JPH04362001A - Methanol reforming catalyst - Google Patents

Abstract

PURPOSE:To improve a heat transfer function by forming a coat of a porous carrier on a metal or alloy material by thermal spray coating and depositing platinum and/or palladium on the coat. CONSTITUTION:Heat exchanger tubes, etc., made of iron, copper, etc., are chosen for a metal or alloy material (A). Next, a porous carrier (B) is selected from double oxides, etc., such as Al2O3/ZrO2, TiO2/ZrO2. Then, the A component is covered with the B component by thermal spray coating, such as plasma spraying to form a coat 0.01 to 0.5mm thick, permitting a coat formed body (C) to be obtained. Then, the C component is immersed in aqueous solution of platinum and/or palladium (D) chloride, etc., and dried, baked, and then reduced to produce a methanol reforming catalyst where the D component of 0.1 to 20 pts.wt. is deposited on the B component of 100 pts.wt.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for reforming methanol, and more particularly to a catalyst for reforming methanol or a mixture of methanol and water into a hydrogen-containing gas.

0002

[Prior Art] Conventional catalysts for reforming methanol have been proposed in which platinum metal elements such as platinum or base metal elements such as copper, nickel, chromium, zinc, and their oxides are supported on a carrier such as alumina. has been done. In addition to the above-mentioned metal supported catalyst, there is also a precipitation method, and typical examples of catalysts prepared by these methods include methanol reforming catalysts containing zinc, chromium, and even copper. be.

0003

[Problems to be Solved by the Invention] Conventionally, when decomposition or steam reforming reactions are performed using methanol or a mixture of methanol and water as a raw material by using the sensible heat of exhaust gas from engines, gas turbines, etc. as a heat source, the exhaust gas temperature As is well known, the temperature varies from 200℃ to about 700℃, so reforming can be carried out over a wide temperature range with a small amount of catalyst that can be installed in an internal combustion engine. However, there is a need for a reforming method that does not deteriorate reforming performance and a stable catalyst.

[0004] As conventional catalysts for reforming methanol, catalysts prepared by the above-mentioned metal support method or precipitation method have been proposed, but these catalysts have poor low-temperature activity and suffer from thermal deterioration. Currently, there are many problems such as ease of use.

[0005] The reactor is a shell-and-tube heat exchanger type, and the tubes are filled with a catalyst, and methanol vapor or a mixed vapor of methanol and water, which is the raw material, is reacted by contact with the catalyst. Reformed to hydrogen-containing gas. This reforming reaction is a large endothermic reaction, and the necessary reaction heat is supplied from the catalyst on the shell side, but since the heat transfer rate is not very high, the temperature in the catalyst layer is lowered by the reaction heat, reducing the reaction rate. The problem is that it is difficult to make it larger.

[0006] In view of the above-mentioned state of the art, the present invention aims to provide a methanol reforming catalyst which is free from the problems of conventional methods and has an excellent heat transfer function.

[0007]

[Means for Solving the Problems] The present invention is characterized in that a film is formed on a metal or alloy material by thermal spray coating with a porous carrier, and platinum and/or palladium is supported on the film. It is a reforming catalyst.

[0008] In a preferred embodiment, the heat exchanger tube itself is used as the metal or alloy material in the above structure.

The present invention will be explained in detail below. Iron, copper, aluminum, zinc, cobalt, nickel, or an alloy thereof can be used as the base metal material, and the porous carrier is welded to the surface of these materials by thermal spray coating.

[0010] In addition, the porous carrier referred to in the present invention is a single oxide of alumina, titania, or zirconia or a composite oxide thereof, and has a high specific surface area and heat resistance, and is capable of highly dispersing the catalyst. It is preferable as a carrier for supporting on the surface.

Examples of composite oxides include Al2O3
/ZrO2, TiO2 /ZrO2, Al2O3
/TiO2, etc., and a range of 10/90 to 90/10 (hereinafter expressed as a molar ratio) is suitable.

[0012] In the present invention, it is preferable that these porous carriers form a coating on a metal or alloy material by thermal spray coating to a thickness of 0.01 to 0.5 mm. Fire spraying, plasma spraying, etc. can be used.

[0013] In the present invention, platinum and/or palladium is further supported on this film. The supporting method is to immerse the metal or alloy material on which the porous carrier film obtained by the above method is formed into an aqueous solution of platinum and/or palladium chloride or ammine complex of platinum, dry it, sinter it, and then reduce it. This can be done by

[0014] The amount of platinum and/or palladium supported is 0.1 to 20 parts by weight, preferably 0.5 to 5 parts by weight (hereinafter abbreviated as wt%) based on 100 parts by weight of the porous carrier.
It is.

Note that the hydrogen-containing gas in the present invention is a gas containing 50% or more of hydrogen and 35% or less of carbon monoxide. Further, the reaction conditions in the methanol reforming method using the methanol reforming catalyst of the present invention are as follows. Reaction temperature: 200-700°C, particularly preferably 30°C
0~600℃ Reaction pressure: 0~30Kg/cm2G
, particularly preferably 0 to 15 Kg/cm2 G Molar ratio of water supplied to 1 mole of methanol: 10 or less, particularly preferably 3 or less

[0016]

EXAMPLES The present invention will be explained in more detail below using specific examples. (Example 1) After thoroughly cleaning a SUS304 plate of 15 mm x 70 mm x 2 mm (thickness), the three types of powder shown in Table 1 are supplied to a powder type fire spraying machine through a powder supply pipe. Perform powder fire spraying on the board,
Three types of porous carriers were coated, and then a dinitrodiammine platinum(II) nitric acid solution [chemical formula: Pt(NH3)2
(NO 2
of platinum (1 part by weight of platinum per 100 parts by weight of porous carrier)
Catalysts 1 to 3 were prepared.

[0017] Catalysts 1 to 3 described above were packed into a reactor, and the catalytic activity was evaluated under the conditions shown in Table 2 below. The results are shown in Table 3.

[Table 1]

[Table 2] * Purity 99% ** H2O/CH3OH=1.5 [mol/
mol]

[Table 3]

[0018] The composition of the produced gas (mol % - dry basis, excluding H2O and CH3OH,
(the same applies hereinafter) were as follows.

(1) Methanol raw material H2: 64-67%, CO: 31-33%C
O2: 0.1-2%, CH4: 0.02-2%

(2) Methanol/water mixture raw material H2:
62-67%, CO: 22-28% CO2:
2-8%, CH4: 0.01-2%

0
(Example 2) In the same manner as in Example 1, a film of alumina was formed as a porous carrier, and then Example 1 was prepared using an aqueous solution of palladium chloride.
Catalyst 4 supporting 2 wt% of palladium was prepared in the same manner as above.

Catalyst 5, which supported 1 wt% of platinum and 1 wt% of palladium, was prepared in the same manner as in Example 2, except that an aqueous mixed solution of platinum chloride and palladium chloride was used instead of palladium chloride.

[0023] These catalysts were charged into a reactor and 200
After hydrogen reduction treatment at ~400°C, catalytic activity was evaluated under the conditions shown in Table 4. The results are shown in Table 5.

[Table 4] *H2O/CH3OH=1.5 [mol/m
ol]

[Table 5]

(Example 3) Catalyst 6 was prepared in the same manner as in Example 1 except that a zirconia-containing composite oxide shown in Table 6 was used instead of alumina as the porous carrier.
~9 was prepared. These catalysts were subjected to hydrogen reduction in the same manner as in Example 1, and then their catalytic activity was evaluated. The results are also shown in Table 6.

[Table 6]

The composition of the generated gas was as follows. (1) Methanol raw material H2: 64-67%, CO: 31-33%C
O2: 0.1-2%, CH4: 0.02-2%

(2) Methanol/water mixture raw material H2:
62-67%, CO: 22-28% CO2:
2-8%, CH4: 0.01-2%

0
(Example 4) External diameter 10.5 mm, thoroughly cleaned in advance
, length 100mm, catalyst outer surface area 33cm2 SUS
A catalyst 10 was prepared on the outer wall of the 304 tube in the same manner as in Example 1 above.

Using the catalyst 10 as a reaction tube, the temperature is raised by heating the inside of the reaction tube with the catalyst, and the heating medium temperature is raised to 20
After heating the reaction tube to 0 to 400°C, supplying 3% hydrogen (nitrogen balance) gas to the outer surface of the reaction tube to perform a reduction treatment, and then increasing the temperature of the heating medium and keeping the heating medium temperature constant at 450°C, the reaction tube Mixed vapor of methanol and water at 450℃ on the outer surface {H2 O/CH
3OH=1.5(mol/mol)} to 15(c
c/h), the methanol reaction rate was 9
It was 8%.

On the other hand, as a result of filling the conventional pellet type catalyst on the outside of a double tube so that the catalyst has the same external surface area and conducting the same reaction as a reaction tube with a heating medium passed inside, the methanol reaction The rate was about 90%.

From the above results, it was confirmed that the reaction tube according to the present invention has a high heat transfer rate and therefore has an excellent methanol reaction rate.

[0031]

Effects of the Invention According to the present invention, since a catalyst with excellent heat transfer function is provided, hydrogen-containing gas can be efficiently produced by methanol reforming reaction.

Claims (1)

[Claims] 1. A catalyst for methanol reforming, characterized in that a film is formed on a metal or alloy material by thermal spray coating with a porous carrier, and platinum and/or palladium is supported on the film.