JP7039807B2 - Zeolite catalyst and method for producing lower olefin using the zeolite catalyst - Google Patents

Description

The present invention relates to a zeolite catalyst and a method for producing a lower olefin using the zeolite catalyst.

As a method for producing lower olefins such as ethylene, propylene and butene, steam cracking of naphtha and fluidized catalytic decomposition of vacuum light oil have been generally carried out, and in recent years, a metathesis reaction using ethylene and 2-butene as raw materials has been carried out. And MTO (Methanol to Olefin) processes using methanol and / or dimethyl ether as raw materials are known.

On the other hand, due to the recent decline in the price of natural gas, ethylene production by ethane cracking using ethane contained in natural gas as a raw material is rapidly expanding. However, unlike naphtha steam cracking, ethane cracking produces almost no propylene, butadiene, butene, etc., which are hydrocarbons with 3 or more carbon atoms, so hydrocarbons with 3 or more carbon atoms, especially propylene and butadiene, are deficient. The situation is becoming apparent.
Therefore, as a production method capable of selectively producing an olefin having 3 or more carbon atoms such as propylene and suppressing the amount of ethylene produced, methanol and / or dimethyl ether synthesized from inexpensive coal or natural gas is used. The MTO process used as a raw material is attracting attention.

Zeolites have been used as catalysts in the production of lower olefins from methanol and / or dimethyl ether as raw materials. Known zeolites include CHA-type zeolites with an 8-membered ring structure (SAPO-34), MFI-type zeolites with a 10-membered ring structure (ZSM-5), and CON-type zeolites with a 12-membered ring structure (CIT-1). (For example, Patent Documents 1 to 3, Non-Patent Documents 1 and 2). Above all, by using CON-type zeolite as a catalyst, propylene and butene can be produced in high yield, and further, by-production of ethylene during propylene production can be suppressed.
Further, when used industrially, a molding catalyst molded with a binder is used, and alumina or the like is known as the binder (for example, Patent Document 2). Further, other additives may be used, and it is known that the catalyst life is improved by adding an alkaline earth metal to a zeolite such as MFI type, for example, as disclosed in Patent Document 4. There is. However, in the case of industrial implementation, the present situation is that a catalyst having higher performance is required.

Special Table 2009-507754 Japanese Unexamined Patent Publication No. 2008-08301 Japanese Unexamined Patent Publication No. 2013-245163 Japanese Unexamined Patent Publication No. 59-07523

Energy, 33, 817-833 (2008) ACS Catal. , 5, 4268-4275 (2015)

An object of the present invention is to provide a zeolite catalyst capable of maintaining a high raw material conversion rate for a long period of time, and a method for stably producing a lower olefin for a long period of time using the zeolite catalyst. ..

The present inventors have proceeded with research to solve the above problems, and by using a zeolite catalyst containing at least a zeolite and a compound containing an alkaline earth metal and silicon for producing a lower olefin, the present inventors have used it for a long period of time. We found that it was possible to maintain a high conversion rate of raw materials, and completed the invention.
The present invention includes the following gist.

[1] A zeolite catalyst for producing a lower olefin.
A zeolite catalyst containing at least a zeolite and a compound containing an alkaline earth metal and silicon.
[2] The zeolite catalyst according to [1], wherein the alkaline earth metal is calcium.
[3] A method for producing a lower olefin, comprising a step of contacting a raw material containing methanol and / or dimethyl ether with the zeolite catalyst according to claim 1 or 2.

As used herein, the lower olefin means ethylene, propylene and butene. In other words, it is an olefin having 2 to 4 carbon atoms.

According to the present invention, it is possible to provide a zeolite catalyst capable of maintaining a high raw material conversion rate for a long period of time, and a method for stably producing a lower olefin for a long period of time using the zeolite catalyst. .. In addition, the number of catalyst regenerations required for producing the lower olefin can be reduced, and the production efficiency can be improved.

It is a graph which shows the methanol conversion rate in the production II of the lower olefin of an Example. It is a graph which shows the C2-C4 olefin selectivity in the production II of the lower olefin of an Example.

Hereinafter, the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents. It can be modified in various ways within the scope of the gist.

One embodiment of the present invention is a zeolite catalyst for producing lower olefins, the zeolite catalyst containing at least zeolite and a compound containing an alkaline earth metal and silicon.

The zeolite used in this embodiment is not particularly limited, but is, for example, a code defined by the International Zeolite Association (IZA), AEI, AEL, AFI, AFX, APC, ATO, BEA, BRE, CDO, CHA, CON, DDR, etc. EAB, EPI, ERI, ESV, EUO, FAU, FER, GIS, GME, HEU, ITH, KFI, LEV, LTA, LTL, MER, MEL, MFI, MON, MOR, MSE, MTF, MTT, MTW, MWW, NES, OFF, PAU, PHI, RHO, RTE, RTH, SOD, STI, STT, SZR, TON, TSC,
Examples include TUN, UFI, VNI, WEI, YUG and the like. Among them, AEI, CHA, CON, MFI, MOR, MSE are preferable, and CON is more preferable. One of these may be used alone, or two or more thereof may be mixed and used.

The pore size of the zeolite used in this embodiment is not particularly limited, but is preferably 0.3 nm or more, and more preferably 0.35 nm or more. Further, it is preferably 0.9 nm or less, more preferably 0.8 nm or less. The pore diameter referred to here refers to the crystallographic channel diameter defined by the International Zeolite Association (IZA).

The zeolite used in this embodiment is not particularly limited, but is preferably crystalline metallosilicate. The elements constituting the metallosilicate are not particularly limited, but are, for example, aluminum (Al), boron (B), titanium (Ti), vanadium (V), iron (Fe), zinc (Zn), and gallium (Ga). ), Germanium (Ge), zirconium (Zr), tin (Sn), one or more selected.

Specifically, preferred examples include crystalline aluminosilicate containing Al and crystalline gallosilicate containing Ga as constituent elements. These zeolites are excellent in catalytic activity because Al and Ga in the zeolite skeleton serve as acid points and act as active points for catalytic reaction.

In the case of the crystalline aluminosilicate and the crystalline aluminosilicate, the ratio of the constituent elements is not particularly limited, but the Si / Al molar ratio or the Si / Ga molar ratio is usually 5 or more, preferably 5 or more. It is 10 or more, more preferably 20 or more, still more preferably 25 or more, particularly preferably 50 or more, particularly preferably 100 or more, and usually 5000 or less, preferably 1000 or less, still more preferably 500 or less.

The ion exchange site of zeolite is not particularly limited, and may be H-type or may be exchanged with metal ions. Here, the metal ion is specifically an alkali metal ion, an alkaline earth metal ion, or the like.

The BET specific surface area of the zeolite used in the present embodiment is not particularly limited, and is usually 200 m ² / g or more, preferably 250 m ² / g or more, more preferably 300 m ² / g or more, and usually 2000 m. It is ² / g or less, preferably 1500 m ² / g or less, and more preferably 1000 m ² / g or less.
The pore volume of the zeolite is not particularly limited, and is usually 0.1 ml / g or more, preferably 0.2 ml / g or more, and usually 3 ml / g or less, preferably 2 ml / g or less. be.

The average particle size of the zeolite used in the present embodiment is not particularly limited, and is usually 10 μm or less, preferably 3 μm or less, more preferably 1 μm or less, and particularly preferably 700 nm or less. Further, it is usually 20 nm or more, preferably 40 nm or more.

Zeolites may be commercially available or may be synthesized by known methods. In the case of CON type zeolite, ACS Catal. , 5, 4268-4275 (2015) and the like synthesized by a known method can be used.

Zeolites can generally be prepared by hydrothermal synthesis. For example, an aluminum source, an alkali source, a silica source, etc. are added to water to generate a uniform gel, a structure-defining agent is added thereto, and the mixture is stirred, and the obtained raw material gel is placed in a pressurized heating container at 120 to 200 ° C. Hold in and crystallize. Seed crystals may be added as needed during crystallization, and it is preferable to add seed crystals in terms of manufacturability in terms of improving operability. The crystallized raw material gel is then filtered and washed, and then the solid content is dried at 100 to 200 ° C. and subsequently calcined at 400 to 900 ° C. to obtain a zeolite powder.

The zeolite catalyst of the present invention contains this zeolite and a compound containing an alkaline earth metal and silicon. The compound is not particularly limited as long as it contains an alkaline earth metal and silicon, and examples thereof include magnesium silicate, calcium silicate, strontium silicate, barium silicate, wollastonite, talc, atapulsite, and sepiolite. Examples of the alkaline earth metal include magnesium, calcium, strontium and barium, preferably calcium and strontium, and particularly preferably calcium. It is considered that the inclusion of the compound causes the alkaline earth metal to modify the acidity of the zeolite, and the silicon repairs the lattice defects of the zeolite to improve the catalyst life.

The compound is not particularly limited, but can be used as a zeolite catalyst by, for example, kneading / extrusion molding with zeolite and firing. At this time, the compound also functions as a binder in the zeolite catalyst, and its content is not particularly limited, but is usually 5 parts by weight or more, preferably 10 parts by weight or more, and usually 500 parts by weight or less with respect to 100 parts by weight of zeolite. It is preferably 400 parts by weight or less. A binder other than the above compound (also referred to as another binder) may be used. Examples of other binders include γ-alumina, alumina sol, boehmite, colloidal silica, fumed silica, fused silica, silica gel, clay and the like.
The weight ratio of the alkaline earth metal to silicon in the zeolite catalyst is not particularly limited, but is usually 1: 100 to 10: 1, preferably 1:20 to 5: 1.

The zeolite catalyst of this embodiment is used in producing a lower olefin. Examples of the raw material include methanol and dimethyl ether, but the raw material is not limited to this, and can be appropriately selected depending on the type of the target olefin.
The origin of production of methanol and dimethyl ether is not particularly limited. For example, those obtained by hydrogenation reaction of hydrogen / CO mixed gas derived from coal and natural gas and by-products in the iron manufacturing industry, those obtained by reforming reaction of alcohols derived from plants, and those obtained by fermentation method. , Those obtained from organic substances such as recirculated plastics and municipal waste. At this time, a compound in which compounds other than methanol and dimethyl ether derived from each production method are arbitrarily mixed may be used as they are, or a purified compound may be used.
As the reaction raw material, only methanol may be used, only dimethyl ether may be used, or a mixture thereof may be used. When methanol and dimethyl ether are mixed and used, there is no limitation on the mixing ratio.

Hereinafter, a method for producing a lower olefin using the catalyst and a raw material will be described by way of exemplifying a case where the raw material is methanol and / or dimethyl ether.
Another production method of the present invention comprises a step of contacting the zeolite catalyst with a raw material containing methanol and / or dimethyl ether. The reaction mode in the present embodiment is not particularly limited as long as the methanol and / or dimethyl ether feedstock is a gas phase in the reaction region, and a known gas using a fluidized bed reaction device, a moving bed reaction device or a fixed bed reaction device is used. A phase reaction process can be applied. In the case of a fixed bed reactor, it is particularly advantageous in terms of equipment cost including ancillary equipment, catalyst cost, and operation management.
Further, it may be carried out in any form of batch type, semi-continuous type or continuous type, but it is preferably performed in a continuous type, and the method may be a method using a single reactor, or in series or in parallel. A method using a plurality of arranged reactors may be used.

When the fluidized bed reactor is filled with the above-mentioned catalyst, particles inactive to the reaction such as quartz sand, alumina, silica, and silica-alumina are mixed with the catalyst in order to keep the temperature distribution of the catalyst layer small. And fill it. In this case, the amount of granules that are inert to the reaction, such as quartz sand, is not particularly limited. The particle size of the granules is preferably about the same as that of the catalyst from the viewpoint of uniform mixing with the catalyst.
Further, the reaction substrate (reaction raw material) may be divided and supplied to the reactor for the purpose of dispersing the heat generated by the reaction.

The total concentration (substrate concentration) of methanol and dimethyl ether in all the supply components supplied to the reactor is not particularly limited, but the sum of methanol and dimethyl ether is preferably 90 mol% or less in all the supply components. More preferably, it is 10 mol% or more and 70 mol% or less.

In the reactor, in addition to methanol and / or dimethyl ether, hydrocarbons such as helium, argon, nitrogen, carbon monoxide, carbon dioxide, hydrogen, water, paraffins, methane, aromatic compounds, and them. A gas (also referred to as a diluent) that is inert to the reaction can be present, such as a mixture of the above, but it is preferable that water (steam) coexists among them because the separation is good.
As such a diluent, impurities contained in the reaction raw material may be used as they are, or a separately prepared diluent may be mixed with the reaction raw material and used. Further, the diluent may be mixed with the reaction raw material before being put into the reactor, or may be supplied to the reactor separately from the reaction raw material.

The lower limit of the reaction temperature is usually about 200 ° C. or higher, preferably 250 ° C. or higher, more preferably 300 ° C. or higher, and the upper limit of the reaction temperature is usually 750 ° C. or lower, preferably 700 ° C. or lower. If the reaction temperature is too low, the reaction rate is low, a large amount of unreacted raw materials tend to remain, and the yield of lower olefins also decreases. On the other hand, if the reaction temperature is too high, it is difficult to obtain the stable activity of the catalyst, and the yield of the lower olefin is remarkably lowered. Here, the reaction temperature refers to the temperature at the inlet of the catalyst layer.

The upper limit of the reaction pressure is usually 5 MPa (absolute pressure, the same applies hereinafter) or less, preferably 2 MPa or less, more preferably 1 MPa or less, and particularly preferably 0.7 MPa or less. The lower limit of the reaction pressure is not particularly limited, but is usually 0.1 kPa or more, preferably 7 kPa or more, and more preferably 50 kPa or more. If the reaction pressure is too high, the amount of unfavorable by-products such as paraffins and aromatic compounds produced increases, and the yield of lower olefins tends to decrease. If the reaction pressure is too low, the reaction rate tends to be slow.

As the reactor outlet gas (reactor outflow), a mixed gas containing a lower olefin which is a reaction product, a by-product, and a diluent can be obtained. The concentration of the lower olefin in the mixed gas is usually 5 to 95% by weight.
Depending on the reaction conditions, methanol and / or dimethyl ether is contained as an unreacted raw material in the reaction product, but it is preferable to carry out the reaction under reaction conditions such that the conversion rate of methanol and / or dimethyl ether becomes 100%. As a result, the separation of the reaction product and the unreacted raw material becomes easy, preferably unnecessary.
By-products include olefins with 5 or more carbon atoms, paraffins, aromatic compounds and water.

The mixed gas containing the reaction product lower olefin, unreacted raw material, by-product and diluent as the reactor outlet gas is introduced into a known separation / purification facility, and is recovered and purified according to each component. , Recycle, and discharge.

Hereinafter, the present invention will be described in more detail by way of examples, but it goes without saying that the scope of the present invention is not limited to the examples.
[Example 1]
0.4 kg of sodium hydroxide, 30 wt% N, N, N-trimethyl- (-)-cis-miltanyl ammonium hydroxyside aqueous solution 23.6 kg and 24.4 kg of water were mixed, and 0.4 kg of boric acid and 0.4 kg of boric acid and 24.4 kg of water were mixed. After 0.08 kg of aluminum sulfate was added and stirred, 32.6 kg of Cataloid SI-30 was added as a silica source and the mixture was sufficiently stirred. Further, 0.2 kg of BEA type zeolite was added as a seed crystal and stirred to prepare a raw material gel.

The obtained raw material gel was placed in an autoclave and heated at 170 ° C. for 4 days. The product was filtered, washed with water and dried at 100 ° C. to give a white powder. From the X-ray diffraction (XRD) pattern of the product, it was confirmed that the obtained product was a CON-type zeolite. Elemental analysis by inductively coupled plasma emission spectroscopy (ICP-AES) revealed a Si / Al ratio of 270 and a Si / B ratio of 25. After drying, it was calcined at 600 ° C. for 6 hours in an air atmosphere to obtain a sodium-type zeolite powder.

The obtained powder was ion-exchanged at 80 ° C. for 1 hour in a 1N aqueous ammonium nitrate solution, and then filtered. The filtered powder was again subjected to ion exchange at 80 ° C. for 1 hour in a 1N aqueous ammonium nitrate solution, and then filtered and dried to obtain an ammonium-type CON-type zeolite.
400 g of ammonium-type CON-type zeolite (Si / Al = 270) and 100 g of Wollastonite (manufactured by NYCO) were mixed, and an appropriate amount of methyl cellulose and desalinated water were further added and kneaded to obtain a mixture thereof. .. This mixture was extruded by an extruder, dried, and then fired at 600 ° C. to obtain a molded product.

[Example 2]
2.0 g of the ammonium-type CON-type zeolite (Si / Al = 270) obtained in Example 1 and 0.5 g of calcium silicate (manufactured by SIGMA-ALDRICH) are mixed, and an appropriate amount of methyl cellulose and desalted water are further mixed. Was added and kneaded to obtain a mixture thereof. The mixture was dried and then fired at 600 ° C. to obtain a molded product.

[ Reference example 1 ]
2.0 g of ammonium-type MFI-type zeolite (Si / Al = 820 manufactured by ZEOLYST) and 0.5 g of wollastonite are mixed, and an appropriate amount of methyl cellulose and desalinated water are added and kneaded, and the mixture thereof is kneaded. Got The mixture was dried and then fired at 600 ° C. to obtain a molded product.

[Comparative Example 1]
2.0 g of the ammonium-type CON-type zeolite (Si / Al = 270) obtained in Example 1 was added with an appropriate amount of methyl cellulose and desalinated water and kneaded to obtain a mixture thereof. The mixture was dried and then fired at 600 ° C. to obtain a molded product.

[Comparative Example 2]
250 g of the ammonium-type CON-type zeolite (Si / Al = 270) obtained in Example 1, 63 g of alumina (manufactured by JGC Catalysts and Chemicals Co., Ltd.) and 16 g of calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed. Further, an appropriate amount of methyl cellulose and desalted water were added and kneaded to obtain a mixture thereof. This mixture was extruded by an extruder, dried, and then fired at 600 ° C. to obtain a molded product.

[Comparative Example 3]
400 g of the aluminum-type CON-type zeolite (Si / Al = 270) obtained in Example 1, 100 g of molten silica (manufactured by Admatex), and 25 g of calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed, and further. An appropriate amount of methyl cellulose and desalted water were added and kneaded to obtain a mixture thereof. The mixture was dried and then fired at 600 ° C. to obtain a molded product.

[Comparative Example 4]
2500 g of the ammonium-type CON-type zeolite (Si / Al = 270) obtained in Example 1 and 156 g of calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed, and an appropriate amount of crystalline cellulose and desalted water are further added. Granulated. After drying, it was fired at 600 ° C. to obtain a molded product.

[Comparative Example 5]
2.0 g of ammonium type MFI type zeolite (manufactured by ZEOLYST, Si / Al = 820), 0.5 g of alumina (manufactured by JGC Catalysts and Chemicals), and 0.1 g of calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.). After mixing, an appropriate amount of methyl cellulose and desalted water were added and kneaded to obtain a mixture thereof. The mixture was dried and then fired at 600 ° C. to obtain a molded product.

<Manufacturing of lower olefin I>
Lower olefins were produced using the zeolite catalysts obtained in Examples 1 and 2 , Comparative Examples 1 to 5 , and Reference Example 1 . Examples 1 and 2 use a CON-type zeolite and a compound containing an alkaline earth metal and silicon, and Reference Example 1 uses an MFI-type zeolite and a compound containing an alkaline earth metal and silicon. In Comparative Example 1, when neither the compound containing an alkaline earth metal nor the compound containing silicon is used in combination with the CON type zeolite, in Comparative Example 2, the CON type zeolite and the compound containing an alkaline earth metal are used in combination, but when aluminum is contained. In Comparative Example 3, a compound containing a CON-type zeolite and an alkaline earth metal is used in combination, but when molten silica is contained, Comparative Example 4 is an example in which only a compound containing an alkaline earth metal is used in combination. In Comparative Example 5, a compound containing MFI-type zeolite and an alkaline earth metal is used in combination, but this is an example in which aluminum is contained.
For the reaction, a fixed bed flow reactor was used, and the zeolite catalysts obtained in Examples 1 , 2 , Comparative Examples 1 to 5 , and Reference Example 1 were placed in a quartz reaction tube having an inner diameter of 6 mm so that the amount equivalent to zeolite was 50 mg. Each was filled. A mixed gas of 50 mol% methanol and 50 mol% nitrogen was supplied to the reactor so that the weight space velocity of methanol was ^-1 for 10 hours, and the reaction was carried out at 500 ° C. and 0.1 MPa (absolute pressure). The product was analyzed by gas chromatography every hour from the start of the reaction. Table 2 shows the results of measuring the amount of cork 15 hours after the start of the reaction. The amount of cork was measured using TGA-50 manufactured by Shimadzu Corporation. After holding at room temperature for 30 minutes under He distribution, the temperature was raised to 550 ° C. and held for 30 minutes. Then, the flow gas was switched from He to Air, the temperature was raised to 600 ° C., and the temperature was maintained for 120 minutes. The amount of cork was defined as (weight loss during Air distribution) / (weight after measurement).

<Manufacturing of lower olefin II>
Lower olefins were produced using the zeolite catalysts obtained in Example 1 and Comparative Examples 2 to 4.
For the reaction, a fixed bed flow reactor was used, and a SUS reaction tube having an inner diameter of 24 mm was filled with 46 g of the zeolite catalysts obtained in Example 1 and Comparative Examples 2 to 4, respectively. A mixed gas of 25 mol% methanol, 50 mol% water, 24 mol% nitrogen and 1 mol% 1-hexene was supplied to the reactor so that the weight space velocity of methanol was 1.5 hours ^-1 . The reaction was carried out at 0.2 MPa (absolute pressure). The product was analyzed by gas chromatography every 2 hours from the start of the reaction. Table 3 shows the catalyst life and C2-C4 olefin selectivity of each zeolite catalyst. Further, FIG. 1 shows a graph of methanol conversion rate, and FIG. 2 shows a graph of C2-C4 olefin selectivity. The catalyst life was defined as the average of the C2-C4 olefin selectivity during the time when the methanol conversion was maintained at 95% or higher, and the C2-C4 olefin selectivity was defined as the average of the C2-C4 olefin selectivity during the time when the methanol conversion was maintained at 95% or higher.

Regarding the CON-type zeolite, as shown in Production I of the lower olefin, the reaction was carried out using the zeolite catalyst containing the compound containing the alkaline earth metal of Examples 1 and 2 and silicon, and the reaction was carried out. The amount of cork was small compared to the result of. That is, it can be said that the zeolite catalyst according to the embodiment is less likely to be deactivated by caulking and has a long catalyst life. Further, as shown in Production II of Lower Olefin, when the life was evaluated using the zeolite catalyst of Example 1, a high raw material conversion rate was maintained for a long period of time, and the catalyst life was long. Similarly, regarding the MFI-type zeolite, it can be said that the zeolite catalyst of Reference Example 1 has a smaller amount of cork and a longer catalyst life as compared with the result of Comparative Example 5.

Claims (3)

A zeolite catalyst for producing lower olefins.
A zeolite catalyst containing at least a CON-type zeolite and a compound containing an alkaline earth metal and silicon. The zeolite catalyst according to claim 1, wherein the alkaline earth metal is calcium. A method for producing a lower olefin, comprising a step of contacting a raw material containing methanol and / or dimethyl ether with a zeolite catalyst according to claim 1 or 2.

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