JP4065709B2 - Regeneration method of deteriorated catalyst - Google Patents

Description

【００２６】
【発明の効果】
以上のように、この発明によれば、プロピレンからアクロレインを、イソブテンまたはターシャリーブタノールからメタクロレインを製造する気相接触反応に使用されるモリブデン−ビスマス−鉄系複合酸化物触媒について、プラント運転で使用した後の劣化触媒を新触媒と同等レベルの性能を有するまで、再生することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molybdenum-bismuth-iron composite oxide catalyst used in a gas phase catalytic reaction for producing acrolein from propylene and methacrolein from isobutene or tertiary butanol. It relates to the method of playing.
[0002]
[Prior art]
Molybdenum-bismuth-iron composite oxide catalysts are useful catalysts for selective oxidation reactions such as propylene to acrolein, isobutene or tertiary butanol to methacrolein, and are also used industrially.
[0003]
The catalyst used in such a gas phase catalytic reaction is used for a relatively long time, and is replaced with a new catalyst when the catalyst performance deteriorates to some extent. Most of the spent catalyst is recovered to the extent that some useful metals are recovered, and others are discarded.
[0004]
It is well known that the performance deterioration of the molybdenum-bismuth-iron composite oxide catalyst used in these gas phase catalytic reactions is mainly caused by loss due to sublimation of molybdenum.
[0005]
Regarding the regeneration method of the above-mentioned catalyst, Japanese Patent Publication No. 5-29502, Japanese Patent Publication No. 5-70503, Japanese Patent No. 3140135, Japanese Patent Application Laid-Open No. 7-165663, Japanese Patent Application Laid-Open No. 7-185349 and Japanese Patent Application Laid-Open No. 9-12489. There are those shown in the gazettes.
[0006]
For example, Japanese Patent Publication No. 5-29502 or Japanese Patent Publication No. 5-70503 discloses a method for heat-treating a deteriorated catalyst in air or an oxygen-containing gas atmosphere as a method for regenerating a molybdenum-bismuth-iron multi-component oxide catalyst. Has been proposed. However, in these methods, in the regeneration treatment, the molybdenum that has been substantially scattered due to deterioration is not supplemented, and the catalyst is brought into contact with the air under heating conditions, thereby diffusing molybdenum into the catalyst particle surface. Since the performance is restored, the effect as a reproduction method is not sufficient.
[0007]
Japanese Patent Application Laid-Open No. 7-165663 or Japanese Patent Application Laid-Open No. 9-12489 discloses a substantially inert molybdenum oxide or unused catalyst as a method for regenerating the above-mentioned oxide catalyst in order to compensate for molybdenum scattered due to deterioration. A method has been proposed in which powder is mixed or pulverized and then mixed and then heat-treated. However, in these methods, molybdenum is diffused and regenerated by a solid-phase reaction during heat treatment for replenishment of molybdenum, so that it is considered that a sufficient regeneration effect cannot be obtained, and the unused catalyst In mixing, 100% regeneration cannot be expected, so industrial utility is not so high.
[0008]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to use a molybdenum-bismuth-iron composite oxide catalyst used in a plant operation for a gas phase catalytic reaction for producing acrolein from propylene and methacrolein from isobutene or tertiary butanol. It is an object of the present invention to provide a more effective method for regenerating a deteriorated catalyst.
[0009]
[Means for Solving the Problems]
As a result of diligent investigations to solve the above problems, the inventors of the present invention have used molybdenum-bismuth-iron-based composite oxide catalysts used in the above-mentioned reaction to regenerate a deteriorated catalyst used in plant operation. After adding the contained solution, heat treatment under specific conditions to more effectively replenish molybdenum necessary for the used deteriorated catalyst, in the same method, further including a pulverization step, or in the same method Furthermore, it was found that the catalyst can be regenerated as a catalyst having performance comparable to that of the new catalyst by the method of regenerating after returning to an aqueous slurry.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in more detail below.
The target catalyst in this invention is a molybdenum-bismuth-iron-based composite oxide catalyst used in a gas-phase catalytic oxidation reaction for producing acrolein from propylene and methacrolein from isobutene or tertiary butanol. This is a deteriorated catalyst.
[0011]
The regenerating process includes a pulverizing process for pulverizing the deteriorated catalyst, a molybdenum adding process for adding a molybdenum solution, a forming process, and a firing process. However, the above steps other than the molybdenum addition step and the firing step are not essential, and regeneration is performed by combining the steps as necessary. Moreover, the method which passes through the aqueous | water-based slurrying process of returning to the aqueous | water-based slurry form as needed and drying this slurry again and also reproducing | regenerating is also possible.
[0012]
Next, each step will be described in detail.
<Crushing process>
In order to improve the regeneration effect, this is a step of once crushing the deteriorated catalyst. The effect of this process on regeneration is not clear, but it is thought that the effect of making the compositional difference between the particles uniform and the effect of adding molybdenum or the diffusion effect during regeneration can be improved and more effectively regenerated. Various methods can be used as the pulverization method, and the average particle size after pulverization is 5 μm to 100 μm, more preferably 10 μm to 60 μm. However, the optimum particle size depends on the subsequent process. If the molding process is to be continued in the subsequent process, the particle handling during molding, mainly to improve flowability, or keep the secondary structure of the catalyst. In order to do so, the average particle size is preferably about 20 to 60 μm, and it is preferable that the fine powder of less than 10 μm is as little as possible. In addition, when adopting a method of regenerating the slurry after returning it to an aqueous slurry once in a subsequent step, an average particle size of about 10 to 30 μm is good for suppressing sedimentation of solids in the slurry, It is preferable that the coarse powder of 100 μm or more is as little as possible.
[0013]
<Molybdenum addition process>
In order to improve the regeneration effect, it is desirable to add molybdenum lost by scattering in a solution state. The weight loss of molybdenum can be calculated by measuring the content of molybdenum element in the catalyst before and after the plant operation by ordinary elemental analysis methods (fluorescence X-ray analysis method, ICP emission spectroscopic method, etc.). The molybdenum solution can take various forms, but generally a solution in which a water-soluble molybdenum compound is dissolved in water is used. The concentration of this solution is not particularly limited, but may be a sufficiently low concentration to improve dispersibility, and a solution of 20% by weight or less is often used. The step is not particularly limited except that it is essential to be carried out before the firing step, and can be carried out appropriately. However, if it includes a grinding step, it may be carried out after grinding and before molding. preferable.
[0014]
<Aqueous slurrying process>
This step is not essential, but can be employed as necessary. Prior to this step, the slurry is once pulverized for slurrying. The slurry concentration is not particularly limited. However, if the concentration is too high, the handling property is deteriorated. If the concentration is too low, the energy cost is increased in the drying process, and the economy may be deteriorated. The weight is often 20% to 50% by weight. Moreover, it is preferable to add an organic binder as appropriate in order to improve the dispersibility of the slurry or to maintain the particle shape when the slurry is dried. There are various kinds of organic binders, but generally used are water-soluble polymers such as polyvinyl alcohol, and various celluloses. The addition amount of the organic binder is 0.5 to 5% by weight, more preferably 1 to 3% by weight, based on the pulverized particles. This is because when the amount added is too small, the effect of the addition is not sufficient, and when it is too large, abnormal heat generation may occur in the firing step. Various methods can be used as the drying method. Generally, a spray drying method using a spray dryer or the like is employed to improve the uniformity of the precursor particles during drying.
[0015]
<Molding process>
This step is not essential, but it is employed in the case of a catalyst used in a fixed bed reactor. Various methods can be considered as the molding method, such as tableting molding or extrusion molding. In the case of extrusion molding, it is preferable to add a necessary amount of water once and, if necessary, an organic binder as a molding aid. It is preferable to add an organic binder as a molding aid as necessary during tableting. Examples of the organic binder include various organic binders, and are generally water-soluble polymers such as polyvinyl alcohol as described above, or various celluloses. The addition amount of the organic binder is 1 to 10% by weight, more preferably 2 to 6% by weight, based on the pulverized particles. This is because when the amount added is too small, the effect of the addition is not sufficient, and when it is too large, abnormal heat generation may occur in the firing step.
[0016]
<Baking process>
In order to improve the regeneration effect, it is a step of heat treatment at the end of the regeneration step. The effect of this process on regeneration is not clear, but the molybdenum component in the added molybdenum solution is incorporated into the catalyst and has the effect of restoring the catalyst performance and the effect of sufficiently thermally diffusing the molybdenum component in the catalyst. it is conceivable that. As firing conditions, it is preferable to carry out at a temperature of 400 ° C. to 600 ° C., and to fire under an air flow. More preferably, it is 420 degreeC-550 degreeC. This is because when the firing temperature is too low, thermal diffusion of the molybdenum element is not sufficient, and when it is too high, the molybdenum element may be lost by sublimation. In addition, when an organic binder is added in the previous step, abnormal heat generation may occur in this step. Therefore, it is desirable that the temperature rise is appropriately maintained at a lower temperature or the rate of temperature rise is controlled.
[0017]
【Example】
<Preparation of unused new catalyst>
2.7 kg of ammonium paramolybdate is dissolved in 2.2 L of pure water by heating. Next, 325 g of ferric nitrate, 1.05 kg of cobalt nitrate and 1.59 kg of nickel nitrate are heated and dissolved in 3 L of pure water. These solutions are gradually mixed with good stirring.
Next, 2.9 kg of silica is added and stirred thoroughly.
The slurry is heat-dried and then subjected to a heat treatment at 300 ° C./1 hour in an air atmosphere.
The obtained granular solid is pulverized, and 2.0 kg of ammonium paramolybdate is dispersed in a solution in which 0.5 L of ammonia water is added to 7.5 L of pure water and dissolved. Next, 43 g of borax and 18 g of potassium nitrate are dissolved in 2 L of pure water under heating and added to the slurry. Next, 2.7 kg of secondary bismuth carbonate in which 0.45% of sodium is dissolved is added and mixed with stirring.
After drying this slurry by heating, 2% by weight of graphite (manufactured by Raymond Mill Co., Ltd., with a combustion start temperature of 540 ° C. and a proportion of particles of 47 μm or less in the differential thermogravimetric analysis is 98% by weight or more) per 100 parts by weight of the obtained granular solid After mixing well, the mixture was compressed into tablets with a diameter of 5 mm and a height of 4 mm with a small molding machine, and then calcined at 500 ° C. for 4 hours to obtain a catalyst.
The catalyst was pretreated by the glass bead method and then subjected to elemental analysis with a fluorescent X-ray analyzer (manufactured by Rigaku Denki Kogyo Co., Ltd .: ZSX-100e). The atomic ratio was as follows.
Mo: Bi: Ni: Co: Fe: Na: B: K: Si = 12: 4.60: 2.44: 1.62: 0.36: 0.35: 0.20: 0.08: 22. 00
20 ml of this catalyst was filled into a stainless steel nighter jacketed reaction tube with an inner diameter of 15 mm, and a raw material gas having a propylene concentration of 10%, a steam concentration of 17%, and an air concentration of 73% was obtained at normal pressure with a contact time of 1.8 seconds. The propylene oxidation reaction was carried out.
The results shown in Table 1 were obtained at a reaction bath temperature of 305 ° C. The reaction product was analyzed by gas chromatography according to a conventional method.
[0018]
<Preparation of spent catalyst>
The above unused catalyst is filled in a stainless steel nighter jacketed reaction tube with an inner diameter of 25 mm, and a raw material gas having a propylene concentration of 10%, a steam concentration of 17%, and an air concentration of 73% is brought to a contact time of 1.8 seconds at normal pressure. The propylene oxidation reaction was continued for 2 years. Thereby, the catalyst was extracted from the reaction tube to obtain a deteriorated catalyst. About this deteriorated catalyst, when the elemental analysis was carried out by the method similar to an unused catalyst, the atomic ratio was the following.
Mo: Bi: Ni: Co: Fe: Na: B: K: Si = 12: 4.65: 2.46: 1.64: 0.36: 0.35: 0.20: 0.08: 22. 22
When this degraded catalyst was reacted in the same manner as the unused catalyst, the results shown in Table 1 were obtained.
[0019]
<Example 1>
0.8 g of ammonium paramolybdate is dissolved in 90 ml of pure water by heating. Next, this solution is cooled to 40 ° C., then added and impregnated with 300 g of the above deteriorated catalyst by hand spraying, stirred for 30 minutes in a stirring vessel, and then dried at 120 ° C. for 12 hours in a drier. Finally, the dried precursor was calcined at 500 ° C. for 4 hours under air flow to obtain a regenerated catalyst.
The catalyst calculated from the charged raw materials is a complex oxide having the following atomic ratio.
Mo: Bi: Ni: Co: Fe: Na: B: K: Si = 12: 4.60: 2.44: 1.62: 0.36: 0.35: 0.20: 0.08: 22. 00
When this regenerated catalyst was reacted in the same manner as the new catalyst, the results shown in Table 1 were obtained.
[0020]
<Comparative Example 1>
The above deteriorated catalyst was calcined at 500 ° C. for 4 hours under air flow to obtain a regenerated catalyst. When this regenerated catalyst was reacted in the same manner as the new catalyst, the results shown in Table 1 were obtained.
[0021]
<Comparative example 2>
A regenerated catalyst was obtained in the same manner as in Example 1 except that the temperature during calcination was 350 ° C. When this regenerated catalyst was reacted in the same manner as the new catalyst, the results shown in Table 1 were obtained.
[0022]
<Example 2>
1000 g of the above-mentioned catalyst used in the plant was dry pulverized with a hammer mill to obtain pulverized particles. When the particle size distribution of the pulverized particles was measured with a laser diffraction / scattering particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd., LMS-24), the average particle size was 49 μm. Next, a solution in which 0.8 g of ammonium paramolybdate was dissolved in 90 ml of pure water was cooled to 40 ° C., and then added and impregnated with 300 g of the pulverized particles obtained above by spraying. After stirring for 1 minute, it was dried at 120 ° C. for 12 hours in a dryer. Next, 18 g of microcrystalline cellulose and 3 g of the same graphite used in the preparation of the above-mentioned unused new catalyst were added to the precursor particles and mixed well. Molded to 4 mm. Finally, the molding precursor was calcined at 500 ° C. for 4 hours under air flow to obtain a regenerated catalyst.
The catalyst calculated from the charged raw materials is a composite oxide having the same atomic ratio as in Example 1.
When this regenerated catalyst was reacted in the same manner as the new catalyst, the results shown in Table 1 were obtained.
[0023]
<Example 3>
1000 g of the above-mentioned catalyst used in the plant was dry pulverized with a hammer mill to obtain pulverized particles. When the particle size distribution of the pulverized particles was measured by the same method as in Example 2, the average particle size was 25 μm. Next, after a solution prepared by heating 2.0 g of ammonium paramolybdate in 890 ml of pure water and cooling to 40 ° C., 160 g of a 5% aqueous solution of polyvinyl alcohol was added, and then 800 g of the pulverized particles obtained above were added. An aqueous slurry was obtained. Next, this aqueous slurry was dried by controlling the outlet temperature at 140 ° C. with a spray dryer. When the particle size distribution of the dry particles was measured in the same manner as in Example 2, the average particle size was 69 μm. Next, to 300 g of the dried particles, 18 g of microcrystalline cellulose and 3 g of the same graphite used in the preparation of the new unused catalyst were added and mixed well. Molded to 4 mm. Finally, the molding precursor was calcined at 500 ° C. for 4 hours under air flow to obtain a regenerated catalyst.
The catalyst calculated from the charged raw materials is a composite oxide having the same atomic ratio as in Example 1.
When this regenerated catalyst was reacted in the same manner as the new catalyst, the results shown in Table 1 were obtained.
[0024]
Table 1 shows the reaction evaluation at a reaction bath temperature of 330 ° C. The definitions of propylene conversion rate, acrolein selectivity, and acrolein yield are as follows.
Propylene conversion rate (mol%) = (number of moles of reacted propylene / number of moles of supplied propylene) × 100
Acrolein selectivity (mol%) = (number of moles of acrolein produced / number of moles of propylene reacted) × 100
Acrolein yield (mol%) = (number of moles of acrolein produced / number of moles of propylene supplied) × 100
[0025]
[Table 1]

[0026]
【The invention's effect】
As described above, according to the present invention, a molybdenum-bismuth-iron composite oxide catalyst used in a gas phase catalytic reaction for producing acrolein from propylene and methacrolein from isobutene or tertiary butanol is used in a plant operation. The used deteriorated catalyst can be regenerated until it has the same level of performance as the new catalyst.

Claims (9)

  Degradation by using a complex oxide catalyst mainly composed of molybdenum, bismuth and iron used in the process of producing the corresponding unsaturated aldehyde by catalytic gas phase oxidation reaction of propylene, isobutylene or tertiary butanol in the plant operation A method for regenerating a deteriorated catalyst, comprising adding a molybdenum-containing solution to the deteriorated catalyst, followed by firing at a temperature of 400 ° C to 600 ° C. The method for regenerating a deteriorated catalyst according to claim 1, comprising: a pulverizing step for pulverizing the deteriorated catalyst ; and a molded calcination step for remolding the pulverized particles pulverized in the pulverizing step and performing calcination in claim 1. .   3. The method for regenerating a deteriorated catalyst according to claim 2, wherein an organic binder is added during molding in the molding and firing step.   4. The method for regenerating a deteriorated catalyst according to claim 3, wherein an organic binder is added in an amount of 1% by weight to 10% by weight with respect to the pulverized particles at the time of molding in the molding and firing step. 2. The method for regenerating a deteriorated catalyst according to claim 1, wherein the pulverized particles obtained by pulverizing the deteriorated catalyst are made into an aqueous slurry, and the slurry is dried, followed by calcination in claim 1.   6. The method for regenerating a deteriorated catalyst according to claim 5, wherein the molybdenum-containing solution is added to the aqueous slurry.   The method for regenerating a deteriorated catalyst according to claim 5 or 6, wherein an organic binder is added to the aqueous slurry.   The method for regenerating a deteriorated catalyst according to claim 7, wherein 0.5% by weight to 5% by weight of an organic binder is added to the aqueous slurry with respect to the pulverized particles.   The method for regenerating a deteriorated catalyst according to any one of claims 2 to 8, wherein the average particle size of the pulverized particles after pulverization is 5 to 100 µm.