JPH07232074A - Oxidation dehydrogenation catalyst - Google Patents

Abstract

PURPOSE:To prepare selectively alkenes with a functional group being useful as a raw material for a polymer by performing oxidation dehydrogenation of alkanes with a functional group. CONSTITUTION:An oxidation dehydrogenation catalyst consists of iron, phosphor and oxygen wherein the atomic ratio of phosphor to iron (P/Fe) is l-1.5 and 20-80% of iron atom has divalent atomic valence and in an X-ray diffraction spectrum (CuKalpha line), the diffraction peaks are 2theta=19.98 deg., 21.24 deg., 35.04 deg. and 35.54 or 2theta=29.50 deg..

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel oxidative dehydrogenation catalyst capable of selectively producing alkenes having functional groups such as aldehyde groups, carboxyl groups, ester groups and cyano groups. Alkenes having such a functional group are industrially very useful compounds as raw materials for polymers such as methacrylic resins.

[0002]

Alkenes having a functional group such as an aldehyde group, a carboxyl group, an ester group and a cyano group are generally obtained by a method of oxygen-oxidizing or ammoxidating a methyl group of an alkene, and oxidizing an alkane having the functional group. It is manufactured by a method such as dehydrogenation. Among them, as a method for oxidative dehydrogenation of alkanes having the functional group, for example, isobutyraldehyde is used as a Fe—P—X—O-based catalyst (X = Ag, Al, B, Be, Cd, Co, Cr, C
u, Ga, Ge, In, Mn, Ni, Te, Th, T
i, U, V, Zn, Zr, a rare earth metal) to produce methacrolein by oxidative dehydrogenation (US438)
1411), and a method of producing methacrylic acid by oxidative dehydrogenation of isobutyric acid in the presence of a Fe-P-Pd-O-based catalyst (see Japanese Patent Laid-Open No. 50-7161).

However, in the known method for producing alkenes having the above functional groups by the oxidative dehydrogenation reaction of alkanes having the above functional groups, it is relatively easy to increase the reaction rate of the raw materials. However, it was difficult to selectively obtain the target compound in a state where the reaction rate of the raw materials was high, and the yield was only about 80%.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an oxidative dehydrogenation catalyst capable of selectively producing an alkene having a functional group by an oxidative dehydrogenation reaction of an alkane having a functional group. Is.

[0005]

The object of the present invention is to provide an iron having an atomic ratio of phosphorus to iron (P / Fe) of 1 to 1.5,
A catalyst composed of phosphorus and oxygen, having 20 to 80 iron atoms
% Has divalent valence, and X-ray diffraction spectrum (CuK
α-ray) 2θ = 19.98 °, 21.24 °, 3
Achieved by an oxidative dehydrogenation catalyst characterized by having a diffraction peak of 5.04 °, 35.54 ° or 2θ = 29.50 °.

The present invention will be described in detail below. The catalyst of the present invention has an atomic ratio of phosphorus to iron (P / Fe) of 1 to
It is a catalyst composed of iron (Fe), phosphorus (P), and oxygen (O) of 1.5, and mainly contains iron phosphate. The composition of each element in the catalyst is such that phosphorus is 1 to 1 atom of iron.
It is 1.5 atoms, and oxygen is usually 2 to 6 atoms as a value naturally determined by the valences of the elements other than oxygen. When the atomic ratio of phosphorus to iron (P / Fe) becomes less than 1, F
Since e ₂ O ₃ is generated and a catalyst containing iron phosphate as a main component cannot be obtained, side reactions increase in the oxidative dehydrogenation reaction. On the other hand, if this ratio exceeds 1.5, an excessive amount of amorphous phosphorus is present and a catalyst containing iron phosphate as a main component cannot be obtained. .

The catalyst of the present invention is a catalyst having the above composition and further having the following properties. That is, the catalyst of the present invention has an atomic ratio of phosphorus to iron (P / Fe) of 1 to
A catalyst composed of iron (Fe), phosphorus (P) and oxygen (O) of 1.5, wherein 20 to 80%, preferably 25 to 75%, and more preferably 30 to 60% of iron atoms are 2%. X-rays having a valence of valence (in other words, 20 to 80%, preferably 25 to 75%, and more preferably 30 to 60% of reduced iron atoms of iron phosphate) 2θ = 19.98 °, 21.24 °, 35.04 as shown in FIG. 2-C or D in the diffraction spectrum (CuKα line)
The main component is a novel compound having a diffraction peak at °, 35.54 ° or 2θ = 29.50 °. In addition,
The valence of the iron atom can be determined by general redox titration.

Further, in the catalyst of the present invention, lead (Pb), zinc (Zn), magnesium (M
g), calcium (Ca), barium (Ba), nickel (Ni), and cobalt (Co) can be contained as phosphates. These elements may be contained singly or more, and usually 0 to 0.
5, preferably 0.01 to 0.2.

The catalyst of the present invention partially reduces a compound containing iron (III) phosphate as a main component, which is easily prepared by a conventional catalyst preparation method, with a reducing gas (Fe ³⁺ to Fe
Partially reduced to ²⁺ ). In addition, after reducing a compound containing iron (III) phosphate as a main component (reducing Fe ³⁺ to Fe ²⁺ ), the reduced iron is partially oxidized with a molecular oxygen-containing gas (Fe ^{2 +} To F
can also be prepared by partial oxidation to e ³⁺ ). Examples of the compound containing iron (III) phosphate as a main component include FePO ₄ and a novel compound (referred to as X-phase) shown in FIG. 1-A.

As a method for preparing a compound containing iron (III) phosphate as a main component, for example, a compound such as a salt or oxide of each element containing each element of iron phosphate and a cocatalyst is added in the presence of water. After mixing under the following conditions, a method of drying and baking, a method of forming a coprecipitate from nitrates, ammonium salts, acids, etc. of each element, then separating and drying and baking, A method of preparing iron (III) phosphate or a phosphate of a co-catalyst, mixing them in the presence of water, and drying / calcining.

In these methods, drying is usually carried out in air at 50 to 200 ° C., firing is carried out in air at 300 ° C. or higher,
It is preferably carried out at 400 to 800 ° C. Firing 300
If it is carried out at a temperature of not higher than 0 ° C, iron phosphate will not be formed, and if it is carried out at a temperature of not lower than 800 ° C, the specific surface area will be very small, and the phosphorus compound will be partially scattered, which is not preferable.

The raw materials used in the above catalyst preparation are not particularly limited, but salts and oxides of the above respective elements include iron nitrate, iron carbonate, iron oxalate, iron acetate, and chloride. Iron, iron salts such as iron hydroxide, ammonium phosphate, phosphoric acid or phosphorus salts such as phosphorus trichloride, phosphorus tetrachloride, phosphorus pentachloride, lead nitrate, lead carbonate, lead oxalate, lead acetate, lead chloride Lead salts such as lead hydroxide, zinc nitrate, zinc carbonate, zinc oxalate, zinc acetate, zinc chloride, zinc salts such as zinc hydroxide, magnesium nitrate, magnesium carbonate, magnesium oxalate, magnesium acetate, magnesium chloride , Magnesium salts such as magnesium hydroxide, calcium nitrate, calcium carbonate, calcium oxalate, calcium acetate, calcium chloride, calcium salts such as calcium hydroxide, burr nitrate Barium carbonate, barium carbonate, barium oxalate, barium acetate, barium chloride, barium hydroxide, etc., barium salts, nickel nitrate, nickel carbonate, nickel oxalate, nickel acetate, nickel chloride, nickel hydroxide, etc., nickel salts, nitric acid Cobalt salts such as cobalt, cobalt carbonate, cobalt oxalate, cobalt acetate, cobalt chloride, and cobalt hydroxide, and iron oxide, lead oxide, zinc oxide, magnesium oxide, calcium oxide, barium oxide, nickel oxide, cobalt oxide, etc. Examples include oxides of iron and co-catalyst.

The nitrates, ammonium salts and acids of the above-mentioned elements include the nitrates and ammonium salts mentioned above, and the acids include pyrophosphoric acid, metaphosphoric acid, orthophosphoric acid and the like. Examples of the salt include lead phosphate, zinc phosphate, magnesium phosphate, calcium phosphate, barium phosphate, nickel phosphate, and cobalt phosphate.

Further, the catalyst of the present invention can be prepared not only from the compound containing iron (III) phosphate as the main component obtained by the above-mentioned preparation method but also from the one in which each element is supported on the carrier. it can. As a method for supporting each element on the carrier, known methods such as an impregnation method, a kneading method, a deposition method, an evaporation-drying method, and a coprecipitation method can be mentioned, but among these methods, it is simple. Therefore, the coprecipitation method, the impregnation method, or the evaporation-drying method is preferably adopted as the supporting method. Generally, the supported amount of each element is preferably 10 to 90% by weight in terms of metal, based on the carrier. As the carrier, silica, alumina, silica lumina, zirconia, titanium oxide, carborundum, diatomaceous earth, etc. are known. Any carrier can be used.

Iron (III) phosphate obtained as described above
The reducing gas such as hydrogen or carbon monoxide used for the reduction of the compound containing as a main component may be a pure gas or one diluted with an inert gas such as nitrogen.
The one diluted with nitrogen gas to a concentration of 80% by volume is used. Then, the reduction process usually has a gas flow rate of 0.1 to 10.
100l / g ・ cat ・ hr, temperature 100 ~ 600
C., preferably 200 to 500.degree. C. for 10 minutes to 5 hours.

The molecular oxygen-containing gas used for the partial oxidation may be air or oxygen gas diluted with an inert gas such as nitrogen or steam, but air is usually used. And, this partial oxidation usually has a gas flow rate of 0.1.
~ 100l / g ・ cat ・ hr, temperature 50 ~ 500
C., preferably 100 to 400.degree. C., and 10 minutes to 5 hours.

The catalyst thus prepared has a divalent valence of 20 to 80%, preferably 25 to 75%, and more preferably 30 to 60% of iron atoms, and has an X-ray diffraction spectrum ( 2K = 19.98 °, 21.24 °, 35.0 as shown in FIG.
The main component is a novel compound having a diffraction peak of 4 °, 35.54 ° or 2θ = 29.50 °. The former compound having a diffraction peak (referred to as B-phase in the figure) is obtained by partially reducing a compound containing iron (III) phosphate as a main component, and the latter compound having a diffraction peak (in the figure, Y-phase) is obtained by completely reducing a compound containing iron (III) phosphate as a main component and then partially oxidizing it, both of which exhibit excellent activity and selectivity. Under the conditions of general oxidative dehydrogenation reaction, Fe ²⁺ is gradually oxidized to Fe ³⁺ , but due to its slow rate, 20 to 80% of iron atoms are kept as Fe ^2+. The catalytic activity is maintained.

The catalyst of the present invention can be applied to an oxidative dehydrogenation reaction for producing an alkene having a functional group by reacting an alkane having a functional group represented by the general formula (I) with molecular oxygen. it can.

[Chemical 1] (In the formula, R ¹ and R ² are alkyl groups having 1 to 5 carbon atoms, X is COOH, CHO, CN, COOR ³ , Cl, Br or I, and R ³ is an alkyl group having 1 to 5 carbon atoms. Show)

Specific examples of the compound represented by the general formula (I) include one of isobutyric acid, methyl isobutyrate, isobutyraldehyde, isobutyronitrile, isopropyl chloride, isopropyl bromide, isopropyl iodide and the like. Butanes having one functional group such as propane having a functional group, α-methyl n-butyric acid, methyl α-methyl n-butyrate, α-methyl n-butyraldehyde and α-methyl n-butyronitrile. To be

From the above compounds, alkenes having the following functional groups, for example, isobutyric acid to methacrylic acid, methyl isobutyrate to methyl methacrylate, isobutyraldehyde to methacrylonitrile, isopropyl chloride to propene chloride, odor, etc. Isopropyl iodide to propene bromide, isopropyl iodide to iodopropene, α-methyl n-butyric acid to α-methyl crotonic acid, α-methyl n-
Methyl α-methylcrotonate is obtained from methyl butyrate, α-methylcrotonaldehyde is obtained from α-methyl n-butyraldehyde, and α-methylcrotonnitrile is obtained from α-methyl n-butyronitrile.

In carrying out the oxidative dehydrogenation reaction, a gas substantially inactive to the reaction is used as a diluent gas in addition to the alkanes having a functional group represented by the general formula (I) as a raw material and molecular oxygen. It can be mixed and used. Examples of the diluting gas include water vapor, nitrogen gas, and carbon dioxide gas. Among them, water vapor is most preferable because it improves the selectivity and yield of the target compound and further has a function of maintaining the catalytic activity. . When reacting an alkane having an ester group, alcohols such as methanol can be added as a diluent gas as well.

The amount of steam used is usually 5 to 100 mol, preferably 15 to 80 mol, based on 1 mol of the raw material.
It is preferable that the amount of water vapor used is larger than that of the raw material in order to improve the selectivity and yield of the target compound, but if it is too large, the space-time yield of the target compound is reduced and energy is lost due to steam supply, which is economical. Sex will be reduced.

The molecular oxygen used does not have to be a high-purity oxygen gas, but generally, a molecular oxygen-containing gas,
For example, oxygen gas or air diluted with the above diluent gas is used. The amount of molecular oxygen used is usually 0.4 to 1 mol, preferably 0.5 to 0.8 mol, based on 1 mol of the raw material.

The oxidative dehydrogenation reaction can be carried out by reacting the alkanes as raw materials with molecular oxygen in the gas phase in the presence of the catalyst under the following conditions. The reaction temperature varies depending on the kind of the raw material, but the higher the electron withdrawing property of the substituent X in the compound represented by the general formula (I), the lower the temperature, and usually 250 to 550.
C., preferably 300 to 450.degree. The reaction pressure may be normal pressure, low pressurization or reduced pressure, but normal pressure is generally suitable. The contact time is usually 0.1
It is 7 seconds, preferably 0.2 to 5 seconds. The reaction system is preferably a continuous system, and the catalyst may be present in any of a fixed bed, a moving bed, and a fluidized bed, but industrially, it is advantageous to carry out the reaction in a fixed bed. The particle size of the catalyst is usually 1/3 to 1/10 of the reaction tube diameter. The target compound thus obtained can be separated and purified by a known method such as distillation.

[0025]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The reaction rate (%) of the raw material (alkane having a functional group) and the selectivity (%) of the target compound (alkene having a functional group) in each Example and Comparative Example were determined by the following formulas.

[0026]

[Equation 1]

[0027]

[Equation 2]

Example 1 [Preparation of catalyst] Ferric nitrate [Fe (NO
₃)₃・ 9H₂O] 100 g was dissolved and water was added to this solution.
Ammonium phosphate [(NH_Four)₃PO_Four
・ 3H ₂O] A solution containing 60.3 g was added to form a precipitate.
Was generated. The precipitate formed is filtered and washed in air.
After drying at 150 ° C for 8 hours, crush and crush 4-10 mesh
Were sized and then calcined in air at 500 ° C. for 5 hours. Profit
More than 95% of iron atoms in the fired product obtained by redox titration
Is Fe³⁺[Compound containing iron (III) phosphate as the main component]
And its X-ray diffraction spectrum (CuKα ray) is shown in Fig. 1-A.
It was shown in.

The above fired product was filled into a stainless steel reaction tube having an inner diameter of 18 mm, and then the molar ratio of nitrogen: hydrogen was set to 1 :.
While flowing the mixed gas of 1 at a flow rate of 50 ml / min,
Reduction was performed at 400 ° C. for 5 hours. The iron valence of the obtained reduced product was 95% or more of the iron atom by F by the redox titration method.
e ²⁺ , the main component of which is iron pyrophosphate Fe ₂ P ₂ O according to the X-ray diffraction spectrum (CuKα line) shown in FIG. 1-B.
₇ (reduced iron phosphate).

After filling the above-mentioned reduced product into a stainless steel reaction tube having an inner diameter of 18 mm, the molar ratio of air: steam is 1 in the reaction tube.
Partial oxidation was performed at 400 ° C. for 1 hour while flowing a mixed gas of 0: 3 at a flow rate of 100 ml / min. The iron valence of the obtained catalyst was 56% of iron atoms Fe ²⁺ by redox titration, and the main component was 2θ = 29.50 ° according to the X-ray diffraction spectrum (CuKα line) shown in FIG. 2-D. It was a novel compound (Y-phase) having a diffraction peak of.

[Oxidative dehydrogenation reaction] 10 ml of the above catalyst was charged into a stainless steel reaction tube having an inner diameter of 18 mm, and then, under normal pressure, a molar ratio of isobutyric acid: steam: nitrogen: oxygen was 1: 10: 16.3 :. Mixed gas of 0.7 10.3 l /
While flowing at a flow rate of hr, the oxidative dehydrogenation reaction was carried out at a reaction temperature of 380 ° C. and a contact time of 3 seconds. The results of gas chromatography analysis of the target compound are shown in Table 1.

Example 2 In Example 1, the fired product [iron (III) phosphate as a main component
The time required for reducing the
Same as Example 1 except that partial oxidation was not performed
A catalyst was prepared and the oxidative dehydrogenation reaction was performed. In addition, I got
The valence of iron in the prepared catalyst was determined by redox titration to be 5
4% is Fe ²⁺And the main component is X-ray diffraction as shown in Fig. 2-C.
According to the spectrum (CuKα line), 2θ = 19.98 °,
21.24 °, 35.04 °, 35.54 ° diffraction peaks
It was a novel compound (B-phase) having a crack. Eye
Table 1 shows the results of analysis of specific compounds.

Examples 3 to 5 In Example 1, except that isobutyric acid was changed to butyraldehyde, isobutyronitrile, and methyl isobutyrate, and the reaction conditions were changed to those shown in Table 1, respectively.
A catalyst was prepared and an oxidative dehydrogenation reaction was carried out in the same manner as in Example 1. The results of analysis of the target compound are shown in Table 1.

[0034] In Example 6 Example 1, ferric nitrate [Fe (NO _{3) 3} · 9
H ₂ O] 100 g, ammonium phosphate [(NH ₄ )]
_[3 PO ₄ .3H ₂ O] was changed to 65.3 g and the reaction temperature was changed to the conditions shown in Table 1, and a catalyst was prepared and an oxidative dehydrogenation reaction was carried out in the same manner as in Example 1. The results of analysis of the target compound are shown in Table 1.

Example 7 Same as Example 1 except that the temperature and time for partial oxidation of the reduced product were changed to 250 ° C. for 1 hour and the reaction temperature was changed to the conditions shown in Table 1. A catalyst was prepared and the oxidative dehydrogenation reaction was performed. The results of analysis of the target compound are shown in Table 1.

Example 8 The same as Example 1 except that the temperature and time for partial oxidation of the reduced product were changed to 270 ° C. for 1 hour and the reaction temperature was changed to the conditions shown in Table 1 in Example 1. A catalyst was prepared and the oxidative dehydrogenation reaction was performed. The results of analysis of the target compound are shown in Table 1.

Example 9 In Example 1, except that the temperature and time for partial oxidation of the reduced product were changed to 240 ° C. and 40 minutes, and a part of the reaction conditions was changed to the conditions shown in Table 1. A catalyst was prepared in the same manner as in No. 1 and oxidative dehydrogenation reaction was performed. The results of analysis of the target compound are shown in Table 1. The main component of the obtained catalyst was a mixture of Y-phase and iron pyrophosphate Fe ₂ P ₂ O ₇ (reduced iron phosphate) from the X-ray diffraction spectrum (CuKα line) shown in FIG. 3-E.

Example 10 In Example 1, the salt dissolved in 500 ml of water was treated with nitric acid first.
Ferrite [Fe (NO₃) ₃・ 9H₂O] 100 g and nitric acid
Lead [Pb (NO₃)₂] Change to 8.2g, raw materials and reaction
Example 1 was repeated except that the conditions were changed to those shown in Table 1.
A catalyst was prepared and an oxidative dehydrogenation reaction was performed in the same manner as in. Purpose
The results of analyzing the compounds are shown in Table 1.

Example 11 In Example 1, the salt dissolved in 500 ml of water was treated with nitric acid first.
Ferrite [Fe (NO₃) ₃・ 9H₂O] 100 g and nitric acid
Lead [Co (NO₃)₂・ 6H₂O] changed to 2.3 g,
In addition to changing the raw materials and reaction conditions to those listed in Table 1.
Was prepared in the same manner as in Example 1 to carry out the oxidative dehydrogenation reaction.
went. The results of analysis of the target compound are shown in Table 1.

[0040]

[Table 1]

Comparative Example 1 Similar to Example 1 except that the calcined product [compound containing iron (III) phosphate as a main component] was not reduced and the reduced product was not partially oxidized. A catalyst was prepared and an oxidative dehydrogenation reaction was performed. The results of analysis of the target compound are shown in Table 2.

Comparative Example 2 A catalyst was prepared and an oxidative dehydrogenation reaction was carried out in the same manner as in Example 1 except that the partial oxidation of the reduced product was not carried out. The results of analysis of the target compound are shown in Table 2.

[0043] In Comparative Example 3 Example 1, ferric nitrate [Fe (NO _{3) 3} · 9
H ₂ O] 100 g, ammonium phosphate [(NH ₄ )]
₃ PO ₄ .3H ₂ O] was changed to 45.2 g, and a catalyst was prepared in the same manner as in Example 1 to carry out the oxidative dehydrogenation reaction. The results of analysis of the target compound are shown in Table 2.

[0044] In Comparative Example 4 Example 1, ferric nitrate [Fe (NO _{3) 3} · 9
H ₂ O] 100 g, ammonium phosphate [(NH ₄ )]
_[3 PO ₄ .3H ₂ O] was changed to 85.4 g, and a catalyst was prepared in the same manner as in Example 1 to carry out the oxidative dehydrogenation reaction. The results of analysis of the target compound are shown in Table 2. The obtained catalyst contained a large amount of amorphous phosphorus.

[0045]

[Table 2]

[0046]

INDUSTRIAL APPLICABILITY The present invention can provide a novel catalyst capable of selectively oxidatively dehydrogenating alkanes having a functional group. By using this catalyst, it is possible to produce highly useful alkenes having functional groups such as methacrylic acid, methyl methacrylate, and methacrolein as polymer raw materials from alkanes having functional groups in high yield. You can

[Brief description of drawings]

FIG. 1A is a fired product obtained in Example 1 [iron phosphate (I
B of the compound containing II) as a main component] shows an X-ray diffraction spectrum of the reduced product obtained in Example 1.

FIG. 2 C is the oxidative dehydrogenation catalyst (2
D of the compound having a diffraction peak of θ = 29.50 °), D is the oxidative dehydrogenation catalyst obtained in Example 1 (2θ = 19.98).
The X-ray diffraction spectrum of (compound having diffraction peaks of 21.24 °, 35.04 °, and 35.54 °) is shown.

FIG. 3E is an oxidative dehydrogenation catalyst (2) obtained in Example 9.
₂ shows an X-ray diffraction spectrum of a compound having a diffraction peak of θ = 29.50 ° and a mixture of iron pyrophosphate Fe ₂ P ₂ O ₇ (reduced iron phosphate).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C07C 69/54 9279-4H 255/08 9357-4H

Claims (1)

[Claims] 1. A catalyst composed of iron, phosphorus and oxygen having an atomic ratio of phosphorus to iron (P / Fe) of 1 to 1.5, wherein 20 to 80% of iron atoms have a divalent valence. And 2θ = 19.9 in X-ray diffraction spectrum (CuKα ray)
An oxidative dehydrogenation catalyst having a diffraction peak of 8 °, 21.24 °, 35.04 °, 35.54 ° or 2θ = 29.50 °.