KR960003795B1 - Process for the preparation of heteropoly-acid catalysts - Google Patents

Abstract

This is new heteropolyacid-based catalyst of formula (I). The manufacturing method comprises :1)dissolving 12-molybdophosphoric acid in water followed by adding phosphoric acid and vanadium pentoxide; 2)refluxing the mixture for 12hrs at an elevated temp. to produce molybdovanadophosphoric acid solution(A); 3)dissolving one kind of Cu, Ce, Ru, Bi, Sb N-heterocyclic compd and above one of oxalic acid or its salts(B); 4)adding solution B to solution A with stirring at 30-80deg.C and maturing the stirred mixture; 5)cooling it to room temp and stirring for 30min, filtering and washing it; 6)drying the cake and molding; and 7)1st firing at 380-450deg.C for 2-10hrs, and 2nd firing at 260-420deg.C for 2-10hrs.

Description

Method for preparing heteropolyacid catalyst

The present invention is based on phosphomolybdic acid, which is useful for gas phase oxidation reaction of methacrolein, oxidative dehydrogenation reaction of isobutyl acid, oxidative dehydrogenation reaction of isobutyl aldehyde, oxidative dehydrogenation reaction of saturated fatty acid ester compound and oxidation reaction of isobutane. It relates to a new method for producing a heteropolyacid catalyst of the general formula (1).

(X _a Cu _b Y _c ) (P _{1 + d} As _e ) (Mo ₁₂ V _f W _g ) O _h. ········· (1)

Wherein Cu, P, As, Mo, V, W, O represent copper, phosphorus, arsenic, molybdenum, vanadium, tungsten, oxygen, X is at least one element selected from cesium, rubidium, potassium, thallium, Y is composed of elements selected from bismuth, antimony, tin, chromium, silver, palladium, lead, calcium, magnesium, barium, tellurium, selenium, strontium, cobalt, zirconium, germanium, ammonium and pyridinium ions.

Until now, heteropolyacid catalysts based on phosphorus and molybdenum have been usefully used as catalysts for the above reactions due to their unique strong acid properties and oxidizing ability, but phosphomolybdic acid itself is easily deteriorated due to poor thermal stability and strong oxidation ability. It is reduced, and the crystallization property is strong at the low temperature of the solution state, whereas the crystallization water is more than 150 ℃ and the cohesion between particles is extremely weak and easily crushed, there was a very bad moldability.

Therefore, the catalyst performance can be improved by improving the electrical, chemical and physical and chemical properties of the catalyst using various metals or by adding organic and inorganic compounds in the preparation of the catalyst to control the physical properties of the catalyst such as surface area, pore volume and pore distribution. The results of partial technical development to remedy the above disadvantages can be found in the following patent documents.

For example, U.S. Patents 4,042,625, 4,272,408, JP-A-82-32734, 83-74142, 83-166938, 86-5043, 86-76436, 88-167152, Korean Patent 36019, 36020, and the like, The Japanese Patent Application Laid-Open Publication Nos. 82-12830, 84-66349, 89-119942, 92-16242 and others disclose organic and inorganic compounds such as nitrogen heterocyclic compounds, urea, organic reducing substances, ammonium nitrate, ammonium carbonate, and ammonium sulfate. Additives were added, and the catalyst production conditions and methods such as addition time and aging temperature of the catalyst components were controlled to improve catalyst performance.

In order to explain the present invention in more detail, a heteropolyacid-based catalyst is generalized as a catalyst for oxidation of methacrolein, oxidation dehydrogenation of isobutyl acid and its ester compound, oxidation dehydrogenation of isobutylaldehyde, and oxidation of isobutane. Marked as (1).

(X _a Cu _b Y _c ) (P _{1 + d} As _e ) (Mo ₁₂ V _f W _g ) O _h. ··········· (1)

Wherein Cu, P, As, Mo, V, W and O represent copper, phosphorus, arsenic, molybdenum, vanadium, tungsten and oxygen, respectively, X is at least one element selected from cesium, rubidium, potassium and thallium , Y represents an element selected from bismuth, antimony, tin, chromium, silver, palladium, lead, calcium, barium, magnesium, tellurium, selenium, strontium, cobalt, zirconium, germanium, ammonium ion and pyridinium ion.

The parentheses in the formula (1) are shown to systematically indicate the properties of the 12-heterpolyacid catalyst system, and the first parentheses indicate that the proton, which is a relative cation of 12-phosphomolybdate anion, is partially substituted with other metals. The second parenthesis indicates some substitution of phosphorus by the central element phosphorus and arsenic, and the third parenthesis indicates some substitution of molybdenum for the condensation elements molybdenum, vanadium and tungsten.

In the above formula (1), a, b, c, d, e, f, g and h represent the atomic ratios of the elements. When the composition of molybdenum is 12, a is 0.5 to 2, b is 0.05 to 1, and c is It has a value from 0 to 2 and a + b + c has a value of 3 + f or less. d is 0 to 2, e is 0 to 1, f and g have a value of 0 to 3, and h has a value necessary to match valences in each composition.

According to the known technique, X is added as an essential component in order to increase the thermal stability of the heteropolyacid and to control the physical and chemical properties of the catalyst.

In addition, the catalyst represented by the general formula (1) should have appropriate physical properties in order to exhibit good activity in the above reaction, in particular the pore volume and pore size are important factors. In order to achieve the above object, Japanese Patent Application Laid-Open No. 82-12830 European Patent 0043100 and many patents use nitrogen heterocyclic compounds such as pyridine, piperidine, piperazine and pyrimidine as precipitants to induce an active structure. have.

However, according to the experiences of the present inventors, when a nitrogen heterocyclic compound such as pyridine and piperazine and an ammonium salt are used as a precipitant, or in the formula (1), a combination of a monovalent cation having a relatively large ion radius such as cesium, rubidium, thallium and potassium in formula (1) There were found defects in which 12-phosphomolybdate was precipitated but the copper compound was dissolved in water and not precipitated.

The combination of these water-insoluble and water-soluble elements places a lot of care and limitations in the preparation of the catalyst.

For example, when a part of the condensation element molybdenum is replaced with vanadium, some unsubstituted vanadium compound is dissolved in the heteropolyacid solution, which, when evaporated and dried, forms an extra phosphorus and phosphorus-vanadium compound, which adversely affects catalyst selectivity. However, there is no method for removing dissolved vanadium without changing the composition of the catalyst.

In addition, in order to obtain a powder having a desired composition from the slurry obtained in the catalyst manufacturing process, the spray dried or concentrated cake can be dried as it is, and at this time, the water-soluble components cannot be avoided from moving to the particle surface.

Attempts have been made to mold the catalyst powder using a penis or extruder, making it difficult to form shaped catalyst particles having a uniform composition.

Localization of these components lowers the selectivity of the catalyst and acts as a trigger point for local hot spots during the reaction.

Moreover, localization of the components leads to non-uniformity of the catalyst composition, which accelerates the separation and recrystallization of the catalyst components, thereby promoting catalyst deactivation and shortening the catalyst life. Therefore, in the present invention, it was found that the mixed precipitant of the nitrogen heterocyclic compound, oxalic acid and its salts exerts an excellent effect in order to remove the above defects and obtain an improved catalyst.

Accordingly, an object of the present invention is to provide a nitrogen heterocyclic ring for preparing a catalyst for oxidation of methacrolein, oxidation dehydrogenation of isobutyl aldehyde, isobutyl acid, isobutyl acid ester, and oxidation reaction of isobutane. A high activity, high selectivity, and long lifespan characterized by the production of primary particles with uniform component distribution by controlling the physical properties of the catalyst using a mixed precipitant of the compound with oxalic acid or salts thereof and allowing all of the added components to precipitate out simultaneously. It is to provide a new method for preparing a catalyst.

More specifically, all the components are obtained in a uniform precipitation state, and the filtration and washing processes are introduced in the catalyst manufacturing process, thereby simplifying the manufacturing process in a shorter manner than the known method of the conventional evaporation and drying process. By removing only the uncompromised and free components and unnecessary anions in the process, only a catalytic composition effective for chemical reactions can be prepared, resulting in high activity, high selectivity, long life catalysts, and at the same time anion during drying and activation In addition, it eliminates the risk of deterioration of the catalyst due to heat generation during the decomposition and removal of these materials. In addition, the obtained non-aqueous powder can minimize the localization of components even when using an extruder or a stirrer at the time of molding. Also provided.

Here, even if the filtration and washing process are not introduced, the use of the mixed precipitant in the production and subsequent processes of the primary particles, for example, drying and molding, is not departing from the gist of the present invention.

The object of the present invention and its advantages and industrial usability is clearly defined by the following detailed description and the appended claims.

According to the present invention, the precipitant is used oxalic acid and / or salt thereof with one component selected from nitrogen heterocyclic compounds such as known pyridine, piperidine, piperazine, pyrimidine and the like. The oxalates used are ammonium salts, lithium, sodium and potassium salts. The cations and extra oxalates should be removed during filtration and washing after aging.

Nitrogen heterocyclic compounds such as pyridine, piperidine, piperazine and pyrimidine in the precipitant form precipitates with 12-heteropolyacid and / or 12-molybdovanadophosphoric acid as is known, and the physical properties of the catalyst (surface area, Pore volume, pore size), and oxalic acid and / or its salt precipitating agents include thallium, cesium, luminium, potassium and nitrogen heterocyclic compounds including copper and 12-heteropolyacids and non-precipitate transition metals. By effectively coprecipitation with the heteropolyacid of, it is possible to prepare primary particles with a uniform component distribution.

The amount of the precipitant used is 6-2a or more and 2 (3 + f) -a in the molar ratio in the general formula (1) for the nitrogen heterocyclic compound, and the precipitant for oxalic acid and / or its salt is b or more and 5 or less (b + c) or less. Used as.

Hereinafter, the catalyst production method of the present invention will be described in detail.

12-molybdophosphate is dissolved in water, and quantitative phosphoric acid and vanadium pentoxide are added, followed by reflux for at least 2 hours to obtain a crimson solution of molybdovanadophosphoric acid in which vanadium is substituted for molybdenum sites (solution A). When arsenic and tungsten are added as the central element and condensation element, it is obtained by refluxing in the same manner by adding arsenic oxide, arsenic acid and 12-tungstoic acid.

At this time, the method of obtaining the solution A can also use any well-known method other than the above-mentioned method.

For example, sodium or ammonium salts of molybdenum trioxide or molybdate can be obtained by reacting with phosphoric acid and vanadium pentoxide or ammonium metavanadate.

In another vessel, at least one precipitant selected from copper and one of X, Y, nitrogen heterocyclic compounds, oxalic acid or salts thereof is mixed and dissolved in a constant composition ratio (solution B). Mixing only copper and oxalic acid in solution B forms a precipitate, but addition of one of the nitrogen heterocyclic compounds, for example pyridine, results in many solutions making complexes of copper and pyridine. The solution A is kept at 100 degrees C or less, Preferably it is 30-80 degreeC, The solution B is added, stirring vigorously, and aged for 3 hours or more. After aging, the temperature of the slurry liquid is lowered, stirred at room temperature for 30 minutes or more, filtered and washed with deionized water.

When a water-insoluble metal such as bismuth is added as a Y component in the catalyst preparation process, bismuth nitrate is dissolved in a dilute nitric acid solution, and this is first added to Solution A, and then a catalyst is prepared in the same manner.

The filtered cake is dried and molded at 50 to 150 ° C. In order to improve the mechanical strength of the formed catalyst particles, or to effectively disperse the heat of reaction to suppress the heat storage in the catalyst particles, conventional carriers such as silica or alumina, microfibrous materials such as silicon carbide and silicon nitride or glass fibers It can mix and shape | mold.

The carriers may be prepared by mixing the solution A in the preparation process, or after mixing the dried catalyst particles with uniformity. However, when the fibrous material is added, it is preferable to mix the solution A first.

Molding may be carried out using any method such as extrusion, tableting, coating, or globular method, and the shape of the molded body may be in any form such as spherical, tablet, hollow, and the like.

The formed catalyst is activated through a calcination process, which is first calcined at 380 to 450 ° C. for 2 to 10 hours under a nitrogen atmosphere, and then calcined for 2 to 10 hours under an air flow of 260 to 420 ° C. The activated catalyst is charged to a stainless steel tube reactor and reacted in a fixed bed.

The catalytic activity test results are defined as follows.

* Reactant [product]: methacrolein [methacrylic acid], isobutyl aldehyde [methacrolein + methacrylic acid], isobutyl acid [methacrylic acid], isobutyl acid ester [methacrylic acid ester + methacrylic acid ]

Example 1

100 g of 12-molybdate phosphoric acid is dissolved in 300 ml of water, 0.49 g of 85% phosphoric acid and 4.26 g of vanadium pentoxide are added and refluxed for 12 hours to obtain a crimson solution (solution A).

Dissolve 2.3 g of thallium acetate, 12.5 g of cesium nitrate, 2.0 g of copper nitrate, 16.9 g of pyridine, and 2.7 g of oxalic acid in 150 ml of water (solution B).

10 g of SiC (diameter 0.2-0.5, length 50-100 micrometers) is added to solution A maintained at 50 degreeC, and solution B is added, stirring vigorously. The resulting yellow slurry was aged at 60 ° C. for 12 hours and stirred at room temperature for 1 hour. The slurry solution is filtered and washed once with 100 ml of deionized water. The moisture of the cake-like material obtained is blown out appropriately and molded into a cylindrical shape in an extruder (5 mm in diameter and 5 mm in length).

The molded body is dried at 150 ° C., first calcined at 430 ° C. for 3 hours under nitrogen atmosphere, and secondaryly calcined for 3 hours under 400 ° C. air atmosphere.

The composition of the catalyst obtained is Cs _1.45 Tl _0.2 Cu _0.18 P _1.1 Mo ₁₂ V _1.0 (atomic ratio excluding oxygen) + SiC.

The catalyst was charged to a stainless steel reactor and a gas mixture consisting of methacrolein (3.5%), oxygen (7.7%), steam (15%) and nitrogen (73.8%) was subjected to a space velocity of 1200 hr ⁻¹ at 300 ° C. Pass through the catalyst bed and react.

The results are shown in [Table 1].

Example 2

In the same manner as in [Example 1], a catalyst slurry liquid was prepared. The solution is concentrated in the aging process to obtain a cake-like material and the appropriate moisture is blown out to prepare a catalyst in the same manner as in Example 1.

The composition of this catalyst was Cs _1.5 Tl _0.2 Cu _0.2 P _1.1 Mo ₁₂ V _1.1 (atomic ratio excluding oxygen) + SiC.

This catalyst was subjected to gas phase oxidation of methacrolein under the same reaction conditions as in Example 1.

Reactivity test results are shown in [Table 1].

Comparative Example 1

Solution A is prepared as in Example 1. Solution B used only 20.2 g of pyridine without using oxalic acid as a precipitant. Under the same conditions as in Example 1, 10 g of SiC was added to Solution A, and solution B was added thereto while stirring to prepare a slurry liquid. After aging, the slurry solution was concentrated, evaporated, and dried without filtration to prepare a catalyst.

The composition of the prepared catalyst was Cs _1.5 Tl _0.2 Cu _0.2 P _1.1 Mo ₁₂ V _1.1 (atomic ratio excluding oxygen) + SiC.

This catalyst was subjected to gas phase oxidation of methacrolein under the same reaction conditions as in Example 1.

Reactivity test results are shown in [Table 1].

Comparative Example 2

A slurry solution is prepared in the same manner as in Comparative Example 1. After aging, the slurry solution is filtered and washed once with 100 ml deionized water. Thereafter, a catalyst was prepared in the same manner as in Example 1.

The composition of the prepared catalyst was Cs _1.45 Tl _0.2 P _1.1 Mo ₁₂ V _1.0 (atomic ratio excluding oxygen) + SiC, and all of the copper components were filtered out and remained in the catalyst.

This catalyst was subjected to gas phase oxidation of methacrolein under the same reaction conditions as in Example 1.

The experimental results are shown in [Table 1].

Example 3

144.0 g of molybdenum trioxide, 12.5 g of 85% phosphoric acid, and 8.27 g of vanadium pentoxide were added to 1 L of water, and the mixture was refluxed for 24 hours to obtain a crimson solution.

The solution is filtered to remove insoluble solids and then concentrated to give red crystals.

After drying, the water of crystallization is determined, 70 g of which is dissolved in 200 ml of water (solution A). Dissolve 8.8 g of cesium nitrate, 1.4 g of copper nitrate, 12.7 g of piperidine, and 2.2 g of sodium oxalate in 150 ml of water (solution B).

After the same preparation as in Example 1.

The filtered cake-like material is dried in an electric furnace at 100 ° C., uniformly mixed with 17 g of silica powder, and then molded in a penis machine. The composition of the prepared catalyst was Cs _1.5 Cu _0.15 P _1.09 Mo ₁₂ V _0.9 (atomic ratio excluding oxygen) + SiO 2.

Gas phase oxidation of methacrolein was carried out under the same reaction conditions as in Example 1.

The experimental results are shown in [Table 1].

Example 4

Dissolve 113 g of Na ₂ MoO ₄ · 2H ₂ O and 4.91 g of 85% -H ₃ PO ₄ in 500 ml of water. In another container, 5.96 g of NaVO (H2O) is dissolved in 100 ml of boiling water, mixed with molybdate and phosphoric acid solution, and 40 ml of nitric acid is added to pH 2 or less (solution A). Since the manufacturing method is the same as in Example 1.

The catalyst composition is Ca _1.4 Cu _0.2 P _1.1 Mo ₁₂ V _0.9 (atomic ratio excluding oxygen) + SiC. The gas phase oxidation reaction of methacrolein under the same reaction conditions as in Example 1 is shown in [Table 1].

TABLE 1

Example 5

100 g of 12-molybdate phosphoric acid is dissolved in 300 ml of water, 0.49 g of 85% phosphoric acid and 4.26 g of vanadium pentoxide are added, and the mixture is refluxed for 12 hours to obtain a crimson solution. 2.1 g of bismuth nitrate is dissolved in 30 cc of 1N nitric acid solution and added to the solution (solution A).

Dissolve 3.0 g of copper nitrate, 3.2 g of oxalic acid, 16.9 g of pyridine and 12.5 g of cesium nitrate in 150 ml of water (solution B). 10 g of SiC (diameter 0.2-0.5, length 50-100 micrometers) is added to the solution A maintained at 50 degreeC, and solution B is added dropwise, stirring vigorously.

The resulting yellow slurry was aged at 60 ° C. for 12 hours and maintained at room temperature for 1 hour. The slurry liquid is filtered, and the moisture of the cake-like material obtained is blown off appropriately, and then molded in a cylindrical shape in an extruder (5 mm in diameter and 5 mm in length). Drying and baking are carried out under the same conditions as in Example 1.

The composition of this catalyst was Cs _1.45 Cu _0.27 P _1.1 Mo ₁₂ V _1.0 (atomic ratio excluding oxygen) + SiC.

The catalyst was charged to a stainless steel reactor and a gas mixture consisting of isobutyl acid (3.1%), oxygen (2.8%), steam (6.2%) and nitrogen (87.9%) was subjected to a space velocity of 2,800 hr ^-1 at 290 ° C. The reaction is carried out by passing through the catalyst layer.

The results are shown in [Table 2].

Comparative Example 3

It is the same as Example 5 except having concentrated and dried without using an oxalic acid precipitation agent.

Isobutyl acid oxidative dehydrogenation result is shown in [Table 2].

Example 6

A catalyst, such as Example 5, was charged to a stainless steel reactor and a gas mixture consisting of isobutylaldehyde (3.1%), oxygen (3.1%), steam (6.2%) and nitrogen (87.9%) at 280 ° C. was spaced at 2,800hr. ^It reacts by passing through a catalyst layer on condition of ^-1 .

The results are shown in Table 2.

Comparative Example 4

The catalyst is the same as in Comparative Example 3 and the reaction test is the same as in Example 6.

The reaction test results are shown in Table 2.

TABLE 2

Claims (5)

In preparing a slurry of heteropolyacids and / or salts thereof having a composition of formula (1) in which methacrylate, isobutyl acid, isobutylaldehyde, saturated fatty acid esters, isobutane, etc. are oxidized and oxidatively dehydrogenated using molecular oxygen. A method for preparing a heteropolyacid catalyst comprising coprecipitation with a mixed precipitant of copper, oxalic acid, and / or salts thereof, and nitrogen heterocyclic compounds in 12-molybdo vanadium phosphate, followed by filtration, drying, molding, and calcining. . (X _a Cu _b Y _c ) (P _{1 + d} As _e ) (Mo ₁₂ V _f W _g ) O _h ... … … … … … … … … … … … (One) In the formula, Cu, P, As, Mo, V, W, O represents copper, phosphorus, arsenic, molybdenum, vanadium, tungsten, oxygen, X is at least one element selected from cesium, rubidium, potassium, thallium, Y is an element selected from bismuth, antimony, tin, chromium, silver palladium, lead, calcium, magnesium, barium, tellurium, selenium, strontium, cobalt, zirconium, germanium, ammonium and pyridinium ions, and a, b, c, d, e, f, g, and h represent the atomic ratios of each atom. When molybdenum is 12, a is 0.5 to 2, b is 0.05 to 1, c has a value of 0 to 2, and d is 0 to 2 And e is from 0 to 1, f and g are from 0 to 3, a + b + c has a value less than or equal to 3 + f, and h has a value necessary to match the valence of each composition. The method for producing a catalyst according to claim 1, wherein copper and vanadium are added as essential components. The method of claim 1, wherein the nitrogen heterocyclic compound is at least one selected from pyridine, piperidine, piperazine, pyrimidine and derivatives thereof and at least one selected from ammonium, lithium, sodium and potassium salts of oxalic acid and / or oxalic acid. Method for producing a catalyst using the above mixed precipitating agent. The process for producing a catalyst according to claim 1, wherein the precipitate in slurry form is filtered. The method according to claim 1, wherein conventional carriers such as silica and alumina, fine fibrous materials such as silicon nitride and silicon carbide or glass fibers are mixed to form spherical particles, tablets, beads, or the like using extrusion methods such as extrusion, tableting, coating, and beading. A method for producing a catalyst in the form of a hollow or the like.