JPH06145160A - Production of maleic anhydride - Google Patents

Abstract

PURPOSE:To obtain maleic anhydride in high catalytic activity, in high conversion ratio and in high selectivity by using a specific orthophosphoric acid-based catalyst and subjecting butane to vapor-phase catalytic oxidation with molecular oxygen. CONSTITUTION:Butane is subjected to vapor-phase catalytic oxidation with molecular oxygen by using a catalyst which is a mixture of orthophosphoric acid-hydrogen vanadyl of the formula VOHPO4.0.5H2O and bivalent metal orthophosphate of the formula M3(PO4)2.nH2O (M is bivalent metal of Mg, Ca, Ba, Mn, Fe, Co, Ni, Cu or Zn; (n) is number of coordinated water differs depending upon preparation temperature) and is prepared by burning the mixture having the atomic ratio of M/V of 0.003-0.5 at 300-400 deg.C to give a catalyst and pretreating the catalyst in an inert gas or a mixed gas of a molecular oxygen-containing gas at 350-700 deg.C to give the objective maleic anhydride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing maleic anhydride by vapor-phase catalytic oxidation of butane with molecular oxygen. More specifically, it relates to the above-mentioned method using a phosphorus-vanadium-oxygen composite catalyst containing a specific metal, which is prepared by a specific preparation method.

[0002]

2. Description of the Related Art A method for producing maleic anhydride by gas-phase catalytic oxidation of butane with molecular oxygen is well known in the art, and various proposals and reports have been made for catalysts used in the method. There is. For example, Japanese Patent Publication Sho 5
No. 3,124,96 discloses Cr, Fe, Hf, Zr,
A phosphorus-vanadium-oxygen composite catalyst containing La or Ce is disclosed in Japanese Patent Publication No. 57-45229, Z.
A phosphorus-vanadium-oxygen composite catalyst containing n, Cu, Bi or Li, and JP-B-57-45233 propose a phosphorus-vanadium-oxygen composite catalyst containing Co, Ni or Cd, respectively. ing. In addition, "catalyst" Vol. 33, No. 2 (1991), Mo, Sb, Cr, Fe, As, Mn, Sn, C
There have been reports on the catalytic activity of phosphorus-vanadium-oxygen composite catalysts containing o, Cu, Zn, W, Ca, Mg, Na, K and Cs. However, phosphorus-vanadium-oxygen composite catalysts containing these various kinds of metals that have been proposed or reported hitherto are not sufficient in terms of catalytic activity, selectivity to maleic anhydride, etc., and improvement thereof is desired. It is rare.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a catalyst exhibiting excellent catalytic activity and selectivity to maleic anhydride when producing butane by gas-phase catalytic oxidation of butane with molecular oxygen. To provide.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that the conventional phosphorus-vanadium-oxygen composite catalyst containing various metals is not suitable for the preparation method. It has been found that the catalyst activity, the selectivity to maleic anhydride, etc. are insufficient, and that the catalyst activity, the selectivity to maleic anhydride, etc. can be remarkably improved according to a specific preparation method. That is, in the preparation of the above-mentioned conventional catalyst, generally, when preparing a precursor solution from a vanadium compound such as vanadium pentoxide, a reducing agent such as hydrogen chloride and a phosphorus compound such as orthophosphoric acid, chlorides of various metals such as This has been done by adding solutions of various metal salts, evaporating the precursor solution to dryness to obtain a solid, and firing the solid. On the other hand, solid vanadyl orthophosphate consisting of a vanadium compound, a reducing agent and a phosphorus compound [V
[OHPO ₄ .0.5H ₂ O] was prepared, vanadyl monohydrogen orthophosphate was mixed with orthophosphates of various divalent metals at a specific ratio, and the mixture was calcined. Found that their catalytic activity, selectivity to maleic anhydride, etc. were remarkably improved. Further, in order to find a certain metal to be contained in order to achieve the intended purpose, and further to sufficiently achieve the intended purpose, the catalyst prepared as described above is mixed with an inert gas or butane. It was also found here that pretreatment should be performed under a certain condition in a mixed gas of molecular oxygen-containing gas before the reaction. The present invention has been completed based on these findings.

That is, the gist of the present invention is to produce a maleic anhydride by subjecting butane to vapor-phase catalytic oxidation using molecular oxygen to produce maleic anhydride as a catalyst of the formula (I) VOHPO ₄ .0.5H ₂ O (I ) Vanadyl orthophosphate represented by the formula: and a formula (II) M ₃ (PO ₄ ) ₂ · nH ₂ O (II) (wherein M is a divalent Mg, Ca, Ba, M
It represents a metal selected from n, Fe, Co, Ni, Cu and Zn, and n represents the number of coordinated water which varies depending on the preparation temperature. ) A mixture of divalent metal orthophosphates having an M / V atomic ratio in the range of 0.003 to 0.5, the catalyst prepared by calcining at 300 to 400 ° C. The method for producing maleic anhydride is characterized in that it is used after pretreatment at 350 to 700 ° C. in an inert gas or a mixed gas of butane and a molecular oxygen-containing gas.

In order to achieve the intended object of the present invention, the mixing ratio of vanadyl monohydrogen orthophosphate (I) and orthophosphate (II) of a divalent metal is 0.003 in terms of M / V atomic ratio.
It is important to set the range to 0.5. That is, M
If the / V atomic ratio is less than 0.003 or exceeds 0.5, the intended purpose of the present invention cannot be achieved. Moreover, the preferable range of this mixing ratio is 0.01-0.
The range is 2. That is, when the M / V atomic ratio is less than 0.01, the activity is improved, but the selectivity to maleic anhydride is not so improved. On the other hand, M /
When the V atomic ratio exceeds 0.2, the selectivity for maleic anhydride is improved, but the activity is hardly improved.

The divalent metals of the orthophosphate (II) are Mg, Ca, Ba, Mn, Fe, Co, Ni,
It is selected from Cu and Zn, and the orthophosphate (II) of different metals may be used together.

The vanadyl monohydrogen orthophosphate (I) and the divalent metal orthophosphate (II) used in the preparation of the catalyst of the present invention can be prepared by known methods commonly used in this field, such as the following: It can be prepared by such a method. That is, vanadyl monohydrogen orthophosphate (I) is
Vanadium pentoxide, metavanadic acid, vanadium compounds such as pyrovanadate, after reducing with hydrogen chloride, alcohols, reducing agents such as aldehydes, orthophosphoric acid,
It is prepared by reacting with a phosphorus compound such as pyrophosphoric acid, phosphorus pentoxide, alkali phosphate, phosphorus pentachloride, etc., separating the precipitate from the resulting reaction solution, washing the precipitate well, and then drying it. You can Further, the divalent metal orthophosphate (II) can be prepared by adding divalent sodium phosphate or dipotassium hydrogenphosphate to an aqueous solution of a compound such as the above-mentioned divalent metal chloride, sulfate, nitrate or organic acid salt. Aqueous solution of
Generally, it can be prepared by adding and reacting so as to have a molar ratio of about 3: 2, separating the resulting precipitate, thoroughly washing the precipitate, and then drying.

The catalyst used in the present invention comprises vanadyl monohydrogen orthophosphate (I) and the divalent metal orthophosphate (II) at an M / V atomic ratio of 0.003 to 0.
5, preferably 0.01 to 0.2, to form a mixture, and if necessary, heat-mix as a solution, preferably a weakly acidic aqueous solution having a pH of 4 to 5, and then mix. The solution is evaporated to dryness to form a mixture, and the obtained mixture is calcined at 300 to 400 ° C to prepare the mixture. This firing may be carried out in a gas containing molecular oxygen such as air or in an inert gas such as nitrogen. A firing time of 30 minutes to 12 hours is appropriate. When the prepared catalyst is subjected to a catalytic gas phase oxidation reaction, it is 350 to 700 ° C. in an inert gas such as nitrogen or carbon dioxide, or a mixed gas of butane and a molecular oxygen-containing gas, that is, a reaction composition gas. It is essential to pre-treat. In this pretreatment, the treatment temperature is important for developing the catalytic activity. At temperatures below 350 ° C, the desired catalytic activity is not exhibited, and at temperatures above 700 ° C, the desired catalytic activity is lost. Be seen. Further, it is appropriate to carry out this pretreatment for 30 minutes to 20 hours.

The catalytic gas phase oxidation reaction for producing maleic anhydride according to the present invention can be carried out by employing known reaction conditions generally used in this field, but it is usually carried out as follows. To be done. That is, a mixed gas having a composition of 1 to 4% by volume of butane, 10 to 20% by volume of molecular oxygen, and 76 to 89% by volume of a diluent gas was used as a source gas on the catalyst after the above-mentioned pretreatment, ~ 500
It is carried out at a temperature of [deg.] C under an arbitrary pressure, generally under normal pressure, at a space velocity of 300 to 5000 / hr in terms of normal pressure. Pure oxygen may be used as the molecular oxygen, but air is generally used. Needless to say, when using air, it is not necessary to add a diluent gas depending on the desired concentration of molecular oxygen. Further, as the above-mentioned dilution gas, an inert gas such as nitrogen or carbon dioxide is usually used industrially.

[0011]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The conversion, selectivity and yield in the examples and comparative examples are defined as follows.

Conversion = (moles of butane reacted / moles of butane fed) × 100 Selectivity = (moles of maleic anhydride formed / moles of butane reacted) × 100 Yield = (generation Number of moles of maleic anhydride prepared / number of moles of butane fed) × 100

Example 1 10 g of vanadium pentoxide in 80 ml of benzyl alcohol
Was added and stirred under heating. After confirming that vanadium pentoxide was reduced, 98% orthophosphoric acid 12.0 was added to it.
g (a P / V ratio is slightly in excess of 1.0, P / V = 1.06 in the example) was added and refluxed for 1 hour, and the formed precipitate was taken out. The precipitate was washed well with toluene and then dried at 120 ° C. to obtain vanadyl monohydrogen orthophosphate [VOHPO ₄ .0.5H ₂ O] (I).

9. Magnesium dichloride in 100 ml of water
An aqueous solution in which 5 g was dissolved and an aqueous solution in which 9.5 g of disodium hydrogen phosphate was dissolved in 100 ml of water were slowly added in equal amounts and mixed, and this mixture was left for one day and night, and the formed precipitate was taken out. After thoroughly washing this precipitate with water,
After drying at 80 ° C, magnesium orthophosphate [Mg
_{3 (PO 4) 2 · 8H} 2 O] to give the (II).

10 g of the obtained vanadyl monohydrogen orthophosphate (I) and 1 g of magnesium orthophosphate (II)
(Mg / V atomic ratio is 0.13) 50 ml distilled water
Mix well in and evaporate to dryness at 100 ° C. to give a solid.
The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

3 g of the above tablet-molded catalyst was packed in a flow reactor, and a raw material gas consisting of 2% by volume of butane, 20% by volume of oxygen and 78% by volume of helium was stored at 460 ° C. under atmospheric pressure at a space velocity of 2400 / hr. After performing the pretreatment by flowing under the conditions of 6 hours, the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was 400 ° C. The evaluation results are shown in Table 1.

Example 2 Vanadyl monohydrogen orthophosphate (I) was prepared as in Example 1. Manganese dichloride 12.
An aqueous solution prepared by dissolving 6 g and an aqueous solution prepared by dissolving 9.5 g of disodium hydrogen phosphate in 100 ml of water were slowly added and mixed, and the mixture was left for 24 hours, and the formed precipitate was taken out. After washing this precipitate well with water, it is dried at 80 ° C. and manganese orthophosphate [Mn
_{3 (PO 4) 2 · 5H} 2 O] to give the (II).

10 g of the obtained vanadyl monohydrogen orthophosphate (I) and 1 g of manganese (II) orthophosphate (Mn
/ V atomic ratio is 0.12) was mixed well in 50 ml of distilled water and evaporated to dryness at 100 ° C. to obtain a solid. The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

Using 3 g of the above tablet-molded catalyst, pretreatment was carried out in the same manner as in Example 1, and then the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was 400 ° C. The evaluation results are shown in Table 1.

Example 3 Vanadyl monohydrogen orthophosphate (I) was prepared as in Example 1. An aqueous solution prepared by dissolving 12.7 g of iron dichloride in 100 ml of water and an aqueous solution prepared by dissolving 9.5 g of disodium hydrogen phosphate in 100 ml of water were slowly added in equal amounts and mixed, and the mixture was left standing for 24 hours. The formed precipitate was taken out. After washing this precipitate thoroughly with water,
℃ in dried orthophosphate iron _{[Fe 3 (PO 4) 2} · 8H 2
O] (II) was obtained.

10 g of the obtained vanadyl (I) hydrogen orthophosphate and 1 g of iron (II) orthophosphate (Fe / V atomic ratio: 0.10) were thoroughly mixed in 50 ml of distilled water and then at 100 ° C. Evaporation to dryness gave a solid. The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above tablet-molded catalyst, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was 380 ° C. The evaluation results are shown in Table 1.

Example 4 Vanadyl monohydrogen orthophosphate (I) was prepared as in Example 1. Cobalt dichloride in 100 ml of water 13.
An aqueous solution in which 0 g was dissolved and an aqueous solution in which 9.5 g of disodium hydrogen phosphate was dissolved in 100 ml of water were slowly added in equal amounts and mixed, and this mixture was allowed to stand for 24 hours, and the formed precipitate was taken out. The precipitate was thoroughly washed and then dried at 80 ° C to obtain cobalt orthophosphate [Co
_{3 (PO 4) 2 · 8H} 2 O] to give the (II).

10 g of the obtained vanadyl monohydrogen orthophosphate (I) and 1 g of cobalt orthophosphate (II) (Co
(/ V atomic ratio is 0.10) was thoroughly mixed in 50 ml of distilled water and then evaporated to dryness at 100 ° C. to obtain a solid.
The solid was calcined in nitrogen at 360 ° C. and tableted to prepare the catalyst.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above tablet-molded catalyst, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was 380 ° C. The evaluation results are shown in Table 1.

Example 5 Vanadyl monohydrogen orthophosphate (I) was prepared in the same manner as in Example 1. Nickel dichloride in 100 ml of water 13.
An aqueous solution in which 0 g was dissolved and an aqueous solution in which 9.5 g of disodium hydrogen phosphate was dissolved in 100 ml of water were slowly added in equal amounts and mixed, and this mixture was allowed to stand for 24 hours, and the formed precipitate was taken out. The precipitate was washed well with water and dried at 80 ° C. to obtain nickel orthophosphate [Ni
_{3 (PO 4) 2 · 8H} 2 O] to give the (II).

10 g of the obtained vanadyl (I) hydrogen orthophosphate and 1 g of nickel (II) orthophosphate (Ni
(/ V atomic ratio is 0.10) was thoroughly mixed in 50 ml of distilled water and then evaporated to dryness at 100 ° C. to obtain a solid.
The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above tablet-molded catalyst, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was changed to 400 ° C. The evaluation results are shown in Table 1.

Example 6 Vanadyl monohydrogen orthophosphate (I) was prepared as in Example 1. An aqueous solution prepared by dissolving 13.4 g of copper dichloride in 100 ml of water and an aqueous solution prepared by dissolving 9.5 g of disodium hydrogen phosphate in 100 ml of water were slowly added in equal amounts and mixed, and the mixture was left standing for 24 hours. The formed precipitate was taken out. After washing this precipitate thoroughly with water,
℃ in dried orthophosphate copper _{[Cu 3 (PO 4) 2} · 3H 2
O] (II) was obtained.

10 g of the obtained vanadyl monohydrogen orthophosphate (I) and 1 g of copper (II) orthophosphate (Cu / V atomic ratio is 0.12) were mixed well in 50 ml of distilled water and then at 100 ° C. Evaporation to dryness gave a solid. The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above tablet-molded catalyst, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was changed to 400 ° C. The evaluation results are shown in Table 1.

Example 7 Vanadyl monohydrogen orthophosphate (I) was prepared as in Example 1. 13.6 g of zinc dichloride in 100 ml of water
And an aqueous solution of 9.5 g of disodium hydrogen phosphate dissolved in 100 ml of water were slowly added in equal amounts and mixed, and the mixture was allowed to stand for 24 hours, and the formed precipitate was taken out. After washing this precipitate well with water, 8
0 ℃ in dry zinc orthophosphate _{[Zn 3 (PO 4) 2} · 4
H ₂ O] (II) was obtained.

10 g of the obtained vanadyl monohydrogen orthophosphate (I) and 1 g of zinc orthophosphate (II) (Zn / V
(Atomic ratio is 0.12) was thoroughly mixed in 50 ml of distilled water and then evaporated to dryness at 100 ° C. to obtain a solid. The solid was calcined in air at 360 ° C. for 6 hours and tableted to prepare a catalyst.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above tablet-molded catalyst, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperature was 380 ° C. The evaluation results are shown in Table 1.

Comparative Example 1 10 vanadium pentoxide in 80 ml of benzyl alcohol
g was added and the mixture was heated and stirred. After confirming that vanadium pentoxide was reduced, 98% orthophosphoric acid was added thereto.
After adding 4 g and refluxing for 1 hour, the formed precipitate was taken out. After thoroughly washing the precipitate with toluene, 120
After drying at ℃, vanadyl monohydrogen orthophosphate [VOHPO
₄ · 0.5H ₂ O] was obtained (I). The catalyst was prepared by firing this vanadyl monohydrogen orthophosphate in air at 360 ° C. for 6 hours. The prepared catalyst was vanadyl pyrophosphate [(VO) ₂ P ₂ O ₇ ], and P /
The V atomic ratio is 1.1.

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above-mentioned catalyst tableted, and the performance of the catalyst was evaluated under the same conditions as the pretreatment except that the reaction temperatures were 400 ° C. and 470 ° C., respectively. . The evaluation results are shown in Table 1.

Comparative Example 2 Cobalt orthophosphate [Co ₃ (PO ₄ ) ₂ .8H ₂ O] (II) similar to that obtained in Example 4 was calcined in air at 360 ° C. for 6 hours, Further, it was calcined at 460 ° C. for 6 hours to prepare a catalyst. The resulting catalyst was cobalt phosphate [Co ₃ (PO ₄ ) ₂ ].

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above-mentioned catalyst tableted, and then the reaction temperature was 400 ° C.
The performance of the catalyst was evaluated under the same conditions as in the pretreatment except that. The evaluation results are shown in Table 1.

Comparative Example 3 To 100 ml of water, 11.0 g of 98% orthophosphoric acid and 7.0 g of hydroxylamine hydrochloride were added, heated to 80 ° C., and 9.1 g of vanadium pentoxide was gradually added with stirring. 1.3 g of manganese dichloride in the obtained dark blue solution
10 ml of an aqueous solution was added, and the mixture was stirred, then, this was evaporated and concentrated, and then dried. 500 more in a nitrogen stream
Catalyst burned at ℃ for 2 hours (Mn / V atomic ratio = 0.10)
Got

Pretreatment was carried out in the same manner as in Example 1 using 3 g of the above-mentioned catalyst tableted, and then the reaction temperature was 400 ° C.
The performance of the catalyst was evaluated under the same conditions as in the pretreatment except that the temperature was set to 440 ° C. The evaluation results are shown in Table 1.

[0041]

[Table 1] Table 1 ─────────────────────────── Reaction temperature Catalyst performance (%) (℃) Conversion rate Selectivity Yield ─ ────────────────────────── Example 1 400 86 72 61.9 〃 2 400 90 90 69 62.1 〃 3 380 92 71 71 65. 3 〃 4 380 89 73 73 65.0 〃 5 400 400 84 76 63.8 〃 6 400 400 94 67 62.9 〃 7 380 93 70 65.1 Comparative Example 1 400 16 79 12.6 470 87 87 61 53.1 2 〃 400 4 20 0.8 〃 3 400 400 36 76 27.4 440 84 64 64 53.8 ────────────────────────────

[0042]

EFFECTS OF THE INVENTION According to the present invention, when the butane is vapor-phase catalytically oxidized with molecular oxygen to produce maleic anhydride, the catalyst used has excellent catalytic activity and selectivity to maleic anhydride. Maleic anhydride can be obtained with high conversion and selectivity.

Claims (1)

[Claims] 1. A method for producing maleic anhydride by subjecting butane to vapor-phase catalytic oxidation using molecular oxygen to produce maleic anhydride,
Vanadyl monohydrogen orthophosphate represented by the formula (I) VOHPO ₄ .0.5H ₂ O (I) and the formula (II) M ₃ (PO ₄ ) ₂ .nH ₂ O (II) (wherein M is an atom) Divalent Mg, Ca, Ba, M
It represents a metal selected from n, Fe, Co, Ni, Cu and Zn, and n represents the number of coordinated water which varies depending on the preparation temperature. ) A mixture of divalent metal orthophosphates having an M / V atomic ratio in the range of 0.003 to 0.5, the catalyst prepared by calcining at 300 to 400 ° C. A method for producing maleic anhydride, which is used after pretreatment at 350 to 700 ° C. in an inert gas or a mixed gas of butane and a molecular oxygen-containing gas.