JPS6278A - Production of maleic anhydride - Google Patents

Abstract

PURPOSE:To produce the objective compound economically, by adjusting the amounts of the cocatalyst and the catalyst components in the production of the titled compound by the catalytic vapor-phase oxidization of benzene, thereby controlling the catalytic activity at the inlet side of the gas and improving the catalytic activity at the outlet side of the gas. CONSTITUTION:Benzene is subjected to the catalytic vapor-phase oxidization reaction using a catalyst obtained by supporting an active substance containing 1mol of V2O5, 0.3-1.0mol of MoO3 and 0.03-0.2mol or Na2O on a porous inert carrier containing >=50wt% SiC and <=10wt% Al2O3. In the above process, the amount of P2O5 in the active substance is adjusted to (A) 0.01-0.5mol (in combination with 0.0001-0.5mol of an oxide of K, etc.) or (B) 0-0.01mol at the inlet side of the gas (30-70% of the total height of the catalyst layer) and adjusted to 0.05-0.4mol for the composition A or 0.01-0.4mol (in combination with 0.0001-0.5mol of an oxide of Mg, etc.) for the composition B at the remaining gas outlet part. The objective compound can be produced in high yield and stability under high load of benzene.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to the production of maleic anhydride by catalytic gas phase oxidation of benzene with air or molecular oxygen-containing gas in a fixed bed process. The present invention provides a method for obtaining maleic anhydride stably and in high yield under loaded conditions, and a catalyst for the same.

<Prior Art> In order to industrially advantageously produce maleic anhydride by catalytic gas-phase oxidation of benzene, high selectivity and long-term durability have been imposed on catalysts as the greatest requirements.
Recently, due to the demand for energy saving and improved production efficiency in processes, it has become increasingly important to have the ability to oxidize benzene with a smaller amount of air.In other words, it has become possible to oxidize benzene with a smaller amount of air, which means it has better selectivity and durability even when operating with a higher concentration of benzene in the supply gas. Excellent quality has become the third requirement.

Catalysts that have been proposed so far have not always been able to fully meet this third requirement. For example, Japanese Patent Publications No. 55-5379 and No. 56-1933 state that maleic anhydride can be obtained at a high yield of 95 to 100% by weight, but according to their examples, such high yields can be obtained. The yield is when the concentration of benzene in the feed gas is 40a
- Benzene/NM - Air (hereinafter 40111/NM
This was achieved only under relatively low conditions (abbreviated as ), and the inventors' follow-up test results show that under oxidizing conditions where the benzene concentration was increased to about 50 g/NM, the hot 5pot of the catalyst layer was Humidity exceeds 500℃ and 85
A yield of ˜90% by weight of maleic anhydride was obtained, but only. Further, in the reaction at a high benzene concentration of 50 g/NM3 or more, uncontrollable abnormal excessive oxidation occurred near the hot spot of the catalyst layer, resulting in half-melting of the catalyst and deactivation. On the other hand, as the loading of benzene increases, the amount of catalytically active material falling off the surface of the carrier increases during long-term continuous use, and in this respect as well, it is impossible to employ these catalysts in high-concentration processes.

<Problems to be Solved by the Invention> Therefore, an object of the present invention is to provide a fixed-bed process for producing maleic anhydride by catalytic gas phase oxidation of benzene with air or molecular oxygen-containing gas. By operating at an oxygen-containing gas ratio, 1) reducing the amount of air or molecular oxygen-containing gas blown per unit of production to reduce the energy required for blowing; 2) reducing the amount of air blown per unit of production. 3) To reduce the amount of heat waiting for gas from the reactor, increase the amount of heat recovered in the reactor, and increase the amount of high-pressure steam recovery space that is highly utilized; 3) maleic anhydride by increasing the concentration of maleic anhydride in the produced gas 4. To increase the liquid collection rate in the collector and reduce the amount of maleic acid collected in the rear flapper, thereby reducing the dehydration energy from maleic acid to maleic anhydride and reducing the drainage volume of the flapper. ) To provide a catalyst having a high benzene loading property that brings about benefits in terms of energy saving and productivity improvement such as increasing production efficiency and reducing the size of the oxidation reactor and ancillary equipment per unit production amount, It is also important to establish how to use it.

<Structure and operation of the invention> The present inventors added silicon carbide SiC to an active material obtained by adding a specific promoter to a composition mainly composed of vanadium pentoxide V205, molybdenum trioxide MoOs, and sodium oxide Na2O. In a catalyst supported on a porous inorganic inert carrier, in particular, by mixing an appropriate amount of inorganic whiskers in the active substance, it is possible to prevent the catalytically active substance from receiving mechanical stress from the carrier surface and heat load in the catalyst layer. They have also found that at least one component selected from the group consisting of potassium, cesium, thallium and rubidium is added as a co-catalyst to the feed gas inlet side of the catalyst layer. A catalyst whose activity is controlled by reducing the amount of phosphorus pentoxide P205 added or a catalyst whose activity is controlled by reducing the added amount of phosphorus pentoxide P205 (hereinafter referred to as the front stage catalyst) is filled, and the gas outlet side portion of the catalyst layer is filled with a catalyst whose activity is controlled by reducing the amount of phosphorus pentoxide P205 added. Compared to potassium.

Cesium, thallium, rubidium, magnesium.

A catalyst whose activity is increased by reducing or not adding at least one component selected from the group consisting of calcium, strontium, and barium, or an increased amount of phosphorus pentoxide P2O5 compared to the preceding catalyst. By using a stacked catalyst that has a catalyst with increased activity (hereinafter referred to as a post-catalyst),
We have completed the catalyst of the present invention by discovering that the loading of benzene per unit catalyst amount is greatly increased and the durability of the catalyst is significantly improved.

The active substance of the catalyst of the present invention basically consists of vanadium pentoxide V2O5 as a main component, and furthermore, per mole of vanadium pentoxide V2O5, molybdenum trioxide MOO30.3~1.0-El, sodium oxide N8200.03~0 .2 mol, phosphorus pentoxide P
The composition contains 50 to 0.4 mole of 2O and at least 61 components selected from the group consisting of potassium, cesium, thallium, rubidium, magnesium, calcium, strontium and barium in the range of 0 to 0.5 mole as an oxide. and phosphorus pentoxide, potassium, and cesium as previously described depending on the front and rear catalysts, respectively.

The composition ratios of thallium, rubidium, magnesium, calcium, strontium and/or rubidium are changed as appropriate.

As a carrier, silicon carbide SiC content is 50
5% by weight or more, preferably 80% by weight or more, and the aluminum oxide content is 10% by weight or less, preferably 3% by weight.
% by weight or less, and the apparent porosity is 10 to 70
%, especially from 15 to 40%, and a high thermal conductivity porous inorganic compound with a specific surface area of 1 tri/Q or less is used. The shape of the carrier is not particularly limited, but may be appropriately selected from spheres, rings, saddles, cylinders and cones, etc. each having a size of about 3 to 15 mm.

The whiskers used to properly support the catalytically active substance on the carrier are not limited to metal whiskers, but refractory whiskers are also suitably used. For example, metal whiskers such as tungsten, iron, and nickel, silicon carbide, and nitrogen silicon.

Refractory whiskers such as aluminum oxide, titanium carbide, and calcium phosphate. As for size, the average diameter is 5 microns or less, preferably 1 micron or less, the length is 1,000 microns or less, preferably 500 microns or less, and the aspect ratio is 10 to 500, especially 20 to 3.
00 range.

The active substance is supported on the carrier by a conventionally known method. That is, there are methods in which a catalyst liquid or slurry liquid containing the active ingredient is sprayed onto the surface of a carrier preheated to 150 to 250° C., and a method in which the carrier is impregnated in the catalyst liquid or slurry liquid and concentrated and deposited.

At this time, whiskers are present in the catalyst liquid or slurry in an amount of 1 to 20% by weight, preferably 3 to 1% by weight based on the finished catalyst active material.
A suitable amount of the above whiskers is dispersed so as to contain 0% by weight. The active substance is supported at a ratio of 3 to 40 g, preferably 5 to 25 CI, per carrier having an apparent volume fi of 100 cc.

The reaction is carried out using a catalyst with an inner diameter of 15 to 4 Qms, especially 20 to 30 m.
The first 30 to 70% of the total catalyst bed height in the gas flow direction is filled with the front stage catalyst, and the rear 7
This is carried out by arranging post-stage catalysts in a stacked manner in the 0 to 30% portion.

As a first-stage catalyst, (A) vanadium pentoxide v205 and molybdenum trioxide MOO30.3 to 1 mole thereof.
1.0 mol, sodium oxide Na 200.03-0.
2 mol, phosphorus pentoxide P205 0.01-0.05 mol and potassium, cesium.

An active substance consisting of 0.0001 to 0.5 mol of at least one component selected from the group consisting of thallium and rubidium as an oxide, or (B) vanadium pentoxide V2
Molybdenum trioxide MOO30 per mole of O5
, 3-1.0 mol, sodium oxide Na 200.03
The active substance consisting of ~0.2 mol and 50~0.01 mol of phosphorus pentoxide P2O is supported on the above porous carrier, and in particular, the whisker content is 1 to 20% by weight based on the active substance. Preferably, sweetened catalysts are used.

As the second-stage catalyst, (C) an active substance (C-1) having P2O5 in a molar range exceeding O, OS and 0.4 or less for the above active substance composition A;
and P205 from 0.01 to the above active substance composition A
an active substance (C-2) containing 0.4 mol and further adding at least one component selected from the group consisting of magnesium, calcium, strontium and barium as an oxide in the range of 0.0001 to 0.5 mol; (
D) The porous carrier supports any one of the active substances having a molar range of P205 of more than 0.01 and less than 0.2 for the active substance composition; 1-2 whiskers especially for active substances
A supported catalyst containing 0% by weight is preferably used.

350-600℃ for both front and rear catalysts, especially 400-600℃
The catalyst is calcined at a temperature of 500° C. for 12 to 10 hours under air or inert gas flow to obtain a finished catalyst.

The catalyst prepared in this way is prepared by first placing the latter stage catalyst in a reaction tube immersed in a molten salt bath, for example, and placing it in a reaction tube immersed in a molten salt bath.
70% of the height of the catalyst layer, and then a pre-catalyst was packed on top of it to a height of 70-30% of the total catalyst bed height, and air or molecular oxygen-containing was added at a molten salt bath temperature of 330-400°C. Benzene is mixed with the gas at a ratio of 20 to 100 g/NM 1, especially 50 to 80 g/NM, and 10
The raw material gas preheated to 0 to 150°C is fed from the top of the tube at a space velocity of 1500 to 6000 Hr, especially 2000 to 6000 Hr.
The conduction reaction takes place at a rate of 4000 Hr-1.

Under such high loading conditions, maleic anhydride is 95-10
It can be obtained stably over a long period of time with a yield of 0% by weight (based on 100% pure benzene), and the degree of dropout of the active substance from the carrier due to high benzene loading is small, as is the rate of change in reaction temperature during long-term operation. It was also found that the pressure increase in the catalyst layer over time was hardly observed, indicating a significant improvement.

Hereinafter, the catalyst of the present invention will be explained in more detail with reference to Examples.

Example 1 260 g of oxalic acid was dissolved in 1500 cc of water, and ammonium metavanadate 234 (1, ammonium molybdate 123.6 g, sodium carbonate 6.36 g, sodium dihydrogen phosphate 4.6 g and cesium sulfate 72
．． 4 g was added and dissolved by heating to obtain a catalyst liquid. Furthermore, the diameter is 0.
．． Silicon nitride whiskers 210 having a diameter of 5 microns and an average length of 180 microns were added and stirred for 30 minutes using an emulsifier to uniformly disperse the mixture.

Silicon carbide (SiC) 92% by weight, alumina (
AJ203) 2% by weight and 6% by weight of silica (SiO2), outer diameter 7++ua, inner diameter 3.5IIIl
and length 7mm, apparent porosity 30%, specific surface area 0.0
A porous ring carrier of 4 rrt/Q, 1800 CC, was placed in a rotating drum equipped with an external heating device, and the above catalyst slurry was sprayed while maintaining the temperature at 200 to 250 °C.
Carrying 15g of active substance per cc, 400% in air
C. for 5 hours to obtain Catalyst-8. The composition ratio of the active substance thus obtained is V205:MO03:N
a20:P20s: Cs20-1: 0.
The molar ratio was 7:0.06:0.02:0.2, and the whisker content was 6% by weight based on the active substance.

The composition ratio of the active substance was V205:MoOs:Na20:P205:C in exactly the same manner as Catalyst-8 except that the amount of ammonium dihydrogen phosphate was 80.512.
S20=1:0.7:Q,06:0.35
: Catalyst-B was prepared with a molar ratio of O12 (whisker content 6% by weight).

A tube with an inner diameter of 2511 and a length of 3.5 meters immersed in a molten salt bath was filled with catalyst-B to a height of 1.5 meters, and then catalyst-A was layered on top of it to a height of 1 meter. It was filled and the temperature was maintained at 355°C.

A benzene-air mixed gas with a benzene concentration of 65 (1/NM3) is introduced from the top of the reaction tube at a space velocity of 3000 Hr” (STP).
When conduction was conducted with 100% pure benzene, the voltage was 98.
Maleic anhydride was obtained with a yield of 5%.

Example 2 Dissolve 300 cc of 12N hydrochloric acid in 1200 cc of water,
To this, 160 g of ammonium metavanadate, 96.6 g of ammonium molybdate (1, 8.7 g of sodium carbonate)
g and 6.7 BQ of ammonium dihydrogen phosphate were dissolved, and 10.5 g of silicon carbide whiskers having a diameter of 0.2 microns and a length of 20 microns were added, and the mixture was thoroughly stirred for 30 minutes to obtain a catalyst slurry liquid.

88% by weight St C, 4% by weight A, i! 2000 cc of porous spherical carrier made of 203 and 8% by weight of 8102, having an average diameter of 6 mm, an apparent porosity of 35%, and a specific surface area of 0.03 rtt/Q was immersed in the above catalyst slurry, and heated and concentrated from the outside to support the active substance. I forced it. The loading rate is 8g/
It was a 100cc carrier. This was calcined at 430° C. for 6 hours under air circulation to obtain catalyst-C. The composition ratio of the active substance of the catalyst thus prepared is V2O5:MOO3:
Na2O:P2O5=1: 0.8: 0.12
: 0.005 molar ratio, whisker content is 5
The weight was %.

On the other hand, the amount of ammonium dihydrogen phosphate added was 23.4a.
A catalyst was prepared in exactly the same manner as Catalyst-C except that: The composition ratio of the catalytic active material is V205:MO03:
Na2O:P20s = 1:0.8: 0.12
: 0.15 molar ratio (5% by weight of whisker Kanayama).

A tube with an inner diameter of 25 mm and a length of 3.5 meters immersed in a molten salt bath was first filled with catalyst-〇 to a height of 1.5 meters.
Catalyst-C was then packed thereon in a layered manner to a height of 0.8 meters and maintained at a temperature of 350°C. Benzene concentration 6
(Benzene-air mixed gas preheated to 120℃ with 1/NM3 is introduced from the top of the reaction tube at a space velocity of 3500Hr-1 (S
9 for 100% pure benzene when conducting with TP)
Maleic anhydride was obtained with a yield of 6.5% by weight.

Example 3 Oxalic acid 260Q was dissolved in 1500 cc of water, and ammonium metavanadate 234111, ammonium molybdate 70.6a, and sodium carbonate 8.48a were added to the solution.
, ammonium dihydrogen phosphate 9.2 g, potassium nitrate 2
After dissolving 0.2a and 44.30 rubidium nitrate, tungsten whiskers 20 (0.3 microns in diameter and 80 microns in length) were added and dispersed with a stirrer to obtain a catalyst slurry.

90% by weight sr C, 3% by weight fvloo and 7
The apparent porosity is 28%, the specific surface area is 0.05rd/u, the diameter is 5flI11, and the length is 5.
The active substance was supported on a pellet-like porous carrier of 1.0 mm in diameter in the same manner as in Example 1 at a loading ratio of 1217/100 cc of carrier, and was calcined at 450° C. for 4 hours under air circulation to obtain Catalyst-E. The composition ratio of the active substance is V2O5:MOO3:
Na2O:P2O5:20:Rb20=1:0
．． 4: 008: 0.04: 0, 1:
The molar ratio was 0.15, and the whisker content in the active substance was 7% by weight.

On the other hand, potassium nitrate and rubidium nitrate were not added at all, and the amount of ammonium dihydrogen phosphate added was 41.41.
The catalyst composition ratio was V205:MOOs:Na2O:P2O5=1 except that it was changed to 1.
:0.4+0.08:0.18 molar ratio and whisker content of 7% by weight Catalyst-F was prepared.

A tube with an inner diameter of 20 mm and a length of 3.5 meters immersed in a molten salt bath was first filled with catalyst-F to a height of 1 meter, and then filled with catalyst-E to a height of 1.8 meters above it. death,
The temperature was maintained at 365°C. Benzene concentration 70a/NM
Benzene-molecular oxygen-containing gas (12% oxygen) preheated to 120°C at 3.

When a mixed gas (10% water vapor, 78% nitrogen) was introduced from the top of the reaction tube at a space velocity of 2800 Hr''(STP>), maleic anhydride was obtained at a yield of 97% based on 100% pure benzene.

Example 4 Oxalic acid 260°C was dissolved in 1500cc of water, and ammonium metavanadate 234 (+), ammonium molybdate 106g, sodium carbonate 3.18g (], and ammonium dihydrogen phosphate, 23g were dissolved in the solution, and a diameter of 0.25g was dissolved in 1500cc of water.
Silicon carbide whiskers 110 of 4 microns and 15 microns in length were added and stirred to form a catalyst slurry. Using this catalyst slurry liquid, an SRC self-sintering carrier (diameter 5.5 mm, spherical) with an apparent porosity of 25%, a specific surface area of 0.03 G/Q, and a purity of 98.5% was prepared in the same manner as in Example 1. An active substance was supported on the catalyst, and the mixture was calcined at 420° C. for 6 hours under air flow to obtain Catalyst-G.

The loading rate of the active substance is 10 (J/100CC carrier,
The composition ratio is V20s:MOO3:Na2O:P20s
: = 1 : 0.6: 003 : 0.
There was a 001-E ratio. Moreover, the SiC whisker content was 4% by weight based on the active substance.

On the other hand, the composition ratio of the active substance was adjusted to V20 in the same manner as Catalyst-G except that 53.30% of thallium nitrate was added and the amount of ammonium dihydrogen phosphate was 57.5+I+.
s :MOO3:Na2 Q:P20s :T120=
1: 0.6: 0.03: 0.25:
Catalyst-H with 0.1 molar ratio and whisker content of 4% by weight
was prepared.

A 25-ffl inner diameter, 3.5 meter long tube immersed in a molten salt bath was first filled with Catalyst-H to a height of 1.4 meters and then topped with Catalyst-G to a height of 1.4 meters. The containers were stacked and packed to the same height, and the temperature was maintained at 355°C. Benzene concentration 60
(Benzene-air mixed gas preheated to 120°C at 1/NM was pumped from the top of the reaction tube at a space velocity of 3000 Hr.
According to STP), it is 9 for 100% pure benzene.
Maleic anhydride was obtained with a yield of 9% by weight.

Example 5 260 g of oxalic acid was dissolved in 1,500 cc of water, and 234 g of ammonium metavanadate, 141 g of ammonium molybdate, 8.5 g of sodium nitrate, 4.6+I+ ammorum dihydrogen phosphate, and 20.2(+) potassium nitrate were dissolved in 1500 cc of water.
After dissolving cesium nitrate 39C1, the diameter is 0.
Silicon carbide whiskers 11 (+) having a diameter of 3 microns and a length of 50 microns were added and stirred to obtain a catalyst slurry. Using this catalyst slurry, an active substance was supported on the same carrier as in Example 1 in the same manner. , 450℃ in air
The catalyst was calcined for 8 hours to obtain catalyst (2). The composition ratio of the active substance thus obtained is V20s:Moos:Na20
: P2 0s: C320: 2 0=1 :
0.8: 005: 0.02: 0.1:
The molar ratio was 0.1 and the whisker content was interquadruple % with respect to the active substance.

The active substance composition ratio was V205 in exactly the same manner as the catalyst layer except that the amount of ammonium dihydrogen phosphate added was 230 and barium nitrate was 26.1 g instead of potassium nitrate.
:MOO3:Na2O:P205 :C320:Ba
O=1: 0.8: 0.05: 0.10
:0.1:0.1 molar ratio of catalyst-J was obtained.

A tube with an inner diameter of 25 m+ and a length of 3.5 m immersed in a molten salt bath was filled with catalyst J to a height of 1.25 m, and then catalyst -■ was filled on top of it to a height of 1.25 m. The temperature was maintained at 355°C. Benzene concentration 6! M/NM
benzene-air mixed gas at a space velocity of 3000 Hr.
-' (STP), maleic anhydride was obtained at a yield of 99.5% by weight based on 100% pure benzene.

Comparative Example 1 272 g of oxalic acid was dissolved in 150 OId of water, and 230 Q of ammonium metavanadate, 69.4 g of ammonium molybdate, 11.2 CI of trisodium phosphate, and 6.7 g of sodium nitrate were sequentially dissolved to prepare a catalyst liquid.

Apparent porosity 38%, specific surface area 0.05d/Q as carrier
S with a diameter of 7 to 8 mm and a SiC purity of 98.7% by weight.
An active substance was supported in the same manner as in Example 1 using 1800 cc of iC's self-sintering spherical product. The obtained support was calcined for 8 hours under air circulation to form a catalyst. The loading rate of the active substance is 8a/100cc carrier, and the composition ratio is V205:MoOs:Na2O:P205-
The molar ratio was 1:0.40:006:0.015.

A tube with an internal diameter of 25 m + 1 and a length of 385 meters, immersed in a molten salt bath, was filled with catalyst-K to a height of 2.5 meters,
The temperature was maintained at 365°C. Benzene concentration 50o/NM
When a benzene-air mixture gas preheated to 120°C was passed through the catalyst layer at a space velocity of 3006 hours, the temperature at the hot spot reached 520°C, which was 100% pure benzene.
Only a yield of 86% by weight of maric anhydride was obtained.

Example 6 The catalysts according to Example 1 (A, B stacked packing) and the catalysts of Example 1 obtained without the addition of whiskers and M (active substance loadings of 15 and 12 o, respectively)
A long-term oxidation reaction comparison was conducted under the stacking format and reaction conditions described in Example 1. The results are shown in Table 1.

For catalyst (A+8), no increase in pressure loss over time in the tIIi layer was observed, and almost no change in maleic anhydride yield was observed. On the other hand, in the case of catalyst (L+M), although the retention rate had to be lowered somewhat due to the non-use of whiskers, an increase in the pressure loss in the catalyst layer over time was observed, and at the same time, the yield of maleic anhydride decreased. A decrease was observed. This is due to deterioration in which the active substance flakes off the surface of the carrier due to the high loading of benzene. In addition, the reason for the difference in the initial pressure drop value is due to the active material when filling the catalyst into the tube.
This is due to the difference in the degree of peeling of the quality.

Examples 7 to 10 The reaction was carried out in the same manner as in Example 1 using a catalyst prepared in the same manner as in Example 1 except as shown below.
The results shown in Table 2 were obtained.

(Example 7) In catalyst A, cesium sulfate was 72. Instead of thallium nitrate 106. fl Add catalyst-N).

(Example 8) In catalyst B, the amount of ammonium dihydrogen phosphate added was 230, and the amount of cesium sulfate added was 54.31.
11, and in addition, calcium sulfate 27.2a was added (catalyst-○).

(Example 9) In catalyst B, the amount of ammonium dihydrogen phosphate added was 23 (J), 17.4 g of potassium sulfate was added instead of cesium sulfate, and 18 g of magnesium sulfate was added.
．． 10 and 6.3 g of strontium nitrate were added (
Catalyst-P).

(Example 10)

Claims (8)

[Claims] (1) In a method for producing maleic anhydride by catalytic gas phase oxidation of benzene with air or molecular oxygen-containing gas in a shell-and-tube heat exchanger type reactor, the catalyst packed bed of the reactor is placed on the gas inlet side. A: Vanadium pentoxide (V_2O_5) and molybdenum trioxide (MoO_3) 0.3 to 1.0 per mole of vanadium pentoxide (V_2O_5).
Mol, sodium oxide (Na_2O) 0.03-0.2
Mol, phosphorus pentoxide (P_2O_5) 0.01-0.05
active substance consisting of 0.0001 to 0.5 mole of at least one component selected from the group consisting of potassium, cesium, thallium and rubidium as an oxide; or B: vanadium pentoxide (V_2O_5) and 1 mole thereof; On the other hand, molybdenum trioxide (MoO_3) 0.3 to 1.0
mol, 0.030.2 mol of sodium oxide (Na_2O) and 0 to 0.01 mol of phosphorus pentoxide (P_2O_) with a silicon carbide (SiC) content of at least 50% by weight and aluminum oxide (Al_2
O_3) Consists of a material supported on a porous inert carrier with a content of 10% by weight or less, followed by the remaining 70-30%
C: P_2O_5 is 0.05 for the above active material composition A.
The active substance (C-
1), P_2O_5 is 0.0 for the above active substance composition A
1 to 0.4 mol, and at least one component selected from the group consisting of magnesium, calcium, strontium, and barium is 0.0001 to 0 as an oxide.
．． Active substances (C-2) and D added in a range of 5 mol: P_2O_5 is 0.01 to the above active substance composition B.
silicon carbide (SiC
) content of 50% by weight or more and aluminum oxide (Al
_2O_3) A method for producing maleic anhydride, characterized in that the maleic anhydride is supported on a porous inert carrier having a content of 10% by weight or less. (2) Claim (1) characterized in that the carrier is a porous inert carrier having a silicon carbide content of 80% by weight or more and an aluminum oxide content of 3% by weight or less.
Method described. (3) The method according to claim (1), wherein the carrier is a self-sintering porous inert carrier having a silicon carbide content of 98% by weight or more. (4) Claim (1) characterized in that the shape of the carrier is spherical, ring, cylindrical, saddle-shaped, conical, or block-shaped.
Method described. (5) In a method for producing maleic anhydride by catalytic gas phase oxidation of benzene with air or molecular oxygen-containing gas in a shell-and-tube heat exchanger type reactor, the catalyst packed bed of the reactor is placed on the gas inlet side. A: Vanadium pentoxide (V_2O_5) and molybdenum trioxide (MoO_3) 0.3 to 1.0 per mole of vanadium pentoxide (V_2O_5).
Mol, sodium oxide (Na_2O) 0.03-0.2
Mol, phosphorus pentoxide (P_2O_5) 0.01-0.05
active substance consisting of 0.0001 to 0.5 mole of at least one component selected from the group consisting of potassium, cesium, thallium and rubidium as an oxide; or B: vanadium pentoxide (V_2O_5) and 1 mole thereof; On the other hand, molybdenum trioxide (MoO_3) 0.3 to 1.0
Mol, sodium oxide (Na_2O) 0.03-0.2
mol and 0 to 0.01 mol of phosphorus pentoxide (P_2O_5) in an amount of 1 to 20
a silicon carbide (SiC) content of 50% by weight or more and an aluminum oxide (Al_2O_3) content of 10% by weight, with whiskers having an average diameter of 5 microns or less and an aspect ratio of 10-500.
C: P_2O_5 is 0.05% of the active material composition A above, and the remaining 70-30% of the catalyst is supported on a porous inert carrier by weight % or less.
The active substance (C-
1), P_2O_5 is 0.0 for the above active substance composition A
1 to 0.4 mole, and at least one component selected from the group consisting of magnesium, calcium, strontium, and barium as an oxide of 0.0001 to 0.4 mole.
Active substances (C-2) and D added in a range of 5 mol: P_2O_5 is 0.01 to the above active substance composition B.
1 to 2% of the active substance in a molar range exceeding 0.2 molar range.
0% by weight of whiskers with an average diameter of 5 microns or less and an aspect ratio of 10 to 500, with a silicon carbide (SiC) content of 50% or more and an aluminum oxide (Al_2O_3) content of 1
1. A method for producing maleic anhydride, characterized in that maleic anhydride is supported on a porous inert carrier in an amount of 0% by weight or less. (6) Claim (5) characterized in that the carrier is a porous inert carrier having a silicon carbide content of 80% by weight or more and an aluminum oxide content of 3% by weight or less.
Method described. (7) The method according to claim (5), wherein the carrier is a self-sintering porous inert carrier having a silicon carbide content of 98% by weight or more. (8) Claim (5) characterized in that the shape of the carrier is spherical, ring, cylindrical, saddle-shaped, conical, or block-shaped.
Method described.