JPS6021772B2 - Method for producing nickel metal catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a process for producing a nickel metal catalyst from a relatively high-purity rolled nickel plate that has a highly active catalytic surface, good heat transfer properties and low pressure loss, and is easy to handle. Regarding the method.

Here, relatively high-purity nickel rolled plate has a purity of about 9
It refers to a commercially available nickel plate with a content of 5% or more, and contains a certain amount of impurity elements that cannot be removed during manufacturing.

There are two types of nickel-based catalysts that are currently in practical use, such as those used in steam reforming of hydrocarbons:

One of them is a nickel-based supported catalyst. Although this catalyst has high activity, its carrier is made of alumina, silica, etc., so its heat transfer properties are poor, and its granular shape causes a large pressure loss, making it difficult to handle during filling or unloading. This is inconvenient and, in addition, is unsuitable for use in processes where scattering of catalyst dust is a problem. This catalyst is not suitable as a catalyst for a steam waste reaction, which is a large endothermic and bulk-enhancing reaction. The other is the Raney nickel metal catalyst, which has high catalytic activity and good heat transfer properties, but it can only take forms that are limited by manufacturing methods, and therefore this catalyst is also used in water mill reforming reactions, etc. It does not fully meet the conditions required as a catalyst. The purpose of the present invention is to oxidize a relatively high-purity rolled nickel plate that has been processed into an arbitrary shape in a high-temperature oxidizing atmosphere and reduce it in a high-temperature reducing gas stream. The object of the present invention is to provide a method for producing a nickel metal catalyst that solves the drawbacks of the nickel metal catalyst.

The manufacturing method of the present invention involves preparing a relatively high-purity nickel rolled plate as shown in Table 1 that has been previously processed* into an arbitrary shape, or forming a nickel rolled plate containing characteristic components into an arbitrary shape. After processing and cleaning the surface of the processed nickel rolled plate with acetone and formic acid/hydrogen peroxide aqueous solution,
A method of obtaining a nickel metal catalyst by oxidizing a rolled nickel plate for several hours or more in an oxidizing atmosphere containing 0 or more oxygen, and then reducing it in a high-temperature reducing gas stream for a relatively short period of time. be.

Table 1 The nickel metal catalyst produced by the production method of the present invention not only has a highly active catalytic surface, but also has excellent heat transfer properties because the main component is nickel, and its morphology is also excellent prior to redox treatment. Since the catalyst can be processed into any desired shape in advance, catalysts having any desired shape can be manufactured without any restrictions on the shape.

Example '11 A nickel rolled plate with a plate thickness of 2 Yanagi shown in Sample D in Table 1 was oxidized in air by changing the oxidation temperature and oxidation time, and then reduced in a hydrogen stream to produce a nickel metal catalyst. Obtained.

As shown in Table 2, the reduced nickel layer forms an aggregate of dense crystal grains exhibiting a known high catalytic activity.

The superiority of the nickel metal catalyst having such a highly active catalyst surface (reduced nickel layer) as a catalyst is clear from the description of Example (2) and the comparison thereof. Example ■ Sample D with dimensions of 8 ribs in width, 10Q in length, and 2 skins in thickness.
After processing a rolled nickel plate into a spiral shape, degreasing the processed product with acetone and washing it with a formic acid/hydrogen peroxide aqueous solution,
A nickel metal catalyst according to the method of the present invention was obtained by oxidizing in air at 1200 qC and reducing in a steam stream at 860°C for 1 hour.

When steam reforming of methane was carried out using this catalyst under the reaction conditions shown in the four columns starting from the leftmost column of Table 3, the conversion rate of methane (%) was as shown in the rightmost column of Table 3. )was gotten.

The processed product in Example ① above was not subjected to high-temperature oxidation treatment. Immediately after washing, a reference product obtained by performing high-temperature reduction treatment under the same reduction conditions as in Example {21] was used as a catalyst, and the following reaction conditions were applied. Empty cylinder speed = 1060 (1/hour)
, (steam nomethane) ratio = 3, reaction temperature = 86 pi 0,
When steam reforming of methane was carried out at a reaction pressure of OK9/Funa G, the conversion rate did not even reach several percent.

Table 3 The effects of the present invention will become clearer from FIGS. 1 and 2.

That is, FIG. 1 is a graph showing the relationship between the reforming reaction time and the C ratio conversion rate using the oxidation treatment time of the nickel rolled plate as a parameter, and the nickel metal catalyst subjected to the high temperature oxidation treatment as described above is (see Table 2), all oxidized catalysts exhibit very high activity. On the other hand, a nickel metal catalyst (indicated by e in the figure) which was simply subjected to a reduction treatment without being subjected to a high-temperature oxidation treatment had a very low activity. In addition, Fig. 2 is a graph showing the relationship between the waste material reaction time and the CA conversion rate using the oxidation treatment temperature of the nickel rolled plate as a parameter.
The catalyst when oxidized at 00oo shows almost 100% CH4 conversion over a long period of time;
When oxidizing with 000, the catalyst temporarily becomes CH
4 A conversion rate of nearly 100% is achieved, but the average value is around 80%, which is not very sufficient. Furthermore, the conversion rate of both the catalyst when oxidized at 770 oo and the catalyst when no oxidation treatment is performed is low. It turns out that it is completely insufficient as a catalyst. The nickel metal catalyst obtained by the production method of the present invention can be used in chemical reactions that use conventional nickel-based catalysts, such as steam reforming and hydrogenation of hydrocarbons.

As is clear from the above description, according to the present invention, a rolled nickel plate is oxidized at a high temperature of 120 qo or more, and then this rolled plate is reduced in a high-temperature reducing gas stream of about 850 qo. , a highly active nickel metal catalyst can be obtained. Since the catalyst is mainly composed of rolled nickel plate, it has high heat transfer properties and is therefore advantageous as a catalyst for high absorption, exothermic reactions such as steam reforming.

In addition, since the nickel metal catalyst is obtained by catalytically activating the surface of the nickel rolled plate after the nickel rolled plate has been arbitrarily processed, it is not difficult to handle unlike granular catalysts, and there is no dust during handling or reaction. There is no risk of it being blown away. Because of the various advantages mentioned above, it is possible to increase the number of reaction tube seats in, for example, an apparatus using reaction tubes, which greatly contributes to reducing the cost of the apparatus.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the reforming reaction time and CH4 conversion rate using the oxidation treatment time of the nickel rolled plate as a parameter, and Figure 2 is a graph showing the relationship between the reforming reaction time and the CH4 conversion rate using the oxidation treatment temperature of the nickel rolled plate as a parameter. It is a graph showing the relationship with the rate. Figure 1 Figure 2

Claims (1)

[Claims] 1. The surface of a relatively high-purity nickel rolled plate is cleaned, then the nickel rolled plate is oxidized in an oxidizing atmosphere containing oxygen at 1200°C or higher, and then the oxidized nickel rolled plate is heated at about 850°C. A method for producing a nickel metal catalyst, the method comprising obtaining a nickel metal catalyst by reducing the catalyst in a high-temperature reducing gas stream.