JP5646279B2 - Production method of light olefin - Google Patents

Description

  The present invention relates to a method for producing olefins by converting methanol or dimethyl ether (hereinafter referred to as “DME”) using a zeolite catalyst MCM-68.

Since light olefins such as propylene are industrially important raw materials, studies for producing light olefins from petroleum and other raw materials have been actively conducted (Patent Document 1, etc.). It is also known that methanol obtained from natural gas or the like is converted to olefin using a zeolite catalyst, and this conversion is known to pass through DME as an intermediate (Non-patent Document 1, etc.). The use of DME as a raw material is less by-produced than methanol as a raw material, and permanent deactivation due to dealumination of the zeolite catalyst can be suppressed. In addition, DME is often used as a raw material for evaluating zeolite catalysts.
In a process for producing light olefins using methanol as a raw material, it is known that zeolite with small pores such as SAPO-34 gives good results (Patent Documents 2, 3 and the like). However, since zeolite with small pores is markedly deactivated due to carbon deposition and accompanying pore blockage, medium pore zeolites such as MFI type zeolite ZSM-5 are often used (Non-patent Document 1). -3, patent documents 4, 5 etc.).
The present inventors have also disclosed a method for producing light olefins in high yield by catalytic cracking of paraffin using zeolite catalyst MCM-68 (Patent Document 6).

US2003 / 0181777 Special Table 2002-542929 Special table 2003-500189 JP2006-8655 JP2008-56593 JP2010-202613

Petroleum Science and Technology 17 (3 & 4), 273-289, 1999 Energy Sources, 27: 489-500, 2005 Petroleum Chemistry, vol.48, No. 1, 15-21, 2008

Light olefins include ethylene and propylene as well as C4 or higher olefins, but depending on the field of use, there are cases where demand for C3 or higher olefins is higher than ethylene. In such fields, methanol and DME are more than C3 and higher. There is a need for a catalyst that selectively converts to any olefin.
Accordingly, an object of the present invention is to provide a zeolite catalyst for olefin conversion that uses methanol or DME as a raw material and suppresses the yield of ethylene to a low level and increases the yield of C3 or higher olefins.

As a result of intensive investigations, the inventors of the present invention used a zeolite catalyst MCM-68 to optimize the Si / Al ratio, thereby suppressing the yield of ethylene when converting methanol or DME into olefins. Thus, the inventors have found that the yield of C3 or higher olefin can be increased, and have completed the present invention.
That is, the present invention is a method for selectively producing C3 or higher olefins by converting methanol or DME, and using aluminosilicate MCM-68 having a Si / Al ratio (molar ratio) of 100 to 200 as a catalyst. Is the method.

  The aluminosilicate of the present invention has a basic skeleton of MCM-68 and has a Si / Al ratio of 100 to 200. In a region where the Si / Al ratio is smaller than this, the instantaneous activity at the initial stage of the reaction is high, but the activity deterioration due to carbon deposition is severe, resulting in a catalyst with low activity. On the other hand, if the Si / Al ratio is too high, the activity as an acid catalyst decreases.

In the present invention, the Si / Al ratio (molar ratio) is a value quantified using inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. That is, the Si / Al molar ratio calculated from the number of moles of Si and the number of moles of metal calculated from the weight (mg / L) of Al obtained by ICP-AES measurement.
Usually, a silicate having a desired Si / Al molar ratio can be obtained by preparing a calibration curve in advance for the Si / Al molar ratio with respect to conditions such as processing time and temperature and managing the conditions.

The aluminosilicate of the present invention comprises (1) a step of producing MCM-68 having a Si / Al of about 8.3-15, and (2) the MCM-68 having a Si / Al of 100-200. Can be obtained by a production method comprising a step of performing an acid treatment (dealuminization step).
Hereafter, the manufacturing method of the aluminosilicate of this invention is demonstrated in order.
(1) First, MCM-68 (hereinafter also referred to as “Al-MCM-68”) having Si / Al of about 8.3 to 15 is manufactured.
MCM-68 is an aluminosilicate with a structure in which 12-membered and 10-membered channels intersect three-dimensionally. A unit cell (unit cell) is a tetragonal system with a composition of T ₁₁₂ O ₂₂₄ (T = Si or Al) when expressed by atoms with a fixed spatial coordinate. For the MCM-68 structure, the three-letter code of the International Zeolite Association Structure Commission (IZA-SC) is MSE, and has a skeletal topology that is uniquely determined by the atomic coordinates shown in Table 1. There is a straight 12-membered ring channel (diameter 0.67 nm) in the c-axis direction, and two wavy 10-membered ring channels (diameter 0.50-0.55 nm) in the a-axis and b-axis directions. Moreover, it has a cavity (cage) (0.65 × 1.73 nm) accessible only through a 10-membered ring (J. Phys. Chem. B, 2006, 110, 2045-2050).

注）空間群 P4₂/mnm （International Union of Crystallography (IUCr)の定めるNo. 136の空間群）格子定数 a (=b) = 18.286(1) Å, c = 20.208(2) Å、T = Si or Al

Note) Space group P4 ₂ / mnm (No. 136 space group defined by International Union of Crystallography (IUCr)) Lattice constant a (= b) = 18.286 (1) Å, c = 20.208 (2) Å, T = Si or Al

Aluminosilicate MCM-68 is represented by the following composition formula.
H _{n ′} Al _{n ′} Si _{112-n ′} O ₂₂₄
(In the formula, n ′ represents 7 to 12.)
Si / Al is about 8.3-15.
In the aluminosilicate MCM-68 used in the present application, metal components other than the above components can enter and leave the skeleton of MCM-68 as long as the performance of the present invention is not impaired. In this case, MCM-68 is represented by the following formula.
_{M 'x' H n '+} (4-y) m [M m Al n' Si 112-n'-m O 224]
In the formula, M is a metal constituting the zeolite skeleton similarly to Si and Al. M is a metal having a tetracoordinate structure, and examples thereof include Ga and Fe. M is usually introduced by substituting Si or Al constituting the zeolite framework. These metals usually function as a catalyst of the present application by entering the zeolite framework. Whether or not these metals are in the zeolite framework can usually be confirmed by NMR or the like.
M ′ is not a metal constituting the zeolite skeleton but is present in the micropores and the outer surface of the zeolite. M ′ is mainly a metal having a six-coordinate structure, and may be Al or metal M (Ga or Fe), and may be an alkaline earth metal, rare earth, titanium group metal, vanadium group metal, or iron group metal. There may be. Examples of M ′ include Ca, Mg, Zr, Ti, La, Ce, Co, Zr, Ti, V, Al, Ga, and Fe.
When the precursors of these metals (M and M ′) are mixed in the raw material during the production of the zeolite, a part thereof enters the zeolite skeleton (that is, expressed as M) and does not enter the zeolite skeleton. Exists in the micropores and on the outer surface without constituting a zeolite framework (ie, expressed as M ′).
m is 0 or more, and n ′ + m is 12 or less.
y represents the valence of M (2, 3, 4, etc.).
x ′ represents a number such that the content of M ′ in the catalyst does not exceed 30% by weight.
M ′ is present in either or both of the form exchanged with H as an ion and the oxide form (M′O _{z / 2} ). z represents the valence of M ′ (1, 2, 3, 4, etc.).

The X-ray diffraction data includes the following values.
2θ = 6.56 ± 0.10, 6.88 ± 0.10, 8.16 ± 0.10, 8.80 ± 0.10, 9.70 ± 0.10, 19.50 ± 0.10 21.76 ± 0.10, 22.56 ± 0.10, 23.10 ± 0.10

This aluminosilicate MCM-68 can be produced, for example, as follows.
1. As a template for making MCM-68 (structure directing agent: SDA), N, N in 3 steps from bicyclo [2.2.2] oct-7-ene-2,3: 5,6-tetracarboxylic dianhydride , N ′, N′-Tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide is synthesized.
2. The gel obtained by mixing the iodide, colloidal silica, potassium hydroxide, aluminum hydroxide, and water is heated at 160 ° C. for 16 days in an autoclave. In addition to this component, a precursor (usually a metal salt) of the metal component (M or M ′) may be included as appropriate.
3. The crystals (as-synthesized sample) obtained by filtration are fired at 600 ° C. for 10 hours.

  In addition, once MCM-68 is prepared as described above, it is immersed in a solution of the above-mentioned metal component (M ′) precursor (usually metal salt) (solvent is ethanol, water, etc.) to evaporate the solvent. (Evaporation to dryness method) or removing the solvent by filtration (equilibrium adsorption method or ion exchange method). The content of M 'in -68 can be increased. The metal component (M ′) added in this way is present in the micropores and the outer surface without constituting a zeolite skeleton. Its content is up to 30% by weight with respect to the zeolite support.

(2) De-Al treatment (acid treatment) stage In this stage, the aluminosilicate MCM-68 is acid-treated so that the Si / Al (molar ratio) is 100-200.
The acid treatment is performed under the following conditions.
Examples of the acid include nitric acid, hydrochloric acid, and sulfuric acid. The acid is preferably used in an aqueous solution of about 1-6M.
In this aqueous solution, the aluminosilicate MCM-68 is heated at an oil bath temperature of about 80-130 ° C. for about 2-12 hours, preferably about 2-24 hours.
In order to set Si / Al (molar ratio) to a desired value, knowledge is obtained in advance about the degree of dealumination (Si / Al molar ratio) with respect to conditions such as acid type, concentration, treatment time, and temperature. Control by managing conditions.
The aluminosilicate thus obtained is also referred to as deAl-MCM-68.

The deAl-MCM-68 obtained at this stage is represented by the following composition formula.
_{M 'x H n + (4} -y) m [M m Al n Si 112-n-m O 224]
n represents a number such that the Si / Al ratio (molar ratio) is 100 to 200.
M, M ′, and y are defined in the same manner as described above.
m is 0 or more and n + m is 12 or less, provided that n + m is smaller than n ′ + m by the amount of Al removal treatment.
x represents a number such that the content of M ′ in the catalyst does not exceed 30% by weight.
M and M ′ are arbitrary, and when these are not included (that is, x = 0, m = 0), deAl-MCM-68 is represented by the following composition formula.
_{H n Al n Si 112-n} O 224
Further, the X-ray diffraction data of this deAl-MCM-68 includes the following values.
2θ = 6.56 ± 0.10, 6.86 ± 0.10, 8.16 ± 0.10, 8.80 ± 0.10, 9.68 ± 0.10, 19.48 ± 0.10 21.76 ± 0.10, 22.66 ± 0.10, 23.18 ± 0.10

The industrial process for producing light olefins from DME or methanol is usually carried out as follows.
A catalyst layer (0.1 g to 10 kg) held in a reaction tube (inner diameter: 4 mm to 400 mm, length: 100 mm to 10 m) is heated to 300 to 500 ° C., and DME or methanol is circulated in the gas phase together with an inert gas. The contact time (W / F) during the catalytic reaction is usually adjusted to be in the range of ^{1 to} 100 g-catalyst h mol ⁻¹ .

The following examples illustrate the invention but are not intended to limit the invention.
In this example, Si / Al was determined by a calibration curve method (aqueous solution mode) using an inductively coupled plasma atomic emission spectrometer (ICPE-9000 manufactured by Shimadzu Corporation).

(1) Synthesis of aluminosilicate Prior to the synthesis of aluminosilicate, N, N, N ', N'-tetraethylbicyclo [structure-directing agent (SDA) for crystallization of Al-MCM-68 2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide (TEBOP2 + (I-) 2) was prepared according to a previous report (Japanese translation 2002-535227).
Next, hydrothermal synthesis of Al-MCM-68 was performed using this SDA. Specifically, first, 6.01 g (40 mmol, SiO ₂ ) of colloidal silica (DuPont, LUDOX (registered trademark) HS-40, SiO ₂ : 40 wt%) in a fluororesin (PFA) container with an internal volume of 180 mL. Then, 312 mg (4.0 mmol) of Al (OH) ₃ (Pfaltz & Bauer) was dissolved and stirred for 10 minutes. Then KOH (8mol / L, 6.047mmol / g) a (Wako) was added, and stirred for 30 min and finally the structure directing agent ^{SDA (TEBOP 2+ (I -)} 2) 2.23g (4.0 mmol) was added 3 hours Stir. The gel composition ratio was SiO ₂ −0.1 TEBOP ²⁺ (I ⁻ ) ₂ −0.375 KOH-0.1 Al (OH) ₃ -30 H ₂ O. The prepared gel was transferred to a 125 mL autoclave and left in an oven at 160 ° C. for 16 days. The obtained product was centrifuged and then dried in an oven at 80 ° C. to obtain 2.55 g of white powder (Al-MCM-68 (as-synthesized)).

(2) Preparation of aluminosilicate catalyst The obtained Al-MCM-68 was calcined in a muffle furnace at 600 ° C for 10 hours to remove SDA contained in the aluminosilicate. At this time, the heating rate was set to 1 to 2 ° C./min. The solid sample after firing was confirmed to retain the MSE structure by powder X-ray diffraction.
Al-MCM-68 after firing was appropriately dealuminated by nitric acid treatment. Specifically, 45 mL of 0.5-10 M nitric acid aqueous solution was put into a 200-mL eggplant flask, and 1.5 g of baked Al-MCM-68 was added thereto, followed by stirring for 2 hours in an air atmosphere and under reflux conditions. . After the nitric acid treatment, filtration and washing with distilled water were performed, and then the collected solid was dried at 100 ° C. overnight. It was confirmed that the solid sample after the nitric acid treatment also retained the MSE structure by powder X-ray diffraction. Nitrogen treatment gave moderately dealuminated Al-MCM-68 (deAl-MCM-68, Si / Al ratio = 52, 100, 130, 177, 258 and 613).

For comparison, Al-MCM-68 without dealumination was also prepared. Ammonium ion exchange was performed to remove K cations present at the ion exchange site of Al-MCM-68 after firing. Specifically, after dissolving 3.0 g of ammonium nitrate (NH ₄ NO ₃ ) in 75 g of distilled water in a 250 mL-PP bottle, 1.5 g of baked Al-MCM-68 was added and heated at 80 ° C. for 24 hours. After heating, the solid sample was collected by filtration. After the ion exchange and filtration operations were repeated three times, the solid sample was dried to obtain ammonium-type Al-MCM-68. Thereafter, baking was performed at 550 ° C. for 6 hours in a muffle furnace to obtain proton type Al-MCM-68. It was confirmed that the solid sample after ion exchange and firing also retained the MSE structure by powder X-ray diffraction. This proton type Al-MCM-68 has a Si / Al ratio of 12, and it is considered that dealumination has not occurred.

(3) Catalytic reactor Prior to the catalytic reaction, powdered aluminosilicate was molded and sized. Specifically, 1 to 2 g of aluminosilicate powder was packed in a tablet molding machine having an inner diameter of 20 mm, and then press-molded at 0.2 MPa with a hydraulic press to obtain pellets having a diameter of 20 mm. The pellets were appropriately pulverized on a sieve and sized to 500 to 600 μm and used as a catalyst.
The catalytic reaction in this example was performed using a fixed bed normal pressure flow reactor.
When methanol was used as a reaction product, it was supplied from a syringe using a syringe pump and introduced into a methane (10%)-argon mixed gas as a carrier gas. The methanol supplied from the syringe pump was evaporated into a gas because it was introduced into the preheated vaporization chamber, and this gas was accompanied by the carrier gas. A stainless steel pipe with an inner diameter of 2 mm was used for the gas line of the reactor, and the vaporized methanol was prevented from condensing by heating from the outside to an appropriate temperature with a heater.
When DME was used as a reactant, it was supplied from a DME gas cylinder and introduced into a methane (1%)-argon mixed gas as a carrier gas. The process after introduction into the mixed gas was the same as that of methanol.
The reaction tube used was a quartz tube having an inner diameter of 8 mm, packed with 100 mg of the aluminosilicate catalyst previously sized, and the catalyst layer was held in the center of the reaction tube with quartz wool. As a pretreatment for the reaction, the temperature was raised to 500 ° C. at a rate of temperature increase of about 7 ° C./min under air flow, and this atmosphere was maintained for 1 hour. Then, after switching to helium flow, the reaction tube temperature was lowered to 400 ° C. for DME and 350 ° C. for methanol at 5 ° C./min. After confirming that the temperature was stable at the set temperature, a methane-argon mixed gas accompanied by DME or methanol was supplied to the catalyst layer to initiate a catalytic reaction. By switching the hexagonal valve at a predetermined time during the reaction, the reaction products accumulated in the sampling loop are introduced into the gas chromatograph, separated by a capillary column, and each product / unreacted product is detected by a hydrogen flame detector (FID). The reaction product was qualitatively and quantitatively determined. After a predetermined time (210 minutes) elapsed, the supply of DME or methanol to the catalyst layer was stopped, and the helium flow was switched to. The W / F during the catalytic reaction was 21.5 g-catalyst h (mol-DME) ⁻¹ and 43.0 g-catalyst h (mol-methanol) ⁻¹ . After stopping the catalytic reaction, it was allowed to cool naturally under a helium flow.

(4) Results Table 2 shows the results of the DME conversion reaction using each aluminosilicate catalyst, and Table 3 shows the results of the methanol conversion reaction. The yield of each product was determined as a percentage of the yield of each product relative to the amount of DME or methanol introduced. The yield is expressed on a carbon basis (C% conversion, C%). The numbers in parentheses in the catalyst notation represent the Si / Al ratio (atomic ratio).

表１と２から、メタノール又はＤＭＥを転換してオレフィンを製造する方法において、Ｓｉ／Ａｌ比（モル比）が１００〜２００のアルミノシリケートＭＣＭ−６８を触媒として用いた場合には、エチレンの収率を低く抑えて、Ｃ３以上のオレフィンの収率を顕著に高くすることができることがわかる。

From Tables 1 and 2, in the process for producing olefins by converting methanol or DME, when aluminosilicate MCM-68 having a Si / Al ratio (molar ratio) of 100 to 200 is used as a catalyst, the yield of ethylene is reduced. It can be seen that the yield of C3 or higher olefin can be remarkably increased by keeping the rate low.

Claims (2)

A method for selectively producing C3 or higher olefins by converting methanol or dimethyl ether, wherein aluminosilicate MCM-68 having a Si / Al ratio (molar ratio) of 100 to 200 is used as a catalyst.
The MCM-68 has the following composition formula M ′ _x H _{n + (4-y) m} [M _m Al _n Si _112-nm O ₂₂₄ ]
(In the formula, M is a metal with a tetracoordinate structure and represents Ga or Fe, M ′ is a metal with a hexacoordinate structure and is Al, Ga or Fe, an alkaline earth metal, a rare earth, a titanium group metal, It represents a vanadium group metal or an iron group metal, n represents a number such that the Si / Al ratio (molar ratio) is 100 to 200, m is 0 or more, n + m is 12 or less, and x is in the catalyst. The method according to claim 1, wherein the M ′ represents a number such that the content of M ′ is 30% by weight or less, and y represents the valence of M.