JPH02280838A - Preparation of reaction tube for catalytic methanol reforming - Google Patents

Abstract

PURPOSE:To obtain a catalyst by dipping a metallic reaction tube material containing nickel and copper in a molten aluminum to form an aluminum layer on the metallic material, activating the surface of the metallic with an alkali. CONSTITUTION:A metallic reaction tube material containing nickel and copper as a reaction tube to reform methanol or a mixture of methanol and water into a hydrogen-containing gas is dipped in molten aluminum to form a metal aluminum layer on the surface of the tube material. After that, aluminum is leached for the metal aluminum layer by an alkali such as sodium hydroxide in order to activate the surface. A reaction tube having a high catalytic function is thus obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a reaction tube catalyzed for methanol reforming, and more specifically to a catalytic method for reforming methanol or a mixture of methanol and water into a hydrogen-containing gas. The present invention relates to a method for manufacturing a reaction tube.

[Conventional technology]

As a conventional catalyst for reforming methanol, a catalyst has been proposed in which a platinum metal element such as platinum or a base metal element such as copper, nickel, chromium, zinc, or an oxide thereof is supported on a carrier such as alumina. In addition to the above-mentioned metal supported catalyst, there is also a precipitation method, and a typical example of a catalyst prepared by this method is a methanol reforming catalyst containing zinc, chromium, and even copper. .

[Problem to be solved by the invention]

Conventionally, when decomposition or steam reforming reactions are carried out using methanol or a mixture of methanol and water as a raw material using the sensible heat of exhaust gas from engines, gas turbines, etc. as a heat source, the exhaust gas temperature ranges from 200°C to 700°C, as is well known. Therefore, reforming can be carried out over a wide temperature range with a small amount of catalyst that can be mounted on an internal combustion engine, and the reforming performance does not deteriorate even if it is exposed to high temperatures of about 700°C as mentioned above. Reforming methods and stable catalysts are needed.

As for the conventional methods of reforming methanol, catalysts prepared by the metal support method or precipitation method mentioned above have been proposed and discussed, but these catalysts have poor low-temperature activity and are susceptible to thermal deterioration. Currently, there are many problems such as water, etc.
Ru.

In addition, the reactor is a shell-and-tube heat exchanger type, and the tube is filled with a catalyst, and the raw material methanol vapor or mixed vapor of methanol and water is converted into hydrogen through a catalytic reaction with the catalyst. It is reformed into containing gas. This reforming reaction is a large endothermic reaction, and the necessary reaction heat is supplied from the heat medium on the shell side, but since the heat transfer rate is not very high, the temperature inside the catalyst layer is lowered by the reaction heat. There is a problem that it is difficult to increase the reaction rate.

[Means to solve the problem]

In order to increase the heat transfer rate of the reactor, the present inventors used a heat transfer tube (FF reaction tube) carrying a catalyst as a methanol reforming reactor to achieve both heat transfer and catalytic functions. The present invention was achieved by discovering that it is possible to simultaneously combine the following.

That is, in the present invention, a reaction tube member made of a metal containing nickel and copper is immersed in molten aluminum to form a metal layer of aluminum on the surface of the reaction tube member, and aluminum is eluted from this metal layer with an alkaline aqueous solution. This is a method for manufacturing a methanol reforming catalyzed reaction tube in which the surface is activated by

The present invention will be explained in detail below.

The hydrogen-containing gas used in the present invention is a gas containing 50% or more hydrogen, 354% or less carbon oxide, and 25% or less carbon dioxide.

Furthermore, in the present invention, the reaction tube member made of metal containing nickel and copper refers to not only nickel and copper thread alloys, but also impurities in the respective ingots and impurities mixed during production when nickel and copper alloys are produced. However, most of these impurities are iron, manganese, silicon, and their oxides, and do not affect the catalytic activity at all. Therefore, reaction tube members made of metals containing nickel and copper as described above """ means not only nickel steel alloys but also those containing impurities that do not affect the catalytic activity as described above, and will be used in the following description with the same meaning.

Furthermore, the alkaline aqueous solution as used in the present invention is an aqueous solution containing 1% or more and 40% or less of any one of sodium hydroxide, potassium hydroxide, and sodium carbonate.

The reaction conditions in the methanol reforming method using the methanol reforming catalyzed reaction tube of the present invention are as follows.

Reaction temperature = 200-700°C, particularly preferably 300-700°C
600℃ Reaction pressure 0~30kg/cIR''G1 Particularly preferably 0~15kII/α2G Molar ratio of water supplied to 1 mole of methanol: 10 or less,
Particularly preferably 3 or less In the present invention, after forming an aluminum metal layer on the surface of a reaction tube member made of a metal containing nickel and copper, eluting aluminum with an alkaline aqueous solution is the same as the principle of the so-called Raney catalyst. In this way, a reaction tube activated as a catalyst can be obtained.

Hereinafter, the present invention will be specifically explained with reference to Examples.

[Example 1] Nickel with 70 wtl nickel and 50 wtl copper.

A reaction tube member made of a metal containing copper was immersed in molten aluminum at 750°C for 10 minutes, and after cooling, it was heated to 80°C.
Aluminum was eluted using 2-6 wtl of sodium hydroxide solution at ℃, washed with water and dried, and the catalytic reaction tube 1
was prepared.

[Example 2] Nickel 50wt, copper 50wt4 nickel.

A catalyzed reaction tube 2 was prepared using a reaction tube member made of a copper-containing metal in the same manner as in Example 1.

The catalytic activity of these catalytic reaction tubes 1 and 2 was evaluated under the conditions shown in Table 1. The results are shown in Table 2. As is clear from Table 2, hydrogen and carbon monoxide were obtained in almost stoichiometric amounts, indicating that the selectivity was higher.

〔Effect of the invention〕

As is clear from the above examples, by immersing a reaction tube member made of a metal containing nickel and copper in the molten aluminum of the present invention, a metal layer of aluminum is formed on the metal member. Next, aluminum is eluted from the surface with an alkaline aqueous solution, and by using a methanol reforming catalyst whose surface has been activated, hydrogen-containing gas is extracted from a mixture of methanol or water in a methanol reforming reaction. was found to be manufactured.

Claims (1)

[Claims] A reaction tube member made of a metal containing nickel or copper is immersed in molten aluminum to form a metal layer of aluminum on the surface of the reaction tube member, and aluminum is eluted from this metal layer with an alkaline aqueous solution. A method for manufacturing a methanol reforming catalyzed reaction tube.