JP3161011B2 - How to reduce carbon dioxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneously producing carbon monoxide and aromatic hydrocarbons, which are important as raw materials in the organic chemical industry.

[0002]

2. Description of the Related Art Carbon dioxide is a major cause of global warming, and reduction and effective use of carbon dioxide are urgently required. On the other hand, carbon monoxide is a very important compound as a raw material when producing acetic acid from methanol or as a raw material when producing various organic compounds by hydrophoromylation. Therefore, if carbon dioxide can be converted into useful carbon monoxide as a raw material, it is very significant from an environmental problem and industrially.

As a method for producing carbon monoxide by reducing carbon dioxide, a method using hydrogen as a reducing agent (US Pat. No. 3,718,418) and a method using methane (O.M.
Tokunaga and S.M. Ogasawara,
React. Kinet. Catal. Lett. ,
39 (1), 69 (1989)), a method using toluene (66th, Symposium on Catalysis (A) 3L407 (1990)
Year)) is known.

[0004]

In the method using hydrogen as a reducing agent, hydrogen is expensive and economically disadvantageous. Also,
In the method using methane as a reducing agent, high reactivity is required to obtain a high conversion rate due to low reactivity of methane, and there is an energy problem. Further, in the method using toluene as a reducing agent, there is a problem that toluene is economically expensive and the activity is significantly reduced with time in terms of performance.

[0005]

The present inventors have conducted intensive studies on the reduction reaction of carbon dioxide to carbon monoxide.
By using propane or propylene, which are inexpensive lower hydrocarbons, as a reducing agent, they found a new fact that carbon dioxide can be produced efficiently and economically by reducing carbon dioxide, and the present invention has been completed.

That is, in the present invention, propane, propylene and carbon dioxide are selected from vanadium pentoxide supported on alumina, potassium-vanadium pentoxide supported on alumina, gallium supported on HZSM-5, platinum supported on HZSM-5 and zinc supported on HZSM-5. The present invention also relates to a method for reducing carbon dioxide, comprising producing carbon monoxide and an aromatic hydrocarbon by contacting the catalyst with one or more catalysts.

Hereinafter, the present invention will be described in more detail.

[0008] The catalyst used in the method of the present invention comprises vanadium pentoxide on alumina, potassium on alumina.
Vanadium pentoxide, gallium supported on HZSM-5, HZS
A catalyst combining one or more of platinum supported on M-5 and zinc supported on HZSM-5 is used.

Among these, there is no particular limitation on the method of preparing the alumina-supported vanadium pentoxide catalyst, and the usual catalyst preparation is carried out by impregnating alumina with a solution such as vanadium nitrate or ammonium vanadate and then calcining in air to obtain the catalyst. Method can be used. There is no particular limitation on the method for adding potassium, and potassium salts such as potassium carbonate and potassium chloride may be impregnated into alumina simultaneously with the vanadium salt, or prepared by impregnating the alumina-supported vanadium pentoxide catalyst with a potassium salt solution. You can also. These vanadium pentoxide-based catalysts may be used in the reaction as they are, or may be converted to oxides and then subjected to a pretreatment at a high temperature and used in the reaction.

The crystal form of alumina used as a carrier is not particularly limited, but it is preferable to use one which has been calcined at 500 ° C. or higher in advance.

The loading ratio of vanadium pentoxide as a catalyst component may be from 0.1% to 50% by mole, preferably from 0.2 to 50%.
% To 20%. If the loading is less than 0.1%, sufficient activity may not be obtained, and if it exceeds 50%, the effect is not significantly increased and the economy may be uneconomical. The amount of potassium added can be defined by the molar ratio with vanadium, and is 0 to 2, preferably 0.05 to 1, with respect to vanadium. If the amount of potassium exceeds 2, sufficient activity may not be obtained.

HZSM-5 supported gallium, HZSM-5
There are no particular restrictions on the method of preparing supported platinum and zinc supported on HZSM-5. Examples of the raw material used for the support include chlorides such as gallium chloride, chloroplatinic acid, and zinc chloride; nitrates such as gallium nitrate and zinc nitrate; and organic compounds such as zinc acetate. The method of supporting the metal is not particularly limited, but a method of dissolving the metal compound in an appropriate solvent, impregnating the metal compound with HZSM-5, and then calcining the metal compound may be used. It is also possible to use a method in which powder is added, ion exchange is performed by heating and refluxing, and then firing is performed.

[0013] The method for preparing HZSM-5 used as a carrier is not particularly limited.
81).
-10064, JP-B-56-49851, JP-A-5
ZSM prepared by the method described in JP-A-9-54620
It can also be obtained by immersing -5 in an aqueous hydrochloric acid solution, performing ion exchange at 50 ° C to 80 ° C, and then performing washing, filtration, and drying.

Further, ZSM-5 is immersed in an aqueous solution of ammonium nitrate, ion-exchanged at 50 ° C. to 80 ° C., washed, filtered and dried to form ammonium type ZSM-5, and then baked in air to form HZSM-5. 5 can also be obtained.

The supported amount of gallium, platinum and zinc may be 0.1% to 40% by weight, preferably 0.2% to 20%.
It is. If the loading is less than 0.1%, sufficient activity may not be obtained, and if it exceeds 20%, the effect is not remarkably increased and the economy may be uneconomical.

In the method of the present invention, propane or propylene is used as a reducing agent of carbon dioxide alone or in a mixture at an arbitrary ratio. Also, the amounts of propane and propylene can be defined as a molar ratio to carbon dioxide. Specifically, the reducing agent for carbon dioxide can be 0.05 to 25, and preferably 0.1 to 20. If the amount of the reducing agent is less than 0.05, a sufficient rate of carbon monoxide generation may not be obtained. On the other hand, if the amount of the reducing agent exceeds 25, the amount of the reducing agent to be recycled becomes large and uneconomical. There is. The source gas may be diluted with an inert gas such as nitrogen, helium, or water vapor.

The reaction temperature in the method of the present invention is 300 ° C.
~ 850 ° C. More preferably 400 ° C to 800 ° C
It is. If the reaction temperature is lower than 300 ° C., a sufficient conversion of carbon dioxide may not be obtained. If the reaction temperature is higher than 850 ° C., the activity may decrease over time due to sintering or coking, or the generated aromatic hydrocarbon may be decomposed. This may lead to a decrease in the yield of aromatic hydrocarbons. The reaction pressure is not particularly limited, and the reaction is preferably performed at normal pressure to 20 atm, preferably at normal pressure to 10 atm.

The feed rate of the raw material to the catalyst can be defined by the feed rate (SV) of the raw material per unit catalyst volume. In the method of the present invention, SV is 500 to 10,000.
0 / h may be used. If the SV is less than 500 / h, the production rate of carbon monoxide may decrease, and if the SV is less than 1000 / h.
If it exceeds 00 / h, the conversion rate of the raw material may be reduced, and it may not be economical.

The reaction method is not particularly limited as long as the catalyst and the raw material can be efficiently contacted. For example, the reaction can be performed in a fixed bed, a fluidized bed, or a moving bed. The catalyst may be used after being molded or used as a powder, and may be molded into a desired size and used depending on the reaction method.

According to the above method, carbon dioxide is reduced to obtain carbon monoxide and aromatic hydrocarbons of benzene, toluene and xylene.

[0021]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 A solution obtained by dissolving ammonium vanadate in oxalic acid was impregnated into alumina, and calcined at 500 ° C. for 3 hours in an air stream to obtain a vanadium pentoxide catalyst supported on alumina (5 mol%).

Next, 1.5 g of the catalyst sized to 28 to 48 mesh was filled in a reaction tube, and pretreated at 550 ° C. for 1 hour in a hydrogen stream, and then at 550 ° C. in a molar ratio of 2: 3: 2. A mixed gas of propylene, carbon dioxide, and nitrogen was supplied at a rate of 35 ml per minute. The reaction results are shown in FIG.

Example 2 An aqueous potassium carbonate solution was added to an alumina-supported vanadium pentoxide catalyst prepared in the same manner as in Example 1, and evaporated to dryness, and then calcined at 500 ° C. in an oxygen stream to carry alumina (2.
A 5%) potassium- (5%) vanadium pentoxide catalyst was obtained. A reaction tube was charged with 1.5 g of the catalyst sized to 28 to 48 mesh, and the reaction was carried out in exactly the same manner as in Example 1.
The results are shown in FIG.

Example 3 15 g of ZSM-5 (Si / Al ratio = 23.3) was added to water 4
The resultant was immersed in an aqueous solution in which 16.3 g of ammonium nitrate was dissolved in 00 ml, and ion-exchanged for 3 days while heating at 80 ° C. It was washed with water, filtered, dried at 120 ° C. for 12 hours, and calcined at 400 ° C. in an air stream to obtain HZSM-5.
An aqueous gallium nitrate solution was added to the HZSM-5 powder, and the mixture was heated to reflux. After filtering the obtained slurry, it was calcined at 550 ° C. in an air stream to carry HZSM-5 (1).
% By weight) gallium catalyst was obtained. 0.3 g of this catalyst was charged into a reaction tube, and a mixed gas of propane, carbon dioxide and nitrogen at a molar ratio of 2: 5: 5 was supplied at a rate of 38 ml / min. The reaction results are shown in FIG.

Example 4 A catalyst was prepared in exactly the same manner as in Example 3 except that chloroplatinic acid was used as a raw material to obtain a HZSM-5-supported (1% by weight) platinum catalyst. The reaction between propane and carbon dioxide was carried out in exactly the same manner as in Example 3. FIG. 4 shows the results. Example 5 A catalyst was prepared in exactly the same manner as in Example 3 except that zinc nitrate was used as a raw material to obtain a HZSM-5-supported (1% by weight) zinc catalyst. The reaction between propane and carbon dioxide was carried out in exactly the same manner as in Example 3. The results are shown in FIG.

[0027]

By using propane or propylene as a reducing agent for carbon dioxide, it is possible to economically produce both carbon monoxide and aromatic hydrocarbons.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of the carbon dioxide reduction reaction of the present invention performed in Example 1.

FIG. 2 is a diagram showing the results of the carbon dioxide reduction reaction of the present invention performed in Example 2.

FIG. 3 is a view showing a result of a reduction reaction of carbon dioxide of the present invention performed in Example 3.

FIG. 4 is a diagram showing the results of the carbon dioxide reduction reaction of the present invention performed in Example 4.

FIG. 5 is a diagram showing the results of the carbon dioxide reduction reaction of the present invention performed in Example 5.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07C 15/02 C07C 15/02 15/06 15/06 15/08 15/08 // C07B 61/00 300 C07B 61/00 300 Preliminary application for Article 30 (1) of the Patent Act is available. The proceedings of lectures at THE INTERNATIONAL SYMPOSIUM ON CHE MICAL FIXATION OF CARBON DIOXIDE (Chemical Society of Carbon Dioxide Fixation, The Chemical Society of Japan, issued December 2, 1991) Article 30 of the Patent Law Proceedings of the research presentation of “CO ▲ 2 ▼ Fixation Study Group” Research Presentation Lectures (Catalyst Society of Japan “CO ▲ 2 ▼ Fixation Study Group”, distributed on December 11, 1991) (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 15/04 B01J 23/22 C01B 31/18 C07C 2/42 C07C 2/84 C07C 15/02 C07C 15/06 C07C 15/08 C07B 61/00 300

Claims (1)

(57) [Claims] 1. A method comprising the steps of: propane or propylene and carbon dioxide, vanadium pentoxide on alumina, potassium-vanadium pentoxide on alumina, gallium on HZSM-5,
A method for reducing carbon dioxide, comprising contacting a catalyst selected from platinum supported on HZSM-5 and zinc supported on HZSM-5 to produce carbon monoxide and aromatic hydrocarbons.