JPH0729056B2 - Catalyst for phthalic anhydride production - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for producing phthalic anhydride, and more specifically, it produces phthalic anhydride by orthoxylene and / or naphthalene by gas phase catalytic oxidation with molecular oxygen or a gas containing molecular oxygen. For catalysts.

[0002]

2. Description of the Related Art A catalyst for producing phthalic anhydride in which a catalytically active substance containing vanadium oxide and titanium oxide as a main component is carried on an inert carrier is widely known. For example, Japanese Patent Publication Nos. 47-15323 and Sho. 49-41036, Japanese Patent Publication No. 52-4538, Japanese Patent Application Laid-Open No. 47-5661, and Japanese Patent Application Laid-Open No. 49-89694. Each of these catalysts has its own characteristics, and some of them have been used industrially and have a proven track record.

However, there is still room for improvement in catalyst performance. First, in terms of selectivity, even if the yield is improved by 1% from the scale of the production apparatus, its economic effect is large. . Further, the improvement of the selectivity facilitates the heat treatment and the distillation operation until the product is obtained. Therefore, the improvement of the selectivity can be expected to produce a high-quality product at a low cost. As described above, the improvement of the selectivity is important for effectively using the raw material.

In addition, it is important to secure stable production by improving productivity and maintaining catalytic activity. One of the methods for improving productivity is to carry out an oxidation reaction under high load reaction conditions such as increasing the concentration of raw material gas. However, since the reaction for obtaining phthalic anhydride from orthoxylene or naphthalene is accompanied by a marked exotherm, the temperature rise in the hot spot portion under a high concentration condition is excessive and an excessive oxidation reaction occurs, resulting in a high yield of phthalic anhydride. At the same time, the deterioration of the catalyst is significantly accelerated.

A catalyst which can be used under such a high load reaction condition is also disclosed in, for example, Japanese Patent Publication No. 59-1 by the present applicant.
It is proposed in Japanese Patent No. 378, etc.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a catalyst which is further improved in catalytic performance as compared with conventionally known catalysts and which is suitable for the production of phthalic anhydride.
Accordingly, one object of the present invention is to provide a catalyst for producing phthalic anhydride which produces phthalic anhydride with high selectivity by vapor phase catalytic oxidation of orthoxylene and / or naphthalene.

Another object of the present invention is a catalyst for producing phthalic anhydride by vapor-phase catalytic oxidation of orthoxylene and / or naphthalene, which is excellent in durability and has a lowered catalytic activity even after long-term use. It is an object of the present invention to provide a catalyst for producing phthalic anhydride that enables stable production of phthalic anhydride in a small amount. Yet another object of the present invention is to produce phthalic anhydride by vapor phase catalytic oxidation of orthoxylene and / or naphthalene, which enables the production of phthalic anhydride with high selectivity even under high load reaction conditions, and It is intended to provide a catalyst for producing phthalic anhydride, which has excellent durability and enables stable production of phthalic anhydride over a long period of time.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors have achieved the above object by introducing silver as a component of a catalytically active substance into a vanadium-titanium-based catalyst. Knowing what can be achieved, the present invention has been completed based on this finding. That is, the present invention provides a catalyst for producing phthalic anhydride by vapor-phase catalytic oxidation of orthoxylene and / or naphthalene with molecular oxygen or a gas containing molecular oxygen, wherein vanadium oxide is used as V ₂ O ₅ 20 parts by weight,
99 to 80 parts by weight of anatase type titanium oxide having a specific surface area of 10 to 60 m ² / g as TiO ₂ , and these 2
0.05 to 1.2 parts by weight of at least one element selected from potassium, cesium, rubidium and thallium as an oxide and silver as A per 100 parts by weight of the total of components.
A catalyst for the production of phthalic anhydride, characterized in that 0.05 to ₂ parts by weight of g ₂ O is contained in a heat-resistant inorganic carrier as a catalyst active substance (hereinafter, this catalyst is referred to as “catalyst (1)”). ) Concerning.

Further, the present invention relates to orthoxylene and
And / or naphthalene with molecular oxygen or molecular oxygen
Production of phthalic anhydride by gas-phase catalytic oxidation with gas
Vanadium oxide in a catalyst for₂O_FiveAs
1 to 20 parts by weight, specific surface area 10 to 60 m²/ G Ana
Tase type titanium oxide is TiO₂As 99-80 weight
Parts, and also 100 parts by weight of these two components in total, niobium
Nb₂O_Five0 to 1 part by weight, potassium, cesium
At least selected from aluminum, rubidium and thallium
0.05 to 1.2 parts by weight of one element as an oxide,
To P₂O_Five0 to 1.2 parts by weight, antimony S
b₂O₃0 to 5 parts by weight and silver as Ag ₂As O
0.05 to 2 parts by weight (however, niobium, phosphorus,
And each content of antimony becomes 0 at the same time
(Never) A catalytically active substance is supported on a heat-resistant inorganic carrier.
A catalyst for the production of phthalic anhydride characterized by
Hereinafter, this catalyst is referred to as "catalyst (2)").

The present invention will be described in more detail below.
One of the features of the present invention is that one component of the catalytically active substance has a specific surface area of 10 to 60 m ² / g, preferably 15 to
The use of 40 m ² / g of anatase titanium oxide. The specific surface area of this anatase type titanium oxide is 10
If it is less than m ² / g, the activity of the obtained catalyst is low, while
When it exceeds 60 m ² / g, the durability of the catalyst is deteriorated and the yield is reduced in a short period of time, which is not preferable.

In the present invention, among the above anatase type titanium oxides, the average particle size is 0.4 to 0.7 μm.
m, preferably 0.45 to 0.60 μm, and a substantially spherical one is particularly preferably used. The anatase-type titanium oxide used particularly preferably in the above invention is produced by a method known as a "solution method", and has high mechanical strength while being porous, and is not crushed by mechanical pulverization such as an ordinary ball mill. It has such strength that it can be regarded as "primary particles". However, this anatase type titanium oxide has a high specific surface area of 10 to 60 m ² / g in spite of having a large average particle diameter in the range of 0.4 to 0.7 μm, and has an essentially small diameter. It is an aggregate of primary particles having Therefore, the anatase-type titanium oxide does not have to be a true sphere and may be a substantially spherical one.

According to the above solution method, ilmenite (Fe
OTiO ₂ ) is treated with sulfuric acid having a lower concentration than in the production of titanium oxide by the solidification method, usually about 70 to 80% sulfuric acid to obtain titanium sulfate, and the titanium is then added to 150 to 180%.
Hydrolyze under pressure at 600C, and 600-900 ° C
The anatase type titanium oxide can be obtained by baking at. It should be noted that iron, zinc, aluminum, manganese, chromium, calcium, lead, etc. may be mixed in this anatase-type titanium oxide due to the relationship with the raw material ore, but 0.5% as an oxide relative to titanium oxide.
There is no particular problem with respect to catalyst performance if the content is at most wt%.

The heat-resistant inorganic carrier used in the present invention is
It is necessary that the catalyst is stable for a long period of time at a temperature that is sufficiently higher than the calcination temperature of the catalyst and the catalyst temperature for producing phthalic anhydride, and that it does not react with the catalytically active substance. Examples of such a heat-resistant inorganic carrier include silicon carbide (Si
C), alumina, zirconium oxide, titanium oxide and the like can be used. Among these, a silicon carbide carrier having an alumina (Al ₂ O ₃ ) content of 20% by weight or less, preferably 5% by weight or less, and an apparent porosity of 10% or more, preferably 15 to 45% or more is suitable. Used for. In particular, the alumina content is 5% by weight or less,
A silicon carbide carrier having a silicon carbide content of 95% by weight or more and an apparent porosity of 15 to 45% is preferably used. More preferred is a purity of 98%
The silicon carbide carrier obtained by self-sintering the above silicon carbide powder can be mentioned.

Regarding the shape of the above heat-resistant inorganic carrier,
There is no particular limitation, but spherical or cylindrical ones are easy to handle.
It is preferable that the average diameter is about 2 to 15 mm.
It is preferably used. The catalyst (1) of the present invention has the above heat resistance
Vanadium oxide as V₂O _FiveAs 1
20 parts by weight, anatase type titanium oxide was added to TiO₂As
99-80 parts by weight and a total of 100 parts by weight of these two components
Potassium, cesium, rubidium and tariu per part
At least one element selected from
0.05-1.2 parts by weight, and Ag for silver₂As O
Support the catalytically active component in an amount of 0.05 to 2 parts by weight.
Is obtained.

One feature of the present invention is that silver is introduced as one component of the catalytically active substance as described above, and the silver content in the catalyst (1) is 0.02 as Ag ₂ O.
It is 5 to 2 parts by weight, preferably 0.1 to 1 part by weight. If the silver content is too high or too low, the object of the present invention cannot be achieved. That is, the amount of silver added is A
When the amount of g ₂ O is less than 0.05 part by weight, the effect of improving the performance by adding silver becomes low. Further, if the amount of silver added exceeds 2 parts by weight, the performance of the catalyst is adversely affected, and the selectivity to phthalic anhydride is reduced.

The catalyst (2) of the present invention comprises 1 to 20 parts by weight of vanadium oxide as V ₂ O _{5 and} 99 to 8 of anatase type titanium oxide as TiO _{2 on} a heat-resistant inorganic carrier.
0 parts by weight, and 0 to 1 parts by weight of niobium as Nb ₂ O ₅ per 100 parts by weight of the total of these two components, and 0.05 to at least one element selected from potassium, cesium, rubidium and thallium as an oxide. 1.2 parts by weight, phosphorus is P ₂ O ₅ as 0 to 1.2 parts by weight, antimony is Sb ₂ O ₃ as 0 to 5 parts by weight, and silver is Ag ₂
It can be obtained by supporting a catalytically active substance containing 0.05 to 2 parts by weight of O (however, the respective contents of niobium, phosphorus and antimony do not become 0 at the same time).

Also in this catalyst (2), the silver content is 0.05 to ₂ parts by weight as Ag ₂ O, preferably 0.1 to 1 part by weight, like the catalyst (1). If the silver content is too high or too low, the object of the present invention cannot be achieved. In the catalyst (2), niobium was added to Nb
0.01 parts by weight ₂ O _5, 0.2 to 1.2 parts by weight of phosphorus as P ₂ O _5, and antimony Sb ₂ O
A catalyst in which 0.5 to 5 parts by weight of ₃ as a catalytically active substance is supported on a heat-resistant inorganic carrier is particularly preferable because it improves the selectivity of phthalic anhydride.

When preparing catalyst (1) and catalyst (2)
, Vanadium, niobium, potassium, cesium, rubid
Starting of each component of um, thallium, phosphorus and antimony
As a raw material, V₂O_Five, Nb₂O_Five, K₂O, Cs₂
O, Rb₂O, Tl₂O, P ₂O_Five, Sb₂O₃Such as
In addition to oxides, ammonium salts of each element, nitrates, sulfuric acid
Heating salts, halides, organic acid salts, hydroxides, etc.
Selected from the compounds that change into oxides as described above.
You can

With respect to the silver component, besides Ag ₂ O, nitrates, ammonium salts, sulfates, halides, organic acid salts, hydroxides, amine complexes, phosphates, sulfides and the like can be used. Among these, there are some such as silver halides and silver phosphates, which do not become oxides under the heating conditions during catalyst preparation, but can be used in the present invention without any trouble. In addition, when silver phosphate is used, it is not necessary to consider the amount of phosphorus in the silver phosphate when adding the phosphorus component as a catalytically active substance, and the amount of the phosphorus component as an oxide is It should be set within the range.

There is no particular limitation on the method for supporting the above-mentioned catalytically active substance on the heat-resistant inorganic carrier at the time of preparing the catalyst of the present invention, and it can be supported by a generally used method. Especially, a certain amount of carrier is put into a rotary drum that can be heated from the outside,
The most convenient method is to spray the slurry containing the catalytically active substance while keeping the temperature at ° C so that the catalytically active substance is supported.

The amount of the catalytically active substance supported on the heat-resistant inorganic carrier varies depending on the size of the carrier used, but it is usually preferably 3 to 20 g per 100 cc of the carrier. The catalytically active substance layer obtained by supporting the catalytically active substance on the carrier has a total fine pore size of 0.15 to 0.45 μm and a total fine pore volume of 10 μm or less. It preferably has surface characteristics such that it is 50% or more of the pore volume, especially 0.15 to 0.45.
The total pore volume occupied by pores having a diameter of μm is 10 μm.
75% of the total pore volume occupied by pores having a diameter of m or less
It is preferable to have surface characteristics that occupy the above.

By providing the catalytically active layer having such surface characteristics, the object of the present invention can be achieved more effectively. The catalytically active substance layer having the above-mentioned surface characteristics can be easily prepared, for example, in the supporting method using the rotating drum by adjusting the slurry concentration according to the particle diameter of the essential primary particles of anatase type titanium oxide. Can be formed (Japanese Patent Publication No. 49-4103)
No. 6 publication). Specifically, the particle size of the primary particles is 0.0
When anatase type titanium oxide having a particle size of 05 to 0.05 μm is used, the slurry concentration is 5 to 25% by weight, preferably 10 to 20% by weight, and the primary particle size is 0.05.
When using anatase type titanium oxide having a size larger than μm, the slurry concentration is 10 to 40% by weight, preferably 1
By adjusting the amount to 5 to 25% by weight, the catalytically active substance layer having the above surface characteristics can be formed.

In the present invention, the pore volume was determined from the pore size distribution measured by a mercury porosimetry porosimeter. The specific surface area of anatase type titanium was measured by the BET method, and the average diameter was measured by using a transmission electron microscope. After supporting the catalytically active material layer as described above, 450
The catalyst of the present invention can be obtained by calcination at a temperature of ˜700 ° C., preferably 500˜600 ° C. for 2 to 10 hours under air flow.

The oxidation reaction of orthoxylene and / or naphthalene using the catalyst of the present invention can be carried out under usual reaction conditions. For example, the inner diameter is 5-40m
m, preferably 15-27 mm reaction tube with 1-5 catalyst
m, preferably 1.5 to 3 m, and the reaction tube is heated to 300 to 400 ° C., preferably 3 to 400 ° C.
The temperature is maintained at 30 to 380 ° C., and the raw material orthoxylene and / or naphthalene is added to the reaction tube together with air or a gas containing 5 to 21% by volume of molecular oxygen.
At a rate of 5 to 70 g / Nm ³ (air) in the case of air, and at a rate of 5 to 110 g / Nm ³ (molecular oxygen containing gas) in the case of a molecular oxygen-containing gas, a space velocity of 1000 to 6000 h.
r ^-1 (STP), preferably 1000 to 4000 hr ^-1
Introduced in (STP).

In the above oxidation reaction, the catalyst layer in the reaction tube is divided into two or more layers to provide a plurality of reaction zones, and a plurality of catalysts whose catalytic activity is controlled are introduced into these reaction zones as the raw material gas of the reaction tube. The catalyst of the present invention can be advantageously used by arranging the catalyst so that the activity becomes higher from the inlet portion toward the outlet portion. Specifically, the catalyst (2) of the present invention will be described as an example. First, the reaction tube is divided into two layers, and the inlet portion is provided with a predetermined catalyst (previous stage) at a layer height of 30 to 70% of the total catalyst layer height. (Catalyst) is filled in the remaining bed height at the outlet with a catalyst having higher activity (post-catalyst) than the pre-catalyst.
Catalysts having the same catalyst composition but different activities can be easily prepared, for example, by changing the content of the phosphorus component. Specifically, the phosphorus component as an oxide is adjusted to 0.
By using 2 to 0.4 parts by weight, the pre-stage catalyst can be prepared, and by using 0.4 to 1.2 parts by weight, the post-stage catalyst having higher activity than the pre-stage catalyst can be prepared. The catalytic activity can also be controlled by changing the type and / or amount of the element selected from potassium, cesium, rubidium and thallium.

By carrying out the oxidation reaction under the conditions as described above, the heat storage in the hot spots in the catalyst layer is suppressed, whereby the deterioration of the catalyst due to the heat load is prevented, and the stable operation for a long term is industrially performed. It can be carried out. Further, excessive oxidation reaction at the hot spot is prevented, and various effects such as improvement in selectivity can be obtained. Such an effect is remarkable under high load reaction conditions such as increasing the concentration of the raw material gas, and the productivity can be significantly improved by increasing the concentration of orthoxylene or naphthalene.

[0027]

INDUSTRIAL APPLICABILITY By using the catalyst of the present invention, phthalic anhydride can be produced from orthoxylene and / or naphthalene with high selectivity. Therefore,
The heat treatment and the distillation operation until obtaining the phthalic anhydride product becomes easy, and a high-quality product can be obtained at a lower cost than the conventional method.

The catalyst of the present invention is excellent in durability and therefore can be stably operated for a long time industrially. The catalyst of the present invention produces phthalic anhydride with a high selectivity even under a high load reaction condition such as increasing the concentration of the raw material gas, and is excellent in durability even when used for a long time. The use of a catalyst significantly improves the productivity of phthalic anhydride production.

Therefore, it can be said that the catalyst of the present invention is a very useful catalyst for the production of phthalic anhydride.

[0030]

The present invention will be described in more detail with reference to the following examples. -Example 1- (Preparation of catalyst) After ilmenite was mixed with 80% concentrated sulfuric acid and sufficiently reacted, it was diluted with water to obtain a titanium sulfate aqueous solution. Iron pieces were added as a reducing agent to this, and the iron content in the ilmenite was reduced to ferrous ions, followed by cooling and precipitation separation as ferrous sulfate. Water vapor heated to 150 ° C. was blown into the titanium sulfate aqueous solution thus obtained to precipitate hydrous titanium oxide. This was washed with water, pickled and secondary water, and then calcined at a temperature of 800 ° C. for 4 hours under air flow.
This is pulverized with a jet stream, and the average particle size is about 0.5μ.
Anatase type titanium oxide having a specific surface area of 22 m ² / g in m (hereinafter, sometimes referred to simply as “titanium oxide”) was obtained.

200 g of oxalic acid was dissolved in 6400 cc of deionized water to prepare an aqueous oxalic acid solution, and 47.25 g of ammonium metavanadate and 5.98 of ammonium monophosphate were added to the solution.
g, niobium chloride 18.79 g, cesium sulfate 5.90
g, 5.39 g of silver nitrate and 36.7 antimony trioxide.
3 g was added and thoroughly stirred. 1800 g of titanium oxide was added to the solution thus obtained and stirred by an emulsifier to prepare a catalyst slurry liquid.

Externally heatable diameter 35 cm, length 8
In a 0 cm stainless steel rotary furnace, spherical with a diameter of 6 mm,
2000 cc of SiC self-sintering carrier with apparent porosity of 35% was put in it, preheated to 200 to 250 ° C., the catalyst slurry liquid was sprayed on the carrier while rotating the furnace, and 8 g / 100 cc of catalytically active substance was added. (Carrier) was carried. Then, 580 ° in an electric furnace while circulating air.
The catalyst (A) was prepared by calcining at a temperature of C for 6 hours.

The composition of the catalyst (A) and the ratio of the total pore volume occupied by pores having a diameter of 0.15 to 0.45 μm in the catalyst active material layer to the total pore volume occupied by pores of 10 μm or less ( Table 1 shows the average particle diameter and specific surface area of titanium oxide used for the preparation of the catalyst (hereinafter, these are collectively referred to as “catalytic properties”).
The ratio of the volume occupied by pores having a diameter of 0.15 to 0.45 μm to the total pore volume was determined from the measurement result of the pore distribution by the mercury porosimetry porosimeter.

A catalyst (B) was prepared in the same manner as in the above-mentioned method except that the amount of ammonium monophosphate added was changed to 23.92 g in the preparation of the catalyst (A). Table 1 shows the catalyst characteristics of the catalyst (B). The phosphorus content of the catalyst (B) is higher than that of the catalyst (A), and the activity of the catalyst (B) is higher than that of the catalyst (A). (Oxidation reaction) Inner diameter 2 immersed in a molten salt bath maintained at a temperature of 355 ° C
In an iron reaction tube having a length of 5 mm and a length of 3 m, the catalyst (B) was first filled as a post-catalyst at a height of 1 m at the material gas outlet, and then the catalyst (A) was used as a pre-catalyst at a height of 1.5 m at the inlet. Filled.

A mixed gas obtained by mixing ortho-xylene at a rate of 85 g / Nm ³ (synthesis gas) with respect to a synthesis gas consisting of 10% by volume of oxygen, 10% by volume of steam and 80% by volume of nitrogen was introduced from the upper inlet of the reaction tube. Space velocity (SV) 25
It was introduced at 00 hr ^-1 (STP) to carry out the oxidation reaction of orthoxylene. The yield of phthalic anhydride was measured in the initial stage of the reaction, 3 months after the start of the reaction, and 6 months after the start of the reaction. The results are shown in Table 2. The conversion of orthoxylene is almost 100%, and the above yield can be regarded as the selectivity of phthalic anhydride.

-Example 2-Example 1 (Preparation of catalyst) except that 4.94 g of silver sulfate was used in place of 5.39 g of silver nitrate.
Catalysts (C) and (D) were prepared in the same manner as in (Preparation of catalyst), and then an oxidation reaction was carried out in the same manner as in Example 1 (oxidation reaction). Table 1 shows the catalyst characteristics of the catalysts (C) and (D), and Table 2 shows the results of the oxidation reaction.

-Example 3-Example 1 except that in Example 1 (preparation of catalyst), 4.42 g of silver phosphate was used instead of 5.39 g of silver nitrate.
Catalysts (E) and (F) were prepared in the same manner as in (Catalyst preparation), and then an oxidation reaction was carried out in the same manner as in Example 1 (oxidation reaction). Table 1 shows the catalyst characteristics of the catalysts (E) and (F), and Table 2 shows the results of the oxidation reaction.

-Comparative Example 1-In the same manner as in Example 1 (preparation of catalyst), except that the amount of cesium sulfate added was 8.25 g and silver was not added in Example 1 (preparation of catalyst). Catalyst (K), (L)
Was prepared, and the oxidation reaction was carried out in the same manner as in Example 1 (oxidation reaction). Table 1 shows the catalytic properties of the catalysts (K) and (L).
Table 2 shows the results of the oxidation reaction.

-Example 4- (Preparation of catalyst) After ilmenite was mixed with 80% concentrated sulfuric acid and sufficiently reacted, it was diluted with water to obtain a titanium sulfate aqueous solution. Iron pieces were added as a reducing agent to this, and the iron content in the ilmenite was reduced to ferrous ions, followed by cooling and precipitation separation as ferrous sulfate. Water vapor heated to 150 ° C. was blown into the aqueous titanium sulfate solution thus obtained to precipitate hydrous titanium oxide. This was washed with water, pickled and secondary water, and then fired at a temperature of 700 ° C. for 4 hours under air flow. This was subjected to jet stream pulverization treatment, and the average particle size was about 0.
Anatase type titanium oxide having a specific surface area of 33 m ² / g measured by BET method at 45 μm was obtained.

900 g of oxalic acid was dissolved in 6400 cc of deionized water to prepare an oxalic acid aqueous solution. In this aqueous solution, 408.60 g of ammonium metavanadate, 10.34 g of ammonium primary phosphate, 17.33 g of niobium chloride, 2.72 g of cesium sulfate and sulfuric acid were added. Potassium 3.92 g, silver nitrate 31.
05 g and antimony trioxide 42.35 g were added,
Stir well. 1800 g of the above titanium oxide was added to the solution thus obtained, and the mixture was stirred by an emulsifier to prepare a catalyst slurry.

Using the above slurry, a catalytically active substance was loaded in the same manner as in Example 1. Carrying rate is 8.0 g / 10
It was 0 cc (carrier). Then, the catalyst (G) was prepared by firing in an electric furnace at a temperature of 560 ° C. for 6 hours while circulating air. In the preparation of the catalyst (G), a catalyst (H) was prepared in the same manner as the preparation of the catalyst (G) except that the amount of the monobasic ammonium phosphate used was 31.02 g. (Oxidation reaction) Inside diameter 25m immersed in molten salt bath kept at 365 ° C
First, a catalyst (H) as a post-catalyst was filled at a height of 1 m into an iron reaction tube having a length of 3 m and a length of 3 m, and then a catalyst (G) was filled at a height of 1.5 m as a pre-catalyst. 85 g / Nm ^{3 of} naphthalene to a synthesis gas consisting of 10% by volume of oxygen, 10% by volume of steam and 80% by volume of nitrogen.
(Synthesis gas) mixed gas at a space velocity of 2500
It was introduced by hr ^-1 (STP) to carry out an oxidation reaction.

Table 1 shows the catalytic properties of the catalysts (G) and (H).
The results of the oxidation reaction are shown in Table 2. -Comparative Example 2-In Example 4 (preparation of catalyst), the amount of potassium sulfate added was 1.96 g, and the amount of silver nitrate added was 77.63.
Catalysts (M) and (N) were prepared in the same manner as the preparation of catalysts (G) and (H) except that the amount was changed to g, and the reaction was carried out in the same manner as in Example 4 (oxidation reaction).

Table 1 shows the catalytic properties of the catalysts (M) and (N).
The results of the oxidation reaction are shown in Table 2. -Example 5- (Preparation of catalyst) 200 g of oxalic acid was dissolved in 6400 cc of deionized water to prepare an oxalic acid aqueous solution. In this aqueous solution, 96.48 g of ammonium metavanadate, 4.82 g of cesium sulfate, 1.18 g of thallium nitrate and silver nitrate were prepared. 2.75 g was added and stirred well. In the solution thus obtained, the same anatase type titanium used in Example 1 was used as TiO _2.
00 g was added and stirred with an emulsifier to obtain a slurry.

The same method as in Example 1 using the above slurry
The catalytically active substance was supported by the method. The carrying amount is 8.0 g /
It was 100 cc (carrier). Then let the air flow
While calcining in an electric furnace at a temperature of 550 ° C for 6 hours, the catalyst
(I) (pre-stage catalyst) was prepared. Preparation of the above catalyst (I)
In place of cesium sulfate and thallium nitrate
Catalyst (I) except that 2.96 g of rubidium nitrate was used
A catalyst (J) (second stage catalyst) was prepared in the same manner as in
It was (Oxidation reaction) In Example 1, 21% by volume of oxygen was used as a raw material gas.
And syngas consisting of 79% by volume of nitrogen and
70g / Nm of siren³(Syngas) mixed in proportion
A mixed gas is used, which is fed through the upper inlet of the reaction tube at a space velocity.
3000 hours ^-1Example 1 except that it was introduced at (STP)
The oxidation reaction was performed in the same manner as in.

Table 1 shows the catalytic properties of the catalysts (I) and (J).
The results of the oxidation reaction are shown in Table 2. -Example 6-The catalyst (Q) was prepared in the same manner as the preparation of the catalyst (I) except that 19.06 g of niobium chloride was added in the preparation of the catalyst (I) in Example 5 (preparation of catalyst). In addition, in the preparation of the catalyst (J), the amount of rubidium nitrate added was 4.44 g, and the amount of primary ammonium phosphate was 6.08 g.
A catalyst (R) was prepared in the same manner as the catalyst (J) except that was added.

Then, an oxidation reaction was carried out in the same manner as in Example 5 (oxidation reaction). Table 1 shows the catalytic properties of the catalysts (Q) and (R).
Table 2 shows the results of the oxidation reaction. -Example 7-In Example 5 (preparation of catalyst), antimony trioxide 1
Catalysts (S) and (T) were prepared in the same manner as in Example 5 (preparation of catalyst), except that 8.75 g was added.
The oxidation reaction was performed in the same manner as (oxidation reaction).

Table 1 shows the catalytic properties of the catalysts (S) and (T).
The results of the oxidation reaction are shown in Table 2. -Example 8--In the preparation of the catalyst (I) in Example 5 (preparation of catalyst), the addition amount of cesium sulfate was 6.02 g, niobium chloride 19.06 g and primary ammonium phosphate 6.08.
A catalyst (U) was prepared in the same manner as the catalyst (I) except that g was added.

Further, in the preparation of the catalyst (J), the addition amount of rubidium nitrate was 4.44 g, and 6.08 g of primary ammonium phosphate and 18.75 g of antimony trioxide were added. Similarly, catalyst (V)
Was prepared. Then, an oxidation reaction was performed in the same manner as in Example 5 (oxidation reaction). Table 1 shows the catalytic properties of the catalysts (U) and (V).
Table 2 shows the results of the oxidation reaction.

-Example 9-Similar to the preparation of catalyst (I) except that 19.06 g of niobium chloride and 18.75 g of antimony trioxide were added in the preparation of catalyst (I) in Example 5 (preparation of catalyst). To prepare a catalyst (W). In addition, in the preparation of the catalyst (J), the amount of rubidium nitrate added was 4.44 g, niobium chloride 19.06 g, and primary ammonium phosphate 6.08 g.
A catalyst (X) was prepared in the same manner as the preparation of the catalyst (J), except that 18.75 g of antimony trioxide was added.

Then, an oxidation reaction was carried out in the same manner as in Example 5 (oxidation reaction). Table 1 shows the catalytic properties of the catalysts (W) and (X).
Table 2 shows the results of the oxidation reaction. -Comparative Example 3-Similar to the preparation of the catalyst (I) except that the amount of cesium sulfate added was 6.03 g and silver nitrate was not added in the preparation of the catalyst (I) in Example 5 (preparation of catalyst). To prepare a catalyst (O) (first-stage catalyst).

Further, in the preparation of the catalyst (O), the addition amount of rubidium nitrate was 4.44 g, and the silver nitrate was not added in the same manner as in the preparation of the catalyst (O). ) Was prepared. Thereafter, the oxidation reaction was performed in the same manner as in Example 5. Table 1 shows the catalytic properties of the catalysts (O) and (P), and Table 2 shows the results of the oxidation reaction.

In the above Examples and Comparative Examples, the oxidation reaction is continued with the load on the catalyst kept constant, during which the amount of phthalide by-produced in the case of the oxidation reaction of orthoxylene is controlled to 0.1% by weight or less. Thus, the molten salt temperature was set, and in the case of the oxidation reaction of naphthalene, the molten salt temperature was set so that the amount of naphthoquinone by-produced was controlled to 0.5% by weight or less.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

From the comparison between Examples 1 to 3 and Comparative Example 1, and the comparison between Examples 5 to 9 and Comparative Example 3, the improvement of the phthalic anhydride yield due to the addition of silver is clear, and From the comparison between Example 4 and Comparative Example 2, it can be seen that the amount of silver added is limited. As shown in Table 1 and Table 2,
The silver-added catalyst according to the present invention was found to improve the phthalic anhydride yield by about 2% as compared with the catalyst not added,
Furthermore, the performance after 3 months and 6 months is also very stable, and a great economic effect can be expected. For example, if we are currently producing 40,000 tons of phthalic anhydride annually, a yield increase of 2% would give us 8 million tons of phthalic anhydride without increasing the consumption of raw materials. Of.

Front Page Continuation (72) Inventor Chisako Nishio 1 992 Nishikioki, Akihama, Aboshi Ward, Himeji City, Hyogo Prefecture Catalytic Research Institute, Nippon Catalysis Chemical Industry Co., Ltd. Catalysis Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. A catalyst for producing phthalic anhydride by vapor-phase catalytic oxidation of orthoxylene and / or naphthalene with molecular oxygen or a gas containing molecular oxygen, wherein vanadium oxide is V ₂ O ₅ as 1 to 20. Parts by weight,
99 to 80 parts by weight of anatase type titanium oxide having a specific surface area of 10 to 60 m ² / g as TiO ₂ , and these 2
0.05 to 1.2 parts by weight of at least one element selected from potassium, cesium, rubidium and thallium as an oxide and silver as A per 100 parts by weight of the total of components.
A catalyst for producing phthalic anhydride, which comprises a heat-resistant inorganic carrier carrying a catalytically active substance in an amount of 0.05 to ₂ parts by weight as g ₂ O. 2. A catalyst for producing phthalic anhydride by vapor-phase catalytic oxidation of orthoxylene and / or naphthalene with molecular oxygen or a gas containing molecular oxygen, wherein vanadium oxide is V ₂ O ₅ as 1 to 20. Parts by weight,
99 to 80 parts by weight of anatase type titanium oxide having a specific surface area of 10 to 60 m ² / g as TiO ₂ , and these 2
0 to 1 part by weight of niobium as Nb ₂ O ₅ and 0.05 to 1.2 parts by weight of at least one element selected from potassium, cesium, rubidium and thallium as an oxide per 100 parts by weight of the total of components, phosphorus. 0 as P ₂ O ₅
1.2 parts by weight, the antimony Sb ₂ O ₃ 0 to 5
Parts by weight and 0.05 to ₂ parts by weight of silver as Ag ₂ O (however, the respective contents of niobium, phosphorus and antimony do not become 0 at the same time), and the catalytically active substance is a heat-resistant inorganic carrier. A catalyst for producing phthalic anhydride, characterized in that the catalyst is supported on. 3. In the catalytically active substance layer carried on a heat-resistant inorganic carrier, the total fine pores occupied by pores having a diameter of 0.15 to 0.45 μm and the total pore volume being 10 μm or less. It is 50% or more of the pore volume.
Or the catalyst for producing phthalic anhydride according to 2.