JPH0451226B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a catalyst for producing phthalic anhydride by catalytically oxidizing naphthalene in the vapor phase. This invention relates to a method for producing a fluidized catalyst for gas phase catalytic oxidation of naphthalene in which vanadium, potassium sulfate, and sulfuric acid are supported on silica. [Prior Art] Conventionally, as a fluidized catalyst for gas phase catalytic oxidation of naphthalene, a catalyst in which a vanadium component, a potassium component, and sulfuric acid are supported on silica has been used.
Various methods for producing such catalysts have been proposed. Japanese Patent Publication No. 40-15096, British Patent No. 885651, and U.S. Patent No. 2973371 disclose that an ammonium vanadate solution is added to a potassium silicate solution to prepare a mixed slurry of silica hydrogel, a potassium component, and a vanadium component. A method (so-called post-deposition method) is disclosed in which the mixed slurry is then mixed with sulfuric acid to neutralize it, followed by spray drying and calcination to prepare a fluidized catalyst. Furthermore, British Patent No. 1053474 discloses that a carrier is prepared by spray drying a silica hydrogel obtained by neutralizing dilute sodium silicate with sulfuric acid, gelling it, and washing it. A method for preparing a catalyst by supporting a mixed solution of vanadium pentoxide and sulfuric acid (so-called impregnation method) is disclosed. [Problems to be solved by the present invention] However, the above-mentioned Japanese Patent Publication No. 40-15096,
In the post-deposition method described in British Patent No. 885651 and US Patent No. 2973371, even if the specific surface area of the silica support is increased in order to highly activate the catalyst, a low melting point composition is formed during the calcination process. It is not possible to increase the specific surface area or pore volume of the resulting catalyst because it is greatly influenced by active ingredients that are susceptible to oxidation.
In fact, even if a silica carrier with a specific surface area of 200 to 850 m ² /g is used, the specific surface area of the catalyst is only 75 m ² /g or less, and the more a silica carrier with a larger specific surface area is used, the more It is stated that the pore volume of the catalyst is reduced. That is, in these methods, the desired high specific surface area,
It is not possible to produce catalysts with pore volumes. However, in the gas phase catalytic oxidation method of naphthalene, it is necessary to lower the maximum reaction temperature and increase the specific surface area of the catalyst in order to improve the yield of phthalic anhydride. This method was not sufficient as a method for producing a catalyst for gas phase catalytic oxidation of naphthalene. Furthermore, in the conventional post-deposition method of preparing silica hydrogel from potassium silicate and ammonium vanadate, there are restrictions on the composition that can be gelled.
There was also the problem that a highly active catalyst could not be obtained because of restrictions on the composition of the resulting catalyst. On the other hand, in the catalyst prepared by the impregnation method, the distribution of the active component within the catalyst particles is uneven, and the content of the active component varies depending on the catalyst particle size. Therefore, when the catalyst is used, local heat generation occurs in the catalyst, causing sintering of the active component V ₂ O ₅ and scattering of SO ₃ , resulting in poor heat resistance and significant deterioration of catalyst performance. It was hot. In particular, commercially available catalysts in which crushed silica particles are impregnated with active ingredients have poor wear resistance as well as significant problems due to non-uniform distribution of the active ingredients due to the preparation method. . On the other hand, in order to obtain a catalyst in which the active ingredient is uniformly supported by the impregnation method, it is sufficient to use a carrier having a very large specific surface area and pore volume. However, a catalyst obtained by impregnating such a carrier with an active ingredient has an extremely low bulk density and extremely poor wear resistance. On the other hand, US Pat. No. 2,941,957 describes the use of a silica carrier prepared by spheroidizing sodium silicate in a non-aqueous solvent in order to improve the wear resistance of the catalyst. However, the silica carrier obtained by this method has limited properties such as non-surface area and pore volume, and because it is prepared by an impregnation method, it does not solve the problem of uneven distribution of active ingredients. It was still there. As mentioned above, in the conventional post-deposition method using silica hydrogel obtained by neutralizing an alkali silicate such as potassium silicate as a silica source, the catalyst composition to be prepared is limited, and the catalyst with a high specific surface area is In addition, with the impregnation method in which a silica carrier is prepared in advance and then used, the prepared catalyst has poor abrasion resistance and is difficult to obtain a catalyst with a high specific surface area. Since it is difficult to uniformly support the components, there are problems such as poor heat resistance and large performance deterioration. The present invention aims to solve such problems, and has a high specific surface area, appropriate pore volume and bulk density, uniform support of active ingredients, wear resistance,
The object of the present invention is to provide a method for producing a highly active fluidized catalyst for gas phase catalytic oxidation of naphthalene that has excellent heat deterioration resistance. In other words, in the present invention, the specific surface area, pore volume, and bulk density of the catalyst can be adjusted as desired, and the reaction conditions can be varied over a wide range in the gas phase catalytic oxidation of naphthalene using the fluidized bed method. It is an object of the present invention to provide a method for producing a fluidized catalyst for gas-phase catalytic oxidation of naphthalene, which produces a catalyst having excellent heat resistance that can be used in the gas phase catalytic oxidation of naphthalene. [Means for Solving the Problems] As a result of intensive research to solve the problems associated with conventional catalyst manufacturing methods, the present inventors have found that silica sol is generally used as a raw material for silica, which serves as a catalyst support. Use what is sometimes called a polysilicate solution (a very unstable sol containing polysilicate immediately after neutralizing or ion-exchanging low concentrations of sodium silicate or potassium silicate). The present inventors have discovered that colloidal silica having an average particle size of 4 to 50 nm can be used in the form of a sol or gel instead of the above, and have accomplished the present invention. That is, the present invention provides a method for producing a fluidized catalyst for gas phase catalytic oxidation of naphthalene by mixing a silica source, a vanadium compound, a potassium compound, and a sulfuric acid compound, followed by spray drying and sintering. Provided is a method for producing a fluidized catalyst for gas phase catalytic oxidation of naphthalene, characterized in that colloidal silica having a particle size of 4 to 50 nm is used. The present invention will be explained in detail below. The present invention uses a silica source with an average particle size of 4 to 50n.
colloidal silica, preferably 4 to 25 nm, is used as a sol or gel. Here, colloidal silica is particulate polysilicic acid that, when made into a sol, does not settle when left standing or by ordinary centrifugation. Further, the average particle diameter is determined by the following formula. Average particle diameter (nm) = 6000/specific surface area (m ² /g) x 2.2 In the formula, the specific surface area is GWSears, Analytical
Chemistry VOL28, No.12, Dec, P.1981 (1956)
It was determined by the titration method using caustic soda as described in . Therefore, in other words, the present invention has a specific surface area of 700~
50 m ² /g of colloidal silica is used. Colloidal silica sol with an average particle size of less than 4 nm is
Although it is relatively stable compared to a polysilicate solution that has just been neutralized or ion-exchanged with sodium silicate, it is less stable at high concentrations. Therefore, the average particle size is
Even if colloidal silica with a diameter of less than 4 nm is used, only a low concentration of sol can be obtained, spherical particles cannot be obtained, and the abrasion resistance and fluidity of the catalyst will be poor, which is not preferable. Moreover, such colloidal silica generally contains a large amount of alkali metal as a stabilizer, which is undesirable as it contributes to a decrease in catalytic activity. Furthermore, when using colloidal silica with an average particle size of less than 4 nm, when preparing the catalyst,
When molding into spherical particles by spray drying, it is difficult to obtain spherical particles, and the abrasion resistance and fluidity of the catalyst are poor, and when the catalyst is used, it is affected by low melting point substances such as sulfuric compounds and potassium compounds. This is not preferable because the specific surface area and pore volume of the catalyst become smaller, resulting in a lower catalytic activity. On the other hand, when colloidal silica having an average particle diameter of more than 50 nm is used, the specific surface area of the catalyst becomes small, which not only lowers the catalytic activity but also reduces the abrasion resistance of the catalyst, which is not preferable. Therefore, in the present invention, the average particle diameter is 4 to 4.
Colloidal silica in the range of 50 nm, preferably 4 to 25 nm, is used. When colloidal silica in this range is used, the specific surface area of the catalyst to be prepared is in the range of 250 to 50 m ² /g, and varies depending on the specific surface area of the colloidal silica. That is, by using colloidal silica with a large specific surface area, a catalyst with a large specific surface area can be obtained. Furthermore, by changing the degree of aggregation of colloidal silica, the pore volume and bulk density of the catalyst to be adjusted can be freely controlled without changing the specific surface area of the catalyst. For example, in the method of mixing active ingredients in the state of silica sol and spray drying, the pore volume of the resulting catalyst is 0.4 to 0.2
cc/g, bulk density is about 0.7 to 1.0 g/cc,
When silica sol is used after being gelled in advance, the pore volume is 0.7 to 0.3 cc/g and the bulk density is 0.4 to 0.9 g/g.
cc of catalyst can be obtained. By using colloidal silica with an average particle size of 4 to 50 nm, the desired high specific surface area,
It is preferable because it can be prepared into a catalyst having a high pore volume and bulk density, and the catalyst can be made to have high activity and high selectivity. Further, it is preferable because the specific surface area and pore volume of the catalyst do not decrease due to the influence of the low melting point substance during use of the catalyst, thereby preventing the activity from decreasing. In addition, it is preferable to use colloidal silica having an average particle diameter of 4 to 50 nm because the sphericity of the prepared catalyst particles increases and a catalyst with excellent wear resistance and fluidity can be obtained. Such colloidal silica is used as a sol or gel in the present invention, and as the silica sol, one obtained by polymerizing low molecular weight silicic acid under alkaline conditions can be used. Such silica sol is characterized by having a viscosity of 50 c.P. or less at a high concentration of 20 wt% as SiO ₂ and being stable for several months to several years. Therefore, it is different from a polysilicate solution immediately after neutralizing or ion-exchanging low concentration sodium silicate or potassium silicate, which is generally called silica sol. In other words, polysilicate liquid, which is generally referred to as silica sol, is essentially a sol of polysilicate with a very low molecular weight, and unless the concentration of SiO ₂ is less than 7wt%, stable polysilicate liquid cannot be obtained. Moreover, they differ from the silica sol used in the present invention in that they become gel-like after several minutes to several days. As the silica sol that can be used in the present invention, commercially available silica sol can be used as long as the average particle size of colloidal silica is 4 to 50 nm, such as S-30H, S-30L, S-20H, S-20L, SI
−45P, SI−50, SI−40, SI−30, SI−350, SI
-550, SN, (Products of Catalysts Kasei Kogyo Co., Ltd.) -30, -N, -O (Products of Nissan Chemical Industries, Ltd.) under the trade name Snotex, HS-40, HS under the trade name Rudotsu
−30, LS, SM−30, TM, AS (more than EIDupon
Examples include company products). However, when using it, Na ₂ O/
0.005 to 0.05 as SiO ₂ (weight ratio) The content of sodium contained in advance is 0.015 as Na ₂ O / SiO ₂
In the prepared catalyst,
It is preferable that the amount of Na ₂ O is 1.0 wt% or less, preferably 0.3 wt% or less. in catalyst
This is because if the amount of Na ₂ O exceeds 1.0 wt%, the reaction rate of naphthalene will decrease, which is not preferable. Therefore, among the commercially available silica sol, Cataloid S-20L, SN, Snotex -O, -N and Rudotux AS, which have low sodium content,
It is preferable to use LS etc. as is, but
Other foods containing relatively large amounts of sodium include
It is preferable to reduce sodium before use. As a method for removing sodium, well-known methods can be used, such as a method using a cation exchange resin, and a method in which sodium is neutralized with an acid and then removed as a salt using an ultrafiltration membrane or the like. In the present invention, colloidal silica can be used as a silica sol as described above, but when the purpose is to obtain a lighter catalyst, it is preferable to use it in a gel state. In this case, the gel state may be either a state in which the entire sol gels and loses fluidity, or a state in which the sol does not gel as a whole and has fluidity. Methods for producing gel from colloidal silica include methods of mixing silica sol with salts such as sodium chloride and sodium sulfate, methods of mixing polyvalent cations such as calcium, magnesium, and aluminum or their salts, and methods of mixing silica sol with polyvalent cations or their salts. Various methods can be employed, such as a method of mixing an activator, but a method of adjusting the pH by adding an alkali and/or acid to the silica sol is also suitable. In this case, the higher the pH during gel formation in the range of 4-11, the lower the bulk density of the catalyst obtained. When adjusting the pH, it is preferable to use sulfuric acid as the acid and potassium hydroxide as the alkali since they are both active components of the catalyst. In addition, it is appropriate to use a silica concentration of 3wt% or more during gel formation, and it is also preferable to perform gel formation under heating and to heat and age the resulting gel in order to obtain a stable gel. . An effective gel state for obtaining a light catalyst is a gel obtained from a colloidal silica sol with an average particle size of 4 to 50 nm.
After diluting and dispersing with water to a concentration of 2.7 wt% as SiO ₂ , it was centrifuged at 3000 rpm for 30 hours.
It is preferable that the weight percentage of precipitated silica (degree of gelation) when the gel-like material is precipitated under conditions of 30% or more of the total silica. When the amount is less than 30%, the effect of using it in a gel state is not significant, and a catalyst that is not much different from that obtained when a sol alone is used can be obtained. Furthermore, the gel thus obtained is effective for adjusting the bulk density not only when used alone as a silica source for a catalyst, but also when mixed with the above-mentioned colloidal silica sol. The method for producing a catalyst according to the present invention includes forming a mixed slurry of colloidal silica as described above, a vanadium compound, a potassium compound, and a sulfuric compound, and then
It consists of spray drying and firing. Vanadium compounds used in the present invention include those that are soluble in water and turn into vanadium oxide when fired in air, such as ammonium metavanadate, vanadyl sulfate (vanadium oxysulfate), vanadium acetate, vanadium oxalate, and oxalic acid. Examples include ammonium vanadium and vanadium oxyhalide. Potassium compounds used in the present invention include potassium hydroxide, potassium sulfate, potassium chloride, potassium nitrate, potassium oxyhalide, potassium thiosulfate, potassium nitrite, potassium sulfite, potassium hydrogen sulfite, potassium hydrogen sulfate, and potassium sulfate. Potassium acid, potassium hydrogen oxalate, and the like can be mentioned, but among these, potassium sulfate, whose residual component after firing becomes the active ingredient, is particularly suitable. As the sulfuric acid compound, sulfuric acid, ammonium sulfate, etc. can be used. The blending amounts of these colloidal silica, vanadium compounds, potassium compounds, and sulfuric compounds are such that the silica content in the catalyst is 45 to 90 wt% as SiO ₂ ,
Preferably, the content of active ingredients is 65-85wt%
55-10wt as the sum _{of V2O5} , _K2SO4 , _{and SO3}
%, preferably 35 to 15 wt%. If the content of the active component in the catalyst is less than 10 wt%, the activity of the catalyst will be low, which is not preferable. In this case, raising the reaction temperature in order to increase the activity is not preferable because it promotes a decrease in selectivity and deterioration of the activity. On the other hand, the content of active ingredients is 55wt
%, the bulk density of the catalyst increases,
This is undesirable because the specific surface area decreases and the activity and fluidity decrease due to crystallization of the active ingredient. Further, in the catalyst according to the present invention, the content ratio of each active component is such that the SO ₃ /K ₂ O molar ratio is 2.0 ± 0.4, preferably 2.0 ± 0.2, and the K ₂ O / V ₂ O ₅ molar ratio is 4.0.
The range is selected to be ±1.0, preferably 4.0±0.4. In the method for producing a catalyst according to the present invention, when producing a mixed slurry, the mixing order of colloidal silica and each active component can be arbitrarily changed, and two or more components may be dissolved together in water. Alternatively, the active ingredient may be dissolved in the components contained in silica sol or silica gel. However, the amount of water in the mixed slurry is preferably 50 to 95 wt%. The mixed slurry obtained as described above is concentrated as required by a conventional method to adjust the concentration to an appropriate concentration, and then spray-dried to obtain fine spherical particles. As the spray drying method, a known method can be adopted, and the temperature at the time of drying (the outlet temperature of the dryer)
Although there is no particular restriction on the temperature, a temperature of 100 to 200°C is suitable.
Regarding spraying, the weight average particle diameter of the obtained spherical fine particles is 60 ± 20 μm, and the particle size distribution is 44 μm or less.
It is preferable to set spray conditions so that the amount is ~40 wt%. The obtained spherical particles have a density of 300-600 in air.
℃, preferably at a temperature of 400-550℃. By the production method of the present invention as described above, a catalyst having the following properties can be obtained. Particle shape Solid spherical Bulk density (g/cc) 0.7±0.3 Specific surface area (m ² /g) 150±100 Pore volume (cc/g) 0.2-0.6 Wear rate (wt%/15hr) Weight average particles of 3 or less Diameter (μm) 60±20 Particle size distribution 44 μm or less (%) 10-40 Distribution of active components within catalyst particles Uniform Distribution of active component content between catalyst particles Uniform In the above properties, the wear resistance of the catalyst is is mainly correlated with pore volume, but the wear rate of the catalyst obtained by the present invention is 3wt%/15hr or less,
This shows that the wear resistance is superior to that of conventional post-deposition or impregnation catalysts with the same pore volume. In addition, since the catalyst according to the present invention has a uniform distribution of active components within catalyst particles and a uniform content distribution of active components between catalyst particles, when used in a reaction, low melting point components will not melt due to local heat generation on the catalyst. Also, the specific surface area of the catalyst is not reduced and the activity is not lowered. As described above, the excellent heat resistance of the catalyst according to the present invention is due to the fact that the rate of decrease in specific surface area is small even after heat treatment at 600℃ for 2 hours in a Matsufuru furnace, and the activity decreases even after long-term use in a fluidized bed. This is demonstrated by the fact that the ratio is significantly lower than that of conventional catalysts. [Example] The present invention will be explained in more detail with reference to Examples below. Example 1 (Preparation of Na-free silica sol) Ion-exchanged water was added to 50 kg of Cataloid SI-550 (manufactured by Catalysts Kasei Kogyo Co., Ltd.), which has colloidal silica with an average particle size of 5 nm, and was diluted to a concentration of approximately 10%. . This solution was passed through a layer of 7 cation exchange resin (Diaion SK-1B, Mitsubishi Chemical Industries, Ltd.) packed in a column in advance at a superficial velocity SV = 12 hr ^-1 to remove sodium.
93 kg of silica sol was obtained. Table 1 shows the properties of this Na-free silica sol. Moreover, this sol did not gel for more than one month at room temperature. (Preparation of mixed slurry to firing) 1.54 kg of potassium sulfate crystals were added to 9.4 kg of heated ion-exchanged water, and then thoroughly stirred and dissolved to prepare a potassium sulfate solution. On the other hand, ammonium sulfate
1.11Kg was dissolved in 2.5Kg of ion-exchanged water to obtain an ammonium sulfate solution. Place 70.9 kg of the above Na-free silica sol in a stainless steel container equipped with a steam jacket.
Add vanadyl sulfate solution (V ₂ O ₅ as
19.9%) 2.0Kg and previously dissolved potassium sulfate solution,
An ammonium sulfate solution was added and mixed well, and at the same time steam was passed through the jacket for heating and concentration. The obtained mixed slurry contains solids (V ₂ O ₅ ,
Contains 17.8% (including K ₂ SO ₄ , SO ₃ and SiO ₂ ),
The pH at 25°C was 3.4 and the viscosity was 890cP. Dry the mixed slurry using a spray dryer at a temperature of 150
The powder obtained by spray drying at °C was calcined in air at 500 °C for 2 hours to obtain an average particle size of 57 μm and a particle size of 44 μm.
A catalyst was prepared with 30 wt% of: Examples 2, 3, 4 Cataloid SI-30 and SI shown in Table 1 were used as silica sols with different average particle diameters of colloidal silica.
Example 1 except that -50 and SI-45P were used, respectively.
A catalyst was prepared in the same manner. Example 5 Cataloid S-, a low alkali content sol
A catalyst was prepared in the same manner as in Example 1, except that 20 L was used in the preparation without performing the alkali ion removal operation. Example 6 15% aqueous ammonia was added to 70.9 kg of the same Na-free silica sol as in Example 1 with stirring to adjust the pH to 5.8. The sol gradually increased in viscosity and became a viscous gel after 7 minutes. This gel was heated at 70° C. for 1 hour and then treated with a homogenizer to disperse the gel well. A catalyst was prepared in the same manner as in Example 1 using the gel as a silica source. In order to investigate the degree of gelation mentioned above, the gel was diluted with ion-exchanged water to a concentration of 2.7 wt% as SiO ₂ and then homogenized to form a slurry.
Pour the slurry into four settling tubes, each containing 50 c.c.
A centrifugal sedimentation test was conducted at 3000 rpm for 30 minutes. The weight and concentration of the precipitated gel were measured, and the gelation degree was calculated to be 50% on average. Example 7 36.3 kg of Cataloid S-20L was taken and the pH was adjusted to 7.1 by adding dilute nitric acid while stirring. After 2 minutes, the viscosity increased and it became an unstirable gel. Furthermore, this gel was heated at 90°C for 3 hours. Thereafter, a catalyst was prepared in the same manner as in Example 1 using a slurry that was diluted with 12 kg of ion-exchanged water to a concentration of 15 wt% and treated with a homogenizer. The degree of gelation of the gel after heating was calculated using the same method as in Example 6, and found to be 62% on average. Comparative Example 1 A catalyst was prepared in the same manner as in Example 1, except that Cataloid SI-80P, which is a silica sol with a large average colloidal silica particle, was used. Comparative Example 2 Sodium silicate (manufactured by Dokai Chemical Co., Ltd., No. 3 sodium silicate, SiO ₂ concentration 24.0%, SiO ₂ /NaO ₂ molar ratio 3.1)
was diluted with ion-exchanged water to give 5.7% SiO ₂ , and then passed through a cation-exchange resin layer to remove sodium ions to obtain 150 kg of silicic acid solution with an SiO ₂ concentration of 5.4% and a pH of 2.4. Prepare a dilute sodium silicate solution by pouring 126 kg of ion-exchanged water and 22.3 kg of sodium silicate into a 500 stainless steel container, mixing well, and heating this at 50℃. The entire amount of the previously obtained silicic acid solution was added over 1.8 hours. After the addition was completed, the mixture was further heated for 1 hour to obtain a silica sol. This silica sol was passed through a cation exchange resin layer to obtain the deNa-reduced small particle silica sol shown in Table 1.
A catalyst was prepared in the same manner as in Example 1 using 165 kg of this. An attempt was made to obtain Na-free silica sol after concentrating the silica sol, but when the silica sol was concentrated under reduced pressure, the viscosity increased at a SiO ₂ concentration of about 11%, and further concentration was not possible. Furthermore, when the concentrated solution was poured into the cation exchange resin layer, it instantly became a gel, making it impossible to remove sodium. Moreover, the silica sol used for preparing the catalyst gelled in 6 days when left to stand. Comparative Example 3 1N sulfuric acid was added to 250 kg of a sodium silicate solution diluted with ion-exchanged water to 4.0% SiO ₂ with stirring over 10 minutes to adjust the pH to 6.8. The liquid was initially in the form of a sol, but after a few minutes, the entire liquid became a gel. this
After aging at 80℃ for 30 minutes, it was dehydrated using a flat plate filter and at the same time washed with 5000 ion-exchanged water to obtain a SiO ₂ concentration of 5.2%, a Na ₂ O/SiO ₂ weight ratio of 0.009, and a gel constituent particle size of 3.1. 154 kg of nanometer hydrogel was obtained. Using this hydrogel, vanadium sulfate, potassium sulfate, and ammonium sulfate solution were mixed in the same manner as in Example 1, and then the gel was dispersed using a homogenizer. After that, heating and concentration was performed, but the solid content concentration was 7.2%.
It became a viscous liquid and could not be concentrated any further. This slurry was spray dried and fired to obtain a catalyst. Comparative Example 4 The hydrogel obtained in Comparative Example 3 was used as SiO ₂
After concentrating to 6.9% and performing homogenizer treatment, spray drying was performed with only silica hydrogel without mixing with the active component of the catalyst to obtain a powder, and the powder was calcined at 500 ° C for 2 hours to obtain silica powder. Ta. The properties of this powder were as follows. Specific surface area 720m ² /g Pore volume 1.1cc/g Bulk density 0.28g/cc Average particle size 67μm 7.4Kg of this powder was placed in a vacuum impregnation equipment and -600mm
Vanadium sulfate, potassium sulfate, prepared in the same manner as in Example 1 under reduced pressure of Hg (160 mmHg),
After adding a mixed solution of ammonium sulfate to impregnate and support the mixture, it was dried at 120°C for 8 hours and calcined at 500°C for 2 hours to obtain a catalyst. (Evaluation of Examples 1 to 6, Comparative Examples 1 to 4, and commercially available catalysts) Physical properties (shape, specific surface area, , bulk density, pore volume, wear rate), activity, and heat deterioration resistance were measured as follows. () Shape…Microscopic observation () Specific surface area and pore volume…BET method () Bulk specific gravity…Measured cylinder method () Wear rate…British Patent No. 737429 (ACC
Equipment method (2017) described in the company, Inc. Activity was evaluated by the following fixed bed activity evaluation and activity reduction rate in a 48 hour fluidized bed test. Fixed bed activity evaluation…Fixed bed reaction operation (temperature 355
Sum of reaction rate constants (k ₁ + k ₂ ) determined from the yields of naphthoquinone and phthalic anhydride from naphthalene at 1 ml/hr of naphthalene supply rate, 7.5 N/hr of air supply rate, and 5 g of catalyst
(However, k ₁ ; naphthalene→naphthoquinone; k ₂ ; naphthalene→phthalic anhydride). Activity reduction rate in fluidized bed 48 hour test...Fluidized bed reaction operation (temperature 355℃, naphthalene feed rate 105
g/hr, air supply rate 960N/hr, catalyst amount
3.75Kg), the sum of the reaction rates (k ₁ + k ₂ ) was determined in the same manner as in the fixed bed evaluation, and the rate of decrease after 48 hours was used for evaluation. () Heat deterioration resistance Each catalyst was placed in a Matsufuru furnace with a thickness of 5 mm.
Evaluation was made by measuring the rate of decrease in specific surface area when heat treated at 600°C for 2 hours. The results are shown in Table 2. In addition, for the catalyst of Example 1 and the commercially available catalyst, K and V ray analysis SEM-XMA at any location of the sample was performed.
The photographs (simultaneous analysis of scanning electron microscope and X-ray microanalyzer) are shown in Figure 1 a, b and Figure 2 a,
Fig. 3a, b, and c show micrographs of Example 1, Comparative Example 2, and the commercially available catalyst. Note that the measurement conditions for the above SEM-XMA photograph are as follows. K-ray SEM-XMA of the catalyst of Example 1 (Figure 1a) 1000x, Line Kα, Acc.Volt.25kV, Current
2×10 ^-8 A, FS2Kcps, TC3×0.1sec, V-ray SEM-XMA of the catalyst of Example 1 (Fig. 1b) 1000 times, Line Kα, Acc.Volt.25kV, Current
2×10 ^-8 A, FS200cps, TC1×1sec, K-ray SEM-XMA of commercially available catalyst (Figure 2a) 600x, Line Kα, Acc.Volt.25kV, Current
3×10 ^-8 A, FS500cps, TC3×0.1sec, V-ray SEM-XMA of commercially available catalyst (Fig. 2b) 600x, Line Kα, Acc.Volt.25kV, Current
3×10 ^-8 A, FS50cps, TC3×1sec, Figures 1 and 2 show that the active components K and V are more uniformly dispersed in the catalyst of the present invention than in commercially available catalysts. Moreover, from FIG. 3, it can be seen that the particle shape of the catalyst of the present invention is solid spherical.

【table】

【table】

〔effect〕

The catalyst of the present invention simultaneously satisfies high activity, heat deterioration resistance, and high abrasion resistance that conventional catalysts could not simultaneously satisfy in the reaction of producing phthalic anhydride through vapor phase catalytic oxidation of naphthalene using a fluidized bed. do. Further, according to the present invention, it is possible to arbitrarily control the specific surface area, pore volume, and bulk density, and it is possible to produce a catalyst that is compatible with a wide range of reaction conditions.

[Brief explanation of the drawing]

Figures 1a and 1b and 2a and 2b are photographs (SEM-XMA photographs) representing the particle structures of the present invention and commercially available catalysts, respectively. Figure 3 a, b, c
are drawing-substituting photographs (microscopic photographs) representing the particle structures of the present invention, a comparative example, and a commercially available catalyst, respectively.

Claims (1)

[Claims] 1. A method for producing a fluidized catalyst for gas phase catalytic oxidation of naphthalene by mixing a silica source, a vanadium compound, a potassium compound and a sulfuric acid compound, followed by spray drying and sintering, wherein the silica source has an average particle size of 4 to 4. A method for producing a fluidized catalyst for gas phase catalytic oxidation of naphthalene, characterized by using colloidal silica of 50 nm.