, and then the same treatment as in Example 1 was performed.

The obtained product was highly purified β-Mn02 as shown in Table 1 showing the results of chemical analysis.

Example 3 A porcelain evaporating dish was charged with commercially available Mn0OH1ooo and 20 g of 60% manganese nitrate, heated in an electric furnace at 150° C. for 12 hours, and then subjected to the same treatment as in Example 1.

The obtained product was highly purified β-Mn02 as shown in Table 1 showing the results of chemical analysis.

Comparative Example: Manganese nitrate (Mn(NOs)2.6H2) was placed in a porcelain evaporating dish.
300Q of 0) was added and thermally decomposed at 380°C for 8 hours, and then the same treatment as in Example 1 was performed.

According to the results of chemical analysis and X-ray diffraction, the obtained product was N
It was β-MnO2 mixed with o3- and Mn2O3.

The results of chemical analysis are shown in Table 1, and the X-ray diffraction diagram is shown in FIG. 2(C).

(Effects of the present invention) According to the present invention, it is possible to produce highly pure β-Mn02.

Furthermore, in the present invention, since the heat treatment temperature is lower than in the prior art, the obtained product is spongy or powder-like and has a rod-like crystal structure, so it can be easily crushed.

[Brief explanation of drawings]

FIG. 1 shows the crystal structure of the product obtained in Example 1 as a scanning electron micrograph at a magnification of 10,000 times. FIG. 2(a) is an X-ray diffraction diagram of commercially available Mn0OH (manganite manufactured by Toyo Kashitatsu). FIG. 2(b) is an X-ray diffraction diagram of β-MnOz obtained in Example 1. FIG. 2(C) is an X-ray diffraction diagram of β-Mn02 obtained by thermal decomposition of manganese nitrate in a comparative example. Table 1 Figure 2

Claims (1)

[Claims] A method for producing β-manganese dioxide, which comprises adding nitric acid or manganese nitrate to hydrated manganese oxide (MnOOH) and heat-treating the mixture.