JPH05261288A - Catalyst for reforming methanol - Google Patents

Abstract

PURPOSE:To obtain a catalyst having high activity and high selectivity at low temp. and long life in the reaction to produce H-contg. gas from methanol or from a mixture of methanol with water as the source material by incorporating oxides of Ni, copper, zinc and Al into the catalyst. CONSTITUTION:The catalyst for reformation of methanol is obtd. by adding oxides of Ni, Cu, Zn and Al. It is preferable that the catalyst has the compsn. expressed by an atomic ratio of Ni:Cu:Zn:Al=100:(10-200):(6-100):(1-50). Conditions of the reaction to reform methanol using this catalyst are preferably 0-50kg/cm<2> pressure and 150-600 deg.C temp. The catalyst is prepared by adding hydroxides or carbonates of alkali metal elements or alkaline earth metal elements as they are or in the form of soln. to an aq. mixture soln. of Ni, Cu, Zn, and Al compds. to precipitate hydroxides, and then drying and calcining the precipitate.

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, which is applied to a method for producing a gas containing hydrogen from methanol or a mixed solution of methanol and water as a raw material.

[0002]

Methanol, which is obtained from many resources such as petroleum, natural gas and coal, is inexpensive and easy to handle, and is therefore attracting great interest as a future fuel. Also,
Since methanol is decomposed into hydrogen and carbon monoxide at a temperature much lower than that of naphtha, it has an advantage that waste heat can be used as a heat source for decomposition and reforming reaction of methanol and methanol steam.

The decomposition reaction of methanol is described in the following (1),
It is as in the formula (2). CH ₃ OH → CO + 2H ₂ ΔH 25 ° C. = 21.7 kcal / mol (1) CH ₃ OH + nH ₂ O → (2 + n) H ₂ + (1-n) CO + nCO ₂・ ・ ・ (2) where 0 <N <1 Further, the methanol steam reforming reaction is represented by the following formula (3). CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ ΔH 25 ° C. = 11.8 kcal / mol .. (3)

As a conventional catalyst for reforming methanol, there has been proposed a catalyst in which a carrier such as alumina carries a white metal element such as platinum or a base metal element such as copper, nickel, chromium and zinc and an oxide thereof. These catalysts have poor low-temperature activity, and many dimethyl ether and methane by-products remain, and many problems remain until now. Further, there is a preparation method by a precipitation method in addition to the catalyst by the metal supporting method described above, and a typical example of the catalyst prepared by this method is a methanol reforming catalyst containing zinc, chromium and copper. is there. However, these catalysts have a problem that they have relatively high low-temperature activity but poor heat resistance.

[0005]

Conventionally, when the sensible heat of exhaust gas from an internal combustion engine, a gas turbine or the like is used as a heat source and a decomposition or steam reforming reaction is carried out using methanol or a mixture of methanol and water as a raw material, the exhaust gas Since the temperature changes from about 200 ° C. to about 700 ° C. as well known, for example, a small amount of a stable catalyst which does not deteriorate the reforming performance even in a wide temperature range is required for mounting on an internal combustion engine.

Conventional methanol reforming catalysts have been proposed by the above-mentioned metal supporting method and precipitation method, but these catalysts still have many problems such as low temperature activity and poor heat resistance. There is.

In order to solve the above-mentioned problems, the inventors of the present invention have previously proposed methanol containing one or more oxides of the group consisting of copper, zinc and chromium or hydroxides thereof and nickel oxides or hydroxides thereof. A reforming catalyst was proposed. (Japanese Patent Publication Sho 62
However, this catalyst has a problem that there is still room for improvement in heat resistance.

In view of the above-mentioned state of the art, the present invention has a low temperature activity,
It is intended to provide a methanol reforming catalyst having excellent heat resistance and long life.

[0009]

The present invention is directed to nickel, copper,
A methanol reforming catalyst comprising an oxide of zinc and aluminum.

Although the catalyst of the present invention may be used as it is, it is highly likely that the reduction reaction with methanol will rapidly progress when the methanol is supplied and the catalyst will be deteriorated. Therefore, it is preferable to carry out the reduction operation in advance. The reduction operation is performed by heating at 150 to 400 ° C. in a reducing gas atmosphere such as hydrogen, carbon monoxide or a mixed gas thereof, or by heating a heated catalyst with methanol or a mixture of methanol and water with an inert gas. It can be carried out by bringing a diluted gas into contact and reducing with hydrogen and carbon monoxide generated by the decomposition / reforming reaction.

[0011]

To prepare the methanol reforming catalyst of the present invention, a hydroxide or carbonate of an alkali metal element or an alkaline earth metal element is used as a precipitant in a mixed aqueous solution of a compound of nickel, copper, zinc and aluminum. Is used as it is, or as an aqueous solution, or mixed with ammonia water or the like to form a precipitate of hydroxide, followed by drying and firing.

The composition of the catalyst component of the present invention is nickel, copper,
In the combination of zinc and aluminum oxide, the atomic ratio (Ni: Cu: Zn: Al) of Ni is 100.
Then, Cu: 10-200, Zn: 5-100, A
1: 1 to 50 is suitable, and as a particularly preferable range, when Ni is 100, Cu: 25 to 10
0, Zn: 10 to 50, and Al: 5 to 25.

The methanol or the mixture of methanol and water in the present invention has a molar ratio of H ₂ O / CH ₃ OH in the range of 0 to 100, and the reaction of the methanol reforming reaction using the catalyst of the present invention. As conditions, pressure: 0 to 50 kg /
The range of cm ² and temperature of 150 to 600 ° C. is preferable.

[0014]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

An aqueous solution containing 0.03 mol of zinc nitrate and 0.006 mol of aluminum nitrate was used as solution A and copper nitrate 0.06
An aqueous solution containing mol is referred to as solution B, an aqueous solution containing 0.6 mol of nickel nitrate is referred to as solution C, and an aqueous solution containing sodium carbonate in an equimolar amount or more to these nitrate aqueous solutions is referred to as solution D.
The solutions A to D were each kept at 80 ° C., and then the solution A was gradually added dropwise to the solution D with stirring to obtain a suspension. Next, after the dropping of the solution A, the solution B was gradually dropped to the suspension, and after the dropping of the solution B, the solution C was gradually dropped. After the dropping of the solution C was completed, 2
After aging for a time, the precipitated product was washed with ion-exchanged water and dehydrated until Na ion and NO ₃ ion were not detected. After dehydration, dry at 110 ° C for one day and then 300
Catalyst 3 (Ni: Cu: Zn: Al =
100: 10: 5: 1 metal atom ratio) was prepared.

Further, catalysts 2 to 4 (the composition of which is shown in Table 2 below) having different composition ratios (metal atom ratios) were prepared by the same preparation method as described above.

The catalysts 1 to 4 were subjected to hydrogen reduction treatment at 350 ° C. for 12 hours, and then methanol (purity 99%) or a mixed solution of methanol and water (H ₂ O / CH ₃ OH = 1.0).
mol / mol) as raw material, normal pressure, LHSV (liquid hourly space velocity)
An activity evaluation test was conducted at 5 h ⁻¹ and a reaction temperature of 300 ° C. The results are shown in Table 1.

The composition of the produced gas (mol% -excluding unreacted methanol on a dry basis, the same applies hereinafter) was as follows. (1) Methanol raw material H ₂ : 65 to 68%, CO: 29 to 32%, CO ₂ :
_{0.1~2%, CH 4: 0.1~2%} (2) Methanol water mixture feed _{H 2: 68~71%, CO:} 12~17%, CO 2: 1
2~15%, CH _4: 0.1~1%

[0019]

[Table 1]

Next, a mixed solution of methanol and water (H ₂ O /
CH ₃ OH = 2.0mol / mol) as raw material, pressure 10kg
/ Cm ² G, LHSV 5h ^-1 , reaction temperature 250 to 350 ° C
The activity evaluation test was carried out. The results are shown in Table 2 below.

The composition of the generated dust at each temperature was as follows. (1) Reaction temperature: 250 ° C., 300 ° C. H ₂ : 72-74%, CO: 3-8%, CO ₂ : 18-
_{22%, CH 4: 0.01~0.1%} (2) reaction _{temperature: 350 ℃ H 2: 72~74%} , CO: 6~10%, CO 2: 17
~20%, CH _4: 0.05~0.5%

Further, the above reaction conditions (reaction temperature 350 ° C.)
As a result of conducting a continuous test for 1000 hours, the methanol conversion rates of the catalysts 1 to 4 were constant at 100%.

[0023]

[Table 2]

[0024]

As is apparent from the results of the above examples, the methanol reforming catalyst of the present invention has high activity at low temperature in a reaction for producing a hydrogen-containing gas from methanol or a mixed solution of methanol and water as a raw material, It is a very excellent catalyst with high selectivity and long life.

Claims (1)

[Claims] 1. A methanol reforming catalyst comprising an oxide of nickel, copper, zinc and aluminum.