JPH049731B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel iron-titanium-manganese/or vanadium-containing amorphous silicate and a catalyst for synthesizing hydrocarbons from a mixed gas of carbon monoxide and hydrogen containing the same as an active ingredient. Conventionally, the method of producing hydrocarbons by reacting carbon monoxide and hydrogen in the presence of a catalyst is known as Fischer-Tropsch synthesis, and as shown in the following formula, C-C is produced from CO and _H2 . It is a catalytic reaction that forms bonds. CO+2H ₂ →1/n(-CH ₂ )- _o +H ₂ O In this Fischer-Tropsch synthesis, CO undergoes polycondensation while undergoing hydrogenation, so depending on the type of catalyst and reaction conditions, the above The value of n in the formula, that is, the C-C polymerization degree of the product,
There are many different types of products, including olefins and paraffins, as well as aldehydes and ketones, which are incomplete products of hydrodehydration. In the Fischer-Tropsch synthesis, an iron-based catalyst is generally employed, and the addition of a trace amount of an alkali metal salt gives a product with a significantly increased degree of C-C polymerization, but it is difficult to control the carbon number distribution of the product. It has the drawback of being extremely difficult, and improving this drawback is the biggest technical challenge in Fischer-Tropsch synthesis. On the other hand, among the various solid inorganic compounds used in catalysts, in porous materials, the area of the inner walls of the pores is several tens to hundreds of times larger than the outer surface, so most of the active sites of the catalyst are located inside the pores. it is conceivable that. Therefore, if the pore size of the catalyst is appropriate, there will be both molecules that are too large to fit into the pores and molecules that can fit into the pores, and molecules that cannot enter will have a much smaller chance of reacting than molecules that can. Become. As for the product, molecules larger than the pore are not produced within the narrow pore. In this way, the relationship between pore structure and molecular shape determines the selectivity of a catalyst, and zeolite is one such catalyst. Zeolites are generally crystalline aluminosilicates,
It is a porous crystal in which (SiO ₂ ) and (AlO ₂ ) ^- are combined three-dimensionally, and since the entrance of the pores is a crystalline material, they are all the same size, making it a molecular shape selective catalyst. It is suitable as From this point of view, several attempts have been made to combine Fischer-Tropsch synthesis catalysts and zeolites. [PDCaesar, JA
Brennan, WE Garwood, J. Citto, J. Catal.
56, 274 (1979); VUS Rao, R. J., Gormley,
Hydrocarbon Proceeding, Nov. 139 (1980), E.
P.20140, 20141; USP4298695, 4269784] However, the previously proposed
The combination of Tropschule synthesis catalyst and zeolite is
These methods have been limited to simply mixing the two or simply impregnating and supporting zeolite with active components of the Fischer-Tropsch synthesis catalyst, and have not yet provided satisfactory results in terms of controlling the carbon number distribution of the product. Also,
Recently, crystalline metal silicates such as Fe, Ni, Ti, Ru, and Rh have been synthesized and attempts have been made to use them as catalysts for Fischer-Tropsch reaction (USP3941871; EP0050525 AI;
JP-A-56-96720; JP-A-57-183316; JP-A-57
−183317; Japanese Patent Publication No. 1833-183320; Japanese Patent Publication No. 1983-
74521), although in this case some improvement is seen in controlling the carbon number distribution of the product, it is still not sufficient. Furthermore, the proportion of olefin in the product is small, making it insufficient as a catalyst for synthesis of lower olefins. The present inventors have also previously discovered several characteristic catalysts that can control the carbon number distribution of the product by combining a Fischier-Tropsch synthesis catalyst and zeolite. (Patent application 1982-23, Patent application 1982-172737) However,
The present invention is still not sufficient for the purpose of the present inventors, which is to develop a catalyst that allows control of the carbon number distribution of the product, has high activity, and has a large proportion of olefin in the product. As a result of subsequent studies, the present inventors found that instead of crystalline silicate, iron-titanium-manganese or vanadium-containing amorphous assilicate, which was hydrothermally synthesized using a mixture of an iron source, a titanium source, and a manganese or vanadium source, was used. By using it as a catalyst, its activity can be further improved, leading to the completion of the present invention. The iron-titanium-manganese or vanadium-containing amorphous assilicate (hereinafter simply referred to as amorphous assilicate) of the present invention is used as a reaction aid when synthesizing crystalline silicate according to a conventionally known hydrothermal synthesis method. It is formed using organic compounds such as various tetraalkylammonium compounds. Generally, silica is widely used as a carrier for various supported catalysts, but it is extremely rare to use it in a liquid form such as water glass when preparing a catalyst. [Potassium silicate is used as a silica source in Sasol's solid bed catalyst. (CD
Frohning, : Fischer-Tropsch-Synthese,
Chemierohstoff aus Kohle (Farbe J., ed.)
Stuttgart: Thieme1977)]. Furthermore, there are no known examples of its combined use with organic compounds such as various tetraalkylammonium compounds, except for zeolite synthesis. Note that there are examples of using amorphous silica/alumina synthesized using organic compounds as in the present invention as catalysts for methanol conversion reactions and paraffin cracking reactions (MR
S. Manton, JC Davidtz, J. Catal., 60, 156
(1979); RLEspinoza, CMStander, WGB
Mandersloot, Appl. Catal, 6, 11 (1983)). There is no example of using the amorphous silicate of the present invention as a catalyst for hydrocarbon synthesis from a mixed gas of carbon monoxide and hydrogen. The amorphous silicate of the present invention is produced by subjecting an aqueous mixture consisting of a silica source, an iron source, a titanium source, a manganese and/or vanadium metal source, and an alkali metal ion source to a hydrothermal synthesis reaction. In this case, as a reaction aid, for example,
Conventional organic compounds such as various tetraalkylammonium compounds can be used. As silica source water glass, silica gel, silica sol or silica is used. As a source of iron, sulfuric acid No. 1
Iron, ferrous chloride, ferric sulfate, ferric chloride, etc. are used. As the titanium source, titanium oxysulfate, titanium sulfate, titanium tetrachloride, etc. are used. As the alkali metal ion source, sodium oxide, sodium aluminate, sodium hydroxide, potassium hydroxide, etc. in water glass are used. Manganese chloride or the like is used as the manganese source, and ammonium vanadate or the like is used as the vanadium source. As reaction aids, various conventionally known organic compounds such as tetraphosphonium compounds, tetraalkyl compounds, ethylenediamine,
Although choline and the like can be used, tetraalkylammonium compounds are preferred, and among these, tetraalkylammonium bromide is particularly preferred. When producing the amorphous silicate of the present invention, it is generally preferable that the raw material reaction mixture has the following composition. Si/Fe (molar ratio): 2 or more Ti/Fe (molar ratio): 0.01~3 M/Fe (〃): 0.01~3 _H2O / _SiO2 (〃): 30~70 _R4N ⁺ /SiO ₂ (〃): 0.08~0.16 OH ^- / _SiO2 (〃): 0.07~0.3 Here, OH ^- indicates the amount of hydroxyl ion in the mixture,
To adjust this value, an alkali metal hydroxide salt, an alkali metal oxide, etc. are used. R ₄ N ⁺ indicates the amount of tetraalkylammonium ion. Moreover, M represents V or Mn. Amorphous assilicate can be obtained by hydrothermal synthesis by heating and stirring an aqueous gel mixture having such a component composition at a reaction temperature of 0 to 100°C for 0.1 to 200 hours. The reaction product is treated by filtration or centrifugation to separate solids from the aqueous solution. The obtained solid is further washed with water to remove excess ionic substances, and then dried to obtain an amorphous assilicate containing the organic compound used as a reaction aid. By calcining this product in air at a temperature of 300 to 900°C, preferably 400 to 700°C for 1 to 100 hours, an amorphous assilicate containing no organic compounds can be obtained. The amorphous silicate of the present invention is used as a catalyst for synthesizing hydrocarbons using a mixed gas of carbon monoxide and hydrogen as a raw material, that is, as a catalyst for Fischer-Tropsch synthesis. In this case, conventionally known conditions are adopted as the Fischier-Tropsch synthesis reaction conditions, for example, the reaction temperature is
200~500℃, preferably 300~450℃ is adopted,
The reaction pressure is 1 to 100 atm, preferably
A pressure of 10 to 50 atmospheres is used. in the raw material mixed gas
The _H2 /CO molar ratio is between 0.2 and 3, preferably between 0.5 and 1. The amorphous silicate of the present invention can be advantageously used as a catalyst for the Fischer-Tropsch synthesis reaction, as well as in various other reactions using zeolite as a catalyst, such as reactions in the synthesis of hydrocarbons from methanol or dimethyl ether. It can also be used as a catalyst in hydrocarbon decomposition reactions, olefin polymerization reactions, organic compound hydrogenation reactions, aromatic alkylation reactions, etc. Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 4 Colloidal silica (manufactured by Catalyst Kasei Co., Ltd., Cataloid
SI-30), ferrous sulfate heptahydrate, titanium oxysulfate dihydrate, manganese or vanadium compound, potassium hydroxide (purity 85%), tetra-n-propylammonium bromide, and water in Table 1 below. A homogeneous aqueous gel-like mixture containing the composition shown in is placed in a closed container and stirred for 40 m at various reaction temperatures. The reaction mixture was centrifuged to separate solids, which were washed with water until free of ionic substances, dried at 100°C, and then calcined at 500°C for 15 hours to obtain amorphous assilicate. X-ray diffraction measurements of these materials confirmed that they were all amorphous.

[Table] Examples 5 to 8 The fired amorphous silicate bodies obtained in Examples 1 to 4 were compressed into tablets at a pressure of 400 Kg/cm ² , and then crushed to a size of 15 to 30 meshes. A 20 mm reaction tube was filled. Hydrogen treatment was performed at a rate of 100 ml/min at 400 to 500°C for 15 hours, and then the hydrogen was converted into a mixed gas of carbon monoxide and hydrogen (molar ratio 1:1).
The reaction was carried out at 450°C with GHSV = 1000 to 10000 hr ^-1 . Analysis of the product was performed using a gas chromatograph using argon as an internal standard. Second
The reaction results are shown in the table. Note that the conversion rate and selectivity shown below are both based on carbon, and the selectivity was calculated by setting the CO conversion rate excluding the conversion to CO ₂ (CO ₂ yield) as 100.

[Table] Comparative Example Same as Example 1, using an iron-titanium-manganese-containing crystalline silicate fired body (BET surface area 305 m ² /g) hydrothermally synthesized (150°C 40 hours) from the same aqueous gel mixture as Example 1. The reaction was carried out under the following conditions. The results are shown below. Pressure (Kg/ ^cm2 ): 10 Temperature (℃): 450 GHSV (h ^-1 ): 1000 CO conversion rate (%): 10.1 Selectivity (%) C ₁ : 24.7 C ₂ : 29.0 C ₃ : 21.4 C ₄ :4.3 _C5 :1.0 _C6 UP or C :19.6

Claims (1)

[Scope of Claims] 1. Iron-formed by a hydrothermal synthesis reaction using a mixture of an iron source, a titanium source, a metal source selected from manganese and vanadium, and an organic compound as a reaction aid. Titanium-manganese or vanadium-containing amorphous silicate. 2. An iron-titanium-manganese or vanadium-containing product formed by a hydrothermal synthesis reaction using a mixture of an iron source, a titanium source, a metal source selected from manganese and vanadium, and an organic compound as a reaction aid. A catalyst for synthesizing hydrocarbons from a mixed gas of carbon monoxide and hydrogen, characterized by containing an amorphous assilicate as an active ingredient.