JP2001079397A - Tin-rhenium complex oxide catalyst for selective oxidation reaction of lower alkane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for selective oxidation reaction, which is composed of a new Sb-Re complex oxide and capable of catalyzing the selective oxidation to an alkene such as isobutylene and/or an oxygen containing compound such as methacrolein in the presence of an excess amount of oxygen and to provide a method for producing the alkene such as isobutylene and/or the oxygen containing compound such as methacrolein from isobutane or the like using the catalyst for the selective oxidation reaction, which is composed of the Sb-Re complex oxide. SOLUTION: An alkene such as isobutylene or an oxygen containing compound such as methacrolein corresponding to a lower alkane is produced by subjecting the lower alkane such as isobutane to vapor phase catalytic oxidation at 400 to 600 deg.C in the presence of gaseous molecular oxygen of 30 to 60 kPa by using a Sb-Re complex oxide catalyst such as SbRe2O6 or Sb4Re2O13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an Sb-Re selective oxidation catalyst and an alkene such as isobutylene from a lower alkane such as isobutane in the presence of an excess of oxygen by using such a catalyst for Sb-Re selective oxidation reaction. And / or a method for producing an oxygen-containing compound such as methacrolein.

[0002]

2. Description of the Related Art There have been many proposals for the production of methacrolein by gas-phase catalytic oxidation using isobutylene or tertiary butyl alcohol as a raw material. In recent years, a method has been proposed in which isobutane, which is less expensive than isobutylene or tertiary butyl alcohol, is used as a raw material and is subjected to gas-phase catalytic oxidation using molecular oxygen in the presence of a catalyst, whereby methacrolein and the like can be produced. However, the reactivity was poor and not always satisfactory.

[0003] Although a method of raising the oxidation reaction temperature and increasing the conversion rate has been considered, there has been a drawback that excessive oxidation of methacrylic acid or methacrolein, which is the target substance, occurs and the selectivity decreases. JP-A-2-42034 proposes a method for producing methacrolein from isobutane using a phosphorus-molybdenum-based Keggin-type heteropolyacid-based catalyst, but has a problem in heat resistance of such a catalyst. Also,
JP-A-5-178774 and JP-A-5-33108
No. 5 discloses a method using a composite oxide catalyst containing divanadyl pyrophosphate as a main component, but has a problem that a satisfactory selectivity improving effect cannot always be obtained. Further, when preparing a divanadyl pyrophosphate-based catalyst, it is common to use vanadium pentoxide as a vanadium raw material, but since vanadium pentoxide is highly toxic, it is not preferable from an environmental health standpoint. There was a problem. As a solution to the above problems, Japanese Patent Application Laid-Open No. H11-114418 proposes a composite oxide catalyst containing Nb-Mo-Sb as an essential component, which has excellent heat resistance and excellent conversion and selectivity.

In the above-mentioned oxidation reaction, the oxidation reaction and the reduction reaction are constantly repeated on the catalyst, and the catalytic function is maintained by the balance of the oxidation-reduction reaction. However, if the amount of oxygen relative to the raw material drops significantly for some reason, for example, due to an operation error or a local runaway reaction,
The catalyst is reduced, the crystal phase of the chemical species constituting the catalyst changes, and catalyst deterioration is accelerated. JP-A-61-332
No. 34 proposes a means for recovering the catalytic function by oxidizing the deteriorated catalyst, but there is a demand for the development of a catalyst having higher reduction resistance and a catalyst having higher activity and selectivity.

[0005]

The catalysts containing rhenium (Re) exhibit unique activities with respect to the selective hydrogenation and dehydrogenation of organic compounds and the hydrodesulfurization of crude oils, and for these reactions the rhenium compounds have the corresponding Mo It is widely used in many industrial production processes such as refining of petroleum feedstocks and metathesis of alkenes because it has higher activity than catalysts containing W and W. However, as an application relating to the catalytic oxidation reaction, it is only reported that a rhenium compound reacts with ethanol and methanol and reacts as a promoter (such as Co, Mo and V catalyst) in the selective oxidation of alkenes and aromatics. .

On the other hand, antimony (Sb) is V-Sb-
O, Sn-Sb-O, Mo-Sb-O, Fe-Sb-
It has been established that it is one of the important elements in many active selective oxidation reaction catalysts such as O and Nb-Mo-Sb-O. However, it was not known that the Sb-Re composite oxide was useful as a catalyst for a selective oxidation reaction of lower alkanes.

An object of the present invention is to provide a catalyst for the selective oxidation reaction of a lower alkane such as isobutane, particularly to selectively oxidize an alkene such as isobutylene and / or an oxygen-containing compound such as methacrolein in the presence of excess oxygen. Catalyst for selective oxidation reaction comprising a novel Sb-Re composite oxide capable of
An object of the present invention is to provide a method for producing an alkene such as isobutylene and / or an oxygen-containing compound such as methacrolein from isobutane using a selective oxidation reaction catalyst comprising the Re-Sb composite oxide.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and based on the electron configuration of rhenium, the oxides of rhenium were vanadium (V) and molybdenum (M
Based on the finding that it has the same potential as a catalyst for selective oxidation reaction of o) and tungsten (W), a composite oxide of such rhenium oxide and the above-mentioned antimony oxide, in particular, two novel compounds were prepared. , Such Re-S
b When isobutane is subjected to gas-phase catalytic oxidation in the presence of a molecular oxygen-containing gas using the composite oxide as a selective oxidation reaction catalyst, isobutylene and / or methacrolein are selectively produced even in the presence of excess oxygen. To complete the present invention.

That is, the present invention provides an Sb-Re composite oxide
Selective oxidation of lower alkanes characterized by consisting of
Catalyst (claim 1) or Sb-Re complex oxide
Re _TwoO₆, Sb_FourRe_TwoO₁₃Or SbOREO_Four・ 2H_TwoO
The lower alkane according to claim 1, wherein
The catalyst for selective oxidation reaction (Claim 2) and the lower alkane
3. The composition according to claim 1, wherein the substance is isobutane.
The catalyst for the selective oxidation reaction of lower alkanes (Claim 3)
I do.

[0010] The present invention also provides an Sb-Re composite oxide catalyst.
Gas in the presence of oxygen
Corresponding alkene and / or characterized by phase contact oxidation
Is a method for producing the corresponding oxygen-containing compound (Claim 4), or Sb-
Re composite oxide is SbRe _TwoO₆, Sb_FourRe_TwoO₁₃Or
SbOREo_Four・ 2H_TwoO
4. Preparation of the corresponding alkene and / or the corresponding oxygenate described in 4.
And the lower alkane is isobutane.
The corresponding alkene is isobutylene and the corresponding oxygenated
5. The compound according to claim 4, wherein the compound is methacrolein.
Or the corresponding alkene and / or the corresponding oxygenate described in 5
Production method (Claim 6) and gas phase catalytic oxidation
Is performed within a range of 30 to 60 kPa.
7. The corresponding alkene and / or according to any one of claims 4 to 6.
Is a method for producing the corresponding oxygen-containing compound (claim 7),
That the catalytic oxidation is performed at a high temperature of 400 to 600 ° C.
A corresponding alkene according to any of claims 4 to 7, characterized in that
And / or a method for producing a corresponding oxygen-containing compound (claim 8)
Related.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst for selective oxidation reaction of lower alkanes such as isobutane of the present invention is SbRe ₂ O ₆ , Sb ₄ R
characterized by comprising the e ₂ O ₁₃ or SbOReO ₄ · 2H ₂ Sb-Re compound oxide such as O. Further, the method for producing an oxygen-containing compound such as an alkene such as isobutylene and / or methacrolein according to the present invention comprises the step of bringing a lower alkane such as isobutane into contact with a gas containing a molecular oxygen-containing gas in the presence of an Sb-Re composite oxide catalyst. It is characterized by oxidation.

In the present invention, the Sb-Re composite oxide (do
As the double oxide), any oxide may be used as long as it is an oxide in the form of a compound of a metal oxide of antimony and rhenium. For example, SbRe ₂ O ₆ , Sb ₄ Re
Specific examples thereof include ₂ O ₁₃ and SbOREO ₄ .2H ₂ O. Further, the Sb-Re composite oxide of the present invention may contain a metal other than Sb and Re and an oxide of the metal as long as the catalytic activity is not impaired.

As a method for producing the Sb-Re composite oxide, a known method for producing a composite oxide can be used, for example, mixing and heating metal oxides.
For the produced composite oxide, X-ray diffraction, X-ray diffraction,
By examining the crystal structure, valence, and vibration mode using line photoelectron spectroscopy and Raman spectroscopy, the composition and structure can be confirmed.

The lower alkane in the present invention refers to a normal temperature aliphatic saturated hydrocarbon having all single carbon bonds and no unsaturated bond such as a double bond or triple bond in the molecule, Specifically, lower alkanes such as isobutane, n-butane, propane, and pentane can be mentioned.Also, as the corresponding alkene, isobutylene, n-butylene, propylene, pentene, and the like, and as the corresponding oxygen-containing compound, And lower oxides of lower alkanes, such as methacrolein and propylene aldehyde.

In the present invention, examples of the molecular oxygen-containing gas include pure oxygen gas, oxygen-containing gas such as air, and the like.
In the presence of a catalyst for selective oxidation reaction comprising a composite oxide, a raw material gas comprising a mixed gas obtained by adding a molecular oxygen-containing gas and a diluent gas to a lower alkane gas such as isobutane, for example, is fixed bed containing the catalyst. It can be performed by introducing into a reactor. Examples of the diluting gas include nitrogen, carbon dioxide, helium gas, water vapor, and a mixed gas thereof.

In the selective oxidation reaction of a lower alkane such as isobutane using the selective oxidation reaction catalyst comprising the Sb-Re composite oxide of the present invention, in the presence of excess oxygen, for example, an oxygen partial pressure of 30 to 60 kPa, preferably Is 35 to 55 kPa
It is advantageous to carry out the reaction within the range of since the conversion of isobutane can be increased without lowering the selectivity of the alkene and / or oxygenate. Further, by setting the reaction temperature in the selective oxidation reaction to 400 ° C. or higher, preferably 500 to 600 ° C., the conversion of isobutane can be increased without lowering the selectivity of isobutylene and / or methacrolein. It is advantageous.

[0017]

The present invention will be described in more detail with reference to the following examples, but the technical scope of the present invention is not limited to these examples. The conversion, the selectivity, and the yield in Examples will be described with reference to the production of isobutylene and / or methacrolein by the selective oxidation of isobutane as an example. Isobutane conversion = (moles of reacted isobutane) /
(Mol number of supplied isobutane) × 100 isobutylene selectivity = (mol number of generated isobutylene) / (mol number of reacted isobutane) × 100 methacrolein selectivity = (mol number of generated methacrolein) / (reaction Number of moles of isobutane obtained) × 100 Selectivity of active ingredient = (selectivity of isobutylene) + (selectivity of methacrolein) Yield of methacrolein = (number of moles of formed methacrolein) / (number of moles of supplied isobutane) × 100 Yield of isobutylene = (mol number of generated isobutylene) / (mol number of supplied isobutane) × 100

Example 1 (Preparation of Sb-Re complex oxide catalyst) 2.8 g of rhenium (VII) oxide [Re ₂ O ₇ ] (manufactured by Soekawa; purity 99.99%) was placed in a Teflon autoclave. 2 ml of deionized water was added. 1.7g to this
Of antimony (III) oxide [Sb ₂ O ₃ ] (Soekawa; purity 99.99%) was added at room temperature with vigorous stirring, then the autoclave was sealed and heated at 200 ° C. for 24 hours, and further at room temperature for 6 days. the samples obtained by maturing and dried under reduced pressure to give the SbOReO ₄ · 2H ₂ O.
Further, this SbOREO ₄ .2H ₂ O is spray-dried and calcined to obtain rhenium (Re) or antimony (III) oxide.
And baked at 500 ° C. to form SbRe ₂ O ₆ and Sb ₄
A composite oxide catalyst of Re ₂ O ₁₃ was obtained. Next, using an X-ray diffractometer (manufactured by Rigaku Corporation), an X-ray photoelectron spectrometer (manufactured by Rigaku Corporation), and a Raman spectrometer (manufactured by JASCO Corporation),
By analyzing the vibration modes, it was confirmed that the obtained compounds were novel Sb-Re oxidation complexes SbRe ₂ O ₆ and Sb ₄ Re ₂ O ₁₃ .

Example 2 (Selective oxidation reaction of isobutane with SbRe ₂ O ₆ ) SbRe ₂ O which is a composite oxide catalyst obtained above
₆ (0.3 g) was charged into a quartz reaction tube, and a selective oxidation reaction of isobutane was performed using a fixed bed fluidized reaction system shown in FIG. In FIG. 1, 1 is an isobutane cylinder, 2
Is propane cylinder, 3 is oxygen gas cylinder, 4 is helium gas cylinder, 5 is isobutane MFC (mass flow controller), 6 is propane MFC (mass flow controller), 7 is oxygen gas MFC (mass flow controller), 8 is helium gas MFC (mass flow controller) ), 9 is a diaphragm pump, 10 is a flow control valve, 11 is a four-way valve, 12 is a pressure gauge, 13 is a reaction tube, 14 is a needle valve, 15 is a pinhole, 16 is an art sampler, 17 is gas chromatography, 1
8 denotes a mass flow controller, and 19 denotes a rotary pump.

The reaction tube 13 filled with the catalyst is placed in an electric furnace (not shown) controlled by a temperature controller for 500 minutes.
After adjusting the temperature to ℃, the mass flow controller 18
A mixed gas consisting of 18% by volume of isobutane, 36% by volume of oxygen and 44% by volume of helium is converted to about 2500 / h
The gas was introduced into the reactor at a gas hourly space velocity (GHSV) to cause a selective oxidation reaction. The product formed by this reaction is analyzed by gas chromatography, and from the analysis results, the conversion of isobutane, the yield of methacrolein, the yield of isobutane, and the effective amount of methacrolein and isobutylene are calculated according to the above formulas. The selectivity of the components, the selectivity of methacrolein and the selectivity of isobutylene were calculated. The result is shown in FIG. The isobutane conversion is about 6-7% and the methacrolein yield is about 3
%, Isobutylene yield was approximately 2-3%. The selectivity to the active ingredient was about 80 to 90%. From these results, it was found that this catalyst causes a highly stable selective oxidation reaction.

[0021] SbOReO ₄ · an Example 3 (isobutane selective oxidation reaction with SbOReO ₄ · 2H ₂ O) composite oxide catalyst obtained above
2H ₂ O (0.3 g) was charged into a quartz reaction tube, and a selective oxidation reaction of isobutane was performed in the same manner as in Example 2. The result is shown in FIG. The isobutane conversion was around 2%, the methacrolein yield was about 1%, and the isobutylene yield was about 0.5-1%. The selectivity to the active ingredient was about 80%. From these results, it was found that a highly stable selective oxidation reaction also occurred in this catalyst.

Example 4 (Selective oxidation reaction of isobutane with Sb ₄ Re ₂ O ₁₃ ) The composite oxide catalyst Sb ₄ Re ₂ O obtained above was obtained.
₁₃ (0.3 g) was charged into a quartz reaction tube, and a selective oxidation reaction of isobutane was carried out in the same manner as in Example 2. FIG. 4 shows the results. The isobutane conversion was about 4 to 6%, the yield of methacrolein was about 2 to 3%, and the yield of isobutylene was about 1 to 2%. Each of the active ingredients tended to increase with time. Selectivity to about 8
It was found that a highly stable selective oxidation reaction of 0 to 90% occurred.

Example 5 (Effect of partial pressure of isobutane) SbRe ₂ O which is a composite oxide catalyst obtained above
₆ (0.3 g) was charged into a reaction tube made of quartz, and the partial pressure of isobutane was changed to the value shown in FIG.
FIG. 5 shows the results obtained by examining the rate and selectivity of the selective oxidation reaction of isobutane in the same manner as in FIG. The conversion rate of isobutane, the formation rate of methacrolein, and the formation rate of isobutylene tended to increase with an increase in the partial pressure of isobutane, but no change in selectivity to the active ingredient was observed.

Example 6 (Effect of partial pressure of oxygen) SbRe ₂ O, which is a composite oxide catalyst obtained as described above,
₆ (0.3 g) was charged into a quartz reaction tube, and the partial pressure of oxygen was changed to the values shown in FIG. 6, and the rate and selectivity of the selective oxidation reaction of isobutane were examined in the same manner as in Example 2. FIG. 6 shows the results. The isobutane conversion rate, methacrolein formation rate, and isobutylene formation rate increased with an increase in the oxygen partial pressure, and did not increase when the pressure exceeded 35 kPa. Similarly, it was found that the selectivities of the active ingredient and isobutylene also increased with an increase in the oxygen partial pressure, and did not increase when the pressure exceeded 35 kPa.

From the above, it was found that the high oxygen partial pressure in the supply of the raw material gas increased the production rate of isobutylene while maintaining the selectivity of isobutylene and / or methacrolein. It was also suggested that a method for synthesizing alkenes and / or oxygen-containing compounds from lower alkanes in the presence of excess oxygen, which was conventionally difficult, could be established.

[0026]

According to the present invention, by using a catalyst for selective oxidation reaction comprising a novel Sb-Re composite oxide, it is possible to include alkene such as isobutylene and / or methacrolein in the presence of excess oxygen. Selective oxidation to oxygen compounds can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a reaction apparatus for a selective oxidation reaction.

FIG. 2 is a diagram showing the conversion of isobutane, the yield of methacrolein and isobutylene, and the selectivity of active ingredients, methacrolein and isobutylene in the selective oxidation reaction using SbRe ₂ O ₆ of the present invention.

FIG. 3 is a graph showing the conversion of isobutane, the yield of methacrolein and isobutylene, and the selectivity of active ingredients, methacrolein and isobutylene in the selective oxidation reaction using SbOREO ₄ .2H ₂ O of the present invention. .

FIG. 4 is a graph showing the conversion of isobutane, the yield of methacrolein and isobutylene, and the selectivity of active ingredients, methacrolein and isobutylene in the selective oxidation reaction using Sb ₄ Re ₂ O ₁₃ of the present invention. .

FIG. 5 shows the conversion rate of isobutane, the formation rate of methacrolein and the formation rate of isobutylene in the selective oxidation reaction using SbRe ₂ O ₆ of the present invention, and the effect of isobutane on the selectivity of the active ingredient, methacrolein and isobutylene. It is a figure showing the influence of pressure.

FIG. 6 shows the conversion rate of isobutane, the formation rate of methacrolein, and the formation rate of isobutylene in the selective oxidation reaction using SbRe ₂ O ₆ of the present invention, and the effect of oxygen content on the selectivity of active ingredients, methacrolein and isobutylene. It is a figure showing the influence of pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Isobutane cylinder 2 Propane cylinder 3 Oxygen gas cylinder 4 Helium gas cylinder 5 Isobutane MFC 6 Propane MFC 7 Oxygen gas MFC 8 Helium gas MFC 9 Diaphragm pump 10 Flow control valve 11 Four-way valve 12 Pressure gauge 13 Reaction tube 14 Needle valve 15 Pinhole 16 Art sampler 17 Gas chromatography 18 Mass flow controller 19 Rotary pump

Continued on the front page F term (reference) 4G069 AA02 AA08 BB06A BB06B BC26A BC26B BC64A BC64B CB07 CB10 DA05 4H006 AA02 AC45 BA13 BA16 BA30 BA81 BC10 BC11 BE30 BQ20 4H039 CA62 CC20 CC30

Claims (8)

[Claims] 1. A catalyst for selective oxidation of lower alkanes, comprising a Sb-Re composite oxide. 2. The method according to claim 1, wherein the Sb-Re composite oxide is SbRe.
_{2. The} catalyst for selective oxidation of lower alkanes according to claim 1, wherein the catalyst is ₂ O ₆ , Sb ₄ Re ₂ O ₁₃ or SbOREo ₄ .2H ₂ O. 3. The catalyst for selective oxidation reaction of lower alkane according to claim 1, wherein the lower alkane is isobutane. 4. A process for producing a corresponding alkene and / or a corresponding oxygen-containing compound, comprising subjecting a lower alkane to gas-phase catalytic oxidation with a molecular oxygen-containing gas in the presence of an Sb-Re composite oxide catalyst. 5. The method according to claim 1, wherein the Sb-Re composite oxide is SbRe.
The corresponding alkene and / or the alkene according to claim 4, characterized in that it is ₂ O ₆ , Sb ₄ Re ₂ O ₁₃ or SbOREo ₄ .2H ₂ O.
Or a method for producing a corresponding oxygen-containing compound. 6. The corresponding alkene and / or the corresponding oxygenated compound according to claim 4 or 5, wherein the lower alkane is isobutane, the corresponding alkene is isobutylene, and the corresponding oxygenated compound is methacrolein. Production method. 7. The gas phase catalytic oxidation, wherein the oxygen partial pressure is 30-60.
The pressure is set within a range of kPa.
7. The method for producing a corresponding alkene and / or a corresponding oxygen-containing compound according to any one of 6. 8. The method for producing a corresponding alkene and / or a corresponding oxygen-containing compound according to any one of claims 4 to 7, wherein the gas-phase catalytic oxidation is performed at a high temperature of 400 to 600 ° C.