JPS59174519A - Crystalline iron silicate and catalyst containing it as active component - Google Patents

Abstract

PURPOSE:To obtain crystalline iron silicate suitable for a catalyst for Fischer- Tropsch synthesis (having excellent controllability of carbon distribution of product and high activity), by using simultaneously a Fa(II) compd. and a Fe(III) compd. as an iron-supplying source, and carrying out a hydrothermal synthetic reaction. CONSTITUTION:A mixture of a Fe(II) compd. (e.g. ferrous sulfate) and Fe(III) compd. (e.g. ferric sulfate), whose molar ratio [Fe(II)/Fe(III)] is about 0.01-10 is used as an iron-supplying source. And a mixture having a prescribed ratio of a silica source (e.g. silica sol), above-described iron-supplying source, an alkali- metallic ion source (e.g. sodium oxide in water glass) and a reaction auxiliary (tetraalkylammonium bromide) is allowed to react at about 90-200 deg.C and for about 10-200hr. After a solid substance is separated from an aqueous solution, washed with water and dried, it is calcined under an atmosphere at about 300- 900 deg.C and for about 1-100hr to obtain crystalline iron silicate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel crystalline iron silicate and a catalyst containing it as an active ingredient for synthesizing hydrocarbons from a mixed gas of -carbon oxide and hydrogen.

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, O- This is a catalytic reaction that forms 0 bonds.

Co + 2H2M -+0H2-)-H+ H2O This Fischer-Tropsch synthesis smell-1-i, CO
Since it does not undergo hydrogenation, it undergoes polycondensation,
Depending on the type of catalyst and reaction conditions, the value of n in the above formula, i.e.,
The degree of C--C polymerization of the products varies, and the types of products include olefins, .xi. rough ins, as well as aldehydes and ketones, which are incomplete products of hydrodehydration.

In the Fischer-Trosonille synthesis, iron-based catalysts are generally employed, and those with trace amounts of alkali metal salts give products with a significantly increased c-C polymerization degree;
It has the drawback that it is extremely difficult to control the carbon number distribution of the product, 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 tens to hundreds of times larger than the outer surface, so most of the active sites of the catalyst are 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 the molecules that cannot enter will have a much greater chance of reacting than the molecules that can. There are few. 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. Zeolite is generally a crystalline aluminosilicate, and is a porous crystal in which (Si02) and (AtO2)- are combined three-dimensionally, and the entrances of the pores are of equal size because they are a crystalline material. This makes it suitable as a molecular shape selective catalyst.

From this point of view, several attempts have been made to combine Fischer-Tropsch synthesis catalysts and zeolides. [P, D, Caesar, J, A, Bren
Nan.

W, E., Garwood, J., Oirio, J.
, Canal, 56 r 274 (1979)
i V, U, S.

R,ao, R,J, ()ormley, Hy
drocarbon Proceeding, No
v, 139 (1980): B, P, 20140, 2
0141i U, S, P, 4298695.4269
784) However, the combinations of Fischer-Tropsch synthesis catalysts and zeolites that have been proposed so far are merely mixing the two or simply impregnating and supporting the active components of the Fischer-Tropsch catalyst on zeolite, and the carbon number distribution of the product is limited. In terms of control, satisfactory results have not yet been achieved. However, recently, Fe, Ni, Ru
, Rh and other crystalline metal silicates have been synthesized and attempts have been made to use them as catalysts for Fischer-Tropsch reactions (B, p.

0050525 At i JP-A-5'/-18331
6: JP-A-57-183317, i JP-A-57-183
320), although in this case there is some improvement in controlling the carbon number distribution of the product, the problem is that the catalyst activity is extremely low.

The present inventors solved the above-mentioned problems seen in the prior art, made it possible to control the carbon number distribution of the product, and as a result of intensive research to develop a catalyst with high activity, the inventors found that The present inventors have discovered that crystalline iron silicate hydrothermally synthesized using a mixture of Fe(II) and Fe(III) compounds is suitable for the purpose, and have completed the present invention.

The crystalline iron silicate of the present invention is formed using a mixture of Fe(II) compound and Fe(Ill) compound as an iron source when synthesizing crystalline iron silicate according to a conventionally known hydrothermal synthesis method. It is something that

As mentioned above, crystalline iron silicate itself is known, but as an iron source as in the present invention, Fe(II
) and Fe(III) compounds are not known.

The crystalline iron 7-silicate of the present invention is a divalent iron compound CF
(II) compound] and a trivalent iron compound CF (m) compound] as an iron source; 3.
.

It is not incorporated into the skeletal structure of iron silicate, and the
Within the focus of the LD-ite, it is present in a free form from the skeletal structure, and such free ? n) Crystalline iron sheet with increased catalytic activity due to the presence of component 1φ)
This is considered to give l·-t. On the other hand, conventional crystalline iron silicates have not been devised to allow such free iron components to exist in the zeolite pores, and therefore are thought to exhibit only low catalytic activity.

The crystalline iron sisocate according to the present invention adsorbs n-hexane best, and also 3-methylpentane, which has one methyl group, but hardly adsorbs 2,2-dimethylbutane, which has two methyl groups. This shows a unique shape selectivity.

Next, the production of the crystalline iron silicate of the present invention will be described in more detail.

The crystalline iron knobcate of the present invention is produced by subjecting an aqueous mixture consisting of a silica source, an iron source, and an alkali metal ion source to a hydrothermal synthesis reaction according to a conventionally known method. In this case, conventional organic compounds such as various tetraalkylammonium compounds can be used as reaction aids. As the silica source, water glass, silica gel, silica sol or silica can be used, with silica sol being particularly preferred. In the case of the present invention, the iron source is pc
Both the (n) compound and the pc(m) compound are used together, but as the Fe(II) compound, ferrous sulfate, ferrous chloride,
Iron or the like is used, and as the Pe(Ill) compound, ferric nitrate, ferric sulfate, ferric chloride, etc. are used.

As the alkali metal ion source, for example, sodium oxide, sodium aluminate, sodium hydroxide, potassium hydroxide, etc. in water glass are used.

As a reaction aid, various conventionally known organic compounds such as tetraphosphonium compounds, tetraalkyl compounds, ethylenediamine, choline, etc. can also be used, but tetraalkylammonium compounds, especially hydroxides, are preferable. , halides are preferred, and among these, tetraalkylammonium bromide is particularly preferred. In this case, the number of carbon atoms in the alkyl group is 1 to 6, preferably 1 to 6.
There are 4 pieces.

In the present invention, both Fe(If) compounds and Fe(I[l) compounds are used as iron sources, but in this case, the ratio of Fe([1) compounds to Fe([1) compounds]
e(It)/z (m) is a molar ratio of 0. O1210, preferably in the range of 0.1-5.

When producing the crystalline iron silicate of the present invention, it is generally preferable to use a raw material reaction mixture having the following composition.

s1/ie (molar ratio): 2 or more Fe(II)
/Fe(III) (molar ratio): 0.1 to 5
H20/5i02 (molar ratio) = 30-70 liters 4 N 7
S+0□ (molar ratio): O, OS~0.
160H-/5i02 (molar ratio) + 0.07-0.
3 Here, OH- indicates the amount of hydroxide ion in the mixture, and an alkali metal hydroxide, alkali metal oxide, etc. are used to adjust this value. R4N+ indicates the amount of tetraalkylammonium ion.

An aqueous gel mixture having such a component composition is maintained under conditions of temperature, pressure, and time under which ordinary crystalline iron silicate is produced, and hydrothermal synthesis is carried out. In this case, the reaction temperature is 90-20
Hydrothermal synthesis is carried out by heating and stirring the reaction mixture at 0°C, preferably 95 to 170°C, for 1,000 to 200 hours while refluxing the reaction mixture under normal pressure or under self-pressure in a closed container. can be carried out to obtain crystalline iron silicate. The reaction product is processed by filtration or centrifugation.
Separate the solids from the aqueous solution. The obtained solid material is further washed with water to remove excess ionic substances, and then dried to obtain crystalline iron silicate containing the organic compound used as an anti-oxidant. . Crystalline iron silicate containing no organic compounds can be obtained by firing this material in air at a temperature of 1300 to 900°C, preferably 4oo to 7oo°C, for 1 to 100 hours.

The crystalline iron silicate of the present invention is usually used as a catalyst in the form in which the organic compound used as a reaction aid has been removed. It can also be used by replacing it with another cation. The crystalline iron silicate of the present invention is used as a catalyst for synthesizing hydrocarbons using a mixed gas of -carbon oxide and hydrogen as a raw material, that is, as a catalyst for Fischer-Tropsch synthesis. Fisher in this case
Conventionally known conditions are employed as the Tropsch synthesis reaction conditions, for example, the reaction temperature is 200 to 500°C;
Preferably, the temperature is 300 to 450°C, and the reaction pressure is 5 to 100 atm, preferably 10 to 50 atm. The H2/CO molar ratio in the raw material mixed gas is 0.
2-3, preferably 0.5-1.

The crystalline iron silicate of the present invention can be advantageously used as a catalyst for Fischer-Tropsch synthesis reactions, as well as for various other reactions using zeolites as catalysts, such as the synthesis of hydrocarbons from methanol or dimethyl ether. In addition, it can 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 Catalysts Kasei Co., Ltd., C!a+aloi
d 81-30), ferric nitrate nonahydrate, ferrous sulfate
A homogeneous aqueous gel-like mixture containing 7 water 7 salt, potassium hydroxide (purity 85%), tetra-n-propylammonium bromide, and water with the composition shown in Table 1 below was placed in a closed container. The mixture was heated and stirred at 150° C. for 40 hours under autogenous pressure. The reaction product is centrifuged to separate solids,
This solid material was washed with water until the ionic substances disappeared, and
After drying at 00°C, it was fired at 500°C for 15 hours to obtain crystalline iron silicate. It was confirmed that the X-ray diffraction and ξ turns of these materials were substantially the same as that of Mopil's ZSM-5 zeolite.

Table 1* Manufactured by Catalyst Chemicals: 5i0230-31%, Na2
O0,37~0.46%** Fe = Fe(II
)4-Fe(III)*** 5r(O)1300
0)2・%H200,447 Addition Examples 5 to 7 The crystalline iron nosilicate sintered bodies obtained in Examples 1 to 3 were tableted at a pressure of 40'OKg/(?F712, and then crushed to 15 A reaction tube with an inner diameter of 20 mm was filled with 20 mN of 30 meshes. 100 me/m
The mixture was treated at 400° C. for 15 hours at a speed of 0H8V = 1000. The reaction was carried out at 25°C intervals from 325°C to 425°C at hr-'. Analysis of the product was performed using a gas chromatograph. Table 2 shows the reaction results. Note that both the conversion rate and yield shown below are based on carbon.

Table 2 Comparative Examples 1 to 7 Example 1 using only FC(III) compound as iron source
Crystalline iron silicate fired bodies were obtained in the same manner as (Comparative Examples 1 to 4). Further, crystalline iron silicate fired bodies were obtained in the same manner as in Example 1 using only the Fe(II) compound as the iron source (Comparative Examples 5 to 7). Specific manufacturing conditions for the products of these comparative examples are summarized in Table 3. All of the crystalline iron silicates obtained showed essentially the same X-ray diffraction and ξ turns as the product of Example 1.

4 Comparative Examples 7 to 13 Using the crystalline iron silicate fired bodies obtained in Comparative Examples 7 to 13, a reaction between CO and H2 was performed under the same conditions as in Examples 5 to 7. The results are shown in Table 4.

As can be seen from the reaction results shown in Tables 2 and 3, the crystalline iron silicate was synthesized independently using a Fe(II) compound or a pe(m) compound as an iron source. It is clear that the crystalline iron silicate formed by mixing the two is superior as a Fischer-Tropsch synthesis catalyst.

Claims (3)

[Claims] (1) Fe(II) compounds and Pe(I) are used as iron sources.
II) A crystalline iron phosphorus silicate, characterized in that it is formed by a hydrothermal synthesis reaction using a mixture of compounds. (2) As iron sources, Fe(11) compounds and Fe(I
II) A catalyst for synthesizing hydrocarbons from a mixed gas of carbon monoxide and hydrogen, characterized in that it contains as an active component a crystalline iron silicate formed by a hydrothermal synthesis reaction using a mixture of compounds. (3) The catalyst according to claim 2, wherein the crystalline iron nosilicate is a fired product.