JP2677320B2 - Dehydrogenation reaction catalyst, method for producing the same, and methanol decomposition method using the catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehydrogenation catalytic reaction, a method for producing the same, and a method for dehydrogenating methanol by the catalyst.

[0002]

2. Description of the Related Art Conventionally, there have been proposed methods of dehydrogenating methanol to obtain carbon monoxide by using various dehydrogenation catalysts. For example, when using methanol as a fuel for automobiles, it is better to burn hydrogen and carbon monoxide generated by absorbing the thermal energy of exhaust gas by the dehydrogenation reaction of this methanol, rather than burning it directly. It is advantageous in terms of energy efficiency, and since exhaust gas does not contain harmful formaldehyde, it is also desirable from the environmental aspect. In addition, the low temperature waste heat of about 200 ℃ generated from factories is absorbed by the dehydrogenation decomposition of methanol, and its thermal energy can be effectively used.
It is important from the viewpoint of energy saving, but currently 200
No catalyst system has been found that exhibits high activity at a temperature as low as about 0 ° C for practical use.

For example, with a catalyst composed of nickel, copper, zinc and aluminum oxide, the decomposition activity of methanol at a reaction temperature of 300 ° C. is about 20 per 1 g of the catalyst.
It is mmol / h (methanol partial pressure, 1 atm) (Japanese Patent Laid-Open No. 05-261288), and practically requires a reaction temperature of at least 300 ° C.

Raney nickel is a typical hydrogenation / dehydrogenation catalyst, and its methanol decomposition activity is 283.
It is only 1.4 mmol / h (methanol partial pressure, 0.25 atm) per 1 g of the catalyst at 0 ° C. {Chemical Engineering Proceedings Vol. 15, p. 284, 1989}.

[0005]

Therefore, the present invention provides a catalyst that exhibits excellent catalytic activity at a lower reaction temperature than known catalysts and can dehydrogenate and decompose methanol at a practical reaction rate. Is the main purpose.

[0006]

As a result of repeated studies in view of the above-mentioned problems of the prior art, the inventors of the present invention have found that a catalyst having a new composition or structure has a temperature range lower than that of the conventional catalyst. The inventors have found that the catalyst is a practical dehydrogenation reaction catalyst that exhibits excellent catalytic activity and can dehydrogenate and decompose methanol at a good reaction rate, and has completed the present invention.

That is, the present invention provides the following dehydrogenation reaction catalyst, a method for producing the same, and a method for dehydrogenating methanol. Methanol dehydrogenation comprising a complex of a metal and a silicon oxide, characterized by reacting at least one compound of nickel, cobalt and chromium with an organic silicic acid compound to cause gelation, firing, and further reduction. Method for producing reaction catalyst.

[0008] 2. Particle size 6 of at least one of nickel, cobalt and chromium obtained by the sol-gel method
A catalyst for methanol dehydrogenation reaction, which comprises a complex in which reduced metal particles having a size of 22 nm are dispersed in silicon oxide.

3. Item 3. A method for decomposing methanol, which comprises performing the dehydrogenation reaction of methanol in a gas phase in the presence of the catalyst for methanol dehydrogenation reaction according to Item 2.

The catalyst for the dehydrogenation reaction of methanol according to the present invention has a composite structure in which at least one of nickel, cobalt and chromium as a catalytically active component is dispersed in silicon oxide (silica) as a carrier. There is.

In the catalyst according to the present invention, at least one of nickel, cobalt and chromium as a catalytically active component has a particle size of about 6 to 22 nm. Generally, the higher the metal content, the larger the particle size tends to be.
If the particle diameter of the catalytically active component exceeds 30 nm, the outer surface area of the metal component decreases and the catalytic activity decreases,
Not preferred.

The catalyst having such a composite structure can be prepared by the so-called sol-gel method. When the catalyst of the present invention is prepared by the sol-gel method, a large amount of active metal can be present in the carrier in a highly dispersed state. Such a catalyst exhibits excellent catalytic activity in a low temperature range (usually about 150 to 300 ° C.) and is industrially extremely useful.

The preparation of such a catalyst is carried out by uniformly mixing the organosilicon source and the metal source in the liquid phase for about 5 hours to 5 days to cause gelation, and drying and calcination to remove organic substances. After that, the metal component contained in this compound is reduced with a reducing agent.

The method for producing the catalyst according to the present invention is the same as the usual sol-gel method except that the metal source is present in the liquid phase. Therefore, the reaction conditions are not particularly limited, but generally speaking, a liquid phase containing an organic silicic acid compound and at least one of nickel, cobalt and chromium compounds (the liquid medium is water + alcohol, etc. An acid (nitric acid or the like) is added to (1), the hydrolysis reaction is performed with stirring, and the resulting gelled product is dried and heated to obtain a solid product. Next, the solid product is pulverized if necessary, and then contacted with a reducing agent for reduction to obtain the catalyst of the present invention.

Examples of the organic silicon source include ethyl silicate,
Examples are organic silicon compounds such as methyl silicate. Examples of the metal source include nitrates, carbonates, chlorides and acetates of nickel, cobalt and chromium. The mixing ratio of the organosilicon compound and the metal source compound can be appropriately selected according to the content of the metal in the target catalyst.

Further, examples of the reducing agent include hydrogen, carbon monoxide, methanol and the like. The reduction treatment may be carried out immediately before the reaction in which the obtained solid product is used as a catalyst in the dehydrogenation reaction of methanol. Furthermore, even before or after the reduction treatment of the solid product, the stabilization treatment of the solid product may be performed at a temperature of about 500 to 700 ° C. in an inert gas such as helium, nitrogen or argon. Absent.

The metal content in the catalyst according to the present invention is usually about 15 to 70% by weight, preferably about 20 to 60% by weight. The shape of the catalyst according to the present invention is not particularly limited, and examples thereof include powder, granules, flakes, spheres, pellets,
Any shape such as a honeycomb shape may be used. When the catalyst is used in the form of powder or particles or spheres, it is not particularly limited, but usually a particle size of about 10 to 150 mesh,
More preferably, the particle size is about 20-80 mesh.

The catalyst of the present invention may be mixed with a known binder that does not adversely influence the reaction, such as silica gel, and molded by a conventional method before use. When such a shaped catalyst is used, the diffusion of the reaction raw materials can be promoted and the activity of the catalyst can be appropriately controlled.

The dehydrogenative decomposition reaction of methanol according to the present invention is carried out in the gas phase flow system in the presence of the catalyst of the present invention. The reaction temperature is usually about 150 to 350 ° C, preferably 18
It may be about 0 to 300 ° C. If the reaction temperature is too low, the decomposition efficiency of methanol will decrease, whereas if the reaction temperature is too high, the selectivity for the dehydrogenation product of methanol may decrease due to by-products such as methane. is there. The supply method of methanol is not particularly limited,
Usually supplied in gaseous form. Gaseous methanol may be diluted with a gas such as helium, nitrogen, or argon that does not adversely affect the reaction and supplied. The amount of methanol supplied may be appropriately selected according to the size and shape of the reactor, the reaction temperature, etc., but is usually 0.1 to 1 per 1 g of the catalyst.
It may be about 0 mol / h.

[0020]

INDUSTRIAL APPLICABILITY The catalyst according to the present invention exerts good catalytic activity and high carbon monoxide selectivity at low temperature in methanol dehydrogenation reaction as compared with known catalysts, and exhibits good methanol speed at a good rate. Can be disassembled.

[0021]

EXAMPLES The production examples and examples of the catalyst will be given below to further clarify the characteristics of the present invention.

Production Example 1 8.3 g of nickel nitrate 6-hydrate, 25 m of tetraethyl silicate
1, water 10 ml, ethanol 20 ml and concentrated nitric acid 2 m
The mixture of 1 was stirred at room temperature for 5 hours to obtain a gelled product. After drying this at 120 ° C for 2 hours, it is dried in air at 500 ° C for 5
Heated for hours. This product was pulverized and then reduced immediately before the reaction in an argon-hydrogen mixed gas (hydrogen 15%) at 500 ° C. for 1 hour to obtain a methanol decomposition catalyst. The metal content in this catalyst was 20% by weight.

Production Example 2 Cobalt nitrate 6-hydrate 49.7 g, tetraethyl silicate 25
ml, water 10 ml, ethanol 20 ml and concentrated nitric acid 2
The mixture of ml was stirred at room temperature for 10 hours to obtain a gelled product. After drying it at 120 ° C for 2 hours, it is dried in air at 500
Heated at ° C. for 5 hours. After crushing this product, immediately before the reaction, 500 ° C. in an argon-hydrogen mixed gas (hydrogen 15%).
And reduced for 1 hour to obtain a methanol decomposition catalyst. The metal content in this catalyst was 60% by weight.

Production Example 3 11.1 g of nickel nitrate 6-hydrate, 1 part of cobalt nitrate 6-hydrate
A mixture of 1.1 g, tetraethyl silicate 25 ml, water 10 ml, ethanol 20 ml and concentrated nitric acid 2 ml was stirred at room temperature for 10 hours to obtain a gelled product. This at 120 ° C for 2
After drying for an hour, it was heated in air at 500 ° C. for 5 hours. This product was pulverized and then reduced immediately before the reaction in an argon-hydrogen mixed gas (hydrogen 15%) at 500 ° C. for 1 hour to obtain a methanol decomposition catalyst. The metal content in this catalyst was 40% by weight.

Production Example 4 Nickel nitrate 6-hydrate 11.8 g, chromium nitrate 9-hydrate 1
A mixture of 6.2 g, tetraethyl silicate 25 ml, water 10 ml, ethanol 20 ml and concentrated nitric acid 2 ml was stirred at room temperature for 12 hours to obtain a gelled product. This at 120 ° C for 2
After drying for an hour, it was heated in air at 500 ° C. for 5 hours. After crushing this product, immediately before the reaction, it was reduced in an argon-hydrogen mixed gas (hydrogen 15%) at 500 ° C. for 1 hour to obtain a methanol decomposition catalyst. The metal content in this catalyst was 40% by weight.

Production Example 5 22.2 g of nickel nitrate, 25 ml of tetraethyl silicate,
A mixture of 10 ml of water, 20 ml of ethanol and 2 ml of concentrated nitric acid was stirred at room temperature for 8 hours to obtain a gelled product. This was dried at 120 ° C. for 2 hours and then heated in air at 500 ° C. for 5 hours. This product was pulverized and then reduced in an argon-hydrogen mixed gas (hydrogen 15%) at 300 ° C for 16 hours immediately before the reaction to obtain a methanol decomposition catalyst. The metal content of this catalyst was 40% by weight.

Example 1 1 g of the catalyst obtained in Production Example 1 was charged into a stainless steel reaction tube, and methanol (0.2%) diluted with argon (0.2
5 atm, total gas flow 12 l / h) at reaction temperature 250 ° C.
And the decomposition reaction of methanol was carried out. In this reaction, the steady-state decomposition activity of methanol per 1 g of catalyst was 7
The results were 1 mmol / h and a selectivity to carbon monoxide of 93.5%.

Example 2 1 g of the catalyst obtained in Production Example 2 was charged into a stainless reaction tube, and methanol (0.2%) diluted with argon (0.2
5 atm, total gas flow 12 l / h) at reaction temperature 200
It was supplied at a temperature of ℃, and the decomposition reaction of methanol was carried out. In this reaction, a steady-state decomposition activity of methanol per 1 g of the catalyst was 25 mmol / h, and the selectivity to carbon monoxide was 87.8%.

Example 3 1 g of the catalyst obtained in Production Example 3 was filled in a stainless steel reaction tube, and methanol (0.2
5 atm, total gas flow 12 l / h) at reaction temperature 200
It was supplied at a temperature of ℃, and the decomposition reaction of methanol was carried out. In this reaction, the result was that the steady-state decomposition activity of methanol per 1 g of the catalyst was 22 mmol / h, and the selectivity to carbon monoxide was 98.4%.

Example 4 1 g of the catalyst obtained in Production Example 4 was charged into a stainless reaction tube, and methanol (0.2%) diluted with argon (0.2
5 atm, total gas flow 12 l / h) at reaction temperature 200
It was supplied at a temperature of ℃, and the decomposition reaction of methanol was carried out. In this reaction, a steady decomposition activity of methanol per 1 g of catalyst of 20 mmol / h and a selectivity of 100% for carbon monoxide were obtained.

Example 5 1 g of the catalyst obtained in Production Example 5 was charged into a stainless reaction tube, and methanol (0.2%) diluted with argon (0.2
5 atm, total gas flow 12 l / h) at reaction temperature 200
It was supplied at a temperature of ℃, and the decomposition reaction of methanol was carried out. In this reaction, the result was that the steady-state decomposition activity of methanol per 1 g of the catalyst was 34 mmol / h, and the selectivity to carbon monoxide was 73.2%.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C01B 3/22 C10K 3/00 C10K 3/00 B01J 23/74 311M (56) References 58-166937 (JP, A) JP 62-254846 (JP, A) JP 4-26503 (JP, A) JP 1-16767 (JP, B2)

Claims (3)

(57) [Claims] 1. A composite of a metal and a silicon oxide, wherein at least one compound of nickel, cobalt and chromium is reacted with an organic silicic acid compound to cause gelation, followed by firing and further reduction. A method for producing a methanol dehydrogenation catalyst comprising 2. A particle size 6 of at least one of nickel, cobalt and chromium obtained by a sol-gel method.
~ 22nm reduced metal particles dispersed in silicon oxide
A catalyst for a methanol dehydrogenation reaction, which is composed of a complex in the formed state . 3. A method for decomposing methanol, which comprises carrying out a dehydrogenation reaction of methanol in a gas phase in the presence of the catalyst for methanol dehydrogenation reaction according to claim 2.