KR100982831B1 - Method for preparing heteropoly acid catalyst - Google Patents

Abstract

The present invention relates to a method for preparing a heteropolyacid catalyst used in a process for producing methacrylic acid by gas phase oxidation of methacrolein, and more particularly, (A) precursors of Mo and V. Adding a distilled water and H ₃ PO ₄ and stirring to prepare an aqueous solution in which no residual precursor is present (a1); (A2) preparing a concentrated solution by evaporating the aqueous solution at atmospheric pressure or reduced pressure; And (a3) further stirring the concentrate; preparing a heteropolyacid including P, Mo, and V as a metal component; (B) preparing a slurry by adding and stirring a metal precursor, a nitrogen-containing compound and distilled water to the prepared heteropolyacid; And (C) isolating, drying, and calcining the prepared slurry to prepare a catalyst.

According to the present invention, there is an effect of providing a heteropolyacid catalyst having high conversion and high selectivity of methacrylic acid and excellent activity using a high purity heteropolyacid.

Heteropolyacids, residual metal precursors, concentrated, phosphorus, molybdenum, vanadium, catalysts, methacrolein, methacrylic acid, gas phase oxidation

Description

Method for preparing heteropolyacid catalyst {METHOD FOR PREPARING HETEROPOLY ACID CATALYST}

1 is a graph showing the ³¹ P NMR analysis of the heteropolyacid prepared according to an embodiment of the present invention.

Figure 2 is a graph showing the ³¹ P NMR analysis of the heteropolyacid prepared according to the comparative example of the present invention.

The present invention relates to a method for preparing a heteropolyacid catalyst, and more particularly, to a method for preparing a heteropolyacid catalyst having high conversion of methacrolein and high selectivity of methacrylic acid and excellent activity using a high purity heteropolyacid. .

In general, the heteropolyacid catalyst used in the process of gasifying oxidation of methacrolein to produce methacrylic acid is a phosphate based on phosphomolybdate. Molybdenum (Mo) in the form of an oxide having an octahedral structure (12) has a keggin structure (12) share the edge portion.

Such heteropolyacid catalysts are mainly known by co-precipitation using nitric acid or a method of preparing a catalyst precursor by vacuum drying without using nitric acid.

U.S. Patent No. 4,301,031 (11.17.1981 register) is _{Mo 12 P 0 .1-3 M 0 .1-3} Cu 0 .1-2 V 0 .1-2 X 0 .01-2 Y a O b ( where , M is K, Rb or Cs, X is Ba, La, Ga, Al, Ag, Cd, Ti, Tl, Hg, Pb or Zn, Y is Fe, Co, Ni, Sr, Mn, In, Ta, Ge It is explained that the final catalyst prepared by drying a heteropolyacid-based catalyst having a composition of (S, Be), and then molding and calcining to a uniform shape is effective for the oxidation reaction of methacrolein.

U.S. Patent No. 4,621,155 (registered Nov. 4, 1986) claims that catalysts prepared using pyridine, pyrriridine or piperazine as nitrogen-containing materials have excellent formability and physical strength and improve reproducibility of catalyst preparation. have.

U.S. Pat.No. 6,333,293B1 (registered Dec. 25, 2001) dissolves ammonium paramolybdate and ammonium paravanadate in heated water, stirs them, injects 85% of phosphoric acid in an appropriate amount, and injects cesium nitrate and copper nitrate. And a method of preparing a catalyst by heating and drying the prepared solution.

In addition, U.S. Patent No. 6,458,740B2 (October 1, 2002) discloses ammonium paramolybdate and ammonium metavanadate in pyridine and 85% phosphoric acid, followed by coprecipitation by adding nitric acid, cesium nitrate and copper nitrate. After this, the method of heating and drying the catalyst is disclosed.

However, since the catalyst prepared by the above method is still in a low state, it is necessary to improve the conversion and selectivity in the gas phase oxidation of methacrolein.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a method for preparing a heteropolyacid catalyst having high conversion and methacrylic acid selectivity and excellent activity using a high purity heteropolyacid. do.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention

(A) adding a precursor of Mo and V, distilled water and H ₃ PO ₄ and stirring to prepare an aqueous solution in which no residual precursor is present;

(A2) preparing a concentrated solution by evaporating the aqueous solution at atmospheric pressure or reduced pressure; And

  (A3) further stirring the concentrate; preparing a heteropolyacid including P and Mo and V as a metal component;

(B) preparing a slurry by adding and stirring a metal precursor, a nitrogen-containing compound and distilled water to the prepared heteropolyacid; And

It provides a method for producing a heteropolyacid catalyst comprising a; (C) separating, drying and calcining the prepared slurry as a catalyst.

Hereinafter, the present invention will be described in detail.

In preparing the heteropolyacid-based catalyst, the inventors added an oxide-type metal precursor in a distilled water and H ₃ PO ₄ by adjusting the content so that there is no remaining metal precursor and preparing an aqueous solution. The heteropolyacid prepared by condensation and further stirring was confirmed that no unreacted metal precursor was present and impurities were suppressed to have high purity characteristics. To this heteropoly acid, a metal precursor, a nitrogen-containing compound and distilled water were added and stirred to prepare a slurry. After that, the heteropolyacid-based catalyst prepared by separating, drying, and calcining the slurry has high conversion of methacrolein and high selectivity of methacrylic acid, and excellent activity, thereby completing the present invention.

Method for producing a heteropolyacid of the present invention comprises the steps of (A) preparing a heteropolyacid containing P and Mo and V as a metal component; (B) preparing a slurry by adding and stirring a metal precursor, a nitrogen-containing compound and distilled water to the prepared heteropolyacid; And (C) separating, drying, and calcining the prepared slurry to prepare a catalyst.

The heteropolyacid-based catalyst is defined by the following formula (1).

[Formula 1]

P _a Mo _b V _c X _d Y _e Z _f O _g

In Chemical Formula 1, X is at least one metal component selected from the group consisting of Bi, As, Zr, Ge, Tl, Si, B, Te, Sb, and Ta, and Y is Ti, W, Fe, Cu, Zn At least one metal component selected from the group consisting of Cr, Co, Mn, Ga, Ce and La, Z is at least one metal component selected from the group consisting of K, Rb, Na, Cs, Mg and Ba, a is 0.01 to 3, b is 12, c is 0.01 to 3, d is 0.01 to 3, e is 0.001 to 2, f is 0.01 to 3, g is a valence condition of a, b, c, d, e, f Is a number that satisfies

(A) Preparation of Heteropoly Acid

Step (A) of the present invention is to prepare a heteropolyacid including P, Mo, and V.

The preparing of the heteropolyacid may include adding a precursor of Mo and V, distilled water, and H ₃ PO ₄ to prepare an aqueous solution in which no residual precursor is present; (A2) preparing a concentrated solution by evaporating the aqueous solution at atmospheric pressure or reduced pressure; And (a3) further stirring the concentrate.

As the precursors of Mo and V, it is preferable to use an oxide precursor.

In the step (a1), the precursors of Mo and V, distilled water, and H ₃ PO ₄ are added, but the precursor is added and stirred to a content that is soluble so that no unreacted precursor is present, thereby preparing an aqueous solution in which no residual precursor is present. Step. When the above components are added, a slurry is formed, and when the mixture is stirred and completely dissolved, the slurry becomes transparent, and the aqueous solution in this state does not have a residual metal precursor.

The step (a1) is preferably stirred at 60 to 170 ° C. for 6 to 72 hours, more preferably at 80 to 100 ° C. for 12 to 24 hours.

In the step (a1), further distilled water may be added to completely dissolve the precursor, followed by stirring, and when the unreacted metal precursor is less than 0.5%, a solution in which no residual metal precursor is present may be prepared by filtration. .

The step (a2) is a step of preparing a concentrate by evaporating the aqueous solution prepared as described above under atmospheric pressure or reduced pressure to remove distilled water and concentrating.

The step (a2) is preferably carried out at 60 to 120 ° C. until a desired volume of concentrate is reached, more preferably 3 to 72 hours.

In the concentrate of step (a2), the content of distilled water is preferably 5 ml or less, and more preferably 3 ml or less, based on 1 g of the added Mo and V precursor. When the distilled water content of the concentrate is 5 ml or more, there is a problem in that the pH of the entire solution of the heteropolyacid aqueous solution is increased to increase impurities.

The step (a3) is a step of further stirring the concentrate prepared as described above.

The step (a3) is preferably stirred for 12 to 72 hours at 60 to 170 ℃. Through further stirring, there is an effect of further reducing impurities.

As described above, the heteropolyacid solution prepared in the steps (a1) to (a3) is in proton form, and impurities such as laconic anions are suppressed to have high purity characteristics without purification such as crystallization or filtration.

The high purity heteropolyacid solution prepared by the above method may be further concentrated to obtain a solid powder form.

(B) preparing a slurry

This step is a step of preparing a slurry by adding and stirring a metal precursor, a nitrogen-containing compound and distilled water to the heteropoly acid prepared in (A). At this time, it is important to maintain the heteropolyacid in high purity. Therefore, in order to control the concentration of the heteropoly acid, it is necessary not to add excessive amount of distilled water, and an organic solvent such as alcohol can be used with distilled water as necessary.

As the metal precursor, precursors of metal components defined as X, Y, and Z in Formula 1 may be used. The metal component represented by X may be one or more selected from the group consisting of Bi, As, Zr, Ge, Tl, Si, B, Te, Sb and Ta, and the metal component represented by Y may be Ti, W , Fe, Cu, Zn, Cr, Co, Mn, Ga, Ce and La can be selected from one or more, the metal component represented by Z consists of K, Rb, Na, Cs, Mg and Ba One or more types can be selected from the group.

As the metal precursor, precursors such as oxides, hydroxides, chlorides, nitrates, carbonates, fluorides, or acetates can be used.

As the nitrogen-containing compound, a compound containing a nitrogen atom may be used pyridine, piperazine, piperidine or quinoline and the like, and an aqueous solution or acid salt containing them may be used. As the acid salt, nitrate, carbonate, fluorinated salt or acetate salt can be used.

The nitrogen-containing compound may be used in an amount of 0.1 to 12 molecules with respect to Mo 12 atoms.

The metal precursor and the nitrogen containing compound may be directly added to the heteropoly acid. In addition, the metal precursor and the nitrogen-containing compound may be prepared by suspending or dissolving together in distilled water to prepare a single aqueous solution.The metal precursor and the nitrogen-containing compound may be prepared by suspending or dissolving each of the metal precursor and nitrogen-containing compound into dilute water. It may be, but in consideration of the convenience of the process is preferably prepared in one aqueous solution.

In order to add an aqueous solution containing a metal precursor and a nitrogen-containing compound to the heteropoly acid, a method of dropping a heteropoly acid into an aqueous solution or dropping an aqueous solution into a heteropoly acid may be used. The dropping time is preferably 5 seconds to 5 hours.

The step (B) is preferably stirred for 1 to 24 hours at 0 to 90 ℃.

(C) preparing with a catalyst

This step is a step of preparing a catalyst by separating, drying and calcining the slurry prepared in (B).

The prepared slurry may be separated from distilled water, which is a reaction solvent, by a method such as filtration, oven drying, stirring drying, or spray drying.

The separated slurry may be dried for 1 to 24 hours in an oven at 120 ℃.

The separated slurry may be calcined after drying, or may be directly calcined in a state containing water.

Add an additive such as silica, alumina, graphite, zeolite, silicon carbide or glass fiber to the slurry containing water or dry slurry, and if necessary, distilled water or an organic solvent is added to the mixed solvent of the additive, extruded and calcined. It can be prepared with a final heteropolyacid catalyst.

The extrusion may be performed in the form of a sphere, cylinder or ring.

The firing is preferably carried out for 1 to 24 hours at a temperature of 200 to 600 ℃ under air, oxygen or nitrogen atmosphere. Under such conditions, there is an effect of improving the activity of the catalyst.

Heteropolyacid-based catalyst prepared by the above method can be used in the gas phase oxidation reaction for producing methacrylic acid from methacrolein.

In the gas phase oxidation reaction of methacrolein, purified methacrolein may be used as a raw material, and a mixed gas obtained by oxidizing isobutylene, t-butanol, metal-t-butyl ether, or the like may be used. The methacrolein is preferably used in 5% of the total gas content.

In addition, as the additive gas for the gas phase oxidation reaction, molecular oxygen, air, nitrogen, carbon dioxide, or water vapor may be used, and it is preferable to use air containing molecular oxygen from an economical point of view. The additive gas may be a molecular oxygen of 0.5 to 20%, preferably 1 to 10%, water vapor 1 to 20%, preferably 1 to 10% in a molar ratio with respect to methacrolein. In addition, it is preferable to use nitrogen or carbon dioxide together as a balance gas.

The gas phase oxidation reaction is performed at 200 to 380 ° C., preferably 250 to 340 ° C., by supplying a total gas at a space velocity of 100 to 2,000 hr ⁻¹ , preferably at a space velocity of 200 to 1,500 hr ⁻¹ . desirable.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

[ Example ]

Example  One

(A) Preparation of Heteropoly Acid

165 g of MoO ₃ , 4.35 g of V ₂ O ₅ , 14.68 g of 85% H ₃ PO ₄ , 1.2 L of distilled water were added thereto, and the mixture was stirred at 500 rpm at 90 ° C. for 12 hours to completely dissolve and become transparent. An aqueous solution was prepared. The aqueous solution was vaporized at 90 ° C. for 7 hours at atmospheric pressure to concentrate the aqueous solution to 300 ml to prepare a concentrate having 1.77 ml of distilled water based on 1 g of the metal precursor containing MoO ₃ and V ₂ O ₅ . It was. The concentrate was further stirred for 18 hours to prepare a heteropolyacid.

The prepared heteropolyacid was analyzed by ³¹ P NMR and the results are shown in FIG. 1. According to FIG. 1, the peaks of 1.1 and 2.2 ppm were suppressed to about 1% with respect to the total area, thereby confirming that they had high purity of about 99%.

(B) Preparation of Slitter

26.5 g of pyridine, 6.94 g of Cu (NO ₃ ) ₂ .3H ₂ O, 10.58 g of TaO ₂ , and 18.7 g of CsNO ₃ were added to 500 mL of distilled water and stirred at room temperature to prepare a solution solution of a uniform blue slurry. .

While stirring the heteropolyacid prepared in (A) at 30 ° C. and 800 rpm, the prepared additive solution was added dropwise thereto for 30 seconds, and then stirred at 70 ° C. under reflux for 12 hours to prepare a slurry.

(C) Preparation of Catalyst

The slurry of (B) was stirred and dried at 70 ° C. and 800 rpm, separated from the reaction solvent, and dried in an oven at 120 ° C. for 12 hours. To the dry slurry, 5% by weight of glass fiber and a small amount of distilled water were added to the total amount of the slurry, mixed, and extruded to a size of 5 × 5 mm, and then air-fired at 400 ° C. for 3 hours to be represented by Chemical Formula P _1.3 Mo ₁₂ Prepared with the final catalyst represented by V _0.5 Ta _0.25 Cu _0.3 Cs _1.0 O ₄₀ .

Comparative example  One

After preparing an aqueous solution from the (A) step of Example 1, without performing the step of further stirring the phases and concentrate to prepare an aqueous solution concentrate was prepared by the heteropoly acid, the formula using the heteropolyacid P _{1 .3 Mo 12 V 0 .5 Ta 0 .25} Cu 0 .3 Cs , except that a method of preparing a catalyst represented by O _{1 .0 40} was carried out as example 1.

The prepared heteropolyacid was analyzed by ³¹ P NMR and the results are shown in FIG. 2. According to Figure 2, the peak of 1.1 and 2.2 ppm occupies about 19% of the total area, it was confirmed that the purity (lacunary anion) containing about 20% is not high.

[ Test Example ]

The heteropolyacid catalysts prepared in Examples and Comparative Examples were used for the gas phase oxidation of methacrolein in the following manner.

After filling the above-mentioned heteropolyacid catalyst in the stainless steel reactor, using a nitrogen gas as a balance gas with a gas containing raw material methacrolein 3.5%, molecular oxygen 7.6%, water vapor 8.9% at a reaction temperature of 300 ℃ The gas was subjected to a gas phase oxidation reaction by supplying the entire gas at a space velocity of 250 hr ⁻¹ . It was.

Methacrolein conversion (%) = [moles of reacted methacrolein / moles of methacrolein fed] × 100

Methacrylic acid selectivity (%) = [moles of methacrylic acid formed / moles of reacted methacrolein] × 100

division Methacrolein Conversion Rate (%) Methacrylic acid selectivity (%) Example 1 85.6 75 Comparative Example 1 79.8 69.5

As shown in Table 1, the heteroacid catalyst of Example 1 prepared using a high purity heteropolyacid prepared according to the present invention has a high conversion rate of methacrolein and selectivity of methacrylic acid as compared to Comparative Example 1 I could confirm that.

As described above, according to the present invention, there is an effect of providing a heteropolyacid catalyst having high conversion rate and high selectivity of methacrylic acid and excellent activity using heteropolyacid of high purity.

Claims (9)

(A) adding a precursor of Mo and V, distilled water and H ₃ PO ₄ and stirring to prepare an aqueous solution in which no residual precursor is present; (A2) preparing a concentrated solution by evaporating the aqueous solution at atmospheric pressure or reduced pressure; And (a3) further stirring the concentrate; preparing a heteropolyacid including P, Mo, and V as a metal component; (B) adding a metal precursor, a nitrogen-containing compound and distilled water to the prepared heteropoly acid and stirring to prepare a slurry, wherein the metal precursor is Bi, As, Zr, Ge, Tl, Si, B, Te, Sb and At least one metal component selected from the group consisting of Ta, at least one metal component selected from the group consisting of Ti, W, Fe, Cu, Zn, Cr, Co, Mn, Ga, Ce and La and K, Rb, A precursor of at least one metal component selected from the group consisting of Na, Cs, Mg and Ba, and the nitrogen-containing compound includes pyridine, piperazine, piperidine and quinoline; Aqueous solutions containing these; And at least one selected from the group consisting of acid salts thereof; And (C) separating, drying, and calcining the prepared slurry to prepare a catalyst; Method for preparing heteropolyacid catalyst. The method of claim 1, The heteropolyacid-based catalyst is represented by the following formula (1) [Formula 1] P _a Mo _b V _c X _d Y _e Z _f O _g In Formula 1, X is at least one metal component selected from the group consisting of Bi, As, Zr, Ge, Tl, Si, B, Te, Sb and Ta, and Y is Ti, W, Fe, Cu, At least one metal component selected from the group consisting of Zn, Cr, Co, Mn, Ga, Ce and La, and Z is at least one metal component selected from the group consisting of K, Rb, Na, Cs, Mg and Ba a is 0.01 to 3, b is 12, c is 0.01 to 3, d is 0.01 to 3, e is 0.001 to 2, f is 0.01 to 3, g is a, b, c, d, e, f Characterized in that the number is satisfied Method for preparing heteropolyacid catalyst. The method of claim 1, Preparing the (A) heteropoly acid,   step (a1) is stirred at 60-170 ° C. for 12-24 hours,   step (a2) is concentrated at 60-120 ° C.,   Step (a3) is characterized in that the stirring for 12 to 72 hours at 60 to 170 ℃ Method for preparing heteropolyacid catalyst. The method of claim 1, The concentrate of step (a2) is characterized in that the content of distilled water is 5 ml or less with respect to the precursor content of Mo and V of the step (a1) Method for preparing heteropolyacid catalyst. delete The method of claim 1, The metal precursor is in the form of oxides, hydroxides, chlorides, nitrates, carbonates, fluorides or acetates of the metal component Method for preparing heteropolyacid catalyst. delete The method of claim 1, Step (B) is characterized in that for 1 to 24 hours stirring at 0 to 90 ℃ Method for preparing heteropolyacid catalyst. The method of claim 1, Step (C), the separated slurry is dried in an oven at 120 ℃ for 1 to 24 hours, and calcined for 1 to 24 hours at a temperature of 200 to 600 ℃ under air, oxygen or nitrogen atmosphere Method for preparing heteropolyacid catalyst.

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