JP2008266286A - Method for producing alkene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly active method for stably carrying out dehydrogenation of alkanes over a long time while suppressing lowering of catalytic activity during reaction. <P>SOLUTION: The method for producing an alkene comprises dehydrogenating an alkane in an atmosphere containing carbon dioxide in the presence of a supported catalyst containing 1-20 wt.% chromium oxide expressed in terms of metal chromium. The catalyst support is one of zeolites selected from a group consisting of MFI, MEL, MOR, MWW, CHA, BEA and FAU structure or a mixture of a plurality of zeolites and contains a boron atom. The production method of the alkene in which silicon (Si) content is ≥35 wt.% and aluminum content is ≤0.3 wt.% based on the support weight enables stable dehydrogenation reaction. The production method enables stable dehydrogenation reaction of the alkane over further long time by treating the catalyst in the presence of the catalyst, oxygen and steam. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an alkene that is stable and highly active over a long period of time, in which a decrease in catalytic activity during the reaction is suppressed. Specifically, a method for producing an alkene using a catalyst having chromium oxide supported on a zeolite containing a boron atom, a method for producing an alkene in the presence of a catalyst obtained by treating the catalyst in an atmosphere coexisting with oxygen in advance, and the treatment The present invention relates to a method for producing alkenes by catalytically dehydrogenating alkanes in the presence of carbon dioxide gas in the presence of a catalyst.

  Methods for catalytically dehydrogenating alkanes to produce the corresponding alkenes are well known and various catalysts are known. Among them, a catalyst having chromium oxide supported on a carrier is considered to be one preferable for a dehydrogenation reaction in a carbon dioxide gas coexisting atmosphere.

For example, Non-Patent Document 1 discloses a method for producing propylene by dehydrogenating propane in an atmosphere containing carbon dioxide gas using a catalyst in which chromium oxide is supported on silicon dioxide having a specific surface area of 304 m ² / g. ing. Further, Patent Document 1 discloses that ethane is contained in an atmosphere containing carbon dioxide gas by a catalyst in which chromium oxide is supported on ZSM-5 having a silica / alumina (SiO ₂ / Al ₂ O ₃ ) ratio of 1900 and containing no boron atom. A method for producing hydrogen by dehydrogenation is disclosed.

Effect of supports on catalytic of of chromium oxide based catalytic in the dehydration of propoline with CO2 (Catalysis Letters 5-200) JP 2003-12570 A

  However, in these methods, it is described that the catalytic activity decreases relatively rapidly during the reaction, or has been clarified by the inventors' investigation. It is presumed that the carbon activity derived from the lower alkane subjected to the reaction is accumulated on the zeolite catalyst active surface supporting chromium oxide and the catalyst activity is lowered as the cause.

  The present invention has been made as a result of studies to improve the above-described present situation, and provides a catalyst with a small decrease in activity, and suppresses a decrease in catalyst activity during the reaction, and is stable and highly active over a long period of time. It is an object of the present invention to provide an alkane dehydrogenation method.

The present invention has been made as a result of the inventors' diligent study to solve the above-mentioned problems. Specifically, chromium oxide is supported on a zeolite carrier containing a boron atom, and is pretreated in a coexisting atmosphere of oxygen and steam. In the presence of the prepared catalyst, a method for producing alkenes by dehydrogenating alkane stably and highly active in an atmosphere containing carbon dioxide gas and oxygen has been found and the present invention has been completed.

That is, the first gist of the present invention is an alkene characterized in that alkane is dehydrogenated in an atmosphere containing carbon dioxide gas in the presence of a supported catalyst containing 1 to 20% by weight of chromium oxide in terms of metallic chromium. The catalyst support is a mixture of one or more zeolites selected from the group consisting of MFI, MEL, MOR, MWW, CHA, BEA, and FAU structures, and contains a boron atom. And it exists in the manufacturing method of the alkene as described in 1st invention which is 35 weight% or more and aluminum content are 0.3 weight% or less in conversion of silicon (Si) with respect to this support | carrier weight.

  The second gist of the present invention is characterized in that alkane is dehydrogenated in an atmosphere containing carbon dioxide gas in the presence of a supported catalyst containing 1 to 20% by weight of chromium oxide in terms of metallic chromium. A method for producing an alkene, wherein the catalyst support is a mixture of one or more zeolites selected from the group consisting of MFI, MEL, MOR, MWW, CHA, BEA, and FAU structures, and contains a boron atom And it exists in the manufacturing method of the alkene as described in 2nd invention which is 35 weight% or more in conversion of silicon (Si) and aluminum content is 0.3 weight% or less with respect to this zeolite weight.

  The third gist of the present invention is the alkene according to the first or second invention, wherein the catalyst is pretreated at a temperature of 300 to 900 ° C. in an atmosphere containing oxygen and steam. Exist in the manufacturing method.

  Moreover, the 4th summary of this invention exists in the manufacturing method of the alkene as described in 3rd invention which is dehydrogenating in the atmosphere containing a carbon dioxide gas and oxygen.

  According to the present invention, when an alkane is dehydrogenated to produce an alkene, the activity of the catalyst can be stably kept high for a long time.

In the present invention, the carrier is a base material that disperses and immobilizes chromium oxide, which is an active ingredient, and does not itself inhibit the target reaction. In general, silica, alumina, etc. are used. However, when zeolite is used as a carrier, the target product can be obtained by immobilizing the active ingredient into the skeleton lattice by ion exchange or by steric control by the zeolite pore shape. Potential for improved selectivity is also expected.
As the carrier, a zeolite selected from the group consisting of MFI, MEL, MOR, MWW, CHA, BEA, and FAU structure represented by a code stipulated by the International Zeolite Association (IZA) is used. You may mix and use.

The silicon (Si) contained in the carrier is preferably 35% by weight or more, more preferably 40% by weight or more based on the weight of the carrier. Aluminum (Al) is preferably not more than 0.3% by weight, more preferably not more than 0.2% by weight with respect to the weight of the support, and silicalite containing no aluminum is also included. Further, the boron (B) atom in the carrier is 0.01% by weight or more, more preferably 0.1% by weight or more with respect to the weight of the carrier.
Preferably, silicon (Si) contained in the support zeolite is 35% by weight or more, and more preferably 40% by weight or more based on the weight of the zeolite. Aluminum (Al) is preferably 0.3% by weight or less, more preferably 0.2% by weight or less based on the weight of zeolite, and silicalite containing no aluminum is also included.
Further, the boron (B) atom in the zeolite is 0.01% by weight or more, more preferably 0.1% by weight or more with respect to the weight of the zeolite.

The boron atom is preferably incorporated in the zeolite framework, but may be partially present outside the framework. In addition, various dealumination methods are used for the zeolite used as the carrier in order to increase the silicon / aluminum (Si / Al) ratio. As a result, even if some aluminum remains outside the zeolite framework, there is no problem. . Furthermore, it is preferable that the zeolite used for the carrier is preliminarily made into an H type by an ion exchange method, but as a result, even if some Na or the like remains on the zeolite, it does not matter.

Chromium oxide can be supported on the zeolite by a conventional method. In general, a solution of a chromium compound is impregnated in the zeolite and dried, and the chromium compound is supported on the zeolite.
Next, this is heat-treated at 300 to 1000 ° C., preferably 400 to 700 ° C. for 1 to 24 hours under air flow (hereinafter abbreviated as catalyst firing) to convert the chromium compound into chromium oxide.

The oxidation state and crystal structure of chromium oxide are not particularly limited, and the oxidation state may be any of divalent to hexavalent, and the chromium oxide may be crystalline or amorphous.
Examples of the chromium compound to be impregnated include inorganic acid salts such as chromium nitrate, chromium sulfate, and chromium chloride, and organic acid salts such as chromium acetate and chromium oxalate, as well as various kinds known for use in the production of chromium oxide catalysts. Things can be used.
The chromium content of the catalyst in terms of metal chromium {= (weight of chromium oxide in terms of metal chromium) / (weight of support zeolite + weight of chromium oxide in terms of metal chromium) × 100} is preferably 1 to 20% by weight. If the metal-converted chromium content of the catalyst is too low, the activity of the catalyst dehydrogenation reaction will be low, and if it is too high, not only will it be difficult to carry out a uniform support during catalyst preparation, but also active species chromium oxide and a carrier (for example, zeolite) ) Is reduced, and the supported effect is diminished.

  The catalyst may be used as a catalyst as it is, but is preferably molded using a binder that does not adversely influence the reaction. The molded body is not limited in any shape and size as long as it meets the purpose.

The molding method is not particularly limited. For example, a zeolite carrier molding method using a support zeolite such as alumina or alumina sol, silica, silica gel, quartz, and a mixture thereof, or a catalyst supporting a chromium compound in advance. There is a molding method in which a precursor or a powder or granule after preliminary firing is used as a binder, or a chromium compound (including a supported chromium compound) as a binder.

  The catalyst supporting chromium oxide is treated in an atmosphere in which oxygen and steam are present in advance, at least before the alkane dehydrogenation reaction, by any method, such as during the catalyst calcination, continuously after the catalyst calcination, or before the reaction. More preferably.

  In the treatment, the oxygen concentration in the atmosphere is 15% by volume or less, preferably 10% by volume or less, and more preferably 5% by volume or less. The treatment of the catalyst in the present application means that at least the catalyst used for the reaction is exposed under the target conditions (atmosphere, temperature, time).

  The steam concentration during the treatment of the catalyst is 1% by volume or more, preferably 10% by volume or more, based on the total feed gas.

  The treatment temperature of the catalyst is 300 to 900 ° C., preferably 400 to 800 ° C., the treatment time is 1 minute or more, and preferably 5 minutes or more and 24 hours or less in view of process reproducibility stability.

Although the mechanism of the chemical effect on the catalyst by this catalyst treatment is not clear, according to the study by the present inventors, the oxygen in the atmosphere exhibits an effect only when it coexists with steam. Therefore, oxygen in the atmosphere is considered to have a function of suppressing hydroxylation and / or overreduction by chromium steam treatment.

  In addition, it is presumed that the steam generates a silanol group and / or a boranol group on the zeolite surface and reacts with chromium oxide to stably coordinate the active species Cr. Alternatively, it is considered that steam causes deboronation, and it is assumed that chromium oxide is incorporated as an active species Cr in the skeleton portion from which boron is eliminated and is stabilized.

  The oxygen and steam used for the treatment need only be in the form of oxygen and steam when they reach the catalyst to be treated. Oxygen and steam that are generated by decomposition or the like before reaching the catalyst to be treated can be used alone or in combination. It is. Examples of the oxygen source include ozone, nitric oxide, hydrogen peroxide, and the like. However, if this reaction is operated as a single process, it is economically preferable to use air as the oxygen source and water as the steam source.

The alkane used for the dehydrogenation reaction is not particularly limited, and may have, for example, a branch, and a saturated / unsaturated bond group, an aromatic group, a cyclo ring group, or the like may exist in the branch. Atoms such as halogen, oxygen, nitrogen, phosphorus, sulfur may be present. Among these alkanes, an alkane having 2 to 5 carbon atoms is preferable, and examples thereof include ethane, propane, butane and pentane. Although dehydrogenation is possible even with a straight-chain carbon number of 5 or more, it is presumed that the conversion rate is low and that a low-carbon alkene is produced by dehydrogenolysis.
Examples of alkanes having a saturated / unsaturated bond in the side chain include 2-methylbutane, 2,2-dimethylpropane, 2-methylpentane, 1-pentene, 3-methyl-1-butene, 2-methyl- Examples include 1-butene, propyl alcohol, and butyl alcohol. Examples of alkanes having an aromatic group or cyclo ring in the side chain include ethylbenzene, propylbenzene, diethylbenzene, p-chloroethylbenzene, p-ethylsulfonic acid, p-butylstyrene, 2-cyclohexylbutane, and the like. .

  In the present invention, the corresponding alkenes (ethylene, propylene, butene and pentene) are produced from the alkanes described above, such as ethane, propane, butane and pentane. Further, 1,3-butadiene can be produced from butane if desired. This reaction is considered to pass through the route of butane → butene → 1,3-butadiene. In the case of butane, isobutene is produced from n-butane and n-butene is produced from isobutane by an isomerization reaction. Moreover, application to the dehydrogenation reaction from ethylbenzene to styrene is also possible.

  The dehydrogenation reaction is performed in an atmosphere containing carbon dioxide gas. The molar ratio of carbon dioxide gas to alkane subjected to the dehydrogenation reaction is usually 0.1 to 100, but 0.5 to 20 is preferable. When the molar ratio is too small, the activity of the catalyst dehydrogenation reaction is lowered. On the other hand, if the molar ratio is increased, the catalytic activity is increased, but the concentration of the produced alkene in the produced gas is lowered, which is economically disadvantageous.

  In addition, the molar ratio of oxygen to alkane and the oxygen concentration in the atmosphere used for the dehydrogenation reaction are usually 1.0 ratio or less and about 10% by volume or less, preferably 0.7 ratio or less and about 7% by volume or less.

  If no oxygen is present in the reaction atmosphere, the catalyst activity will decrease over time, increasing the number of catalyst regenerations to maintain the target production volume, or filling the reactor with a catalyst amount in anticipation of a decrease in activity in advance. It is economically undesirable. On the other hand, if the oxygen ratio to the alkane and the oxygen concentration in the atmosphere are too high, the combustion reaction of the alkane and the produced alkene is promoted and the selectivity of the target product is lowered, which is economically undesirable.

  It is inferred that oxygen in the reaction atmosphere contributes to the removal of carbonaceous material accumulated on the catalyst active surface by oxidation, stabilization of the valence of active species chromium, and partial oxidative dehydrogenation.

  In the atmosphere, a gas such as nitrogen, helium, argon, or water vapor may coexist in addition to the carbon dioxide gas and oxygen. Therefore, the combustion exhaust gas of fossil fuels such as coal and petroleum can be used as the atmospheric gas.

  The temperature of the dehydrogenation reaction is usually 300 to 1000 ° C., but even within this range, the activity of the catalyst is reduced near the lower limit, and the alkane thermal decomposition reaction occurs near the upper limit, and the alkene selectivity is lowered. At the same time, the catalyst is likely to deteriorate. Therefore, the dehydrogenation reaction is preferably performed at 400 to 800 ° C.

The reaction pressure may be appropriately selected depending on the alkane used for the reaction, but is usually 1 MPa or less, preferably 0.5 MPa or less, and the reaction is preferably performed at a low pressure in view of the reaction equilibrium.
Usually, the reaction is carried out by a fixed bed reaction system in which a mixture of a raw material alkane, carbon dioxide gas, and atmospheric gas containing oxygen is passed through a reactor filled with a catalyst.

  The space velocity is in the range of 0.001 to 1000 / hr, preferably in the range of 0.01 to 100 / hr. If the space velocity is too high, the dehydrogenation conversion rate of the raw material alkane is low, and if the space velocity is too low, the amount of catalyst necessary to obtain a certain production amount increases and the reactor becomes too large. This is not preferable because the selectivity of the product alkene decreases. The space velocity mentioned here is the total weight flow rate per hour of the reaction raw material alkane, carbon dioxide gas, oxygen and inert gas such as nitrogen per catalyst weight, and the catalyst weight is the catalyst filled in the reaction tube. Total weight.

  The reactor may be filled with one type of catalyst, or a plurality of types of catalysts having different activities may be mixed or packed in layers. If desired, use multiple types of catalysts with different activities, or one type of catalyst and an inert inorganic substance used as a diluent, and fill the catalyst so that the activity changes from the reactor inlet to the outlet. It is also possible to do.

  Note that the dehydrogenation reaction can be carried out by a fluidized bed reaction system, a moving bed reaction system, or the like in addition to the fixed bed reaction system. In addition, the catalyst whose activity has been reduced by use in the dehydrogenation reaction can be recovered in catalytic activity by heating to 300 ° C. or higher, preferably 400 to 700 ° C. in an oxygen-containing gas.

The reactor outlet gas varies depending on the reaction raw material, but the target product of the reaction is an alkene typified by ethylene, propylene, butene, etc., an aromatic alkene typified by styrene, or a diene typified by 1,3-butadiene. Gas mixtures containing the desired dehydrogenation products, carbon monoxide, hydrogen, unreacted raw materials, by-products and diluents added separately to the reaction, etc. are introduced into known separation / purification facilities, Recovery, purification, recycling, and discharge processing may be performed according to the components.
It is preferable that some or all of alkanes, alkenes, and the like, which are components other than the target product, are recycled after being separated and purified and mixed with the reaction raw materials or supplied directly to the reactor. In addition, among the by-products, components inactive to the reaction can be reused as a diluent.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples unless it exceeds the gist.

[Example 1]
<Carrier synthesis>
7.44 g of boric acid (H ₃ BO ₃ ) dissolved in 150 g of water by heating was slowly added to a stirring solution prepared by dissolving 62.1 g of water glass and 16.0 g of tetra-n-propylammonium bromide (TPABr) in 30 g of water, The gel was sufficiently stirred for 1 hour or more to obtain an aqueous gel. Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 170 ° C. for 72 hours under an autogenous pressure. Thereafter, the hydrothermally synthesized solid component separated and recovered by filtration was sufficiently washed at 100 ° C. after sufficiently washed with water.
The obtained dried product was subjected to air flow at 550 ° C. for 6 hours to obtain Na-type aluminosilicate.

  2.0 g of this Na type aluminosilicate was suspended in 40 cc of 1M ammonium nitrate aqueous solution and stirred at 80 ° C. for 2 hours. After the treatment, the solid component was separated by suction filtration, sufficiently washed with water, then suspended again in 40 cc of 1M aqueous ammonium nitrate solution, and stirred at 80 ° C. for 2 hours. The liquid after the treatment was separated by solid filtration by suction filtration, sufficiently washed with water, and then dried at 100 ° C. for 24 hours. The dried product was fired at 500 ° C. for 4 hours under air flow to obtain an H-type aluminosilicate.

  The obtained H-type aluminosilicate had a zeolite structure of MFI type by XRD (X-ray diffraction), and as a result of elemental analysis, 44.9% by weight of silicon (Si), 0.04% by weight of aluminum (Al), Boron (B) 0.41 wt%, sodium (Na) <0.01 wt%. From these values, the silicon / aluminum (Si / Al) ratio of the synthetic MFI structure zeolite is 1078, and silicon / boron (Si / B) The ratio was confirmed to be 42.2.

<Catalyst preparation>
Chromium nitrate 9 hydrate dissolved in 0.88 g of water in 1 g of synthetic MFI structure zeolite [Cr
_{(NO 3) 3 · 9H 2} O] 0.2709g was added, after impregnation, and thoroughly dried in a rotary evaporator. The dried product was dried at 120 ° C. for 10 hours or more and then calcined at 550 ° C. for 6 hours under air flow to prepare a catalyst. As a result of elemental analysis, the Cr content of the obtained catalyst was 3.4% by weight.

<Catalyst pretreatment>
0.5 g of the obtained catalyst was diluted with 2 ml of quartz sand and filled into a quartz reaction tube having an inner diameter of 7 mm, and a catalyst layer under a mixed gas feed of oxygen of 0.59 ml / min and nitrogen of 31.1 ml / min was 600. After raising the temperature to 0 ° C., water was fed to the reaction tube at a rate of 0.02 ml (liquid) / min to start the treatment. The feed composition at this time is O ₂ / N ₂ / H ₂ O = 0.02 / 1.0 / 0.8 molar ratio. The treatment was completed in 60 minutes, and the temperature was lowered to room temperature at the same time as the water feed was stopped.

<Reaction>
The pretreated catalyst was heated to 600 ° C. under a mixed gas flow of oxygen 0.6 ml / min, nitrogen 9.1 ml / min and carbon dioxide 50.3 ml / min, and then propane 7.2 ml / min. The reaction was started by feeding. The feed composition at this time is O ₂ / N ₂ / CO ₂ /propane=0.08/1.3/7.0/1.0 molar ratio.

  The reaction tube outlet gas was measured by gas chromatography, and the propane conversion and the propylene selectivity were determined. The results are shown in Table-1. In the table, the conversion ratio after 360 minutes to the reaction after 15 minutes is shown. However, when the reaction time is less than 360 minutes, the conversion ratio of the final time is shown. The amount of carbon accumulated in the catalyst after completion of the reaction was analyzed by a high-frequency furnace combustion-non-dispersive infrared detection method. As a result, it was 0.13% by weight.

[Example 2]
A dehydrogenation reaction from propane to propylene was performed in exactly the same manner as in Example 1 except that the evaluation time was continued up to about 70 hours. The results are shown in Table-2.
[Example 3]
A dehydrogenation reaction from propane to propylene was carried out in the same manner as in Example 1 except that the catalyst pretreatment was omitted. The results are shown in Table-1. The amount of carbon accumulated in the post-reaction catalyst measured by the same method as in Example 1 was 2.96% by weight.
[Example 4]
Dehydration from propane to propylene in exactly the same manner as in Example 1 except that the feed during the catalyst pretreatment was 8.4 ml / min of nitrogen, 24.1 ml / min of carbon dioxide and 0.02 ml (liquid) / min of water. An elementary reaction was performed. The feed composition at the catalyst pretreatment is N ₂ / CO ₂ / H ₂ O = 1.0 / 2.9 / 3.0 molar ratio. The results are shown in Table-1.
[Example 5]
The amount of feed gas at the time of reaction was 0.91 g, oxygen was 0.3 ml / min, nitrogen was 4.2
The dehydrogenation reaction from propane to propylene was carried out in exactly the same manner as in Example 1 except that ml / min, carbon dioxide 23.1 ml / min and propane 3.3 ml / min were used. Feed composition at this time _{is O 2 / N 2 / CO 2} / propane = 0.08 / 1.3 / 7.0 / 1.0 molar ratio. The results are shown in Table-1.
[Comparative Example 1]
Water 230g was added to sodium hydroxide (NaOH) 4.8 g, stirring aluminum nitrate nonahydrate _{[Al (NO 3) 3 ·} 9H 2 O] in solution was slowly added 1.25g boric acid 12.4g Then, a mixed solution of 26.6 g of tetra-n-propylammonium bromide (TPABr) and 50 g of water was added. Next, a mixture of 75.1 g of 40% silica sol aqueous dispersion (Snowtex 40: manufactured by Nissan Chemical Co., Ltd.) and 35.0 g of water is slowly added with stirring. Obtained. Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 170 ° C. for 72 hours under an autogenous pressure. Thereafter, the hydrothermally synthesized solid component separated and recovered by filtration was sufficiently washed at 100 ° C. after sufficiently washed with water.
The obtained dried product was subjected to air flow at 550 ° C. for 6 hours to obtain Na-type aluminosilicate.

2.0 g of this Na type aluminosilicate was suspended in 40 cc of 1M ammonium nitrate aqueous solution and stirred at 80 ° C. for 2 hours. The processed liquid is separated by solid filtration by suction filtration,
After sufficiently washing with water, it was dried at 100 ° C. for 24 hours. The dried product was fired at 500 ° C. for 4 hours under air flow to obtain an H-type aluminosilicate.

  The obtained H-type aluminosilicate had a zeolite structure of MFI type by XRD (X-ray diffraction), and as a result of elemental analysis, silicon (Si) 46.1% by weight, aluminum (Al) 0.43% by weight Boron (B) 0.30 wt%, sodium (Na) <0.01 wt%, and from these values, the silicon / aluminum (Si / Al) ratio of the synthetic MFI structure zeolite is 103, silicon / boron ( It was confirmed that the Si / B) ratio was 59.

<Catalyst preparation>
It was prepared in exactly the same manner as in Example 1 except that the synthetic MFI structure zeolite was used.
<Catalyst pretreatment>
The catalyst support was treated in exactly the same manner as in Example 1 except that the synthetic MFI zeolite was used.
<Reaction>
A dehydrogenation reaction from propane to propylene was carried out in exactly the same manner as in Example 1 except that the pre-treated synthetic MFI structure zeolite was used as the catalyst carrier. The results are shown in Table-1.
[Comparative Example 2]
<Catalyst preparation>
In 3.1 g of ion exchange water, 0.8548 g of chromium nitrate.9 hydrate [Cr (NO ₃ ) ₃ .9H ₂ O] was dissolved. Silica (CARIACT Q-15 specific surface area 177 m ² / g, average pore diameter 180 mm, pore volume 1.03 ml / g, particle diameter 0.85 to 1.7 mm: manufactured by Fuji Silysia Chemical Co., Ltd. ) 3.15 g was added, silica was impregnated with an aqueous solution, and then dried under reduced pressure at about 90 ° C. using a rotary evaporator. Furthermore, after drying at 120 degreeC with a dryer overnight, it baked for 3 hours at 650 degreeC by air circulation, and obtained the catalyst which contains 3.4 weight% of chromium oxide in conversion of metal chromium.

<Catalyst pretreatment>
The catalyst support was treated in exactly the same manner as in Example 1 except that 2.3 ml of the catalyst, which was silica instead of the synthetic MFI structure zeolite, was packed without dilution.
<Reaction>
A dehydrogenation reaction from propane to propylene was performed following the catalyst pretreatment in the same manner as in Example 1 except that the catalyst support was silica instead of the synthetic MFI structure zeolite. The results are shown in Table-1.
[Comparative Example 3]
230 g of water was added to 4.8 g of sodium hydroxide (NaOH), and a mixed solution of 26.6 g of tetra-n-propylammonium bromide (TPABr) and 50 g of water was added with stirring. Next, a mixture of 75.1 g of 40% silica sol aqueous dispersion (Snowtex 40: manufactured by Nissan Chemical Co., Ltd.) and 35.0 g of water is slowly added with stirring. Obtained. Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 170 ° C. for 72 hours under an autogenous pressure. Thereafter, the hydrothermally synthesized solid component separated and recovered by filtration was sufficiently washed at 100 ° C. after sufficiently washed with water.
The obtained dried product was subjected to air flow at 550 ° C. for 6 hours to obtain Na-type aluminosilicate.

2.0 g of this Na type aluminosilicate was suspended in 40 cc of 1M ammonium nitrate aqueous solution and stirred at 80 ° C. for 2 hours. The processed liquid is separated by solid filtration by suction filtration,
After sufficiently washing with water, it was dried at 100 ° C. for 24 hours. The dried product was fired at 500 ° C. for 4 hours under air flow to obtain an H-type aluminosilicate.

  The obtained H-type aluminosilicate has a zeolite structure of MFI type by XRD (X-ray diffraction) and, as a result of elemental analysis, the synthetic MFI-structured zeolite has a silicon / aluminum (Si / Al) ratio of 1454. And no boron.

<Catalyst preparation>
It was prepared in exactly the same manner as in Example 1 except that the synthetic MFI structure zeolite was used.
<Catalyst pretreatment> The catalyst carrier was treated in the same manner as in Example 1 except that the synthetic MFI structure zeolite was used. The results are shown in Table-1.
[Example 6]
A dehydrogenation reaction from ethane to ethylene was carried out in the same manner as in Example 1 except that ethane was used instead of propane. The results are shown in Table-1.

[Example 7]
A dehydrogenation reaction from n-butane to butene and further to 1,3-butadiene was carried out in the same manner as in Example 1 except that n-butane was used instead of propane. The results are shown in Table-3.

[Example 8]
Exactly the same as Example 1 except that isobutane was used instead of propane
Then, a dehydrogenation reaction from isobutane to butene and further to 1,3-butadiene was carried out. The results are shown in Table-3.

[Example 9]
A dehydrogenation reaction from propane to propylene was carried out in the same manner as in Example 1 except that the catalyst pretreatment temperature was 535 ° C. and the treatment was completed in 6 minutes. The results are shown in Table-1.

[Example 10]
The catalyst pretreatment is 3.9 ml / min for oxygen and 27.5 ml / min for nitrogen gas mixture, and the catalyst layer is heated to 550 ° C and then water is fed to the reaction tube at a rate of 0.02 ml (liquid) / min. Started processing. The feed composition at this time is O ₂ / N ₂ / H ₂ O = 0.14 / 1.0 / 0.9 molar ratio. The dehydrogenation reaction from propane to propylene was carried out in the same manner as in Example 1 except that the treatment was completed in 6 minutes. The results are shown in Table-1.

[Example 11]
A catalyst pretreated in the same manner as in Example 1 except that the catalyst pretreatment temperature was 550 ° C. and the treatment was completed in 6 minutes, oxygen 0.3 ml / min, nitrogen 9.5 ml / min, and carbon dioxide were used. Under a mixed gas flow of carbon 50.3 ml / min, the temperature was raised to 600 ° C., and then the reaction was started by feeding propane at a rate of 7.2 ml / min. At this time, the feed composition was O ₂ / N ₂ / CO ₂ /propane=0.04/1.3/7.0/1.0 molar ratio from propane in exactly the same manner as in Example 1. A dehydrogenation reaction to propylene was performed. The results are shown in Table-1.

[Example 12]
A catalyst pretreated in the same manner as in Example 1 except that the catalyst pretreatment temperature was 550 ° C. and the treatment was completed in 6 minutes, nitrogen 9.8 ml / min and carbon dioxide 50.3 ml / min were used. Under a mixed gas flow, the temperature was raised to 600 ° C., and then the reaction was started by feeding propane at a rate of 7.2 ml / min. At this time, the dehydrogenation reaction from propane to propylene was carried out in the same manner as in Example 1 except that the feed composition was N ₂ / CO ₂ /propane=1.4/7.0/1.0 molar ratio. went. The results are shown in Table-1.

Claims (4)

  A method for producing an alkene, comprising dehydrogenating an alkane in an atmosphere containing carbon dioxide gas in the presence of a supported catalyst containing 1 to 20% by weight of chromium oxide in terms of metallic chromium, the catalyst carrier Is a mixture of one or more zeolites selected from the group consisting of MFI, MEL, MOR, MWW, CHA, BEA, and FAU structures, containing boron atoms, and based on the weight of the carrier, A method for producing an alkene having a silicon (Si) content of 35% by weight or more and an aluminum content of 0.3% by weight or less.   A method for producing an alkene, comprising dehydrogenating an alkane in an atmosphere containing carbon dioxide gas in the presence of a supported catalyst containing 1 to 20% by weight of chromium oxide in terms of metallic chromium, the catalyst carrier Is a mixture of one or more zeolites selected from the group consisting of MFI, MEL, MOR, MWW, CHA, BEA, and FAU structures, containing boron atoms, and based on the weight of the zeolite, A method for producing an alkene having a silicon (Si) content of 35% by weight or more and an aluminum content of 0.3% by weight or less.   The method for producing an alkene according to claim 1 or 2, wherein the catalyst is pretreated at a temperature of 300 to 900 ° C in an atmosphere containing oxygen and steam.   The alkane production method according to claim 3, wherein the alkane is dehydrogenated in an atmosphere containing carbon dioxide gas and oxygen.