JPH0732876B2 - Method for producing fluidized catalyst for vapor phase catalytic oxidation of o-xylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a fluidized catalyst used for producing phthalic anhydride by catalytically oxidizing o-xylene in a gas phase.

<Prior Art> Conventionally, as a catalyst used for producing phthalic anhydride by gas phase oxidation of o-xylene in a fixed bed, an inert carrier such as alundum, silicon carbide, quartz, pumice, α-alumina or the like is used. , Vanadium pentoxide and titanium oxide (anatase type), or vanadium pentoxide and tellurium oxide, molybdenum oxide, tungsten oxide, nickel oxide, niobium oxide, tin oxide, chromium oxide and other active metal oxides, and further potassium and lithium. , A catalyst carrying an alkali metal salt such as sodium has been announced (for example, Kimio Tarama, supervised catalyst by reaction, P358 (1970), Kagaku Kogyo Co., Ltd.).

In the fixed bed, in order to remove the high exotherm of this reaction, about 1
A method is used in which a pipe-shaped reaction tube with a small diameter of 1 inch is uniformly filled with the catalyst, and heat is removed by using a heat medium for cooling to the outside. The labor and cost for uniform filling are enormous, and the pressure loss of each reaction tube, the equipment cost for keeping the temperature constant, and the operation management burden are large. Further, the cost and labor required for replacing the catalyst after deterioration are large.

Furthermore, in the case of a catalyst in which an active ingredient is coated on an inert carrier, reaction runaway occurs due to uneven distribution of the reaction gas, hot spots, or increase in pressure loss due to separation and desorption of the active ingredient during packing and operation. There is a risk.
In addition, in the fixed bed, since the concentration must be kept within the explosion limit of the reaction gas, it is required to supply the gas at a low concentration, and thus the productivity is poor.

To solve these problems, it is preferable to use a fluidized bed.

According to the fluidized bed, heat removal is easy and not only the occurrence of uneven flow and hot spots can be suppressed, but also catalyst replacement,
Either way, replenishment or the like is greatly advantageous. Further, it is possible to increase the concentration of the reactant, which is a great advantage in terms of productivity.

As a fluidized catalyst used for producing phthalic anhydride by gas phase oxidation of o-xylene, as in the case of using naphthalene as a raw material, silica is used as a carrier, vanadium pentoxide, potassium sulfate, and further molybdenum oxide, A catalyst supporting tungsten oxide, phosphorus oxide, boron oxide, etc. has been proposed (for example, BP, 941293 (1963); USP, 3.
232955 (1966)). However, it is difficult to obtain phthalic anhydride in a high yield when using the above-mentioned catalyst using silica as a carrier because of an excessive oxidation reaction or a side reaction that produces CO or CO ₂ , and the yield is improved. Therefore, an attempt has been made to mix a halogen gas such as Br ₂ into the reaction gas,
Using halogen gas causes equipment trouble due to corrosion (DP, 1144709 (1963); USP, 3455962 (196
9)).

Many catalysts have been proposed in which titanium oxide is used as a carrier and vanadium pentoxide is supported on the carrier (for example, B.
P., 1067726 (1967); Fr.P., 1537351 (1968)), forming a melt with ammonium thiocyanate and an alkali compound to obtain a strong catalyst,
The catalyst obtained by these methods, by the formation of the melt,
Since the specific surface area is decreased and the pore volume is decreased, the activity is remarkably low, and thus a high reaction temperature is required, and as a result, excessive oxidation and side reactions occur simultaneously, the catalyst obtained by this method is not used. It is difficult to use and obtain phthalic anhydride in good yield.

Further, the formation of the melt also overlaps with the high specific gravity of titanium oxide and gives only a catalyst having a remarkably large bulk specific gravity, and it is difficult to carry out an efficient fluidized bed reaction using these catalysts.

For these reasons, the production of phthalic anhydride by vapor phase oxidation of o-xylene using a fluidized bed has not been put to practical use.

<Problems to be Solved by the Invention> As described above, the present invention provides the production of a catalyst for a fluidized bed, which is remarkably advantageous as compared with a fixed bed, in a reaction of vapor phase oxidation of o-xylene to obtain phthalic anhydride. The purpose of the present invention is to provide a method, and more specifically, to provide a method for producing a highly active and highly selective catalyst for a fluidized bed, which uses titanium oxide as a carrier and has sufficient strength and appropriate bulk specific gravity.

<Means for Solving the Problems> The present inventors have completed the present invention as a result of earnest research on a fluidized bed catalyst for producing phthalic anhydride containing titanium oxide as a main component.

That is, the present invention provides a titanium oxide source, a vanadium compound, an alkali metal compound, a sulfuric acid compound and II of the periodic table.
Oxygen containing titanium oxide, vanadium pentoxide, alkali metal oxides, sulfur trioxide and Group IIIB acid compounds is prepared by mixing the Group IB compound and then spray drying and firing.
A method for producing a catalyst used in the production of phthalic anhydride by a xylene vapor phase catalytic oxidation method, which comprises, as the titanium oxide source, a hydroxide that produces titanium oxide having a crystallite size of 300Å or less when dried at 300 ° C. Using titanium, III B
The compounding amount of the group compound is such that the obtained catalyst is 0.5 in terms of oxide.
Provided is a method for producing a fluidized catalyst for o-xylene vapor-phase catalytic oxidation, which is characterized in that an amount of about 15 to 15% by weight of a Group IIIB compound is used.

Hereinafter, the present invention will be described in detail.

The aqueous solution used for preparing the catalyst by the method of the present invention contains a titanium oxide source, a vanadium compound, an alkali metal compound, a sulfuric acid compound and a group IIIB compound of the periodic table.

The titanium oxide source used in the present invention is titanium hydroxide that produces titanium oxide having a crystallite size of 300 Å or less when dried at 300 ° C. The crystallite diameter specified in the present invention is a value obtained by the following formula from the half-value width of the diffraction peak at 2θ = 25.3 ° (CuKα anatase type titanium oxide) in the X-ray diffraction diagram based on the Debye-Sieler method.

A catalyst containing titanium oxide with a crystallite size of more than 300Å has extremely low wear resistance, and when used in a fluidized bed, it causes large outflow / scattering of the catalyst and is uneconomical. It causes a trouble of closing. Moreover, a large amount of catalyst is mixed into the reaction product, and in addition, a good fluid state cannot be maintained. Furthermore, the crystallite diameter is 300Å
With a catalyst containing super-titanium oxide, the specific surface area of titanium oxide is small, so that uniform and sufficient loading of the active component is not achieved, and the catalytic activity is significantly reduced, so even in a fluidized bed with a long contact time, it is sufficient. Phthalic anhydride yield cannot be obtained.

Here, "titanium hydroxide that produces titanium oxide having a crystallite size of 300Å or less when dried at 300 ° C" used in the present invention means titanium hydroxide, metatitanic acid, orthotitanic acid, titania sol, titania gel, etc. And the powders obtained by drying them at low temperature.

The titanium hydroxide used in the present invention is not limited in its raw material and preparation method as long as the crystallite size of titanium oxide in the powder dried at 300 ° C. is 300 Å or less, preferably 200 Å or less.

Examples of these titanium hydroxides include titanic acid obtained by a thermal hydrolysis method obtained in the intermediate step of producing pigment titanium oxide, and titania sol obtained by adding an acid thereto. Further, titanium hydroxide, titania sol, etc. obtained by neutralizing and hydrolyzing titanium sulfate, titanyl sulfate, titanium tetrachloride and the like, or by deoxidizing and hydrolyzing by an ion exchange method can be mentioned. Especially, a solution such as titanyl sulfate at 40 ° C
Titanium hydroxide obtained by neutralizing and hydrolyzing at a low temperature below shows a crystallite size of several 10Å after drying and is suitable.

Examples of titanium oxide having a crystallite size after drying which is not used in the present invention is more than 300Å, anatase of the thermal hydrolysis method which has already undergone the firing step, pigment titanium oxide such as rutile type, obtained by neutralization or ion exchange. Examples include titanium hydroxide, a sol-baked powder, and titanium hydroxide obtained by crystal growth of a titanium hydroxide type during hydrolysis or by an autoclave.

The vanadium compound used in the present invention is soluble in water and becomes vanadium oxide by firing in air, for example, ammonium metavanadate, vanadyl sulfate (vanadium oxysulfate), vanadium formate, vanadium acetate, vanadyl oxalate, oxalate. Examples thereof include ammonium vanadium acid, vanadyl phosphate, and vanadium oxyhalide. Of these, vanadyl sulfate, ammonium metavanadate, vanadyl oxalate and the like are preferably used.

Further, the alkali metal compound used in the present invention (hereinafter,
(Alkali metal is abbreviated as M), hydroxides such as potassium, cesium and rubidium, sulfates, carbonates, chlorides, nitrates, oxyhalides, thiosulfates, nitrites, sulfites, bisulfites, Examples thereof include hydrogen sulfate, oxalate, and hydrogen oxalate. Of these, hydroxides, sulfates, carbonates and the like are preferably used.

As the sulfuric acid compound, those which can be converted into sulfur trioxide by firing in air, for example, sulfuric acid, ammonium sulfate,
Ammonium hydrogen sulfate etc. are mentioned. Of these, sulfuric acid and ammonium sulfate are preferably used.

In the present invention, a vanadium compound, an alcal metal compound,
Sulfuric acid compounds are used as active ingredients.

The group IIIB compound of the periodic table used in the present invention is a halide of the group IIIB element of the periodic table or a salt of the group IIIB element such as an acid, and any compound soluble in water can be used. .

The IIIB group elements of the periodic table include scandium, yttrium, lanthanoid elements, and actinoid elements, all of which are effective, but lanthanoid elements represented by lanthanum and cerium are particularly preferable.

Examples of the group IIIB compound when the group IIIB element is lanthanum include lanthanum chloride, lanthanum bromide, lanthanum iodide, lanthanum sulfate, lanthanum nitrate, lanthanum carbonate, lanthanum ammonium sulfate, and lanthanum acetate. It is also possible to dissolve lanthanum hydroxide or lanthanum oxide in an acid such as sulfuric acid before use. This also applies to other Group IIIB compounds. Furthermore, the Group IIIB compound does not have to be a single compound, and for example, a mixture of crude rare earth chloride or the like is an inexpensive and suitable raw material.

The Group IIIB compound suppresses thermal deterioration of the catalyst.

That is, a catalyst produced by using an active ingredient and titanium hydroxide as a titanium oxide source, which produces titanium oxide having a crystallite size of 300 Å or less when dried at 300 ° C, also has activity, selectivity and abrasion resistance. However, as in the method of the present invention,
By using a Group IB compound, it is possible to prevent crystallization of titanium oxide at the time of catalyst calcination or reaction, to prevent deterioration of abrasion resistance of the catalyst, to prevent deterioration of activity and to prevent catalyst from becoming heavier.
In addition, in the catalyst manufacturing process, the calcination temperature range for making the wear resistance and bulk specific gravity of the catalyst a preferable range and the calcination temperature range for obtaining a preferable activity come to coincide with each other.

In the method of the present invention, in the production of the catalyst, the group IIIB compound, which is one of the starting materials, has an obtained catalyst of 0.5% in terms of oxide.
An amount is used which will result in containing ~ 15 wt%, preferably 1-10 wt% Group IIIB compound. If the group IIIB compound in the catalyst is less than 0.5% by weight in terms of oxide, the effect of suppressing the thermal deterioration of the catalyst cannot be obtained, and if it exceeds 15% by weight, the catalytic activity, particularly the selectivity is lowered. Not preferable.

The titanium oxide source is used in an amount such that the resulting catalyst contains titanium oxide in an amount of preferably 50 to 95% by weight, more preferably 60 to 90% by weight, as TiO ₂ . As for the active ingredient, the obtained catalyst is V ₂ O ₅ + M ₂ O (M is an alkali metal)
+ SO ₃ is preferably 5 to 50% by weight, more preferably 1
An amount is used which will result in 0-40% by weight of the active ingredient.

The vanadium compound in the active ingredient is used in such an amount that the resulting catalyst will contain 1 to 30% by weight, more preferably 1 to 15% by weight, of the vanadium compound as V ₂ O ₅ . When the content of the active component in the obtained catalyst is less than 5% by weight, sufficient activity cannot be obtained, and 50% by weight is obtained.
If it exceeds, the specific surface area of the catalyst is remarkably reduced, the dispersion state of the active ingredient is deteriorated, and crystal precipitation is caused.
It is not preferable because the catalyst activity and fluidity are lowered.

Further, the content ratio of each active component in the catalyst obtained by the method of the present invention, SO ₃ / M ₂ O (molar ratio) is preferably 0.1 ~
6, more preferably 1 to 4, and M ₂ O / V ₂ O ₅ (molar ratio)
Is preferably 0.1 to 5, more preferably 0.5 to 3, and the raw material components are mixed to prepare an aqueous solution (slurry).

The method for producing a catalyst according to the present invention comprises mixing the above components,
It includes a step of spray drying and firing. The components may be mixed in any order, and a method of dissolving two or more components together, a method of dissolving the active ingredient in the titanium hydroxide dispersion, or the like may be employed. A method of simultaneously obtaining a precipitate from a titanium solution and a Group IIIB compound, or after mixing titanium hydroxide and a Group IIIB compound,
The method of preliminarily depositing the group IIIB compound on the titanium hydroxide surface by neutralization and then used for the preparation is more effective.

Further, as a titanium source, titanium hydroxide that produces titanium oxide having a crystallite size of 300 Å or less may be mixed with other titanium compounds such as those that produce titanium oxide having a crystallite size of more than 300 Å. It is possible.

The mixed slurry obtained as described above is concentrated if necessary, adjusted to an appropriate concentration, and then spray-dried to obtain spherical fine particles.

A known method can be adopted as the spray drying method.
In spraying, it is preferable to set the spraying conditions so that the weight average particle diameter of the obtained spherical fine particles is 40 to 150 μm.

The obtained spherical particles are preferably 300 to 700 in air.
Baking at a temperature of ℃, more preferably 400-600 ℃.

<Examples> Hereinafter, the present invention will be specifically described based on Examples.

Example 1 (1) Preparation of Titanium Hydroxide Gel 310 kg of an aqueous titanyl sulfate solution containing 5.2% by weight of TiO _{2 and} 8.1% by weight of H ₂ SO ₄ was cooled to 12 ° C. and then stirred for 12 minutes. 15% ammonia water was added and neutralized to obtain a titanium hydroxide gel. The pH of this gel is 8.9 and the temperature is 2.
At 9 ° C., the titanium concentration as TiO ₂ in the gel was 4.2% by weight.

20 kg of this gel was taken, dehydrated under reduced pressure with a flat plate filter, and then washed with 230 pure water. The same washing was performed to wash all the neutralized gels to obtain 140 kg of washed titanium hydroxide gel. Ti in the obtained titanium hydroxide gel
The titanium concentration as O ₂ was 11.8% by weight.

A part of this gel was taken and dried at 300 ° C. for 3 hours to obtain a powder. The crystallite diameter of the anatase type titanium oxide determined from the peak of X-ray diffraction diagram 2θ = 25.3 ° of this powder was 41Å.

(2) Preparation of catalyst Take 50 kg of the titanium hydroxide gel obtained in the previous section and add 75 kg of pure water.
Was added and stirred well to form a slurry. Separately prepared lanthanum nitrate solution containing 5% by weight as La ₂ O _3.
7.3 kg, vanadyl sulfate solution containing 19% by weight as V ₂ O ₅ 2.1
2.2 kg of potassium sulphate solution containing 15% by weight as K ₂ SO ₄
And ammonium sulphate solution containing 20% by weight as SO _3.
After 0.79 kg was added and mixed, diluted ammonia water was further added to adjust the pH of the slurry to 2.4. This slurry was heated with stirring to evaporate the water content, and TiO ₂ + La ₂ O
As _{3 + V 2 O 5 + K} 2 SO 4 + SO 3 and concentrated to 12.9% concentration.

Furthermore, after thoroughly dispersing the slurry with a homogenizer,
The powder was obtained by spray drying with a disc spray dryer. It is dried at 150 ° C overnight and then at 500 ° C for 3 hours.
It was calcined for an hour to obtain a catalyst A-500.

Catalyst A-550, A-600 and A-650 were obtained in the same manner except that the calcination temperature was changed to 550 ° C, 600 ° C and 650 ° C.

(Example 2) A catalyst B-500 was treated in the same manner as in Example 1 except that 2.8 kg of a lanthanum nitrate solution containing 5% by weight as La ₂ O ₃ was used.
B-550 and B-600 were obtained.

(Example 3) Catalyst C-50 was treated in the same manner as in Example 1 except that 13.5 kg of a lanthanum nitrate solution containing 5% by weight as La ₂ O ₃ was used.
0, C-550 and C-600 were obtained.

Example 4 Catalyst D-50 was treated in the same manner as in Example 1 except that 19.5 kg of a lanthanum nitrate solution containing 5% by weight as La ₂ O ₃ was used.
0, D-600 was obtained.

Example 5 Example 1 was repeated except that 3.4 kg of a cerium nitrate solution containing 5 wt% as Ce ₂ O ₃ was used instead of the lanthanum nitrate solution.
The same treatment as described above was carried out to obtain catalysts E-500 and E-550.

Instead of (Example 6) lanthanum nitrate solution, except for using cerium nitrate solution 7.2kg containing 5% by weight Ce ₂ O ₃ is Example 1
The catalyst was treated in the same manner as above to obtain catalysts F-500 and F-550.

(Example 7) Titanium hydroxide gel 43.2 containing 11.8% by weight as TiO _2.
7.4k of lanthanum nitrate solution containing 5% by weight as La ₂ O ₃
g, 3.6 kg of vanadyl nitrate solution containing 19% by weight as V ₂ O ₅ ,
4.6 kg of potassium nitrate solution containing 15% by weight as K ₂ SO ₄ and ammonium sulfate solution 1.8 containing 20% by weight as SO _3.
The same procedure as in Example 1 was carried out except that kg was used, and the catalyst G-
500 and G-550 were obtained.

Comparative Example 1 Catalyst H-500, H-550, H-600, and H-650 were obtained in the same manner as in Example 1, except that the lanthanum nitrate solution was removed.

Comparative Example 2 Catalyst I-50 was treated in the same manner as in Example 1 except that 28.6 kg of a lanthanum nitrate solution containing 5% by weight as La ₂ O ₃ was used.
0, I-600 was obtained.

Example 8 (1) Preparation of Titanium Hydroxide Gel 310 kg of an aqueous titanyl sulfate solution containing 5.2% by weight of TiO _{2 and} 8.1% by weight of H ₂ SO ₄ was heated to 60 ° C. with stirring.
Aqueous 15% ammonia water was added and neutralized over time to obtain a titanium hydroxide gel. The pH of this gel is 9.0, the temperature is 62 ℃,
The titanium concentration as TiO ₂ in the gel was 4.0% by weight.

This gel was washed in the same manner as in Example 1 to obtain 120 kg of washed titanium hydroxide gel. In the obtained titanium hydroxide gel
The titanium concentration as TiO ₂ was 13.5% by weight.

A part of this gel was taken and dried at 300 ° C. for 3 hours to obtain a powder. The crystallite size of this powder was 120Å.

(2) Preparation of catalyst Using the titanium hydroxide gel obtained in the preceding paragraph, the same treatment as in Example 1 was carried out to obtain catalysts J-500 and J-550.

Comparative Example 3 (1) Preparation of Titanium Hydroxide Gel 310 kg of an aqueous titanyl sulfate solution containing 5.2% by weight of TiO _{2 and} 8.1% by weight of H ₂ SO ₄ was heated to 60 ° C. and stirred for 8 hours.
Aqueous 15% ammonia water was added and neutralized over time to obtain a titanium hydroxide gel. The gel was dehydrated and washed, and then diluted nitric acid was added thereto with stirring to adjust the pH to 1.8.

Put this in an externally heated autoclave equipped with a stirrer,
While well stirring, perform hydrothermal treatment at 165 ° C for 100 hours,
A titanium hydroxide suspension (containing 9.8% by weight as TiO ₂ ) was obtained. The crystallite diameter of the obtained titanium hydroxide was 330Å.

(2) Preparation of catalyst 60 kg of the titanium hydroxide suspension obtained in the preceding paragraph was mixed with 7.2 kg of the lanthanum nitrate solution and 2.2 k of vanadyl sulfate solution shown in Example 1.
g, potassium sulfate solution 2.2 kg and ammonium sulfate solution
0.82 kg was added to the mixture and made into a slurry form. Dilute aqueous ammonia was added here to adjust the pH of the slurry to 2.5. The slurry was heated with stirring to evaporate the water and concentrated as TiO ₂ + La ₂ O ₃ + V ₂ O ₅ + K ₂ SO ₄ + SO ₃ to a concentration of 14.3% by weight.

Thereafter, the same treatment as in Example 1 was carried out to obtain a catalyst K-500.

The chemical compositions of the catalysts obtained in the above Examples and Comparative Examples are shown in Table 1.
Table 2 shows the physical properties, and Table 3 shows the measurement results of the oxidation activity of o-xylene.

Fluid catalytic properties depend on bulk specific gravity and wear rate,
The reaction characteristics (activity, selectivity) can be evaluated from the o-xylene conversion rate and the phthalic anhydride yield measured by a bench reactor (fluidized bed method).

The physical properties were measured by the following methods.

Specific surface area Measured using the BET method.

Pore volume Measured by the nitrogen gas adsorption method.

Bulk specific gravity was measured using the graduated cylinder method.

Abrasion rate The ACC method (method described in British Patent 737429) was used to measure the rate of abrasion during 5 to 20 hours after the start of flow.

The reaction characteristics (activity, selectivity) are as follows: a bench reactor (fluidized bed system) filled with the catalyst 4 and a reaction temperature of 300
° C, o-xylene supply rate 118 / hr, air supply rate 1300Nl
/ hr, the pressure is a reaction under normal pressure, the reaction product obtained (other than phthalic anhydride, as a by-product,
Maleic anhydride, o-tolyl aldehyde, CO and CO ₂
Was analyzed by gas chromatography to calculate the o-xylene conversion rate and the phthalic anhydride yield.

As is clear from Table 2, the catalyst obtained by the method of the present invention is
The specific surface area is large, the pore volume and bulk specific gravity are appropriate, and the wear rate is small. Therefore, they are suitable as fluid bed catalysts.

Further, as is clear from Table 3, when the catalyst obtained by the method of the present invention is used, a reaction having a high o-xylene conversion rate (activity) and a phthalic anhydride yield (selectivity) can be performed.

<Effects of the Invention> According to the present invention, it is possible to obtain a catalyst having excellent wear resistance, moderate bulk specific gravity and activity.

The catalyst according to the method of the present invention has an appropriate specific surface area and pore distribution, and thus exhibits high activity at low reaction temperature and high selectivity.

Further, since it has high abrasion resistance, it has a low wear rate during flowing, has an appropriate bulk specific gravity, and has a high sphericity of particles, and therefore has excellent fluidity.

Then, the conversion rate of o-xylene and the yield of phthalic anhydride are higher than in the case of using the conventional catalyst.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Noboru Hirooka 2-3 2-3 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation Tokyo headquarters (72) Inventor Yusaku Arima Hiroto 1560, Onga-cho, Onga-gun, Fukuoka ( 72) Inventor Susumu Fujii 1-3-1 Nijima, Wakamatsu-ku, Kitakyushu, Fukuoka

Claims (1)

[Claims] 1. A titanium oxide source, a vanadium compound, an alkali metal compound, and a sulfuric acid compound and III B of the periodic table.
Phthalic anhydride by titanium oxide, vanadium pentoxide, alkali metal oxides, sulfur trioxide, and Group IIIB oxides by o-xylene vapor-phase catalytic oxidation method by mixing group compounds and then spray-drying and firing. A method for producing a catalyst used for the production of the titanium oxide, wherein the titanium oxide source is titanium hydroxide that produces titanium oxide having a crystallite diameter of 300Å or less when dried at 300 ° C. The amount of the obtained catalyst is 0.5 to 15 in terms of oxide.
A method for producing a fluidized catalyst for o-xylene vapor-phase catalytic oxidation, which comprises using an amount such that the compound contains a group IIIB compound by weight.