JPS6246526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention and Industrial Field of Application) The present invention relates to a method for producing lower hydrocarbons containing ethylene and propylene as main components from synthesis gas. (Prior art) It is known that when a mixed gas containing carbon monoxide and hydrogen is catalytically reacted in the presence of an iron-based catalyst or a cobalt-based catalyst, unsaturated hydrocarbons are selectively produced to some extent. (For example, JP-A-51-131809
No. 56-25117, No. 56-136890, No. 57-
No. 82323, etc.) were not fully satisfactory in terms of selectivity for ethylene and propylene. On the other hand, when a mixed gas containing carbon monoxide and hydrogen is catalytically reacted in the presence of a heterogeneous catalyst consisting essentially of metal rhodium, the main product has 2 carbon atoms.
It is an oxygen-containing compound (JP-A No. 51-80806, same)
52-14706, 57-62233, etc.). (Problems to be Solved by the Invention) The present invention provides a method for producing lower hydrocarbons containing ethylene and propylene as main components from synthesis gas with high selectivity. The present inventors reacted (a) a polyol, (ro) a rhodium compound, an alkali metal compound and a manganese compound or a scandium compound, and (c) a metal alkoxide, and then heat-treated the solid obtained by hydrolyzing the reaction mixture. By doing so, rhodium,
When a metal oxide supported on an alkali metal and manganese or scandium was prepared and used as a catalyst for producing lower hydrocarbons mainly composed of ethylene and propylene from carbon monoxide and hydrogen, the compound was highly selectively produced. They found that it can be obtained and completed the present invention. Although the true active species in a dynamic state under the reaction conditions of such a specific rhodium-containing catalyst is not necessarily clear, if the catalyst of the present invention is used as shown in the examples, known rhodium-containing Lower hydrocarbons, which are the main products, are selectively obtained, which is different from when a catalyst is used.Furthermore, as shown in the comparative example, the catalyst prepared by the conventional impregnation method yields lower hydrocarbons, but has a lower selectivity. Since it was not as good as the catalyst of the present invention, it is considered that a new active type of rhodium was formed on the carrier by the chemical mixing method. The catalyst of the present invention reacts (a) a polyol, (ro) a rhodium compound, an alkali metal compound and a manganese compound or a scandium compound, and (c) a metal alkoxide, and then heat-treats the solid obtained by hydrolyzing the reaction mixture. It is prepared as follows. Examples of the polyol used here include ethylene glycol, propanediol, and cyclohexanediol. Examples of rhodium compounds include inorganic salts such as chlorides, nitrates, and sulfates, organic acid salts such as acetates, oxalates, and acetylacetonate salts, oxides or ammine complex salts, clusters, rhodium carbonyl, and rhodium carbonylacetyl. Although any compound commonly used in the preparation of noble metal catalysts such as acetonate can be used, chloride is recommended for ease of handling. Examples of alkali metal compounds used include inorganic acid salts such as halogenates, sulfates, nitrates, and carbonates, and organic acid salts such as hydroxides, acetates, formates, and oxalates, but there are no particular restrictions. do not have. However, in order to facilitate the reaction during catalyst preparation, compounds soluble in polyols are preferably used. As manganese and scandium compounds, for example, inorganic salts such as chlorides, nitrates, oxides, carbonates, organic salts such as acetates, oxalates, acetylacetonate salts, carbonyl compounds, cyclopentadienyl compounds, etc. are used. However, there are no particular restrictions. However, in order to facilitate the reaction during catalyst preparation, compounds soluble in polyols are preferably used. In addition, metal alkoxides include silicon, aluminum, titanium, zirconium, tantalum,
Alkoxides such as niobium, vanadium, thorium, and magnesium can be used, and can be used alone or in combination. In preparing the catalyst of the present invention, the above three
After reaction at a temperature of 80°C, the resulting reaction mixture is hydrolyzed. Hydrolysis is 40~
It can be carried out at 80°C. After the hydrolysis, the gel obtained can be dried and heated to form a catalyst supporting finely dispersed rhodium and the metal. The catalyst prepared by the above-mentioned method is usually activated by reduction treatment and then subjected to reaction. It is convenient and preferable to carry out the reduction using a hydrogen-containing gas at an elevated temperature. At this time, the reduction treatment can be carried out at a temperature at which rhodium and the metals are reduced, that is, about 100°C, but it is preferably carried out at a temperature of 200°C to 600°C. At this time, hydrogen reduction may be carried out while raising the temperature gradually or stepwise from a low temperature in order to sufficiently disperse each component of the catalyst. Further, reduction can also be carried out chemically using a reducing agent. For example, reduction treatment may be performed using carbon monoxide and water, or using a reducing agent such as hydrazine, a borohydride compound, or an aluminum hydride compound. The ratio of rhodium to carrier is 0.0001 by weight
-0.5, preferably 0.001-0.3. The ratio of alkali metal to rhodium (alkali metal/rhodium (atomic ratio)) is in the range of 0.001 to 10, preferably 0.01 to 3. Further, the ratio of manganese or scandium to rhodium is 0.001 to 10, preferably 0.01 in terms of manganese or scandium/rhodium (atomic ratio).
It is in the range of ~3. Catalysts such as those described above are used to convert synthesis gas, a mixture of carbon monoxide and hydrogen, into unsaturated hydrocarbons. The reaction is usually carried out in the gas phase, for example, a raw material gas containing carbon monoxide and hydrogen is passed through a fixed bed reactor packed with a catalyst. In this case, in addition to carbon monoxide and hydrogen, the raw material gas includes carbon dioxide, nitrogen,
It may also contain other components such as argon, helium, methane, and water vapor. Further, the catalytic reactor is not limited to a fixed bed type, but may be of other configurations such as a moving bed type or a fluidized bed type. In some cases, a liquid phase reaction may also be carried out, in which the catalyst is suspended in a suitable solvent and a raw material gas is passed therethrough. Reaction conditions can be varied within wide limits. The preferred range is a molar ratio of carbon monoxide to hydrogen of 20:
1 to 1:5, preferably 10:1 to 1:5, reaction temperature 200 to 400°C, preferably 220 to 350°C, pressure 1 to 300 atm, preferably 20 to 200 atm,
The space velocity is 10 ² in standard conditions (0°C, 1 atm)
to 10 ⁷ Hr ⁻¹ , preferably from 10 ³ to 10 ⁶ Hr ⁻¹ . EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. (Effects of the Invention) The results of the reactions in these specific examples are summarized in Table 1. The conversion rate is expressed as the ratio of the number of moles of carbon monoxide consumed to the number of moles of carbon monoxide supplied. Selectivity (%) is defined by the following formula. Number of moles of CO converted to a specific product x 100/number of moles of CO consumed Esters were calculated by dividing them into acids and alcohols, and acetic acid, ethanol, and acetaldehyde were collectively shown as oxygen-containing compounds. . As can be seen in Table 1, the use of catalysts prepared using chemical mixing methods improves the selectivity to lower hydrocarbons including ethylene and propylene. Example 1 After completely dissolving 0.84 g of rhodium trichloride trihydrate, 0.019 g of manganese chloride tetrahydrate, and 0.0386 g of lithium chloride hydrate in 10 ml of dehydrated ethylene glycol, 24.24 g of tetraethylorthosilicate was added and stirred. , to form a completely homogeneous solution. distilled water8.39
ml and stir until the solution becomes a gel. After drying the gel in vacuum, it was filled into a quartz glass reduction tube and diluted with nitrogen diluted hydrogen (H ₂ :N ₂ =150:75ml/
Gradually raise the temperature from room temperature while flowing 450
The catalyst was prepared by hydrogen reduction at ℃ for 6 hours. Fill 3 ml of this catalyst into a titanium reaction tube and pressure 30
^The raw material gas (CO:
H ₂ =2:3) was fed at a rate of 69 Nl/hour to carry out the reaction and evaluate the activity of the catalyst. Example 2 Rhodium trichloride trihydrate 0.84g, scandium trichloride hexahydrate 0.041g, lithium chloride monohydrate 0.0386
After completely dissolving g in 10 ml of dehydrated ethylene glycol, tetraethylorthosilicate
Add 24.24g and stir to make a completely homogeneous solution.
Add 8.39 ml of distilled water and stir until the solution becomes a gel. Thereafter, drying and heat treatment were performed in the same manner as in Example 1 to obtain a catalyst. Using 10 ml of this catalyst, raw material gas (CO: H ₂ = 10:
7) was fed at a rate of 50 Nl/hour to carry out the reaction. Other reaction conditions are the same as in Example 1. Comparative example After completely dissolving 0.72 g of rhodium trichloride trihydrate, 0.0162 g of manganese chloride tetrahydrate, and 0.033 g of lithium chloride monohydrate in 10 ml of ethyl alcohol, #57
It was impregnated with 6 g of silica and dried in a closed dryer for two days and nights. Thereafter, heat treatment was performed in the same manner as in Example 1 to obtain a catalyst. Using 3 ml of this catalyst, the temperature was 295°C.
A reaction was carried out by feeding raw material gas (CO:H ₂ =1:3) at a rate of 63 Nl/hour. Other conditions are the same as in Example 1. 【table】

Claims (1)

[Claims] 1. A solid obtained by reacting (a) a polyol, (b) a rhodium compound, an alkali metal compound and a manganese compound or a scandium compound, and (c) a metal alkoxide, and then hydrolyzing the reaction mixture,
A method for producing lower hydrocarbons containing ethylene and propylene as main components from carbon monoxide and hydrogen, which comprises using heat-treated and prepared metal oxide catalysts supported on rhodium, alkali metals, and manganese or scandium.