KR100247556B1 - Core-shell structure catalysts - Google Patents

Abstract

The present invention relates to a solid catalyst having a core-shell structure, and more particularly, has a dual structure of a core portion and a shell portion formed by different compositions and preparation methods, and includes olefins and paraffins. The present invention relates to a solid catalyst having a core-shell structure represented by the following Chemical Formula 1, which is used as a catalyst in the preparation of a nitrile compound by ammonia oxidation and shows excellent catalytic activity.

[Formula 1]

In Chemical Formula 1, A is at least one element selected from bismuth, boron, phosphorus, and molybdenum; when d is 1, a is 0.001-3, b is 0.01-5, c is 0.1-5, z is 0-90; x and y are values that are set to match valences by different components in the core and shell parts.

Description

[Name of invention]

Solid catalyst with core-shell structure

Detailed description of the invention

[Purpose of invention]

[Technical field to which the invention belongs and the prior art in that field]

The present invention relates to a solid catalyst having a core-shell structure, and more particularly, has a dual structure of a core portion and a shell portion formed by different compositions and preparation methods, and includes olefins and paraffins. The present invention relates to a solid catalyst having a core-shell structure represented by the following Chemical Formula 1, which is used as a catalyst in the preparation of a nitrile compound by ammonia oxidation and shows excellent catalytic activity.

In Chemical Formula 1, A is at least one element selected from bismuth, boron, phosphorus, and molybdenum; when d is 1, a is 0.001-3, b is 0.01-5, c is 0.1-5, z is 0-90; x and y are values that are set to match valences by different components in the core and shell parts.

Acrylonitrile is used as a raw material for nitrile rubber, plastics, fibers and resins. Conventionally, acetylene or ethylene oxide was reacted with HCN to prepare acrylonitrile. However, since the raw materials were expensive and had problems in economics, they had to be replaced by new processes.

The production method of acrylonitrile is a catalytic reaction using propylene as a raw material, and is produced by the reaction of propylene, ammonia, oxygen or a gas containing oxygen, which is roughly divided into two kinds of production methods.

In the first process, propylene is a kind of 'oxidation reaction' in which propylene is oxidized in contact with oxygen or oxygen-containing gas, converted to acrolein, and then reacted with ammonia to produce acrylonitrile. In this process, not only by-products are generated due to the polymerization of acrolein, but also various unknown by-products are generated by reacting with ammonia, which ultimately lowers the purity of the target product and causes difficulty in the operation of the process. There is a disadvantage in that the unit price is high.

The second manufacturing method is currently the most commercially used method, which is a method of 'ammonooxidation reaction' in which propylene is directly catalytically reacted with ammonia and oxygen to produce acrylonitrile.

The ammonia oxidation of olefins has a history of half a century since its development, and even about 35 years after industrialization, it is still called "allyl oxidation of lower olefins." The ammonia oxidation of such olefins is a kind of catalytic reaction, and as a result of economic and industrial importance, research on this has been conducted in various fields.

The most obvious changes have been made not only in the process of ammonia oxidation of olefins, but also in the development of most catalyst components and processes. As a result, acrylonitrile shows an improved yield of about 80% or more in commercial plants, and acrylic acid yields more than 90% in an oxidation reaction. Catalysts used in commercial plants for the production of acrylonitrile by ammonia oxidation of olefins are bismuth-molybdenum oxides or iron-antimony oxides, which are very complex multicomponent complex oxides with many kinds of elements added thereto. It is known.

As described above, olefin oxidation or ammonia oxidation reaction consists of reaction of olefin, ammonia, and oxygen as a reactant on the catalyst. Among them, the importance of the catalyst is recognized and the existing catalyst is improved rather than the development of a new catalyst. The invention is in the direction of improving performance. In particular, the following description will be made with reference to a patent on a method for producing a catalyst similar or significantly active than the present invention.

In 1972, invented a Mo-Bi-Fe-P series catalyst for producing acrylonitrile from propylene, and impregnated with Fe (No ₄ ) ₃ in a Bi-MO-P-Silica catalyst with a BET specific surface area of 58 m 2 / g. A catalyst having a specific surface area of 7.3 m 2 / g was prepared by a new method, and it was reported that the catalyst exhibited 91.0% conversion and 75.2% selectivity at a reaction temperature of 470 to 485 ° C. [German Patent No. 2,127,996] .

Regeneration after using Bi-Mo-PK-Co-Ni-SiO ₂ catalyst in 1977, including MoO ₃ , H ₃ PO ₄ , HNO ₃ , Bi (NO ₃ ) ₃ · 5H ₂ O, H ₂ O It has been reported that the solution can be used as a catalyst for impregnating a regeneration catalyst into acrylonitrile from propylene again (US Pat. No. 4,052,332).

In 1978, hydrochloric acid was added to the (NH ₄ ) ₆ Mo ₇ O ₂₄ solution and the Fe (NO ₃ ) ₃ · 9H ₂ O solution was mixed, followed by drying, pulverization, and calcining, followed by Bi (NO) ₃ · 5H. It has been reported that acrylonitrile was prepared with a selectivity of about 70% at a reaction temperature of 455 ° C. after repeating the process of spraying ₂ O solution again to dry and calcining [UK Patent No. 1,518,215].

In the United States, Standard Oil Co., Ltd. mixes (NH ₄ ) ₆ Mo ₇ O ₂₄ solution with Bi (NO) ₃ · 5H ₂ O solution to adjust pH to make Solution A, and add KNO ₃ , Ni (NO ₃ ) _3. Make Solution B containing ₃ .6H ₂ O, Co (NO ₃ ) ₂ · 6H ₂ O, Fe (NO ₃ ) ₃ · 9H ₂ O, and then mix H ₃ PO ₄ and silica sol in another container and add the solution A was mixed. Subsequently, Solution B was mixed and dried, calcined and ground. Typical catalysts prepared in this manner are 50% [[Bi ₂ Mo ₃ O ₁₂ ] ½ [K _0.1 Ni _2.5 Co _4.5 Fe ₃ P _0.5 Mo _10.5 O _x ]] + 50% SiO ₂ . Reported increased yields of acrylonitrile and HCN and reduced consumption of ammonia (US Pat. No. 4,212,766).

In addition, Standard Oil manufactures a catalyst by impregnating potassium (K) with Mo, Fe, and Bi complex oxides with an element belonging to groups 1A, 2A, 3A, 4A, and 5A on the periodic table, for example, potassium acetate (KOAc) solution. Using this catalyst, 80% of acrylonitrile was obtained at 430 ° C., and it was reported that the prepared impregnated catalyst was higher in yield than the conventional nonimpregnating catalyst [JP-A-83-143,842]. No. 4,144,134.

Japan's Nitto Chemical Industry Co., Ltd. is a method of preparing an oxide catalyst of Mo-Bi-Fe-Ni-Si, prepared by adjusting pH of a slurry or dispersion composed of Mo, Fe, etc. A fluidized bed catalyst was prepared by spray drying or heat treatment, and it was reported that 98.8% conversion and 83.2% acrylonitrile were obtained at 450 ° C. using this catalyst (Japanese Patent Laid-Open No. Hei 1-265,067).

Standard Oil Co., Ltd. has reported a catalyst for ammonia oxidation reaction mainly composed of oxides of Mo, Bi, Fe, Co, Ni, Cr, P, Sb, and alkali metals, alkaline earth metals, and rare earth metals. 5,134,105].

At the German Technische Hochschule "Carl Schorlemmer" Leuna-Merseurg, the catalyst was prepared by impregnating Bi (NO ₃ ) ₃ · 5H ₂ O with an oxide consisting of Bi, No, Cr, Fe, Co, Na, Si, etc. It was reported that the degree was increased (German Patent Nos. 4,124,666 and 4,200,006).

In addition to the patents exemplified above, many research papers discuss related catalysts.

Burkhardt, I., et al., In Germany, reported that the addition of Fe to MoO ₃ / SiO ₂ catalysts changed acidity by oxidation-reduction properties in the production of Fe ₂ O ₃ -MoO ₃ / SiO ₂ catalysts. Was studied by an infrared spectrophotometer [React. Kinet. Catal. Lett. 1987, 34 (2), 309-15].

Kripylo and Peter of Germany studied the relationship between structure and activity in Bi-Mo multicomponent composite oxides. In Bi-Mo catalysts, the active phase consists of Fe, Co and Cr ions between MoO ₃ layers. It is reported that these ions have a great influence on the formation of the active phase and that the selectivity of acrylonitrile increases with increasing Bi content [Chem. Tech. 1991, 43 (3), 116-20].

In addition, Caldararu, H, et al. Observed the change of catalytic activity according to the position of Fe ³⁺ ions in Bi ₃ FeMo ₂ O ₁₂ and Bi ₃ Fe ₂ Mo ₂ O ₁₂ having a sheelite structure. For example, in Bi ₃ FeMo ₂ O ₁₂ having a monoclinic or tetragonal form, Fe ³⁺ ions are located at the vertices of the tetrahedron and are not affected by reduction in this case [Z. Phys. Chem. 1992, 177 (1), 75-92].

Mehner and H. et al. Reported that active phases related to reactions in multi-component Mo oxide catalysts are not on the surface and all the components participate in the reactions by surface analysis and transmission electron microscope analysis. Mater. Sci. Eng., B 1994, 25 (1), 1-4]

As described above, efforts to increase the catalytic activity have been made in various ways.

[Technical problem to be achieved]

Generally, it is known that Bi ₂ O ₃ -MoO ₃ series catalysts show high activity in ammonia oxidation reactions. In the case of multicomponent composite oxide catalysts, even if the analogous components are different, the catalytic activity varies greatly depending on the preparation method. The present invention has been completed based on the basic technical idea that.

As a result, molybdenum, iron, nickel, bismuth, phosphorus and silicon as active ingredients, in addition to alkali metals or other metals, and by the slurry method [(100-z) Fe _b Ni _c Mo _d O _y / z In the multicomponent composite oxide catalyst prepared by the conventional simple slurry method by forming a core part with% SiO ₂ ] composition and introducing an impregnation method to form a shell part with [A _a O _x ] composition It is an object to provide a solid catalyst having a more excellent core-shell structure.

In addition, the solid catalyst having a core-shell structure according to the present invention is economically advantageous because it exhibits high activity while maximally inhibiting the use of bismuth, which has excellent catalytic activity and is expensive, and in a fixed bed reactor or a fluidized bed reactor during the reaction. All have the advantage of excellent activity.

[Configuration and Function of Invention]

The present invention is characterized by a solid catalyst having a core-shell structure represented by the following formula (1).

[Formula 1]

In Chemical Formula 1, A is at least one element selected from bismuth, boron, phosphorus, and molybdenum; when d is 1, a is 0.001-3, b is 0.01-5, c is 0.1-5, z is 0-90; x and y are values that are set to match valences by different components in the core and shell parts.

Referring to the present invention in more detail as follows.

In describing the composition of the solid catalyst according to the present invention, the core portion and the shell portion of the catalyst are separated by [(100-z) Fe _b Ni _c Mo _d O _y / z% SiO ₂ ] and [A _a O _x ], respectively. Although expressed, the two parts combined (100-w)% A _a Fe _b Ni _c Mo _d O _{x + y} + w% SiO ₂ is the same in overall chemical composition but large to understand and express the present invention Make a difference. Therefore, in the present invention, the core portion and the shell portion will be described separately.

The core portion of the solid catalyst according to the present invention is prepared by a so-called "slurry method" in which silica is used as a carrier and each of an active metal such as iron, nickel and molybdenum is appropriately added. For example, silica sol and anion-containing salts that can be decomposed, i.e., salts or compounds containing acetate, citrate, nitric acid, triphenyl, etc. are made into a solution and mixed. Slurry to remove solvent. The mixed solution is dried in a drier, firstly baked at 200 ° C. to 500 ° C., and then ground to a size of 25 to 70 mesh.

A core portion prepared by the slurry method as described above is impregnated with a salt solution corresponding to [A _a O _x ] to form a shell portion. For example, at least one salt or compound containing element A is dissolved in a suitable solvent to impregnate the core portion. In this case, as the salt containing the component A component to be used, as mentioned in the above core formation, it is also possible to use anion-containing salts or other compounds such as acetate, citrate, nitric acid and triphenyl. The impregnated material is dried at 50 ° C. to 200 ° C. and calcined again at 200 ° C. to 700 ° C. to prepare a solid catalyst having a core-shell structure as an object of the present invention.

On the other hand, for the purpose of catalytic activity of the core portion, suppression of by-product formation and improvement of mechanical strength, cores commonly referred to in the field of catalyst production include transition metals, alkali metals, alkaline earth metals, and rare earth cores. It can also be added to the ingredients. It is also possible to add these enhancers in the shell component for the same purpose as above.

It is very important to have a dual structure of core and shell in the catalytic activity according to the present invention, and they have been found to play different roles. That is, even if the overall chemical composition [(100-w)% A _a Fe _b Ni _c Mo _d O _{x + y} + w% SiO ₂ ] is the same in the composition of the components constituting the core-shell structured solid catalyst, According to the composition and composition ratio constituting the core and the shell portion will show a large difference in the activity. According to the results of the present inventors, as illustrated above, the core portion has a [(100-z) Fe _b Ni _c Mo _d O _y / z% SiO ₂ ] composition, and the shell portion has a [A _a O _x ] composition. If it has, the solid catalyst exhibits maximum activity due to the synergy effect between the components.

In addition, the solid catalyst having a core-shell structure according to the present invention is another superior in that it obtains high catalytic activity while maximally suppressing the use of expensive bismuth, which is included as an essential ingredient in the conventional catalyst for ammonia oxidation. There is this.

The present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Comparative Example 1

18.66 g of Fe (NO ₃ ) ₃ .9H ₂ O and 39.33 g of Ni (NO ₃ ) ₃ .6H ₂ O were dissolved in 150 mL of 10% HNO ₃ to form Solution A. 29.12 g of (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O was dissolved in heat, and then 93.83 g of 40% silica sol was added to make Solution B. Mix solution A and solution B, adjust the pH to 3 with ammonia water, evaporate the solvent by heating on a hot plate, dry in an oven at 140 ° C, calcinate at 290 ° C and 450 ° C, and then 25 ~ Grinded to 70 mesh. As a result, a catalyst having a composition of 50% MoF _0.28 Ni _0.82 O _y / 50% SiO ₂ was prepared.

The ammonia reaction of propylene was carried out using a catalyst prepared according to the above-described method at a reaction temperature of 445 ° C. and the volume ratio of the reactant to propylene / ammonia / oxygen / nitrogen = 1 / 1.3 / 2.2 / 9.6 and a contact time of 0.6 sec. When performed, the conversion was 8.2%, and the selectivity of acrylonitrile was 42%.

Example 1

0.1 ml of H ₃ PO ₄ solution (0.05 g / ml) was added thereto, and water was added thereto. Then, 2.35 g of the oxide prepared in Comparative Example 1 was added thereto, and the water was evaporated by heating on a hot plate, followed by drying at 140 ° C. . 0.1 ml of Bi (NO ₃ ) ₃ .5H ₂ O solution (0.25 g / ml) was further added, and 10% HNO ₃ was added thereto to stir uniformly. The water was then evaporated by heating on a hotplate, dried at 140 ° C., and calcined at 575 ° C. As a result, a catalyst having a composition of [Bi _0.01 P _0.01 O _x ] [50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ ] was prepared.

The ammonia reaction of propylene was carried out using a catalyst prepared according to the above-described method at a reaction temperature of 445 ° C. and the volume ratio of the reactant to propylene / ammonia / oxygen / nitrogen = 1 / 1.3 / 2.2 / 9.6 and a contact time of 0.6 sec. When performed, the conversion was 72.3% and the selectivity of acrylonitrile was 8.32%.

Example 2

A catalyst was prepared in the same manner as in Example 1, except that [Bi _0.03 O _x ] [50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ ] catalyst was prepared.

When the ammonia oxidation of propylene was carried out in the same manner as in Example 1 using the catalyst prepared in the above method, the conversion was 71.9% and the selectivity of acrylonitrile was 81.8%.

Example 3

A catalyst was prepared in the same manner as in Example 1, except that [Bi _0.03 P _0.03 O _x ] [50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ ] catalyst was prepared.

When the ammonia oxidation of propylene was carried out in the same manner as in Example 1 using the catalyst prepared according to the above method, the conversion was 80.1% and the selectivity of acrylonitrile was 86.1%.

Example 4

A catalyst having a composition of [Bi _0.03 P _0.03 O _x ] [50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ ] prepared in Example 4 was prepared.

Conversion rate when ammonia was oxidized at a reaction temperature of 445 ° C. using a catalyst prepared by the above method, and the volume ratio of the reactant was propylene / ammonia / oxygen / nitrogen = 1 / 1.3 / 2.2 / 9.6 and the contact time was 1.8 sec. The selectivity of 96.5% silver and acrylonitrile was 86.1%.

Example 5

A catalyst having a composition of [Bi _0.03 P _0.03 O _x ] [50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ ] was manufactured using Mo instead of P among the components used in the preparation of Example 4.

Conversion rate when ammonia was oxidized at a reaction temperature of 445 ° C. using a catalyst prepared according to the above method, with a volume ratio of propylene / ammonia / oxygen / nitrogen = 1 / 1.3 / 2.2 / 9.6 and a contact time of 0.6 sec. The selectivity of 80.7% silver and acrylonitrile was 85.1%.

Comparative Example 2

A catalyst was prepared in the same manner as in Example 1, except that the oxide was calcined at 575 ° C. for 3 hours. As a result, a catalyst having a composition of 50% MoFe _0.28 Ni _0.82 O _y / 50% SiO ₂ was prepared.

When the ammonia oxidation of propylene was carried out in the same manner as in Example 1 using the prepared catalyst, the conversion was 8.2% and the selectivity of acrylonitrile was 42%, which was the same as in Example 1.

Comparative Example 3

2.33 g of Fe (NO ₃ ) ₃ · 9H ₂ O, 4.92 g of Ni (NO ₃ ) ₃ · 6H ₂ O, and 0.03 g of Bi (NO ₃ ) ₃ · 5H ₂ O were dissolved in 20 ml of 10% HNO ₃ , and dissolved. Made C 3.64 g of (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O was added to dissolve in water, and 0.071 g of 85% H ₃ PO ₄ and 12.2 g of 40% silica sol were added thereto while stirring. Solution C and Solution D were mixed, pH was adjusted to 3 with ammonia water, and the solvent was evaporated by heating on a hot plate, dried at 140 ° C., and calcined in air from 290 ° C. to 575 ° C. And crushed to 25 ~ 70mesh. The catalyst prepared by the slurry method has a chemical formula of 50% MoFe _0.28 Ni _0.82 Bi _0.03 P _0.03 O _x / 50% SiO ₂ .

When the ammonia oxidation of propylene was carried out in the same manner as in Example 1 using the catalyst prepared according to the above method, the conversion was 59.8% and the selectivity of acrylonitrile was 86.7%.

According to the results of Table 1, as in Comparative Example 1, the catalyst composed of only the core part composition had low activity, and showed the same activity in Comparative Example 2 in which the firing temperature was increased, whereby the firing temperature of the catalyst was active. It can be seen that it does not significantly affect the increase.

Example 1 is a case of forming a core portion in the same manner as in Comparative Example 1 and impregnated with bismuth (Bi) and phosphorus (P), it can be seen that the activity is greatly improved. In Example 2, when only the bismuth was included in the shell, activity was greatly increased. In Example 3, as an example of increasing the impregnation amount of the bismuth (Bi) and phosphorus (P), which is the core part in Example 1, the catalytic activity was greatly improved in this case. It can be seen that the part has a great influence on the catalytic activity. And, Example 4 is an example of increasing the activity of the catalyst by increasing the contact time in the ammonia oxidation reaction using the catalyst prepared in Example 3, Example 5 replaces molybdenum (Mo) instead of phosphorus (P) It is added.

In addition, Comparative Example 3 is a purely prepared catalyst of the same composition as in Example 3 by the slurry method, it can be seen that the catalytic activity is significantly lower than the catalyst of Example 3.

[Effects of the Invention]

As described above, the solid catalyst having a core-shell structure according to the present invention is not only different in composition of the catalyst constituting the core portion and the shell portion, but also the production method thereof is set differently from each other by the slurry method and the impregnation method. It can be easily seen that the composition and the catalyst structure are completely different from the oxide catalyst used in the conventional ammonia oxidation reaction. In addition, also in the catalytic activity, although the chemical composition is the same as each other shows a large difference in activity according to the preparation method thereof.

Therefore, the solid catalyst having a core-shell structure according to the present invention is very useful as a catalyst for preparing nitrile compounds by ammonia oxidation of olefins.

Claims (3)

A solid catalyst having a core-shell structure for ammonia oxidation of olefins, which is represented by the following Chemical Formula 1. [Formula 1] In Chemical Formula 1, A is at least one element selected from bismuth, boron, phosphorus, and molybdenum; when d is 1, a is 0.001-3, b is 0.01-5, c is 0.1-5, z is 0-90; x and y are values that are set to match valences by different components in the core and shell parts. The core catalyst of claim 1, wherein the solid catalyst comprises a core portion of [(100-z) Fe _b Ni _c Mo _d O _y / z% SiO ₂ ] and a shell of [A _a O _x ] composition. A solid catalyst having a core-shell structure, characterized in that it has a double structure consisting of a portion. Mixing a solution containing molybdenum and silica sol in a solution containing iron and nickel, adjusting the pH of the mixed solution to 3 to 5 and then performing a slurry reaction to dry grinding to form a core part; And olefin represented by the following Chemical Formula 1, comprising a process of forming a shell portion by impregnating core pulverized with at least one component selected from bismuth, boron, phosphorus and molybdenum. A method for preparing a solid catalyst having a core-shell structure for ammonia oxidation. [Formula 1] In Chemical Formula 1, A is at least one element selected from bismuth, boron, phosphorus, and molybdenum; when d is 1, a is 0.001-3, b is 0.01-5, c is 0.1-5, z is 0-90; x and y are values that are set to match valences by different components in the core and shell parts.