JP3826413B2 - Method for producing catalyst molded body for synthesis of unsaturated aldehyde and unsaturated carboxylic acid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a molded catalyst for synthesis of unsaturated aldehyde and unsaturated carboxylic acid used for catalytic oxidation. More specifically, the present invention relates to a method for producing a catalyst molded body for synthesis of unsaturated aldehyde and unsaturated carboxylic acid used for gas phase catalytic oxidation of propylene, isobutylene or tertiary butanol having excellent mechanical strength.
[0002]
[Prior art]
The unsaturated aldehyde and unsaturated carboxylic acid synthesis reaction by the gas phase catalytic oxidation of propylene or isobutylene is a sequential oxidation reaction of propylene or isobutylene, and by-products increase as the reaction pressure increases. For this reason, it is necessary to make the pressure loss in the reactor as small as possible. In addition, the above measures are also effective in reducing the load on the blower in the plant.
Since the pressure loss in the reactor largely depends on the degree of pulverization when the catalyst is charged, it is important to ensure the mechanical strength of the catalyst.
[0003]
Conventionally, as a method of imparting the mechanical strength of a catalyst, a method of adding whisker, water glass or the like to a catalyst component has been disclosed.
For example, JP-A-59-183832 and JP-A-2-36296 teach that a high-strength catalyst can be obtained by adding whisker to a catalyst component and shaping. Japanese Patent Application Laid-Open No. 7-16463 proposes that a catalyst molded article having excellent mechanical strength can be obtained by adding 1 to 10% by weight of silica sol as silicic anhydride to the catalyst component.
[0004]
[Problems to be solved by the invention]
However, although the catalyst molded body obtained by the above method has a certain degree of mechanical strength improvement effect, it is not yet sufficient, and the appearance of a catalyst molded body having a higher mechanical strength and its production method is desired. It was.
[0005]
In order to solve such problems, the present inventors have intensively studied the types of catalyst components and additives that increase the mechanical strength of the catalyst molded body, and the mixing method thereof. As a result, the propylene, isobutylene, and tertiary butanol have been identified. The present invention has been completed by finding a method for producing a catalyst molded article excellent in mechanical strength suitable for synthesis reaction of unsaturated aldehyde and unsaturated carboxylic acid by phase contact oxidation.
[0006]
[Means for Solving the Problems]
That is, in the present invention, a raw salt aqueous solution containing molybdenum, bismuth, iron, nickel and / or cobalt as a catalyst component is mixed, the precipitate is dried, then subjected to salt decomposition, and the resulting salt decomposition product (anhydrous conversion) An inorganic fiber having 1 to 6 parts by weight of silica sol and 2 to 12 parts by weight of 30 to 300 μm in diameter, 2 to 20 μm in diameter, and a shot content of 10% by weight or less based on 100 parts by weight of silica. Addition , mixing , cultivating at room temperature for 20 hours or less, kneading with an energy of 0.16-0.32 kW · h / kg, then forming , then drying, and heat treatment if necessary The present invention provides a method for producing a catalyst molded body for synthesizing unsaturated aldehydes and unsaturated carboxylic acids used in gas phase catalytic oxidation of isobutylene or tertiary butanol.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The catalytically active substance in the present invention is a catalytically active substance that is applied when synthesizing unsaturated aldehydes and unsaturated carboxylic acids by vapor phase catalytic oxidation of propylene, isobutylene or tertiary-butanol known in the prior art. A composite oxide containing bismuth, iron, nickel and / or cobalt as a main catalyst component, the composition of which is typically represented by the following general formula.
MoaBibFecAdBeCfDgOx
(Wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, A represents nickel and / or cobalt, and B represents the group consisting of manganese, zinc, calcium, magnesium, tin and lead, respectively) Represents at least one element selected, C represents at least one element selected from the group consisting of phosphorus, boron, arsenic, tellurium, tungsten, antimony and silicon; D represents potassium, rubidium, cesium and thallium; Represents at least one element selected from the group consisting of: a to x each representing an atomic ratio of each element, where a = 12, 0 <b ≦ 10, 0 <c ≦ 10, 1 ≦ d ≦ (10, 0 ≦ e ≦ 10, 0 ≦ f ≦ 10, 0 ≦ g ≦ 2 and x is a value determined by the oxidation state of each element.)
[0008]
As raw materials for the catalyst component, oxides, nitrates, carbonates, ammonium salts, halides, and the like of each element can be used in combination. For example, ammonium paramolybdate, molybdenum trioxide, molybdenum chloride, bismuth chloride, ferric nitrate, nickel nitrate, cobalt nitrate and the like are used. These are dissolved and used in the form of a solution.
[0009]
The method for preparing the catalyst using these raw materials is not particularly limited as long as it is a conventionally known method. For example, a precipitation method in which an acidic salt and a basic salt are neutralized and precipitated in the raw material salt aqueous solution is exemplified. It is done. Acids and bases can be added to these solutions for neutralization. The neutralization conditions are a liquid temperature of 50 to 100 ° C. and a pH of 3 to 10. The obtained precipitate is usually dehydrated at room temperature to 150 ° C. to a water content of about 0.1 to 10% by weight or less. As the dehydration method, a conventionally known drying method such as a filter such as a filter press, a ventilation dryer, or an air dryer is used. Then in these dry powder under an air atmosphere, it salt decomposed at about 100 to 500 ° C..
[0010]
The powder after the salt decomposition is used as it is, preferably after the crushing treatment, and the silica sol and the inorganic fiber, which are the characteristics of the present invention, are mixed and formed into a desired shape.
The powder is preferably crushed until the average particle diameter (cumulative 50% diameter D50) is 2 to 10 μm and the cumulative 90% diameter (D90) is 40 μm or less. Although not particularly limited as long as it can be used, for example, a ball mill, a free crusher, a jet mill and the like can be mentioned.
[0011]
The amount of silica sol added to the powder after salt decomposition (hereinafter sometimes referred to as catalyst component) is 1 to 6 parts by weight as silicic acid anhydride with respect to 100 parts by weight of catalyst component (in terms of anhydride). The amount is preferably 2 to 5 parts by weight. When the addition amount is less than 1 part by weight, sufficient mechanical strength cannot be obtained when the molded catalyst is used, and when it exceeds 6 parts by weight, the activity of the catalyst is reduced.
[0012]
On the other hand, the inorganic fiber added to the powder is 2 to 12 parts by weight, preferably 4 to 8 parts by weight, and more preferably 6 parts by weight with respect to 100 parts by weight of the catalyst component.
When the addition amount is less than 2 parts by weight, the effect of reinforcement is small, and when it exceeds 12 parts by weight, the dispersion of the fiber deteriorates, so that sufficient mechanical strength cannot be obtained when a molding catalyst is used.
The inorganic fiber to be used is not particularly limited as long as it is inert to the catalyst, and usually alumina fiber, silica fiber, glass fiber, rock wool, asbestos, silica alumina fiber and the like are applied.
The inorganic fiber having a length of about 30 μm to about 300 μm, a diameter of about 2 μm to about 20 μm, and an aspect ratio (length / diameter) of 1.5 to 150 is used. When the length is less than about 30 μm or the diameter exceeds about 20 μm, sufficient mechanical strength cannot be obtained when the molded catalyst is formed, and when the length exceeds 300 μm or the diameter is less than 2 μm, fiber dispersion When the molded catalyst is used, the variation in strength increases. Further, the shot content is about 25% by weight or less. If it exceeds 25% by weight, sufficient mechanical strength cannot be obtained when a formed catalyst is formed.
[0013]
In the present invention, the addition of silica sol and inorganic fiber to the catalyst component is not particularly limited in the order of addition, but it is recommended that they be added and mixed at the same time because they can be more uniformly dispersed.
In mixing them, it is of course possible to use conventionally known lubricants such as stearic acid and wax, plasticizers such as polyvinyl alcohol and methylcellulose, and other molding auxiliary materials.
[0014]
A known mixer such as an omni mixer, a Henschel mixer or the like can be used as a mixer used when mixing the silica sol and inorganic fibers to the catalyst component, as well as auxiliary materials for molding such as a lubricant and a plasticizer. More preferably, it is recommended to use a cave excavator mixer described in Powder and Industry (August 1982, page 49). In this case, it is preferable that the rotation speed of the chamfered shovel mixer is about 160 to about 230 rpm, and the rotation speed of the chopper is about 4000 to about 6000 rpm. When satisfying such conditions, it can be a molded material raw material having extremely excellent strength.
Mixing may be dry or wet mixing with addition of water or the like.
[0015]
By kneading at an energy of 0.16 to 0.32 kW · h / kg during kneading, the strength when formed into a catalyst molded body is improved. If the kneading power is less than 0.16 kW · h / kg, sufficient strength cannot be obtained when formed into a molded body, and if greater than 0.32 kW · h / kg, the pore volume when formed into a molded body, Both the diameter decreases and the catalytic activity decreases compared to the case where the above conditions are adopted. As the kneader, conventionally known ones such as a kneader and a pug mill can be used.
[0016]
The catalyst component, the mixture of silica sol and inorganic powder, or the kneaded material is then subjected to molding, but a nurturing treatment may be performed in advance during molding. The nurturing treatment is carried out by leaving the mixture at room temperature for about 6 to about 20 hours under conditions that prevent evaporation of moisture from the mixture or the kneaded substance. The time of training may be performed after wet mixing the catalyst component and the other auxiliary material for molding, or may be performed after kneading the wet mixture with a kneader. The longer the training time is, the better the mechanical strength of the molded catalyst is, but if it exceeds about 20 hours, the catalyst activity is lowered, which is not preferable. The reason why the strength of the molded body is improved by the training is not clear, but the contact time between the catalyst component and water etc. is increased, so that the catalyst component is peptized to near the primary particles. I think that this is because it becomes more precise.
[0017]
In the present invention, the molding is not particularly limited as long as it is wet molding, and conventionally known Malmerizer method, extrusion molding method, submerged granulation method and the like are applied. In the extrusion molding method, vacuum deaeration may be performed without reducing the pore volume of the molded body.
[0018]
The shape of the molded product is not particularly limited, and it can be conventionally molded into an arbitrary shape such as a known granular shape, columnar shape, ring shape, clover shape, star shape, or honeycomb shape. The catalyst molded into these shapes is then typically dried at room temperature to 150 ° C. and then heat treated at about 300 to about 600 ° C. in an air atmosphere.
When the heat treatment temperature is lower than the above range, the selectivity for unsaturated aldehydes and unsaturated carboxylic acids decreases, while when it is high, the reactivity of propylene or isobutylene decreases. Such heat treatment can be carried out in a generally known box-type firing furnace, tunnel furnace, rotary kiln, firing furnace, ventilation firing furnace or the like.
[0019]
Various additives such as an organic pore-forming agent and molybdenum oxide substantially inert to the reaction can be added to the catalyst thus obtained for the purpose of further improving the performance.
[0020]
The catalyst of the present invention thus obtained has a pore volume of about 0.2 cc / g or more, usually about 0.2 cc / g to about 0.4 cc / g, and measured by the method described below. The calculated powdered ratio is about 5% or less, usually about 2% or less, and propylene, isobutylene and tertiary butanol are vapor-phase catalytically oxidized with molecular oxygen to give the corresponding unsaturated aldehyde and More specifically, as a catalyst molded body for synthesis of unsaturated carboxylic acid, acrolein and acrylic acid are synthesized by vapor-phase catalytic oxidation of propylene with molecular oxygen, and methanol is synthesized by vapor-phase catalytic oxidation of isobutylene with molecular oxygen. Synthesize Lorraine and methacrylic acid, ammoxidize propylene with molecular oxygen and ammonia to synthesize acrylonitrile, and ammoxidize isobutylene with molecular oxygen and ammonia It is suitable as a catalyst molded body in the synthesis of methacrylonitrile, and its application conditions are conventionally known ranges, for example, reaction temperature 280 to 400 ° C., reaction pressure is reduced pressure to increased pressure, usually normal pressure to 5 atm. The oxygen / olefin (molar ratio) can be appropriately set within the range of 1 to 3 and the space velocity SV = 500 to 5000 / H.
[0021]
【Example】
Hereinafter, although the manufacture example of the catalyst by this invention and the reaction example using them are demonstrated with a comparative example, this invention is not limited to this. In addition, the part in an Example and a comparative example is a weight part unless there is particular notice. In the following examples, the reaction rate, selectivity, and compacted powder ratio of the molded body were defined and calculated as follows.
Reaction rate (%) = [(mol number of reacted olefin) / (mol number of supplied olefin)] × 100
Selectivity (%) = [(number of moles of product) / (number of moles of reacted olefin)] × [(number of carbons of product) / (number of carbons of raw material olefin)] × 100
[0022]
The mechanical strength of the catalyst molded body is evaluated by the packing powder rate. A stainless steel tube having an inner diameter of 30.6 mmφ and a length of 5000 mm installed perpendicular to the horizontal direction is filled with 500 g of the catalyst molded body from the upper portion of the stainless steel tube in 60 seconds, and then recovered from the lower portion of the stainless steel tube. If the amount of the catalyst that remains without passing through the 8-mesh sieve among the recovered catalysts is B, the packing powdering rate is defined as follows.
Filling powder rate (%) = [(500−B) / 500] × 100
[0023]
Measurement of pressure loss due to packing powdering rate A stainless steel tube with a tube diameter of 30.6 mmφ and a length of 5000 mm was installed vertically with respect to the horizontal direction, and after filling the catalyst to 4960 mm in 60 seconds from the top of the tube, from the bottom of the tube Air was allowed to flow at a flow rate of 4 Nm ³ / h, and ΔP was measured between the lower part (air inlet part) and the upper part (air outlet part) of the stainless steel tube.
[0024]
Example 1
144 g of ammonium paramolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O] is dissolved in 470 ml of warm water, and 20.4 g of 20% silica sol (SiO ₂ ) is further added to make solution A. Nickel nitrate [Ni (NO ₃ ) ₂ · 6H ₂ O] 2 g and cobalt nitrate [Co (NO ₃ ) ₂ · 6H ₂ O] 138.5 g and ferric nitrate [Fe (NO ₃ ) ₃ · 9H ₂ O] 55 g and 3.3 g of thallium nitrate (TlNO ₃ ) are dissolved in 250 ml of warm water, and this is designated as solution B. 9.4 g of 60% nitric acid is added to 40 ml of pure water, and 33 g of bismuth nitrate [Bi (NO ₃ ) ₃ .5H ₂ O] is dissolved therein. Next, after mixing the B liquid and the C liquid, the mixed liquid of B and C is added to the A liquid while stirring the A liquid, and then 0.8 g of phosphoric acid (H ₃ PO ₄ ) is added to the slurry. Get. This is concentrated and dried, and then subjected to salt decomposition at 200 to 250 ° C. under air flow. Thereafter, the mixture was crushed using a Nara free crusher to obtain catalyst powder. When the particle diameter of the crushed catalyst powder was measured by a laser diffraction / scattering method, the cumulative 50% diameter was 6.5 μm and the cumulative 90% diameter was 35 μm. Further, the value of the BET specific surface area by the nitrogen adsorption one point method was 20 m ² / g.
[0025]
To 100 parts of this catalyst powder, 2 parts of 40% silica sol as silicic acid and ceramic fiber (SiO ₂ · Al ₂ O ₃ ) [trade name: Toshiba Monoflux RFC-200SF, fiber length 100 to 300 μm, fiber 4 parts of diameter 2-4 μm], 4 parts of hydroxypropylmethylcellulose and 30 parts of pure water were added and mixed with a cave shovel mixer. This mixture was put in a sealed container so as to minimize the evaporation of moisture, cultivated at room temperature for 16 hours, and then kneaded with a kneader. The required power of the kneading machine at this time was 0.24 kW · h / kg. Subsequently, this kneaded material was formed into a ring shape having an outer diameter of 5 mmφ, an inner diameter of 2 mmφ, and a length of 5 mm by an extrusion molding machine. Thereafter, it was dried at 30 ° C., and calcined at 480 ° C. for 6 hours in an air atmosphere to obtain a catalyst. It was 0.27 cc / g when the pore volume of this catalyst was measured by the mercury intrusion method.
[0026]
9.6 g of the catalyst was charged into a glass reaction tube having an inner diameter of 18 mmφ. The catalyst thus charged was reacted at a reaction temperature of 330 ° C., a reaction pressure of 2.0 atm, a molar ratio of propylene: air: steam = 1: 7.5: 3, and a space velocity SV = 1031 / H. A test was conducted. At this time, the reaction rate of propylene was 95.6%, and the selectivity of acrolein and acrylic acid was 93.1%. Moreover, the filling powder rate was 0.72%.
Moreover, when the influence of the pressure loss (ΔP) due to pulverization when this catalyst was used was measured by the above measuring method, it was 0.47 kg / cm ² .
[0027]
Comparative Example 1
In the method of mixing Example 1, a catalyst molded body was obtained under the same conditions as in Example 1 except that no training and kneading were performed. The pore volume of this product was 0.33 cc / g. Next, propylene contact reaction was performed in the same manner as in Example 1 using this catalyst molded body. At this time, the reaction rate of propylene was 95.9%, the selectivity of acrolein and acrylic acid was 93.0%, the packing powdering rate was 1.44%, and ΔP was 0.49 kg / cm ² .
[0028]
Example 3
In measurement by laser diffraction / scattering method, except that catalyst powder (crushed by increasing the number of revolutions of the crusher) having a cumulative 50% diameter of 4.0 μm and a cumulative 90% diameter of 19 μm was used. Molding and reaction were performed under the same conditions as in Example 1. At this time, the reaction rate of propylene was 95.5%, the selectivity of acrolein and acrylic acid was 93.2%, and the packing powdering rate was 0.65%. The pore volume was 0.30 cc / g.
[0029]
Comparative Example 2 The amount of the 40% silica sol added was 4 parts as silicic anhydride with respect to 100 parts of the catalyst powder, and the catalyst was molded under the same conditions as in Example 1 except that the mixed powder was not trained and kneaded. Then, a reaction of propylene was performed using the obtained catalyst molded body. At this time, the reaction rate of propylene was 94.7%, the selectivity of acrolein and acrylic acid was 93.1%, and the packing powdering rate was 0.98%. Moreover, the pore volume of the catalyst molded body was 0.25 cc / g.
[0030]
Example 5
Molding and reaction were carried out under the same conditions as in Example 1 except that in the method of Example 1, the shovel mixer was replaced with an omni mixer and mixed. At this time, the reaction rate of propylene was 95.3%, the selectivity of acrolein and acrylic acid was 93.4%, and the packing powdering rate was 1.61%. The pore volume was 0.32 cc / g.
[0031]
Comparative Example 3
In the method of Example 1, catalyst molding was performed under the same conditions as in Example 1 except that silica sol and ceramic fiber were not added, and propylene reaction was performed using the obtained catalyst molded body. At this time, the reaction rate of propylene was 96.1%, the selectivity of acrolein and acrylic acid was 92.8%, and the packing powdering rate was 20%. The pore volume was 0.36 cc / g.
[0032]
Comparative Example 4
Catalyst molding was performed under the same conditions as in Example 1 except that the amount of 40% silica sol added was 8 parts as silicic acid anhydride with respect to 100 parts of catalyst powder, and propylene reaction was performed using the obtained catalyst molded body. went. At this time, the reaction rate of propylene was 94.5%, the selectivity of acrolein and acrylic acid was 91.6%, and the packing powdering rate was 0.30%. The pore volume was 0.19 cc / g.
[0033]
Comparative Example 5
Except that the fiber was not added in the method of Example 1, catalyst molding was performed under the same conditions as in Example 1, and propylene reaction was performed using the obtained catalyst molded body.
At this time, the reaction rate of propylene was 95.7%, the selectivity of acrolein and acrylic acid was 93.1%, and the packing powdering rate was 12%. The pore volume was 0.34 cc / g.
When the influence of pressure loss (ΔP) due to powdering when this catalyst was used was measured by the same method as in Example 1, it was 1.52 kg / cm ² .
[0034]
Comparative Example 6
Catalyst molding was performed under the same conditions as in Example 1 except that silica sol was not added in the method of Example 1, and propylene was reacted using the obtained catalyst molded body.
At this time, the reaction rate of propylene was 95.5%, the selectivity of acrolein and acrylic acid was 93.3%, and the packing powdering rate was 11%. The pore volume was 0.34 cc / g.

Claims (5)

A raw material salt aqueous solution containing molybdenum, bismuth, iron, nickel and / or cobalt as a catalyst component is mixed, the precipitate is dried, then subjected to salt decomposition, and 100 parts by weight of the obtained salt decomposition product (anhydrous conversion), 1-6 parts by weight of silica sol and 2-12 parts by weight of an inorganic fiber having a length of 30-300 μm, a diameter of 2-20 μm and a shot content of 10% by weight or less are added and mixed as silicic anhydride. Propylene, isobutylene, or tertiary butanol, characterized by being cultivated for 20 hours or less, kneaded with energy of 0.16-0.32 kW · h / kg, then molded, then dried, and optionally heat treated For producing a catalyst molded body for synthesis of unsaturated aldehyde and unsaturated carboxylic acid used for gas phase catalytic oxidation of styrene. The method for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst molded body according to claim 1, wherein the inorganic fiber has a length of 100 to 300 µm, a diameter of 2 to 4 µm, and a shot content of 5 wt% or less. Wherein said salt decomposition product, BET specific surface area of 1-30 m ² / g, an average particle diameter (D ₅₀₎ 2 to 10 [mu] m, after the 90% cumulative diameter (D ₉₀₎ was crushed until 40μm or less, and the silica sol The manufacturing method of Claim 1 or Claim 2 which adds an inorganic fiber . The unsaturated aldehyde and the unsaturated aldehyde according to any one of claims 1 to 3, wherein the pore volume of the molded body after the heat treatment is 0.2 cc / g or more and the filling powder ratio is 5% or less. The manufacturing method of the catalyst molded object for saturated carboxylic acid synthesis | combination. The method for producing a catalyst molded body according to any one of claims 1 to 4, wherein a cave excavator mixer is used in mixing the catalyst component, silica sol, and inorganic fiber.