JP3089677B2 - How to reduce carbon dioxide with propane - 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 co-producing carbon monoxide and propylene, which are important as raw materials for 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 for producing acetic acid from methanol or as a raw material for producing various organic compounds by hydroformylation. 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 (OT).
okunaga and S.K. Ogasawara,
React. Kinet. Catal. Lett. , 3
9 (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]

In view of such circumstances, the present inventors have conducted intensive studies on the reduction reaction of carbon dioxide to carbon monoxide, and as a result, have found that inexpensive lower hydrocarbons having secondary carbon By using propane as a reducing agent, the inventors found a new fact that carbon dioxide can be produced efficiently and economically by reducing carbon dioxide, and completed the present invention.

That is, according to the present invention, in producing carbon monoxide by reducing carbon dioxide, chromium oxide, zinc oxide,
The present invention relates to a method for producing propylene and carbon monoxide from propane and carbon dioxide, using a catalyst obtained by combining one or more selected from gallium oxide or palladium catalyst supported on alumina, and using propane as a reducing agent.

Hereinafter, the present invention will be described in detail.

In the method of the present invention, a catalyst comprising one or a combination of two or more selected from chromium oxide, zinc oxide, gallium oxide and alumina-supported palladium catalyst is used. The method for preparing the oxide catalyst is not particularly limited, and the oxide catalyst may be obtained by calcining an inorganic salt such as nitrate or chloride as a raw material, or the catalyst may be prepared by a precipitation method in which the pH is changed using an acid or a base. It may be prepared. Further, a catalyst may be used as a catalyst by a method such as calcination or hydrolysis using an organic compound such as alkoxide or acetate as a starting material. For example, as an example of chromium, chromium nitrate or chromium acetate can be calcined in an air stream to obtain a chromium oxide catalyst. Alternatively, ammonia water or sodium hydroxide may be added to an aqueous solution of chromium chloride to obtain a precipitate of chromium hydroxide, which may be washed with water, dried and calcined to form a catalyst. These oxide-based catalysts may be used for the reaction as they are, or may be used for the reaction after being converted to an oxide and then subjected to a pretreatment at a high temperature.

The method for preparing the alumina-supported palladium catalyst is not particularly limited. Examples of the palladium material used for the support include, for example, inorganic palladium compounds such as palladium chloride, palladium nitrate, and palladium sulfate, or organic palladium compounds such as palladium acetylacetone, and further, palladium complexes such as tetraamminepalladium dichloride. it can. The method of supporting palladium is not particularly limited, but an example of an impregnation method in which a palladium compound is dissolved in an appropriate solvent and impregnated with alumina is exemplified. After the impregnation, the catalyst can be used as it is, or the palladium compound may be reduced to a metal state with hydrogen or the like in advance and used as a catalyst. The reduction conditions are not particularly limited as long as the palladium compound can be reduced to a metal state, but it is preferable to reduce the temperature up to 700 ° C. If the reduction is carried out at a temperature exceeding 700 ° C., the palladium particles may become too large, resulting in a catalyst having low activity. In the method of the present invention, alumina is used as a carrier. The crystal form of alumina is not particularly limited, but it is preferable to use one that has been previously calcined at 500 ° C. or higher. The loading ratio of palladium as a catalyst component may be 0.1% to 10%, preferably 0.2% to 5%. If the loading is less than 0.1%, sufficient activity cannot be obtained, and if it exceeds 10%, the effect of loading more than this may be small and uneconomical.

In the method of the present invention, propane is used as a reducing agent for carbon dioxide, and the amount of propane used can be defined as a molar ratio of propane to carbon dioxide. Specifically, the molar ratio between carbon dioxide and propane can be 0.05 to 25, and preferably 0.1 to 20. If the ratio of carbon dioxide to propane is less than 0.05, the amount of propane to be recycled increases, while if the ratio of carbon dioxide to propane exceeds 25, a sufficient carbon monoxide generation rate cannot be obtained, which is uneconomical. There is.

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 rate of carbon dioxide cannot be obtained. It may cause a decrease. 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 rate of formation of carbon monoxide is low, and if the SV exceeds 100,000 / h, the conversion rate of the raw material may be reduced, which may be uneconomical.

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.

[0014]

EXAMPLES The present invention will be described below with reference to examples.
It goes without saying that the present invention is not limited by these examples.

Example 1 A commercially available chromium oxide was subjected to pressure molding, classified into 28 to 42 mesh, and oxidized at 600 ° C. for 1 hour under an oxygen flow to obtain a chromium oxide catalyst. 0.5 g of this catalyst was charged into a reaction tube, the temperature was maintained at 600 ° C., and a mixture of carbon dioxide and propane at a molar ratio of 1: 1 was supplied thereto. Table 1 shows the reaction results.

Example 2 Zinc nitrate was calcined at 500 ° C. in an air stream to obtain a zinc oxide catalyst. The reaction was carried out in exactly the same manner as in Example 1 except that 0.5 g of this catalyst was used. Table 1 shows the results. Example 3 A catalyst was prepared exactly in the same manner as in Example 2 except that gallium nitrate nonahydrate was used as a raw material, and a reaction between carbon dioxide and propane was performed exactly in the same manner as in Example 1. Table 1 shows the results.

Example 4 Alumina was added to an aqueous solution of palladium chloride, water was removed under stirring, dried at 115 ° C. overnight, and reduced at 400 ° C. for 2 hours in a stream of hydrogen to carry alumina (1 wt.
%) Palladium catalyst was obtained. The reaction was carried out in exactly the same manner as in Example 1 except that 0.5 g of this catalyst was used. Table 1 shows the results.

[0018]

[Table 1]

[0019]

According to the method of the present invention, by using propane as a reducing agent for carbon dioxide, it is possible to economically produce both carbon monoxide and propylene.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C07C 5/42 C07C 5/42 11/06 11/06 // C07B 61/00 300 C07B 61/00 300 (58) Fields surveyed (Int.Cl. ⁷ , DB name) C01B 31/18 B01J 23/06 B01J 23/08 B01J 23/26 B01J 23/44 C07C 5/42 C07C 11/06 C07B 61/00 300 CA (STN)

Claims (1)

(57) [Claims] In producing carbon monoxide by reducing carbon dioxide, a catalyst obtained by combining one or two or more selected from chromium oxide, zinc oxide, gallium oxide and palladium catalyst supported on alumina is used, and propane is used. A method for producing propylene and carbon monoxide from propane and carbon dioxide, which is used as a reducing agent.