JP6773586B2 - A method for producing a catalyst for producing a hydrocarbon from a synthetic gas, a method for producing a hydrocarbon, and a catalyst for producing a hydrocarbon from a synthetic gas. - Google Patents

Description

The present invention relates to a method for producing a hydrocarbon from a synthetic gas, a method for producing a hydrocarbon, and a catalyst for producing a hydrocarbon from a synthetic gas.

In recent years, environmental problems such as global warming have become apparent. Natural gas has a higher hydrogen / carbon ratio (H / C) than other hydrocarbon fuels, coal, etc., can suppress carbon dioxide emissions, which are the causative agents of global warming, and has abundant reserves. Is. In recent years, the importance of such natural gas has been reviewed, and its importance and demand are expected to increase in the future. As one of the means for developing natural gas, the development of Gas To Liquids (GTL) technology is being vigorously carried out in various places. In the GTL technology, after converting natural gas into synthetic gas, the synthetic gas is subjected to a Fischer-Tropsch synthesis reaction (hereinafter, also referred to as “FT synthesis reaction”) as shown in the reaction formula below. It is used to convert to liquid hydrocarbon fuels such as lamps and light oil, which have excellent transportability and handleability.

Sasol and Shell are operating commercial plants for FT synthesis on the scale of tens of thousands of BPDs. As a catalyst in the FT synthesis reaction, a catalyst in which cobalt is supported on a porous carrier is generally used, and catalysts containing various co-catalysts have been developed (see Non-Patent Document 1).

This FT synthesis reaction is an exothermic reaction that converts syngas into hydrocarbons using a catalyst, but it is extremely important to effectively remove the heat of reaction for stable operation of the plant. Gas phase synthesis process (fixed bed, jet bed, fluidized bed) and liquid phase synthesis process (slurry bed) are known as reaction types that have been proven to date, and in Sasol's commercial plant, slurry bed, Fixed beds are used at Shell.

In the fixed bed, a heat extraction tube is arranged inside the reactor, and the heat generated by the FT synthesis reaction is removed by the heat extraction tube. However, since the heat extraction performance of the heat extraction tube is limited, the fixed floor must be operated with limited productivity. On the other hand, in the slurry bed, since the reaction proceeds in a liquid solvent having a large heat capacity, it is possible to operate with high productivity.

By the way, the above-mentioned commercial plant has a high plant cost and is not economically efficient when targeting a small-scale gas field. For this reason, development by these commercial plants currently targets only large-scale natural gas fields.

Therefore, FT synthesis plants have not been developed so far for many small gas fields on the earth. However, in recent years, technological developments on small-scale plants that can be installed on these small-scale gas fields and offshore drilling vessels have been energetically carried out in various places. Small-scale plants on offshore drillships aim to convert liquid hydrocarbon fuels from petroleum-related gases that are currently being treated as flares. In addition, biomass as a renewable energy is attracting increasing attention from the viewpoint of CO ₂ reduction, and there is also a technology to create clean energy such as bio-jet fuel by performing an FT synthesis reaction after converting biomass into syngas. .. Since biomass requires transportation costs, it is said that it is more advantageous to utilize a small-scale plant than to collect a wide range of biomass in a large-scale plant.

In a series of developments of such small-scale plants, FT synthesis reaction technology using a microchannel reactor has been developed. The microchannel reactor has a fine flow path having an inner diameter of several mm or less, and has high mass transfer and heat transfer performance. Further, the microchannel reactor has a structure in which the flow path of the raw material gas for performing the FT synthesis reaction and the flow path of the refrigerant for removing heat are alternately layered, and the raw material for performing the FT synthesis reaction. By using a metal as the material of the reactor and the gas supply direction and the refrigerant supply direction for removing heat are orthogonal to each other, the heat generated in the reaction process can be efficiently removed and the raw material gas can be used. It is also possible to prevent mixing with the refrigerant.

As described above, in the FT synthesis reaction of a fixed floor in a large-scale plant, it is necessary to suppress the calorific value according to the heat removal performance, and it is often necessary to suppress the production amount for operation. On the other hand, in the FT synthesis using the above-mentioned microchannel reactor, the heat removal performance of the microchannel reactor is high and the productivity can be set high, so that the amount of hydrocarbon produced per reactor volume is high. It will be relatively high.

Further, a method of filling a microchannel with a capsule catalyst in which a zeolite is coated on the outer surface of an FT synthesis catalyst that causes an exothermic reaction has been reported (Patent Document 1). Zeolites lighten hydrocarbons by an endothermic reaction that decomposes them. Generally, the product of the FT synthesis catalyst is mainly n-paraffin, but the capsule catalyst is characterized in that the yields of olefin and isoparaffin are relatively high. Olefin can be used as a chemical raw material. Chemical raw materials are more expensive than fuels, so the resulting olefins are high value-added products. Such capsule catalysts are also reported in Patent Documents 2 and 3.

Japanese Unexamined Patent Publication No. 2014-198332 Japanese Unexamined Patent Publication No. 2007-196187 JP-A-2007-197628

R. Oukaci et al., Applied Catalysis A: General, 186 (1999) 129-144

By the way, in order to improve the yield of olefins, it is necessary to efficiently generate hydrocarbons, and it is necessary to relatively increase the amount of cobalt supported by the Fischer-Tropsch synthesis catalyst. According to the study by the inventors, an alumina carrier, which is a highly water-resistant carrier that increases productivity and has little deterioration in performance even if a large amount of by-product water is generated, is adopted, and Patent Documents 1 to 3 and Non-Patent Document 1 We have found a technique for forming zeolite, particularly beta zeolite, on an alumina carrier with a relatively large amount of cobalt supported by adopting the technique as described in 1.

However, it has been found that the diffusivity of the synthetic gas in the zeolite on the outer surface of the capsule catalyst may not be sufficient under the condition that the flow rate of the synthetic gas is large with respect to the catalyst, and the reaction efficiency is not always good. In zeolite, both the hydrocarbon generated by the FT synthesis catalyst, which is the core catalyst inside the capsule catalyst, and the synthetic gas, which is the raw material, diffuse in the zeolite. These diffusion rates depend on the pore size of the zeolite, but in the conventional technique, the pore size is determined by the crystal structure of the zeolite formed on the outer surface of the capsule catalyst, which greatly affects the reaction performance. .. Further, for example, when a synthetic gas having about H ₂ / CO = 2 (molar ratio) diffuses the zeolite membrane, the diffusion rate differs between hydrogen and carbon monoxide, and when it reaches the core catalyst, H ₂ / CO is 2 The selectivity of methane, which is a by-product, was high.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a yield of olefins which can be used in various reactors such as a microchannel reactor and are useful as a chemical raw material. It is an object of the present invention to provide a method for producing a hydrocarbon from a synthetic gas, a method for producing a hydrocarbon, and a catalyst for producing a hydrocarbon from a synthetic gas, which have a high rate.

While diligently studying to solve the above problems, the present inventors first increase the pore size of the beta-zeolite film formed on the Fischer-Tropsch synthesis catalyst in which cobalt is supported on the alumina carrier to form mesopores. It has been found that when the alkali treatment is carried out for this purpose, good performance such as improvement in activity, decrease in methane selectivity, and improvement in yield of olefin can be obtained. The gist of the present invention is as described below.

(1) It has an alkali treatment for forming mesopores by treating an alumina carrier and a catalyst in which beta zeolite is formed on the outer surface of a Fishertropus synthesis catalyst having cobalt supported on the alumina carrier with an alkaline aqueous solution. , A method for producing a catalyst for producing a hydrocarbon from syngas.
(2) A catalyst for producing a hydrocarbon from the synthetic gas according to (1), which has a hydrothermal synthesis treatment for forming a beta-zeolite film on the outer surface of the Fischer-Tropsch synthesis catalyst by a hydrothermal synthesis method in the presence of potassium nitrate. Manufacturing method.
(3) The synthetic gas according to any one of (1) and (2), which has an ion exchange treatment for ion exchange of a catalyst in which beta zeolite is formed on the outer surface of the Fischer-Tropsch synthesis catalyst after the alkali treatment. A method for producing a catalyst for producing a hydrocarbon from.
(4) A hydrocarbon that produces a hydrocarbon from the synthetic gas in a reactor using a catalyst that produces a hydrocarbon from the synthetic gas produced by the method according to any one of (1) to (3). Manufacturing method.
(5) The reactor is a microchannel reactor having a multi-stage layered structure, and the layer for supplying synthetic gas to produce hydrocarbons and the heat generated in hydrocarbon production by supplying a refrigerant are used. The method for producing a hydrocarbon according to (4), wherein layers for removing heat are alternately arranged, and the flow paths of these layers are arranged in orthogonal directions.
(6) Beta zeolite is formed on the outer surface of the alumina carrier and the Fischer-Tropsch synthesis catalyst having cobalt supported on the alumina carrier.
The beta zeolite is a catalyst that has mesopores and produces hydrocarbons from syngas.

According to the present invention, the reaction efficiency is high and the olefin yield is high because the synthetic gas in the zeolite has good diffusivity as compared with the conventional capsule catalyst in various reactors such as a fixed bed and a microchannel reactor. It is possible to provide a method for producing a catalyst for producing a hydrocarbon from a high syngas, a method for producing a hydrocarbon, and a catalyst for producing a hydrocarbon from a synthetic gas.

It is a figure which shows the carbon number distribution of the product obtained in Example 1. It is a figure which shows the carbon number distribution of the product obtained in Example 2. It is a figure which shows the carbon number distribution of the product obtained in Example 3. It is a figure which shows the carbon number distribution of the product obtained in the comparative example 1. FIG. It is a figure which shows the carbon number distribution of the product obtained in the comparative example 2. It is a schematic diagram which shows the microchannel reactor used in Example 4.

Hereinafter, preferred embodiments of the present invention will be described in detail.

In the method for producing a catalyst according to the present embodiment, an alumina carrier and a catalyst in which beta-zeolite is formed on the outer surface of a Fischer-Tropsch synthesis catalyst having cobalt supported on the alumina carrier by a hydrothermal synthesis method are used in an alkaline aqueous solution. It is a method of processing. In the catalyst according to the present embodiment thus obtained, the beta zeolite has mesopores as described later. First, an example of the catalyst according to the present embodiment will be described prior to the method for producing the catalyst according to the present embodiment.

[1. A catalyst for producing hydrocarbons from syngas]
The catalyst according to the present embodiment is a catalyst in which beta-zeolite is formed on the outer surface of an alumina carrier and a Fishertropus synthesis catalyst having cobalt supported on the alumina carrier by a hydrothermal synthesis method.

The alumina carrier in the Fischer-Tropsch synthesis catalyst is a carrier for supporting and dispersing cobalt. Alumina carriers have high water resistance. Therefore, when the productivity is set high in the production of hydrocarbons in the Fischer-Tropsch synthesis reaction, a relatively large amount of by-product water is generated, but the catalyst according to the present embodiment having an alumina carrier is a carrier even in such an environment. Deterioration of performance due to changes in the properties of the product is suppressed. Therefore, the catalyst according to the present embodiment can be set to have high productivity, and even in such a case, the reaction activity can be maintained high for a relatively long period of time.
Therefore, the production cost is low, the added value of the product is high, and it is possible to produce hydrocarbons from small-scale gas fields and petroleum-related gas, which are expected to be developed using microchannel reactors, and to produce liquid fuel from biomass. It becomes.

The alumina constituting the carrier is not particularly limited, but from the viewpoint of catalytic activity, it may have a relatively large specific surface area in order to maintain a high dispersity of cobalt and improve the efficiency of contributing to the reaction of the carried cobalt. preferable. The specific surface area of the alumina carrier is not particularly limited, but is, for example, 80 to 600 m ² / g, preferably 100 to 550 m ² / g, and more preferably 150 to 500 m ² / g. The specific surface area can be measured, for example, by the BET method.

The specific surface area can be increased by reducing the pore diameter or increasing the pore volume. That is, the pore diameter and the pore volume are related to the specific surface area of the alumina carrier. Generally, it is preferable that the specific surface area is large, but an extremely large specific surface area cannot be obtained when trying to maintain the pore diameter and the pore volume within an appropriate range. Therefore, the upper limit of the specific surface area also has an appropriate range.

When the pore diameter is less than 8 nm, the gas diffusion rate in the pores differs between hydrogen and carbon monoxide, resulting in a higher partial pressure of hydrogen toward the depths of the pores, which is a by-product in the FT synthesis reaction. Since a large amount of hydrocarbons such as methane, which is a gas at normal temperature and pressure, will be generated, the pore diameter is preferably 8 nm or more. On the contrary, if the pore diameter exceeds 50 nm, it becomes difficult to increase the specific surface area and the dispersity of the active metal decreases. Therefore, the pore diameter is preferably 50 nm or less. The pore size of the alumina carrier is preferably 8 to 50 nm, more preferably 10 to 40 nm, and even more preferably 12 to 30 nm.

Further, if the pore volume is less than 0.4 cc / g, it becomes difficult to increase the specific surface area, so it is preferably 0.4 cc / g or more. The pore volume of the alumina carrier is preferably 0.4 to 4 cc / g, more preferably 0.6 to 3.0 cc / g, and even more preferably 0.8 to 2.0 cc / g.
The pore volume can be measured by a mercury intrusion method or a water droplet determination method. The pore diameter can be measured by a gas adsorption method or a mercury intrusion method using a mercury porosimeter, but it can also be calculated from the specific surface area and the pore volume.

The alumina carrier preferably simultaneously satisfies a pore diameter of 8 to 50 nm, a specific surface area of 80 to 600 m ² / g, and a pore volume of 0.4 to 4 cc / g. The alumina carrier more preferably has a pore diameter of 10 to 40 nm, a specific surface area of 100 to 550 m ² / g and a pore volume of 0.6 to 3.0 cc / g, and more preferably a pore diameter of 12 to 30 nm. A specific surface area of 150 to 500 m ² / g and a pore volume of 0.8 to 2.0 cc / g are simultaneously satisfied.
Such an alumina carrier can be produced by a Bayer method, an alkoxide method, or the like, but is not particularly limited. Alumina produced by the alkoxide method is preferable because high purity can be easily obtained.

Further, the alumina carrier having the above-mentioned characteristics can be used by purchasing an appropriate commercially available alumina or by crushing the purchased alumina to optimize it.

Cobalt is supported on an alumina carrier. The cobalt supported on the alumina carrier has catalytic activity for the FT synthesis reaction. The carrying ratio (supporting amount) of cobalt in the Fischer-Tropsch synthesis catalyst is, for example, 5 to 50% by mass, preferably 8 to 40% by mass, and more preferably 10 to 30 when the Fischer-Tropsch synthesis catalyst is used as a population. It is mass%. If the carrying ratio of cobalt is less than the above lower limit, the activity cannot be sufficiently expressed depending on the reaction conditions, and if it exceeds the above upper limit, the dispersity of cobalt is lowered and the utilization efficiency of the carried cobalt is lowered. Therefore, it becomes uneconomical. Further, if the beta zeolite formed on the outer surface has an excessive cobalt loading ratio, it may be difficult to form the beta zeolite by hydrothermal synthesis depending on the reaction conditions, and it may be difficult to form the film thickness. The loading ratio here does not mean that the supported cobalt is finally reduced to 100%, but it is considered that the supported cobalt is 100% reduced, and the mass of cobalt accounts for the total mass of the Fischer-Tropsch synthesis catalyst. Point to.

The cobalt support rate in the produced catalyst can be measured by a high frequency inductively coupled plasma emission spectroscopic analysis (ICP-AES) method after pretreatment such as acid decomposition and alkali melting. At that time, the mass of the Fischer-Tropsch synthesis catalyst can be similarly confirmed by quantifying the components of the alumina carrier other than cobalt by the ICP-AES method after pretreatment such as acid decomposition and alkali melting.

The mass of the alumina carrier is determined by the following method. First, the catalyst alumina (alumina carrier + beta zeolite) and silica in which beta zeolite is formed on the outer surface of the Fisher Tropsch synthesis catalyst by the ICP-AES method are quantitatively analyzed. Next, the silica / alumina ratio of the beta zeolite membrane at the time of cross-sectional analysis is obtained by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS). If the silica / alumina ratio is uniform, the number of measurement points may be several, but if it is not uniform, it is necessary to set measurement points to the extent that an average value can be calculated (for example, 10 points in the observation field of view). .. Then, the mass of the alumina carrier is calculated by distinguishing the entire alumina quantified by the ICP-AES method into an alumina carrier component and a beta zeolite component in consideration of the silica / alumina ratio of the beta zeolite membrane.

A beta zeolite membrane is formed on the outer surface of the Fischer-Tropsch synthesis catalyst by, for example, a hydrothermal synthesis method, which is a method for synthesizing a target material by heating a raw material mixture containing water, which will be described later. By forming the beta zeolite as a film on the outer surface of the Fischer-Tropsch synthesis catalyst in this way, the catalyst of the present invention is an integrated catalyst particle in which the beta zeolite and the Fischer-Tropsch synthesis catalyst are integrated, more specifically. It becomes a capsule type catalyst particle.

The beta zeolite in the beta zeolite membrane has a function of decomposing and isomerizing hydrocarbons. The beta zeolite can then decompose and isomerize hydrocarbons to produce lighter hydrocarbons such as olefins and isoparaffins. Further, the hydrocarbon decomposition reaction is an endothermic reaction. Therefore, the beta zeolite decomposes and isomerizes hydrocarbons, so that heat can be removed in the reaction system.

Conventionally, when the productivity of the Fisher Tropsch synthetic microchannel reactor is set high, the refrigerant of the fluid for heat removal, which was initially liquid in the microchannel for heat removal, becomes steam with a small heat capacity. The heat removal efficiency in the microchannel through which the steam flows may decrease. In such a case, the heat generated in the microchannel (the flow path of the raw material gas for performing the FT synthesis reaction) adjacent to the microchannel cannot be effectively removed, and the reaction may run out of control. When the reaction goes out of control, the temperature inside the microchannel reactor rises excessively, not only the FT synthesis reaction is inhibited, but also the catalyst is deactivated and its regeneration becomes difficult.

However, the catalyst according to the present embodiment can remove heat in the reaction system by beta zeolite, and can prevent the runaway as described above. Further, the catalyst according to the present embodiment makes it possible to set the productivity of the microchannel reactor to be relatively high.

Further, the beta-zeolite in the beta-zeolite membrane according to the present embodiment has mesopores as pores. The conventional beta-zeolite without alkali treatment has micropores having a small pore diameter of sub-nm, but the beta-zeolite according to the present embodiment has mesopores having a larger pore diameter than the conventional one. By having it, the diffusion rate of H ₂ and CO in the synthetic gas is improved, and the ratio of H ₂ and CO reaching the surface of the Fischer-Tropsch synthesis catalyst can be set to a ratio advantageous for the production of zeolite. Specifically, in the conventional zeolite beta no mesopores, the diffusion rate is relatively rapid for H _2, H _{2 /} CO ratio when reaching the surface of the Fischer-Tropsch synthesis catalyst may be higher .. On the other hand, since the difference between the diffusion rates of H ₂ and CO becomes small in the mesopores, it is presumed to be advantageous for olefin formation. In particular, in the catalyst according to the present embodiment, since the beta zeolite has mesopores, the yield of olefin can be increased even when the flow rate of the synthetic gas is relatively large.

Here, the “mesopore” means a pore having a pore diameter of 2 nm or more and 50 nm or less. Thereby, the diffusion rate of H ₂ and CO in the synthetic gas can be more reliably adjusted, and the yield of the olefin can be further increased. When the pore distribution of the catalyst according to the present embodiment is measured by the gas adsorption method, the total pore distribution of the Fischer-Tropsch synthesis catalyst and the beta zeolite can be grasped. Therefore, for the pore size of the beta zeolite, the pore distribution of the Fischer-Tropsch synthesis catalyst is measured in advance, and the pore distribution of the obtained Fischer-Tropsch synthesis catalyst is compared with the pore distribution of the catalyst according to the present embodiment. This makes it possible to measure.

On the other hand, the general beta zeolite used as a catalyst has a pore diameter of about 0.6 to 0.7 nm, and in this case, the diffusion rate of H ₂ in the beta zeolite is higher than the diffusion rate of CO. growing. As a result, the ratio of H ₂ increases on the surface of the Fischer-Tropsch synthesis catalyst that reaches, and the amount of methane produced increases.

The beta zeolite having the mesopores as described above can be formed, for example, by performing an alkali treatment described later.

The film thickness of the beta zeolite membrane is not particularly limited, but is preferably 0.2 to 10 μm, more preferably 0.6 to 5 μm, and further preferably 1 to 3 μm. When the film thickness of the beta zeolite membrane becomes thinner than the above lower limit, the yield of lightened hydrocarbons such as olefins decreases. In addition, the effect of suppressing the calorific value of the entire reaction system becomes insufficient. Further, when the thickness of the beta zeolite membrane is increased, although it is preferable from the viewpoint of suppressing the calorific value, the hydrothermal synthesis time for obtaining a desired film thickness increases and the catalyst production cost becomes remarkably high. Furthermore, the diffusion rate of the FT synthesis reaction product and the synthetic gas is smaller in the beta zeolite having a smaller pore diameter than that of the Fischer-Tropsch synthesis catalyst, and the film thickness is not extremely thick from the viewpoint of reaction efficiency. Is preferable.

The thickness of the beta-zeolite film formed on the outer surface of the Fishertropus synthesis catalyst can be measured by observing the cross section of the catalyst using a scanning electron microscope (SEM). As a sample preparation method for observing the cross section of the catalyst, there is a method of embedding catalyst particles in a resin and then polishing. The above film thickness is an average value, and when measured by observing the cross section of the catalyst by SEM, if the film thickness is uniform, several measurement points are sufficient, but if it is not uniform, the average value is calculated. It is necessary to set measurement points as much as possible (for example, 16 points so as to be substantially evenly spaced in the circumferential direction). When the film thickness is different for each particle, it is necessary to observe and average a plurality of particles (for example, 10 particles) as a representative. In selecting a plurality of representative particles, after observing more particles than the representative particles, select one having an average film thickness excluding particles having extremely different film thicknesses. When catalysts with different particle sizes are mixed, when observing as a representative as described above, a catalyst having a particle size of about the average particle size is selected. To measure the average particle size, a laser diffraction type particle size distribution measuring device is used, which obtains the particle size distribution by irradiating the dispersed catalyst particles with laser light and measuring the angle dependence of the scattered light intensity from the particles. In some cases, there may be a defective portion where the zeolite membrane is not formed, but in such a case, the defective portion is not used as the measurement location, but is the average value of the locations where the zeolite membrane is formed.

As the cations in the beta zeolite pores, protons (H ⁺ ), sodium ions, potassium ions and the like can be used.
The mixing ratio of the Fischer-Tropsch synthesis catalyst and the beta zeolite is not particularly limited, and can be appropriately set according to the particle size of the Fischer-Tropsch synthesis catalyst.

Since the Fischer-Tropsch synthesis catalyst has pores, the surface of Fischer-Tropsch synthesis includes an outer surface of the catalyst particles and a surface inside the pores. In the present embodiment, the beta-zeolite film may be formed on the outer surface of the Fischer-Tropsch synthesis catalyst, and the beta-zeolite may be formed on the surface inside the pores of the Fischer-Tropsch synthesis catalyst. Further, on the Fischer-Tropsch synthesis catalyst, the beta zeolite does not have to form a film. That is, the beta zeolite does not form a membrane and can be present in any form on the surface of the Fischer-Tropsch synthesis catalyst.

The average particle size of the catalyst according to the present embodiment described above is not particularly limited, and can be, for example, 5.0 μm or more and 10.0 mm or less. In particular, when the catalyst according to the present embodiment is used in the microchannel reactor, the average particle size of the catalyst needs to be smaller than the flow path width of the microchannel, and is preferably 2.0 mm or less. .. In such a case, the lower limit of the average particle size of the catalyst according to the present embodiment is not particularly limited, but is usually preferably 5.0 μm or more in consideration of the pressure loss in the catalyst layer due to the supply of the raw material gas. From the viewpoint of operational stability and reactivity, considering both pressure loss and catalyst filling rate, an average particle size of 20 μm or more and 2.0 mm or less is preferable, more preferably 50 μm or more and 1.8 mm or less, and further preferably 80 μm or more. It is 1.5 mm or less.

The average particle size of the catalyst according to the present embodiment referred to here is the volume-based average particle size of the integrated catalyst in which the beta zeolite formed on the outer surface of the Fischer-Tropsch synthesis catalyst is formed. The laser diffraction method is applied to the measurement of the average particle size, but when the measurement by the laser diffraction method is difficult due to poor dispersibility or the like, a method such as an image imaging method can be applied.

By using the catalyst according to the present embodiment described above in a fixed bed, hydrocarbons can be produced with higher productivity and higher olefin yield as compared with the conventional FT synthesis catalyst. In addition, the productivity of hydrocarbons can be increased when used in a microchannel reactor having higher heat extraction performance as compared with a normal fixed bed.

[2. Method for manufacturing catalyst]
Next, an example of a method for producing a catalyst for producing a hydrocarbon from a synthetic gas according to the present embodiment will be described. The production method according to the present embodiment includes a step (alkali treatment) of treating a catalyst in which beta zeolite is formed on the outer surface of a Fischer-Tropsch synthesis catalyst in which cobalt is supported on an alumina carrier with an alkaline aqueous solution.

First, prior to the above step, cobalt is supported on an alumina carrier to obtain a Fischer-Tropsch synthesis catalyst.

The method for supporting cobalt on the alumina carrier is not particularly limited, and a usual impregnation method, an Incipient Wetness method, a precipitation method, an ion exchange method and the like can be used. As the cobalt compound which is a raw material (precursor) used in the carrying, for example, nitrate, carbonate, acetate, chloride and acetylacetonate of cobalt can be used. These cobalt compounds are soluble in a solvent in each of the above methods, and are dried after being supported, and then subjected to a reduction treatment, a calcination treatment, and a reduction treatment to counter ions (for example, Co. in the case of cobalt nitrate). _{(NO 3)} in ₂ NO ₃ ^-) can be volatilized.

Among the above-mentioned cobalt compounds, it is preferable to use a water-soluble compound that can use an aqueous solution during the supporting operation in order to reduce the production cost and secure a safe production work environment. Cobalt nitrate and the like are preferable because they easily change to cobalt oxide during firing, and the subsequent reduction treatment of cobalt oxide is also easy.

As the cobalt compound, any compound is not limited to the compounds listed above as long as it is soluble in a solvent and the counter ions can be volatilized in any of the above treatments.

The cobalt-supported alumina carrier is then dried, if necessary. The drying time is not particularly limited, but can be, for example, 0.5 to 20 hours. The drying temperature is not particularly limited, but can be, for example, 50 to 150 ° C.

Next, the alumina carrier carrying the dried cobalt is calcined. As a result, a Fischer-Tropsch synthesis catalyst can be obtained. The firing time is not particularly limited, but can be, for example, 0.5 to 15 hours. The firing temperature is not particularly limited, but can be, for example, 300 to 600 ° C.

Next, it is preferable to add the Fischer-Tropsch synthesis catalyst to the liquid corresponding to the reaction liquid used in the hydrothermal synthesis described later, and to carry out reflux treatment on the liquid. This facilitates the adhesion of beta-zeolite to the outer surface of the Fischer-Tropsch synthesis catalyst. Therefore, the formation and lamination of the beta zeolite membrane becomes easier.

Examples of such a liquid (reflux liquid) include a liquid in which the reaction substrate component is removed from the reaction liquid during hydrothermal synthesis. The reflux liquid may have a different concentration of the solute from the liquid obtained by removing the reaction substrate component from the reaction liquid at the time of hydrothermal synthesis. In addition, some solutes may be omitted from the solution obtained by removing the reaction substrate component from the reaction solution during hydrothermal synthesis. Further, the reaction substrate component referred to here includes not only a substrate that actually reacts during hydrothermal synthesis, but also a pair of ions when the substrate is an ion.

For example, when the reaction solution at the time of hydrothermal synthesis is an aqueous solution containing tetraethylammonium hydroxide, the reflux solution as a solution corresponding to the reaction solution can be an aqueous solution containing tetraethylammonium hydroxide.

The reflux time is not particularly limited, but can be, for example, 1 to 20 hours. The reflux temperature is not particularly limited, but can be, for example, 60 to 130 ° C.

Next, a capsule catalyst in which a beta-zeolite film is formed on the outer surface of the Fischer-Tropsch synthesis catalyst by a hydrothermal synthesis method is produced (hydrothermal synthesis treatment). The formation of the beta zeolite membrane is carried out, for example, by adding a Fischer-Tropsch synthesis catalyst to an aqueous solution (precursor solution) containing a silica source and an alumina source and heating the membrane.

SiO ₂ (for example, Aerosil 200) can be used as the silica source, and aluminum isopropoxide can be used as the alumina source, but the present invention is not limited thereto.

In the present embodiment, the precursor solution preferably contains potassium nitrate, but may not be contained. By forming the beta zeolite membrane in the presence of potassium nitrate, the beta zeolite membrane is likely to be formed on the outer surface of the Fischer-Tropsch synthesis catalyst. The amount of potassium nitrate added is, for example, 1/100 to 1/2000 with respect to the alumina source in terms of molar ratio.

The temperature in hydrothermal synthesis is not particularly limited, but can be, for example, 120 to 180 ° C, preferably 145 to 170 ° C.

As the time of hydrothermal synthesis increases, the thickness of beta-zeolite formed on the outer surface of the Fischer-Tropsch synthesis catalyst increases. The time for hydrothermal synthesis is, for example, 24 hours or more and 120 hours or less, preferably 48 hours or more and 96 hours or less. If it is less than the lower limit of the above range, the zeolite membrane is not sufficiently formed depending on the reaction conditions, and if it exceeds the upper limit of the above range, the catalyst production cost increases.

In hydrothermal synthesis, the reaction solution may be stirred if necessary. The stirring conditions can be set as appropriate.

The Fischer-Tropsch synthesis catalyst in which the beta zeolite membrane is formed by hydrothermal synthesis is appropriately washed and dried after the completion of hydrothermal synthesis. The drying time is not particularly limited, but can be, for example, 0.5 to 20 hours. The drying temperature is not particularly limited, but can be, for example, 50 to 150 ° C.

Next, the dried catalyst is fired. As a result, a catalyst for producing a hydrocarbon from the synthetic gas according to the present embodiment can be obtained. The firing time is not particularly limited, but can be, for example, 0.5 to 15 hours. The firing temperature is not particularly limited, but can be, for example, 400 to 600 ° C.

Next, the Fischer-Tropsch synthesis catalyst on which the beta zeolite membrane is formed is treated with an alkaline aqueous solution (alkaline treatment). The alkali treatment increases the pore size of the beta zeolite formed on the outer surface of the Fischer-Tropsch synthesis catalyst. In the alkaline treatment, for example, a Fischer-Tropsch synthesis catalyst (hereinafter, also simply referred to as “capsule catalyst”) in which beta zeolite is formed on the outer surface of the Fischer-Tropsch synthesis catalyst by a hydrothermal synthesis method is added to an alkaline aqueous solution and heated. It is done by.

By alkali treatment, for example, silicon is eluted from the crystal structure of beta zeolite having a pore diameter of about 6.6 Å × 7.6 Å, the crystal structure of beta zeolite is partially destroyed, and the mesopores having a pore diameter of 2 nm or more are formed. Is formed. When the pore distribution of the capsule catalyst is measured by the gas adsorption method, the total pore distribution of the Fischer-Tropsch synthesis catalyst and the beta zeolite can be grasped. By comparing the pore distribution measurements before and after the alkali treatment, the mesopore formation of beta zeolite can be confirmed.

As the alkaline aqueous solution, for example, a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, a calcium hydroxide aqueous solution, and a sodium carbonate aqueous solution can be used, but the alkaline solution is not limited thereto.

The pH of the aqueous solution is not particularly limited as long as it is alkaline, but is, for example, 12 to 13.8, preferably 13 to 13.5. With such a range, mesopores of beta zeolite can be surely formed.

The concentration of the alkaline aqueous solution is not particularly limited, but is preferably 0.01 to 2 mol / L. Below this range, elution of silicon is unlikely to occur from the crystal structure of beta zeolite, and it takes an extremely long time. In addition, depending on the alkaline aqueous solution used, in the case of a highly alkaline substance, if it exceeds this range, the crystal structure will be partially destroyed and the function of decomposing and isomerizing the hydrocarbon of beta zeolite will be lost. There is.

After adding a capsule catalyst in which beta zeolite is formed on the outer surface of the Fischer-Tropsch synthesis catalyst to an alkaline aqueous solution, it may be heated to, for example, 50 to 90 ° C., but is not particularly limited. If the heating temperature is lower than this range, elution of silicon from the crystal structure of beta zeolite is unlikely to occur, and if it is higher than this range, the aqueous solution evaporates, making it impossible to maintain stirring for a certain period of time or keeping the concentration constant. It may not be possible to perform the processing. The heating temperature is preferably 60 to 80 ° C.

In the alkaline treatment, if necessary, the slurry in which the capsule catalyst is dispersed in the aqueous solution may be stirred. The stirring holding time (alkali treatment time) can be appropriately set, but is preferably 10 to 120 minutes.
Below this range, the elution of silicon from the beta zeolite crystal structure may be insufficient, and above this range, the crystal structure is not only partially destroyed, and the hydrocarbons of the beta zeolite are decomposed and isomerized. The function to be converted may be lost. The alkali treatment time is preferably 10 to 60 minutes, more preferably 10 to 30 minutes.

The capsule catalyst in which mesopores are formed in the beta zeolite by the alkali treatment is appropriately washed and dried after the completion of the alkali treatment. The drying time is not particularly limited, but can be, for example, 0.5 to 20 hours. The drying temperature is not particularly limited, but can be, for example, 50 to 150 ° C.

In the capsule catalyst in which mesopores are formed by the alkaline treatment, the cations of the beta zeolite are ion-exchanged by the alkaline aqueous solution used in the alkaline treatment. For example, when an aqueous sodium hydroxide solution is used, the cation of the beta zeolite is mainly sodium after the treatment, and it becomes a sodium type beta zeolite.

After the alkali treatment, it is possible to carry out an ion exchange treatment in which the capsule catalyst is ion-exchanged as needed. For example, in the case of the proton type, it can be treated with an aqueous solution of ammonium nitrate. Zeolites have different characteristics depending on the cation species, and when a zeolite other than the sodium-type or potassium-type zeolite formed by the alkali treatment exhibits good characteristics in reaction efficiency and selectivity, ion exchange treatment is preferable. When using sodium-type or potassium-type zeolite formed by alkali treatment, the ion exchange treatment may be omitted.

When the ion exchange treatment is carried out using an aqueous ammonium nitrate solution, the concentration of the aqueous ammonium nitrate solution is not particularly limited, but is preferably 0.1 to 2 mol / L.

After adding the capsule catalyst in the treatment using the aqueous ammonium nitrate solution, it may be heated to, for example, 60 to 90 ° C., but the temperature is not particularly limited. If the heating temperature is lower than this range, ion exchange is unlikely to occur, and if it is higher than this range, the aqueous solution evaporates, making it impossible to maintain stirring for a certain period of time or to perform processing with a constant concentration. There is.

In the treatment using the aqueous ammonium nitrate solution, the slurry may be stirred if necessary. The stirring conditions can be set as appropriate, but 12 to 72 hours are preferable.
If it falls below this range, ion exchange may be insufficient, and if it exceeds this range, the time required for catalyst production becomes long, which may be disadvantageous in terms of cost.

The capsule catalyst after the ion exchange treatment is appropriately washed and dried. The drying time is not particularly limited, but can be, for example, 0.5 to 20 hours. The drying temperature is not particularly limited, but can be, for example, 50 to 150 ° C.

Next, the dried catalyst is fired. As a result, a capsule catalyst (the catalyst according to the present embodiment described above) that forms ion-exchanged beta-zeolite on the outer surface can be obtained. The firing time is not particularly limited, but can be, for example, 0.5 to 15 hours. The firing temperature is not particularly limited, but can be, for example, 400 to 600 ° C.

The following is a more specific example of a method for producing a catalyst for producing a hydrocarbon from the synthetic gas according to the present embodiment. As a matter of course, the method for producing a catalyst according to the present embodiment is not limited to the following specific examples.

First, an aqueous solution of a cobalt precursor is impregnated with an alumina carrier and supported, and then dried (100 ° C., 1 hour) and calcined (450 ° C., 10 hours) as necessary to obtain a Fischer-Tropsch catalyst.

Then, the prepared Fischer-Tropsch synthesis catalyst is refluxed (115 ° C., 4 hours) in a 25 mass% tetraethylammonium hydroxide (TEAOH) aqueous solution as a solution corresponding to the reaction solution.

Next, silica is dissolved in a 25% by mass TEAOH aqueous solution and stirred for about 1 hour to form a uniform colloid. While irradiating ultrasonic waves, aluminum isopropoxide is dissolved in a 25% by mass tetraethylammonium hydroxide aqueous solution and added dropwise to the above colloidal solution over about 15 minutes. Then, ion-exchanged water is added and the mixture is stirred at room temperature for about 2 hours. Then, after adding a small amount of potassium nitrate, an FT synthesis catalyst is added, and the mixture is heated to 155 ° C. by a hydrothermal synthesizer to perform hydrothermal synthesis. The rotation speed during hydrothermal synthesis is 2 rpm for the first 30 minutes, and then repeated for 20 minutes at 0 rpm and 2 minutes at 2 rpm (the rotation speed and the rotation / stop pattern are not particularly limited).

After the completion of hydrothermal synthesis, the catalyst is taken out, washed with ion-exchanged water until the washed ion-exchanged water becomes neutral, and dried at 120 ° C. for 12 hours. After the drying is completed, a capsule catalyst is obtained by performing a firing treatment at 500 ° C. for 5 hours.
Next, as an alkaline treatment, a capsule catalyst is added to a 0.2 mol / L sodium hydroxide aqueous solution, the mixture is stirred at 70 ° C. for 20 minutes, and dried at 120 ° C. for 12 hours. Then, the capsule catalyst after alkali treatment is added to a 1 mol / L ammonium nitrate aqueous solution, the mixture is stirred at 80 ° C. for 48 hours, washed with ion-exchanged water, and dried at 120 ° C. for 12 hours. After completion of drying, a capsule catalyst for forming proton-type beta-zeolite having mesopores on the outer surface can be obtained by performing a calcination treatment at 500 ° C. for 5 hours.

[3. Hydrocarbon production method]
Next, a method for producing a hydrocarbon according to the present embodiment will be described.
In the method for producing a hydrocarbon according to the present embodiment, a hydrocarbon is produced from the synthetic gas in a reactor by using a catalyst for producing a hydrocarbon from the synthetic gas produced by the above-mentioned method.

The hydrocarbon can be produced by contacting the synthetic gas with the catalyst according to the present embodiment.

As the synthetic gas used for producing the above-mentioned hydrocarbon, a gas in which the total amount of hydrogen and carbon monoxide is 50% by volume or more of the total is preferable from the viewpoint of productivity. In particular, it is desirable that the syngas has a molar ratio of hydrogen to carbon monoxide (hydrogen / carbon monoxide) in the range of 0.5 to 4.0. This is because when the molar ratio of hydrogen to carbon monoxide is less than 0.5, the abundance of hydrogen in the raw material gas is too small, so that the carbon monoxide hydrogenation reaction (FT synthesis reaction) proceeds. This is because it is difficult and the productivity of liquid hydrocarbons does not increase. On the other hand, when the molar ratio of hydrogen to carbon monoxide exceeds 4.0, the amount of carbon monoxide present in the raw material gas is too small. This is because the productivity of liquid hydrocarbons does not increase regardless of the catalytic activity.

The synthetic gas may be produced from any raw material. The raw material of the synthetic gas is not particularly limited, and examples thereof include fossil resources such as natural gas, coal, heavy oil, petroleum exhaust gas, and oil shale, and waste containing biomass and hydrocarbons.

The reactor used for contacting the synthetic gas with the catalyst according to the present embodiment is not particularly limited, and for example, a general reactor for a gas phase synthesis process such as a fixed bed, a jet bed, or a fluidized bed. Examples thereof include a reactor for a liquid phase synthesis process such as a slurry bed and a microchannel reactor. In the catalyst of the present invention, it is desirable that beta-zeolite is formed on the outer surface of the FT synthesis catalyst and this structure is maintained, and a fixed bed is preferable to a slurry bed or a fluidized bed which is prone to wear during the reaction. In the fixed bed FT synthesis reaction, the productivity is adjusted based on the heat removal capacity, but in the catalyst of the present invention, the decomposition and isomerization of hydrocarbons, which are endothermic reactions, occur at the same time, so the conversion rates are the same. The amount of heat generated can be suppressed. Further, considering the productivity per catalyst, a microchannel reactor is preferable.

The microchannel reactor is a reactor provided with a flow path having a predetermined width, instead of a container in which a heat extraction tube is arranged inside as in a conventional fixed bed reactor. A catalyst is filled in the flow path, and when the synthetic gas passes through the flow path, it comes into contact with the catalyst, so that a reaction occurs and hydrocarbons are generated. Further, the microchannel reactor is provided with a flow path for passing the refrigerant adjacent to the flow path through which the synthetic gas passes. The heat of reaction from the reaction of the synthetic gas is removed by the refrigerant passing through the adjacent flow path.

The width of such a flow path (flow path width) is not particularly limited, but can be 1 cm or less. Further, from the viewpoint of efficiently removing the reaction heat generated on the catalyst in the flow path by the refrigerant flow in the adjacent flow path, that is, from the viewpoint of controlling the temperature in the flow path of the microchannel reactor, the flow path width. Is preferably 4.0 mm or less, and more preferably 2.0 mm or less. On the other hand, from the viewpoint of temperature control in the flow path, it is preferable that the flow path width is small, but if the flow path becomes too small and the substrate thickness forming the flow path becomes too large, the productivity per unit volume increases. Since it becomes smaller, it is necessary to consider productivity when determining the flow path width. Therefore, the flow path width is preferably 0.50 mm or more, and more preferably 1.0 mm or more.

The structure of the microchannel reactor is not particularly limited, but is, for example, a multi-stage layered structure, in which a layer (reaction layer) for supplying synthetic gas to produce hydrocarbon and a refrigerant for supplying refrigerant are carbonized. It is preferable that layers (refrigerant layers) for removing heat generated in hydrogen production are alternately arranged. More specifically, as such a structure, a structure in which substrates are layered via a plurality of corrugated plates, a structure in which microchannels are formed on the substrate in layers, a honeycomb structure, and the like are adopted. can do. The flow path of the reaction layer and the flow path of the refrigerant layer of such a microchannel reactor can be arranged so as to be orthogonal to each other. That is, the direction of supplying the raw material gas to the flow path in which the FT synthesis reaction is performed can be orthogonal to the direction of supplying the refrigerant to the flow path in which heat is removed.

As the material of the reactor, a metal or an inorganic compound can be used and is not particularly limited, but a metal is preferable. As the metal, steel materials such as stainless steel and aluminum are suitable. The FT synthesis reaction is an exothermic reaction, and efficient heat removal is effective for maintaining stable and high reaction results. Therefore, a reactor in which the flow path is formed in layers is used as a material. Good performance can be obtained by using a microchannel reactor in which a flow path for performing an FT synthesis reaction using a metal and a flow path for passing a refrigerant to remove heat are alternately stacked in layers. Can be done.

Since the thickness of the substrate forming the flow path and the corrugated sheet in the flow path also contributes to the productivity per unit volume of the microchannel reactor, the FT synthesis reaction and heat removal are safely carried out. It is preferable that these thicknesses are as small as possible. For example, in a microchannel reactor using stainless steel, the thickness of the substrate or corrugated sheet can be 30 to 200 μm.

The refrigerant is not particularly limited as long as it can remove heat, but it is preferable to use water, particularly boiler water supply (BFW), because the controllability of the temperature in the flow path for performing the FT synthesis reaction is good.

As a method for fixing a catalyst for producing a hydrocarbon from a synthetic gas into such a microchannel reactor, a method of filling a catalyst having a particle size smaller than the flow path width can be adopted.

When carrying out a reaction for producing a hydrocarbon, the cobalt in the Fischer-Tropsch synthesis catalyst needs to be a reduced metallic cobalt. Therefore, the reduction treatment of the Fischer-Tropsch synthesis catalyst can be performed by flowing a reducing gas such as hydrogen gas before supplying the synthetic gas to produce a hydrocarbon. Such a reduction treatment is not particularly limited, but can be carried out, for example, at a temperature of 300 to 500 ° C. for 2 to 20 hours. For example, the condition of the reduction treatment can be 400 ° C. for 10 hours.

The catalyst may be reduced after filling the reactor, or may be reduced before filling. For example, it is also possible to carry out a reduction treatment before charging the catalyst in the microchannel reactor and then charge the catalyst. The catalyst after the reduction treatment must be handled so that it will not be oxidatively deactivated by contact with the atmosphere. However, if the surface of the cobalt metal or the like on the carrier is stabilized from the atmosphere, it will be handled in the atmosphere. Is possible and suitable. In this stabilization treatment, nitrogen, carbon dioxide, and an inert gas containing low-concentration oxygen are brought into contact with the catalyst to oxidize only the polar surface layer such as cobalt metal on the carrier, so-called passivation (passivation treatment). It is good to do.

Hydrocarbons can be produced by supplying a synthetic gas to the reactor in a state where the cobalt in the catalyst according to the present embodiment is sufficiently reduced to metallic cobalt.

The conditions at the time of producing the hydrocarbon are not particularly limited, and the conventionally applied conditions can be set according to the type of the reactor.

In particular, the reaction temperature during the reaction for producing a hydrocarbon in the microchannel reactor is not particularly limited, but can be 220 to 300 ° C., preferably 240 to 280 ° C. The pressure in the system during the reaction is not particularly limited, but can be, for example, 0.8 to 3.5 MPa, preferably 0.9 to 2.5 MPa. The H ₂ / CO ratio (molar ratio) of the synthetic gas is not particularly limited, but is preferably 0.5 to 3, and more preferably 1.0 to 2.5.

In the reaction carried out under such conditions, hydrocarbons can be selectively produced, and the calorific value in the microchannel reactor can be reduced even under the same conversion rate condition as compared with the case of the Fischer-Tropsch synthesis catalyst alone. Is possible. Therefore, the occurrence of thermal runaway in the microchannel reactor is prevented. When the Fischer-Tropsch synthesis catalyst is used alone, most of the produced oil is linear paraffin, but by coexisting beta zeolite with the Fischer-Tropsch synthesis catalyst, isoparaffin and olefin can be produced at the same time. .. In addition, due to the presence of the beta zeolite membrane, lighter hydrocarbons are relatively selectively produced as compared with the case where the Fischer-Tropsch synthesis catalyst is used alone.

The catalyst mass / syngas flow rate (g · h / mol) is not particularly limited, but is, for example, 1.0 to 10 (g · h / mol), preferably 1.5 to 5.0 (g · h / mol). h / mol). In particular, in the catalyst according to the present embodiment described above, the beta zeolite has mesopores even when the synthetic gas flow rate is relatively large, for example, 3.0 (g · h / mol) or less. Thereby, the production rate of methane can be reduced, and as a result, the yield of olefin can be improved.

When the activity decreases due to factors such as a remarkably high conversion rate or a long reaction time, the catalyst can be regenerated by supplying a gas containing hydrogen (regenerated gas) instead of the synthetic gas. it can. The hydrogen content of the regenerated gas is preferably 5% or more. The hydrogen content in the regenerated gas may be 100%. Further, the regenerated gas may contain an inert gas such as nitrogen or argon in addition to hydrogen.

The conditions for catalyst regeneration are not particularly limited as long as catalyst regeneration proceeds. It is presumed that the catalyst regeneration mechanism by contacting the regenerated gas containing hydrogen with the catalyst is due to the re-reduction of cobalt or the like oxidized by by-product water and the removal of precipitated carbon by hydrogen.

Specifically, the temperature during regeneration can be, for example, 100 to 400 ° C. The pressure during regeneration can be, for example, normal pressure to reaction pressure. In particular, when the regeneration pressure is set to the reaction pressure or less, it becomes possible to use a compressor for boosting the reaction pressure in the reaction, and it is not necessary to install a new compressor for regeneration, which is advantageous in terms of equipment cost. It becomes. The reproduction time can be, for example, one hour or more.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

[Example 1]
Refer to the Society of Catalysis Using the catalyst alumina (JRC-ALO-6, particle size 0.85 to 1.7 mm, specific surface area 180 m ² / g, pore volume 0.96 cc / g, average pore diameter 20 nm) as a carrier, Fisher Tropsch. An aqueous solution of cobalt nitrate hexahydrate was prepared using the synthesis catalyst as a population so that the amount of cobalt supported was 10% by mass, and was impregnated and supported. (Cobalt loading amount (%) = (cobalt mass / (cobalt mass + alumina mass)) × 100) Then, the product is dried at 120 ° C. for 12 hours and calcined at 400 ° C. for 2 hours to obtain a Co / Al ₂ O ₃ catalyst. Obtained. 0.6 g of the prepared Co / Al ₂ O ₃ catalyst was refluxed at 114 ° C. for 4 hours in 5 g of a 25 mass% tetraethylammonium hydroxide (TEAOH) aqueous solution. Then, the solution was filtered to recover the Co / Al ₂ O ₃ catalyst.

4.2 g of silica (Aerosil 200) was dissolved in 10.3 g of a 25 mass% TEAOH aqueous solution and stirred for 1 hour to obtain a uniform colloidal solution. While irradiating ultrasonic waves, 0.3 g of aluminum isopropoxide was dissolved in 4.1 g of a 25 mass% TEAOH aqueous solution, and the solution was added dropwise to the above colloidal solution over 15 minutes. Then, 3.6 g of ion-exchanged water was added, and the mixture was stirred at room temperature for 2 hours. The molar ratio of the precursor solution was silica: TEAOH: alumina: water = 96.53: 34.55: 1.0: 1130. After the potassium nitrate precursor solution was added 0.149 g, was refluxed Co / _Al 2 _{O 3} catalyst 0.6g addition, 155 ° C., hydrothermal synthesis was carried out under conditions of 72 hours. The rotation program during hydrothermal synthesis was repeated at 2 rpm for the first 30 minutes, then at 0 rpm for 20 minutes, and at 2 rpm for 2 minutes. After the completion of hydrothermal synthesis, the catalyst was taken out, washed with ion-exchanged water until the liquid became neutral, and dried at 120 ° C. for 12 hours. After drying, 5 hours at 500 ° C., subjected to baking treatment to obtain a beta zeolite -Co / _Al 2 _{O 3} catalyst to form a beta zeolite membrane on the outer surface of the Co / _Al 2 _{O 3} catalyst.

As an alkali treatment, 4.0 g of β-zeolite-Co / Al ₂ O ₃ catalyst was added to 100 ml of a 0.2 mol / L sodium hydroxide (NaOH) aqueous solution, stirred at 70 ° C. for 20 minutes, and dried at 120 ° C. for 12 hours. Then, 1 g of the alkali-treated β-zeolite-Co / Al ₂ O ₃ catalyst was added to 100 ml of a 1 mol / L ammonium nitrate (NH ₄ NO ₃ ) aqueous solution, stirred at 80 ° C. for 48 hours, and washed with ion-exchanged water. It was dried at 120 ° C. for 12 hours. After drying, 5 hours at 500 ° C., subjected to baking treatment, Co / _Al 2 _{O 3} catalyst zeolite beta to form a proton-type beta zeolite membrane having mesopores on the outer surface of (mesopores) -Co / Al ₂ to give the O ₃ catalyst.

The beta zeolite (mesopores) -Co / _Al 2 _{O 3} catalyst 0.5g obtained above was filled in a tubular reactor of 8 mm, 10 hours at 400 ° C. at atmospheric pressure, subjected to reduction treatment, the nitrogen It was replaced and the temperature was lowered to 80 ° C. Then, switch to the synthesis gas supplied gas H _{2 /} CO = ₂ in tubular reactor. The reaction temperature is set to 260 ° C., the reaction pressure is 2.0 MPa, W (catalyst mass) / F (synthetic gas flow rate); (g · h / mol) = 3, and the composition of the supply gas and the outlet gas of the tubular reactor is gas. determined by chromatography, CO conversion, CH ₄ selectivity, C5 + selectivity, olefin selectivity was calculated isoparaffin selectivity respectively.

CO conversion described in the following examples, CH ₄ selectivity, C5 + selectivity, olefin selectivity, isoparaffins selectivity was calculated by the following equation, respectively. Here, C5 + indicates a hydrocarbon having 5 or more carbon atoms.

Using a catalyst prepared as described above was subjected to reaction, CO conversion was 27.6% CH ₄ selectivity was 34.1% C5 + selectivity (44.8%), olefin selectivity of 20.7%, isoparaffins selected The rate was 19.4%. Moreover, the product of the carbon number distribution shown in FIG. 1 was obtained. Compared to beta zeolite -Co / Al ₂ O ₃ catalyst does not perform alkali treatment as shown in Comparative Example 1 to be described later, CO conversion, C5 + selectivity, that olefin selectivities, isoparaffins selectivity is improved confirmed.

[Example 2]
When the reaction was carried out in the same manner as in Example 1 except that the Co / Al ₂ O ₃ catalyst was prepared so that the amount of cobalt supported was 20% by mass, the CO conversion rate was 49.2% and the CH ₄ selectivity was It was 22.8%, C5 + selectivity 55.2%, olefin selectivity 18.8%, and isoparaffin selectivity 18.4%. Moreover, the product of the carbon number distribution shown in FIG. 2 was obtained.

[Example 3]
When the reaction was carried out in the same manner as in Example 1 except that the Co / Al ₂ O ₃ catalyst was prepared so that the amount of cobalt supported was 30% by mass, the CO conversion rate was 71.4% and the CH ₄ selectivity was It was 16.5%, C5 + selectivity 59.1%, olefin selectivity 16.9%, and isoparaffin selectivity 16.1%. Moreover, the product of the carbon number distribution shown in FIG. 3 was obtained.

[Example 4]
The reaction was carried out in the same manner as in Example 3 except that the orthogonal microchannel reactor shown in FIG. 6 was filled with a catalyst and the temperature was controlled while cooling with boiler water supply (BFW). The orthogonal microchannel reactor has a laminated structure formed of stainless (SUS) foil, and the gap between the stainless foils forms a flow path for boiler water supply or syngas. Further, the flow paths of the boiler water supply and the synthetic gas are alternately arranged in a laminated structure of stainless steel foil, and the moving directions (directions of the flow paths) of the boiler water supply and the synthetic gas are orthogonal to each other. A corrugated sheet is arranged in each flow path, and each flow path width W is 1.3 mm. Analysis of the resulting products revealed a CO conversion of 72.3%, a CH ₄ selectivity of 16.9%, a C5 + selectivity of 57.8%, an olefin selectivity of 16.3%, and an isoparaffin selectivity of 16.5%. there were.

In the reaction in the above-mentioned orthogonal microchannel reactor, no runaway of the reaction occurred. It is presumed that the endothermic reaction in the beta zeolite membrane absorbed the heat generated in the reaction of the Co / Al ₂ O ₃ catalyst and suppressed the excessive temperature rise in the orthogonal microchannel reactor.

[Comparative Example 1]
When the reaction was carried out in the same manner as in Example 1 except that the beta zeolite-Co / Al ₂ O ₃ catalyst not subjected to the alkali treatment was used, the CO conversion rate was 18.9% and the CH ₄ selectivity was 57.2. %, C5 + selectivity was 25.0%, olefin selectivity was 5.8%, and isoparaffin selectivity was 11.9%. Moreover, the product of the carbon number distribution shown in FIG. 4 was obtained.

[Comparative Example 2]
When the reaction was carried out in the same manner as in Comparative Example 2 except that the Co / Al ₂ O ₃ catalyst was prepared so that the amount of cobalt supported was 30% by mass, the CO conversion rate was 62.4% and the CH ₄ selectivity was The selectivity was 19.8%, C5 + selectivity was 45.0%, olefin selectivity was 10.9%, and isoparaffin selectivity was 14.1%. Moreover, the product of the carbon number distribution shown in FIG. 5 was obtained.

The above results are shown in Table 1.

As is clear from Table 1, in the catalysts according to Examples 1 to 4 in which the beta zeolite has mesopores, the selectivity of the olefin was high. Further, the catalyst according to Examples 1 to 4 is also provided under the condition that the flow rate of the synthetic gas is relatively large, that is, W (catalyst mass) / F (synthetic gas flow rate); (g · h / mol) is relatively large 3. Had a high selectivity for olefins. Further, as shown in Example 4, the catalyst according to Example 4 in which the beta zeolite has mesopores was suitably available for the FT synthesis reaction in the microchannel reactor.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

Claims (6)

A synthetic gas having an alkali treatment for forming mesopores by treating an alumina carrier and a catalyst in which beta zeolite is formed on the outer surface of a Fischer-Tropsch synthesis catalyst having cobalt supported on the alumina carrier with an alkaline aqueous solution. A method for producing a catalyst for producing hydrocarbons from. The method for producing a hydrocarbon from a synthetic gas according to claim 1, which comprises a hydrothermal synthesis treatment for forming a beta-zeolite film on the outer surface of the Fischer-Tropsch synthesis catalyst by a hydrothermal synthesis method in the presence of potassium nitrate. .. Produce a hydrocarbon from the synthetic gas according to claim 1 or 2, which comprises an ion exchange treatment for ion exchange of a catalyst in which beta zeolite is formed on the outer surface of the Fischer-Tropsch synthesis catalyst after the alkali treatment. A method for producing a catalyst. A method for producing a hydrocarbon, wherein a hydrocarbon is produced from the synthetic gas in a reactor by using a catalyst for producing a hydrocarbon from the synthetic gas produced by the method according to any one of claims 1 to 3. The reactor is a microchannel reactor having a multi-stage layered structure, and a layer for supplying synthetic gas to produce hydrocarbons and a refrigerant for supplying refrigerant to remove heat generated in hydrocarbon production are removed. The method for producing a hydrocarbon according to claim 4, wherein the layers are arranged alternately, and the flow paths of these layers are arranged in orthogonal directions. Beta zeolite is formed on the outer surface of the alumina carrier and the Fischer-Tropsch synthesis catalyst having cobalt supported on the alumina carrier.
The beta zeolite is a catalyst that has mesopores and produces hydrocarbons from syngas.