JP5424206B2 - Method for producing liquid hydrocarbon - Google Patents

Description

  The present invention relates to a method for producing liquid hydrocarbons. More specifically, the present invention relates to a method for producing a liquid hydrocarbon by a one-stage reaction process from a synthesis gas containing hydrogen and carbon monoxide as main components using a capsule catalyst containing iron.

In recent years, the need for environmental conservation has been demanded, and the demand for clean liquid fuels with low contents of sulfur and aromatic hydrocarbons has rapidly increased. In addition, the development of energy sources that can replace oil has been desired due to the necessity of effectively using crude oil resources with limited reserves. XTL (X to Liquid), which produces liquid fuels that contain almost no sulfur and aromatic hydrocarbons using natural gas, coal, asphalt, biomass, etc. as raw materials, is gaining more and more attention as a technology that meets the above demands. It has come to be.
For example, as a method for producing a liquid fuel by GTL (Gas to Liquid) using natural gas as a starting material, a synthetic gas comprising hydrogen and carbon monoxide after undergoing a reforming process for producing hydrogen and carbon monoxide from natural gas. A process of Fischer-Tropsch synthesis (hereinafter referred to as FT synthesis) for producing higher paraffins from the raw materials, and hydrocracking and isomerization for converting higher paraffin rich FT synthesis products into lower paraffin rich products. A method of processing in two stages of the process to be performed is generally known.

In general, FT synthesis is carried out using a catalyst obtained by supporting an active metal such as iron or cobalt on a carrier such as silica or alumina (hereinafter referred to as FT synthesis catalyst). In addition, a method in which the hydrocracking / isomerization reaction is performed using a zeolite or an amorphous solid acid catalyst is generally known.
On the other hand, Non-Patent Document 1 shows that lower paraffin is produced from synthesis gas in one stage by using a catalyst obtained by physically mixing a FT synthesis catalyst and a solid acid catalyst such as zeolite.
Non-Patent Document 2 describes the production of a gasoline base material rich in isoparaffin from synthesis gas in a single stage using a capsule catalyst in which the outer surface of a cobalt-based FT synthesis catalyst is coated with a ZSM-5 zeolite membrane. . However, the synthesis gas conversion reaction using the capsule catalyst has a high methane selectivity, and as a result, there is a disadvantage that the yield of the gasoline base material is reduced. This is because the FT synthesis reaction, which is advantageous at a relatively low temperature, and the isomerization / decomposition reaction, which is advantageous at a high temperature, are performed at the same time. This is thought to be due to the promotion of methane production. Therefore, a catalyst capable of carrying out a gasoline base material rich in isoparaffin from synthesis gas in a one-step reaction with high yield is desired.

Fujimoto et al., “Chemistry Letters”, 1985, p. 783 Jingjiang He et al., “Langmuir”, 2005, 21, p. 1699

The process in which the FT synthesis and the hydrocracking / isomerization reaction are performed in one stage can be said to be an economical process with a low construction cost of the apparatus as compared with the case of performing the reactions separately. As described above, Non-Patent Document 2 reports a method for producing a liquid fuel by using a capsule catalyst having a cobalt-based FT synthesis catalyst as a core and a ZSM-5 zeolite membrane as a shell. However, there is still no method for producing a high-performance liquid fuel higher than this method, that is, a method for producing a high-yield gasoline substrate rich in isoparaffin by suppressing the selectivity of by-product methane. In order to further improve the economics of this one-stage reaction process, it is necessary to further reduce the methane selectivity. Moreover, in order to improve the octane number of the produced gasoline base material, it is necessary to increase the isoparaffin selectivity.
An object of the present invention is to provide a method for producing a liquid hydrocarbon (gasoline base material) by a one-stage reaction process with reduced methane selectivity and improved isoparaffin selectivity.

As a result of intensive studies, the inventors have succeeded in preparing a capsule catalyst in which the surface of an FT synthesis catalyst containing iron is coated with ZSM-5 zeolite, and using such a capsule catalyst as a catalyst for a one-step reaction. It has been found that the methane selectivity can be reduced and the isoparaffin selectivity of the product oil can be increased, and the above problems have been solved.
That is, the present invention is as follows.

[1] Liquid carbonization characterized by subjecting a synthesis gas containing hydrogen and carbon monoxide to a conversion reaction in the presence of a capsule catalyst having an FT synthesis catalyst containing iron as a core and a ZSM-5 zeolite membrane as a shell. A method for producing hydrogen.
[2] The method for producing a liquid hydrocarbon according to [1], wherein a reaction temperature in the conversion reaction is 250 to 400 ° C.
[3] The ratio [W / F] of the capsule catalyst weight (W) to the supply gas velocity (F) of the synthesis gas in the conversion reaction is 0.1 to 100 g · h / mol, [1] ] Or the manufacturing method of the liquid hydrocarbon as described in [2].
[4] The liquid hydrocarbon according to any one of [1] to [3], wherein a hydrogen / carbon monoxide molar ratio in the synthesis gas in the conversion reaction is 0.5 to 5. Production method.
[5] The method for producing a liquid hydrocarbon according to any one of [1] to [4], wherein a reaction pressure in the conversion reaction is 0.1 to 10 MPa.
[6] The method for producing a liquid hydrocarbon according to any one of [1] to [5], wherein in the capsule catalyst, the ratio of iron in the core is 50% by mass or more.
[7] The method for producing a liquid fuel according to any one of [1] to [6], wherein in the capsule catalyst, a ratio of the ZSM-5 film to the whole capsule catalyst is 8 to 40% by mass. .
[8] The capsule catalyst is allowed to stand after repeating the FT synthesis catalyst containing iron and the synthetic gel containing the ZSM-5 zeolite source at 150 to 200 ° C. at least once and at least once. The method for producing a liquid hydrocarbon according to any one of [1] to [7], wherein the method is produced by a hydrothermal synthesis reaction.

  According to the method of the present invention, it is possible to efficiently obtain a gasoline base material which is reduced in methane selectivity and rich in isoparaffin from the synthesis gas in a one-stage reaction process.

The present invention is described in detail below.
The catalyst used in the method for producing liquid hydrocarbons of the present invention is a capsule catalyst in which a ZSM-5 zeolite film is formed on the surface of an FT synthesis catalyst containing iron.

The FT synthesis catalyst corresponding to the core of the capsule catalyst preferably contains 50 to 100% by mass of iron, and more preferably 60 to 90% by mass. If the ratio of iron is less than 50% by mass, the yield of the gasoline base produced tends to decrease, which is not preferable.
The FT synthesis catalyst can be prepared by supporting iron on a support made of an inorganic oxide such as silica, alumina, titania, silica alumina, etc., but it can be prepared by a molten salt method or a precipitation method without containing an inorganic oxide. It is preferable to use iron as it is.
When copper or potassium is contained in the FT synthesis catalyst as a metal other than iron, the FT synthesis reaction is promoted, resulting in an increase in gasoline yield. In addition, when copper and / or potassium are contained in the FT synthesis catalyst, the total content is preferably 0.1 to 10% by mass based on the FT synthesis catalyst.
The average particle size of the FT synthesis catalyst in the present invention is not particularly limited as long as it is a size that can be charged in the reaction tower because the reaction is carried out using a fixed bed reactor, but usually 100 μm to 30 mm is preferable. More preferably, the one of 500 μm to 20 mm is used. An average particle size of less than 100 μm is not preferable because it tends to generate a differential pressure in the reaction tower. On the other hand, if it exceeds 30 mm, the amount of catalyst charged in the reaction tower decreases, and as a result, the gasoline yield tends to decrease, such being undesirable.

The capsule catalyst in the present invention is formed by coating the surface of an FT synthesis catalyst containing iron with ZSM-5 zeolite.
The amount of ZSM-5 zeolite that coats the FT synthesis catalyst is not particularly limited, but in order to produce a gasoline base material with a high yield, the ratio of ZSM-5 zeolite to the capsule catalyst is 8 to 40% by mass. Is preferred. If the amount is less than 8% by mass, the coating with ZSM-5 zeolite is insufficient and the gasoline yield tends to decrease. Therefore, the lower limit of the proportion of ZSM-5 zeolite is preferably 8% by mass or more, more preferably 10% by mass or more. 20% by mass or more is more preferable. On the other hand, when the proportion of ZSM-5 zeolite exceeds 40% by mass, methane selectivity tends to increase, so the upper limit is preferably 40% by mass or less, and more preferably 30% by mass or less.

  Examples of the method for forming a ZSM-5 zeolite membrane on the FT synthesis catalyst (using the FT synthesis catalyst as a core and the ZSM-5 zeolite membrane as a shell) include the following methods.

First, a synthetic gel necessary for hydrothermal synthesis of ZSM-5 zeolite is prepared. Into a polytetrafluoroethylene (PTFE) container, distilled water, template (molding agent), ethanol, aluminum source and silica source are put in order, and stirred at 40 to 70 ° C. for 1 to 5 hours until the solution becomes transparent.
There are no particular limitations on the template, the aluminum source and the silica source, but preferably isopropyl ammonium hydroxide is used as the template, aluminum nitrate is used as the aluminum source, and tetraethyl orthosilicate is used as the silica source.
The molar ratios of water, template, ethanol, aluminum source, and silica source to the synthetic gel are 80 to 99, 0.1 to 1.0, 3 to 15, 0.01 to 0.1, and 0.2 to 5. 0 is preferable, and it is not preferable because the ZSM-5 film tends not to be formed outside these ranges.

  Although there is no restriction | limiting in the weight ratio of the synthetic gel with respect to an FT synthesis catalyst, 1-50 times are preferable and 5-30 times are more preferable. If it is less than 1 time, it tends to be impossible to completely cover the surface of the FT synthesis catalyst with the ZSM-5 zeolite membrane, and if it exceeds 50 times, ZSM-5 zeolite is produced alone, making it difficult to separate from the capsule catalyst. This is not practical.

The ZSM-5 zeolite membrane is formed by hydrothermal synthesis.
In the present invention, the hydrothermal synthesis reaction is carried out, for example, in a pressure-resistant container made of PTFE or the like. Preferably, it is achieved by standing at 165 to 185 ° C. after repeating the process comprising a combination of stationary and rotating containers at least once. It is not preferable to perform only the standing or only the rotation without rotating, because it tends to be difficult to form a ZSM-5 zeolite membrane.
When the temperature in the hydrothermal synthesis is outside the above range, the crystallinity of ZSM-5 zeolite tends to deteriorate, and as a result, the gasoline yield tends to decrease, such being undesirable.

The number of times of standing and rotating is preferably repeated twice or more, more preferably 3 times or more, still more preferably 5 times or more, and there is no particular limitation on the upper limit. To be determined as appropriate.
The standing time is preferably 1 to 10 hours, more preferably 1 to 5 hours. The rotation is usually performed at a rotational speed of 0.5 to 20 rpm, preferably 1 to 10 rpm, for 1 minute to 2 hours, preferably 1 to 30 minutes. In the case where the stationary and rotation are repeated twice or more, the stationary and rotating conditions may be changed.

After a predetermined number of steps including a combination of standing and rotation, the reaction is completed by standing for a certain period of time. The standing time at this time is preferably 1 hour or longer. Although there is no restriction | limiting in particular about an upper limit, 30 hours or less are preferable from an economical viewpoint.
The hydrothermal synthesis reaction time (total time required for the reaction to be completed after repeating the stationary and rotating steps of the container and the final standing) is preferably 5 hours or more, more preferably 10 hours or more. Yes, more preferably 20 hours or more. Although there is no restriction | limiting in particular about an upper limit, From an economical viewpoint, 50 hours or less are preferable, More preferably, it is 30 hours or less.
When the reaction time in hydrothermal synthesis is outside the above range, the crystallinity of ZSM-5 zeolite tends to deteriorate, and as a result, the gasoline yield tends to decrease, such being undesirable.
In addition, after completion | finish of the said hydrothermal synthesis, a supernatant liquid is removed by decantation, a synthetic gel is newly added, and said hydrothermal synthesis reaction can also be performed again.

After hydrothermal synthesis, the solids in the contents are recovered, washed with distilled water, and calcined in air at 450 to 550 ° C., preferably 480 to 520 ° C. for 2 to 10 hours, preferably 3 to 8 hours.
By this treatment, a ZSM-5 zeolite film can be formed on the surface of the FT synthesis catalyst.

  In the present invention, Pt and / or Pd can be supported on ZSM-5 zeolite as required. Although there is no restriction | limiting in particular about the load of these metals, Usually, it can use in the range of 0.1-3.0 mass% as a metal amount per capsule catalyst.

In the present invention, a liquid hydrocarbon is produced by converting a synthesis gas containing hydrogen and carbon monoxide in the presence of a capsule catalyst having the above-mentioned FT synthesis catalyst as a core and a ZSM-5 zeolite membrane as a shell. .
The synthesis gas used in the present invention is not particularly limited as long as it is obtained by a generally known method, but the hydrogen / carbon monoxide molar ratio in the synthesis gas is 0.5-5. It is preferable that it is 0.5, More preferably, it is 0.5-2.

The conversion reaction in the present invention employs a flow-type fixed bed process as a one-stage reaction process.
In the conversion reaction of the present invention, the ratio (W / F) of the capsule catalyst weight (W) (g) to the syngas feed gas rate (F) (mol / h) is 0.1 to 100 g · h / mol. Preferably, it is carried out at 1.0 to 50 g · h / mol.
Further, the reaction temperature of the conversion reaction in the present invention is preferably 250 to 400 ° C, more preferably 250 to 350 ° C, and the reaction pressure is preferably 0.1 to 10 MPa, more preferably 0.3. It is carried out at ˜5 MPa.

  Before performing the synthesis gas conversion reaction according to the present invention, it is necessary to activate the capsule catalyst. The activation of the capsule catalyst is carried out using synthesis gas at a pressure in the range of atmospheric pressure to 10 MPa, a temperature in the range of 200 to 350, an activation time in the range of 0.5 to 5 hours, and then only hydrogen gas. The pressure is in the range of normal pressure to 10 MPa, the temperature is in the range of 350 to 450, and the activation time is in the range of 1 to 50 hours.

After the capsule catalyst is activated by the above treatment, a synthesis gas conversion reaction is performed. By using the capsule catalyst according to the present invention, it is possible to perform a synthesis gas conversion reaction in which the CO conversion is 95 mol% or more, the methane selectivity is 12 mol% or less, and the isoparaffin selectivity is 50 mol% or more. In addition, liquid hydrocarbons rich in isoparaffin can be obtained by a one-step reaction with high yield.
In the present invention, the CO conversion rate is defined by “(1− (unreacted CO (mol) in the produced reaction product / CO (mol) in the raw synthesis gas) × 100 (mol%)”. The methane selectivity is the proportion of methane in the produced reaction product (mol%), and the isoparaffin selectivity is the proportion of isoparaffin having 4 to 13 carbon atoms in the produced reaction product ( Mol%).

  The liquid hydrocarbon obtained by the above-described synthesis gas conversion reaction is a hydrocarbon rich in isoparaffin having 4 to 13 carbon atoms (isoparaffin selectivity is 50 mol% or more), and can be preferably used as a gasoline base material. it can.

  As described above, according to the method of the present invention, liquid hydrocarbons with low methane selectivity and high isoparaffin selectivity can be obtained with high yield from a synthesis gas containing hydrogen and carbon monoxide in a one-stage reaction process.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.

Example 1
Molten iron (produced by Halder Topsoe, iron content: 76%) was pulverized in an agate mortar and sized to 20 to 40 mesh. In order to remove fine powder, it was washed with distilled water and then vacuum-dried at 120 ° C. for 3 hours to obtain an FT synthesis catalyst.
In a 100 ml PTFE bottle, 6.37 g of distilled water, 4.88 g of 10% tetrapropylammonium hydroxide solution (TPAOH), 1.84 g of 99.5% ethanol (EtOH), 0.0938 g of aluminum nitrate, tetraethyl orthosilicate ( TEOS) 2.08 g was put in order and stirred at 55 ° C. for 2 hours to obtain a transparent synthetic gel. The molar ratio of the synthetic gel at this time was water: TPAOH: EtOH: aluminum nitrate: TEOS = 120: 0.48: 8: 0.05: 2.
The PTFE pressure vessel was charged with 2 g of the FT synthesis catalyst and the synthesis gel, and hydrothermal synthesis was performed at 180 ° C. for 24 hours using a hydrothermal synthesis reactor (manufactured by HIRO). During this time, the PTFE pressure vessel was allowed to stand for 1 hour, then rotated at a speed of 1 rpm for 2 hours, and then allowed to stand for 21 hours for hydrothermal synthesis.
After hydrothermal synthesis, the contents were collected, and the resulting solid was separated and washed thoroughly with distilled water. Then, it baked at 500 degreeC in air for 5 hours, and obtained the capsule catalyst.
In order to grasp the state of the zeolite coating of the capsule catalyst and the amount of zeolite, a scanning electron microscope and fluorescent X-ray analysis were performed. Further, in order to confirm that the coating was ZSM-5 zeolite, X-ray diffraction measurement was performed. The results are shown in Table 1.

In the conversion reaction of synthesis gas (carbon monoxide: hydrogen = 1: 1 mol / mol), the capsule catalyst (0.5 g) and quartz sand (0.5 g) are mixed well and then packed into a fixed bed reactor. I went. After filling the catalyst, the temperature was raised to 250 ° C. at 1 ° C./min while syngas was passed at 80 ml / min at normal pressure, and then held for 2 hours. Thereafter, the synthesis gas was switched to hydrogen, the temperature was raised to 400 ° C. at 1 ° C./min, and reduction treatment was performed for 10 hours. After the reduction, the reaction tower was cooled to 180 ° C., switched from hydrogen to synthesis gas (W / F = 10 g · h / mol), the pressure was increased to 1 MPa, and then the temperature was increased to 300 ° C. at 2 ° C./min. This was the start of the conversion reaction.
The gaseous product was analyzed by on-line gas chromatography to determine CO conversion, methane selectivity and isoparaffin selectivity. The results are shown in Table 1.

(Example 2)
The process consisting of a combination of standing for 2 hours and rotating for 1 minute at a speed of 1 rpm was repeated 11 times, and then left for 2 hours for hydrothermal synthesis. Further, a capsule catalyst was prepared and a synthesis gas conversion reaction was performed in the same manner as in Example 1 except that the same hydrothermal synthesis was performed once again. Table 1 shows the measurement results and conversion reaction results of the ZSM-5 membrane in the capsule catalyst.

(Example 3)
The process consisting of a combination of standing for 1 hour and rotating for 1 minute at a speed of 1 rpm was repeated 22 times, and then left for 2 hours for hydrothermal synthesis. Further, a capsule catalyst was prepared and a synthesis gas conversion reaction was performed in the same manner as in Example 1 except that the same hydrothermal synthesis was performed once again. Table 1 shows the measurement results and conversion reaction results of the ZSM-5 membrane in the capsule catalyst.

(Comparative Example 1)
A capsule catalyst was prepared and a synthesis gas conversion reaction was performed in the same manner as in Example 1 except that hydrothermal synthesis was performed only for 24 hours. Table 1 shows the measurement results and conversion reaction results of the ZSM-5 membrane in the capsule catalyst.

(Comparative Example 2)
Preparation of capsule catalyst and synthesis gas conversion reaction were carried out in the same manner as in Example 2 except that an FT synthesis catalyst in which 20% by mass of cobalt was supported on silica (surface area 330 cm ² / g) was used instead of molten iron. It was. Table 1 shows the measurement results and conversion reaction results of the ZSM-5 membrane in the capsule catalyst.

(Comparative Example 3)
Preparation of capsule catalyst in the same manner as in Comparative Example 2, except that in the synthesis gas conversion reaction, a synthesis gas of 1: 2 was used instead of a synthesis gas having a molar ratio of carbon monoxide to hydrogen of 1: 1. And a syngas conversion reaction was performed. Table 1 shows the measurement results and conversion reaction results of the ZSM-5 membrane in the capsule catalyst.

  From Table 1, it is essential to combine stationary and rotation during hydrothermal synthesis in the synthesis of a capsule catalyst containing iron, and the obtained capsule catalyst is a secondary agent than a capsule catalyst having a cobalt-based FT synthesis catalyst as a core. It can be seen that the selectivity of the product methane is low and the isoparaffin selectivity is high.

  By the method of the present invention, a gasoline base material rich in isoparaffin can be efficiently obtained from synthesis gas in a one-stage reaction process.

Claims (8)

  Production of liquid hydrocarbons characterized by subjecting a synthesis gas containing hydrogen and carbon monoxide to a conversion reaction in the presence of a capsule catalyst having an FT synthesis catalyst containing iron as a core and a ZSM-5 zeolite membrane as a shell Method.   The method for producing a liquid hydrocarbon according to claim 1, wherein a reaction temperature in the conversion reaction is 250 to 400 ° C.   The ratio (W / F) of the capsule catalyst weight (W) to the supply gas velocity (F) of the synthesis gas in the conversion reaction is 0.1 to 100 g · h / mol, according to claim 1 or 2. A method for producing the liquid hydrocarbon as described.   The method for producing a liquid hydrocarbon according to any one of claims 1 to 3, wherein a molar ratio of hydrogen / carbon monoxide in the synthesis gas in the conversion reaction is 0.5 to 5.   The reaction pressure in the said conversion reaction is 0.1-10 Mpa, The manufacturing method of the liquid hydrocarbon in any one of Claims 1-4 characterized by the above-mentioned.   The method for producing a liquid hydrocarbon according to any one of claims 1 to 5, wherein the ratio of iron in the core is 50% by mass or more in the capsule catalyst.   The method for producing a liquid fuel according to any one of claims 1 to 6, wherein the ratio of the ZSM-5 film to the whole capsule catalyst is 8 to 40% by mass in the capsule catalyst.   Hydrothermal synthesis in which the capsule catalyst is allowed to stand after repeating a standing and rotating at least once or more at 150 to 200 ° C., a synthetic gel containing an FT synthesis catalyst containing iron and a ZSM-5 zeolite source. The method for producing a liquid hydrocarbon according to any one of claims 1 to 7, wherein the method is produced by a reaction.