WO2018203615A9 - Method for preparing catalyst for oxidative dehydrogenation reaction and oxidative dehydrogenation method using same catalyst - Google Patents

Abstract

The present invention relates to a method for preparing a catalyst for an oxidative dehydrogenation reaction and an oxidative dehydrogenation process using the same. More specifically, the present invention includes a process of supplying an inert gas or air at specific time when preparing a catalyst for an oxidative dehydrogenation reaction by co-precipitation, thereby reducing an inactive α-Fe2O3 crystal structure and improving the activity of the catalyst, and furthermore, the present invention applies the same to an oxidative dehydrogenation reaction of butene so as to suppress side reactions and improve the selectivity of butadiene, thereby providing a high productivity of butadiene.

Description

METHOD FOR PREPARING CATALYST FOR OXIDATIVE DEHYDRATION REACTION AND METHOD OF OXIDANT DEHYDRATION USING THE CATALYST

[Mutual quotation with application (s)]

This application is based on Korean Patent Application No. 10-2017-0056741 filed on May 04, 2017, and Korean Patent Application No. 10-2018-0047836 re-filed on Apr. 25, 2018, The contents of which are incorporated herein by reference in their entirety.

The present invention relates to a process for preparing a catalyst for oxidative dehydrogenation reaction and an oxidative dehydrogenation process using the catalyst, wherein an inert α-Fe ₂ O ₃ The present invention provides a catalyst for oxidative dehydrogenation reaction of high activity, which can be used in the production of butadiene to inhibit side reactions, improve the selectivity of butadiene, and provide oxidative dehydration A method for producing a catalyst for digestion reaction, and the like.

1,3-butadiene is one of the main raw materials of synthetic rubber, and it is one of the major basic oils that prices fluctuate rapidly in connection with the supply and demand situation of the petrochemical industry. Examples of the method for producing 1,3-butadiene include naphtha cracking, direct dehydrogenation of n-butene, and oxidative dehydrogenation of n-butene. The oxidative dehydrogenation reaction of n-butene is a reaction in which butene reacts with oxygen to produce 1,3-butadiene and water in the presence of a metal oxide catalyst, and is advantageous thermodynamically because stable water is produced. Since the oxidative dehydrogenation reaction of n-butene is an exothermic reaction unlike the direct dehydrogenation reaction, the reaction process is operated at a low temperature to obtain 1,3-butadiene with a high yield, while adding an oxidizing agent There is little generation of carbon deposits that shortens the catalyst life by poisoning the catalyst, and the removal thereof is easy, which is very suitable for the commercialization process.

On the other hand, ferritic catalysts commonly known as catalysts for oxidative dehydrogenation of butene are synthesized by coprecipitation. Catalysts synthesized by coprecipitation have a crystal structure that is active for oxidative dehydrogenation and an inert Fe ₂ O ₃ crystal structures are known to coexist. Therefore, it is necessary to study a technique for producing a catalyst having an inactive Fe ₂ O ₃ crystal structure reduced or a catalyst having an excellent activity even if an inactive crystal structure exists at a certain level or higher.

In addition, when the catalyst is synthesized by the coprecipitation method, since the production amount is small due to the technical and spatial restrictions, it is difficult to improve the productivity because the catalyst must be manufactured by repeating the same procedure several times in order to fill the target amount. It is preferable to synthesize the catalyst, but in this case, the content of the inactive crystal structure increases, resulting in a problem of poor activity and stability.

[Prior art document]

[Patent Literature]

Korean Patent No. 10-0847206

Korean Patent No. 10-1071230

In order to solve the problems of the prior art as described above, the present invention provides a method for preparing a catalyst having excellent oxidative dehydrogenation reaction activity even though an inactive Fe ₂ O ₃ crystal structure exists at a certain level, and furthermore, Which is capable of reducing the Fe ₂ O ₃ crystal structure of iron oxides.

It is another object of the present invention to provide an oxidative dehydrogenation method capable of suppressing side reactions by using a catalyst prepared by the above process for producing an oxidative dehydrogenation reaction and greatly improving the yield and selectivity of butadiene The purpose.

These 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 provides a method for producing a metal precursor solution, comprising: preparing a metal precursor aqueous solution by adding a trivalent cation iron (Fe) precursor and a divalent cation metal (A) precursor to water; Adding the metal precursor aqueous solution and the basic aqueous solution to an aqueous solution adjusted to a pH of 6 or more or a coprecipitation tank prepared with water to coprecipitate iron and an A metal; And a step of firing the coprecipitated co-precipitate, wherein the step of supplying an inert gas or air to the coprecipitate is performed until the coprecipitation, the coprecipitation, or the coprecipitation after the coprecipitation. The present invention also provides a method for producing a catalyst for an inactive dehydrogenation reaction.

The present invention also includes an oxidative dehydrogenation reaction in which a C4 mixture containing n-butene and a reactant containing oxygen are passed through a reactor filled with a catalyst for an oxidative dehydrogenation reaction according to the above production method ≪ RTI ID = 0.0 > a < / RTI >

According to the present invention, when preparing a catalyst for oxidative dehydrogenation reaction by a coprecipitation method, an inert gas or air is introduced into a coprecipitation tank at a specific time point to improve the activity of the catalyst, It is possible to further improve the activity by reducing the Fe ₂ O ₃ crystal structure which is inactive in the catalyst. The catalyst thus prepared is applied to the oxidative dehydrogenation reaction of butene to reduce the side reaction and improve the selectivity of butadiene The yield is improved and high-quality butadiene is provided at a high productivity.

1 is XRD data showing the crystal structure of a zinc ferrite catalyst prepared according to Example 1 (air supply) and Comparative Example 1 (conventional synthesis method).

2 shows the crystal structure of a zinc ferrite catalyst prepared according to Example 2 (feeding N ₂ + lower aqueous solution of metal precursor), Example 3 (feeding air + lower aqueous solution of metal precursor) and Comparative Example 1 It is XRD data showing.

FIG. 3 is a graph showing the particle size distributions of the co-precipitation slurries prepared in Examples 1 to 3 and Comparative Example 1. FIG.

Hereinafter, the production method of the catalyst for oxidative dehydrogenation reaction of the present invention will be described in detail.

The present inventors confirmed that an inert Fe ₂ O ₃ crystal structure which affects the oxidative dehydrogenation reaction is observed when a ferrite catalyst is synthesized by coprecipitation, and when the inactive Fe ₂ O ₃ crystal structure has a certain level (N ₂ ) gas or air was supplied to the coprecipitation solution at a specific time in the catalyst synthesis. The amount of nitrogen (N ₂ ) , And when the aqueous solution of the metal precursor is selectively supplied through the lower part of the co-precipitation tank in the coprecipitation step, the degree of dispersion of the coprecipitate corresponding to the ferrite-based catalyst precursor is maximized and has a favorable effect on the crystal structure of the ferrite-based catalyst , It is confirmed that the above-mentioned problem is solved, and the present invention has been completed on the basis thereof.

The method for producing the catalyst for oxidative dehydrogenation reaction according to the present invention comprises the steps of preparing a metal precursor aqueous solution by adding, for example, a trivalent iron (Fe) precursor and a divalent cation metal (A) precursor to water; Adding the metal precursor aqueous solution and the basic aqueous solution to an aqueous solution adjusted to pH 6 or higher or a coprecipitation tank prepared with water to coprecipitate iron and A metal; And firing said co-coprecipitate, wherein said co-coin; After coping; Or from co-deposition to co-deposition; And an inert gas or air is supplied to the coprecipitating tank.

The process of supplying inert gas or air to the coprecipitation tank may be, for example, a process of supplying an inert gas or air into the coprecipitation tank while stirring the solution in the coprecipitation tank by using stirring means such as an impeller or the like, A process of supplying inert gas or air into the co-bath through the pipe, or a process of supplying a non-activated gas or air to the solution through a pipe, for example, by installing a Teflon pipe in a co- Further, the pipe and the pipe may have an inner diameter of 1/8 "to 1/2" or 1/6 "to 1/2", for example, and the position of the pipe and the pipe may be below the co- But it may be located at a lower end of the co-op tank, specifically, at a point within 1/2 of the distance from the bottom of the co-op tank to the water surface.

Hereinafter, the method for preparing the catalyst for oxidative dehydrogenation will be described in detail.

Examples of the trivalent iron (Fe) precursor and the divalent cation metal (A) precursor in the step of preparing the metal precursor aqueous solution include a nitrate, an ammonium salt, a sulfate or a chloride And the like. Preferably, the catalyst is selected from nitrate or chloride in consideration of the cost of producing the catalyst for mass production as it is cheap and easily available.

Examples of the divalent cation metal (A) include copper (Cu), radium (Ra), barium (Ba), strontium (Sr), calcium (Ca), beryllium (Be), zinc (Zn) ), Manganese (Mn) and cobalt (Co), and is preferably selected from among zinc (Zn) and manganese (Mn) exhibiting particularly high activity in the oxidative dehydrogenation reaction of butene And it may be most preferable to include zinc (Zn) in terms of yield and selectivity of butadiene.

The trivalent cationic iron (Fe) precursor and the divalent cationic metal (A) precursor are mixed with water to prepare an aqueous solution. When the metal precursor is dissolved in water to be present in a liquid phase, Ion exchange is easy, and the desired coprecipitate can be easily produced.

The water may be, for example, distilled water.

Typically, a suitable mixing ratio of trivalent cationic iron (Fe) precursor and divalent cationic metal (A) precursor in the metal precursor aqueous solution is such that the trivalent cationic iron (Fe) precursor Is 1.5 to 10 moles, 1.5 to 4 moles or 1.5 to 2.5 moles, and within this range there is an effect of facilitating the formation of a crystal structure that is active in the oxidative dehydrogenation reaction and thus having an excellent catalytic activity.

In addition, the aqueous solution of the metal precursor may have a pH of 0 to 4, 1 to 3 or 1 to 2, for example, and the desired active ingredient is stably formed within this range.

After the aqueous solution of the metal precursor is prepared, a co-precipitation bath prepared with an aqueous solution or water adjusted to a pH of 6 or more is provided for coprecipitation of iron and A metal, and an aqueous solution of the metal precursor is added to the co- Cooperate.

The aqueous solution having the pH adjusted to 6 or more in the coprecipitation step may be at least one selected from an aqueous solution of sodium hydroxide and aqueous ammonia, and the pH of the coprecipitate may be adjusted to 6 or more, 6 to 10 or 7 To 8, it is possible to reduce the width of the initial pH change due to the input of the aqueous solution of the metal precursor, thereby stably forming a catalyst having a uniform composition.

In the catalyst preparation method of the present invention, for example, a step of injecting an inert gas or air into the coprecipitation tank can be performed during the coprecipitation step. By performing such a process, oxygen and the metal precursor can be uniformly combined, the mixing effect is increased, and ultimately, the effect of improving the oxidative dehydrogenation activity can be provided. For example, when the catalyst prepared according to the present invention is applied to an oxidative dehydrogenation reaction of butene, the conversion of butene, the selectivity of butadiene, the yield and the like are improved and the production of side reaction materials is reduced. It also has the advantage of exhibiting excellent reaction activity at relatively low hot spot temperatures.

In the present description, a hot spot means a portion of the catalyst layer filled in the reactor with the highest temperature during the reaction.

For example, inert gas or air may be supplied at a rate of 0.1 to 2 L / min or 0.5 to 1 L / min per 1 L of solution in a co-bath, for 1 to 300 minutes, 10 To 200 minutes, 30 to 100 minutes, or 40 to 90 minutes, and within this range, there is an advantage in favor of a small and uniform particle size distribution and active crystal structure of the catalyst.

In the coprecipitation step, the pH of the coprecipitation solution may preferably be maintained at 7 to 10, or 7 to 8, for example. Within this range, the activity and stability of the catalyst are excellent. In the co-precipitation step, it may be preferable to add a basic aqueous solution simultaneously with the metal precursor aqueous solution for the purpose of maintaining the pH at 7 to 10.

For example, in the co-precipitation step, the metal precursor aqueous solution and the basic aqueous solution may be dripped together in the coprecipitation bath to precipitate iron and A metal. The basic aqueous solution may be at least one selected from sodium hydroxide and ammonia water.

In the present description, the drop refers to, for example, dropping two or more solutions to the same point or container, and the " same point " means that the solution being dropped falls within a range It includes the range within the point where it does not mix completely and maintains its properties.

In another example, in the co-precipitation step, the metal precursor aqueous solution may be supplied through the lower portion of the co-precipitation bath, and the basic aqueous solution may be co-precipitated with iron and the A metal by dropping in the coprecipitation bath. When the metal precursor aqueous solution is directly fed into the co-precipitation vessel separately from the basic aqueous solution, the uniformity of the crystal structure is increased by increasing the diffusion rate of the metal precursor into the solution provided in the co- A catalyst exhibiting activity can be provided.

In the present invention, the method of introducing the metal precursor aqueous solution into the co-precipitation bottom is not particularly limited in the case where the metal precursor aqueous solution is directly introduced below the water surface of the solution in the co-precipitation tank. For example, The metal precursor aqueous solution may be supplied through the pipe or the metal precursor aqueous solution may be supplied through the pipe provided at one end to the solution in the cooperating vessel so that the metal precursor solution is supplied through the pipe. Can be increased.

The co-precipitate is present in the co-precipitate in a slurry state, for example, the median size is 7 탆 or less, or 1 to 7 탆, the mode size of the particle is 7 탆 or less 1 to 7 탆. Within this range, there is an effect of securing a high yield of butadiene compared to a conventional zinc ferrite catalyst.

In the present invention, the median diameter and mode diameter of the slurry particles are measured by a Laser Particle Size Analyzer-960 manufactured by Horiba Co., and the refractive index required here is set based on Fe, which is present most in the slurry state.

Stirring the coprecipitation solution prior to calcining the coprecipitate obtained from the coprecipitation solution having completed the coprecipitation; ferment; Or agitating and aging the mixture. In this case, the effect of ensuring sufficient coprecipitation is provided.

As an example of the method of preparing the catalyst of the present invention, it is possible to carry out a process of supplying an inert gas or air while stirring the coprecipitation solution after completion of the coprecipitation. The catalyst thus prepared has an oxidative dehydrogenation reaction activity And it has an excellent effect, for example, when it is applied to the oxidative dehydrogenation reaction of butene, it enhances the conversion of butene, the selectivity of butadiene, and the effect of reducing the generation of side reactions. It also has the advantage of exhibiting excellent reaction activity at relatively low hot spot temperatures.

As another example, in the catalyst production method of the present invention, a step of supplying an inert gas or air into the co-precipitation tank during the step of coprecipitation by adding the metal precursor aqueous solution and the basic aqueous solution is performed, and after the coprecipitation is completed, And further adding an inert gas or air into the co-precipitation tank. In this case, the oxidative dehydrogenation reaction activity of the catalyst can be further enhanced.

As another example, the catalyst production method of the present invention is characterized in that the metal precursor solution and the basic aqueous solution are continuously added to the coprecipitation solution through the step of adding the coprecipitation solution to the coprecipitation solution, And then an inert gas or air is fed into the co-precipitation tank. In this case, the oxidative dehydrogenation reaction activity of the catalyst is improved.

The inert gas may be, for example, nitrogen (N ₂ ).

The stirring and aging may be performed for 30 minutes to 3 hours or 30 minutes to 2 hours, respectively, but not limited thereto.

Drying the coprecipitation solution; percolation; Or dried and filtered; and was possible to obtain a coprecipitate, it is possible by sintering them to obtain a catalyst containing AFe ₂ O ₄ crystal structure.

The drying and filtration are not particularly limited as long as they are commonly practiced in the art, and the filtration may include, for example, a vacuum filtration and, if necessary, filtration and washing.

The drying may be carried out using a conventional dryer, for example, drying at 60 to 100 ° C, 70 to 100 ° C, or 80 to 100 ° C for 12 to 20 hours, 14 to 20 hours, or 14 to 18 hours .

The firing may be carried out in a conventional firing furnace, for example, at 400 to 800 ° C, 500 to 800 ° C, or 550 to 750 ° C for 1 to 10 hours, 3 to 8 hours, or 5 to 7 hours, It is not limited.

The catalyst obtained through the calcination may include an AFe ₂ O ₄ crystal structure, and a specific example thereof may be a mixed phase including an AFe ₂ O ₄ crystal structure and an α-Fe ₂ O ₃ crystal structure.

The catalysts obtained according to one embodiment of the present invention include, for example, at least 93.7 wt%, at least 94.0 wt%, at least 94.5 wt%, at least 94.8 wt% or 94.8 to 96.0 wt% AFe ₂ O ₄ crystal structure; And 6.3 wt% or less, 6.0 wt% or less, 5.5 wt% or less, 5.2 wt% or less, or 4.0 to 5.2 wt% of the? -Fe ₂ O ₃ crystal structure.

In the present specification, the weight ratio of AFe ₂ O ₄ and α-Fe ₂ O ₃ was determined by AFe ₂ O ₄ peak (29theta: 30.5 °, 34.5-35.5 °, 42-43 °, 52.5-53.5 °, 56.5 To 57.5 °, 62 to 63 °) and the size of α-Fe ₂ O ₃ peak (2theta: 33 to 34 °).

In the XRD diffraction analysis, AFe ₂ O ₄ as (220), (311), (222), (400), (422), (511), (440) And? -Fe ₂ O ₃ is present at the (104) position.

More specifically, the catalyst preparation method of the present invention comprises: 1) preparing a metal precursor aqueous solution by adding a trivalent iron (Fe) precursor and a divalent cation metal (A) precursor to water; 2) coprecipitating the metal precursor aqueous solution with an aqueous solution adjusted to a pH of 6 to 10 or a coprecipitation tank prepared with water, together with a basic aqueous solution to coprecipitate iron and metal A; And 3) stirring the coprecipitation solution having completed the coprecipitation; Or agitating and aging the mixed coprecipitate, followed by calcination of the co-precipitated coprecipitate, wherein the coprecipitating step and the step of introducing nitrogen or air into the cooperating vessel during the stirring are performed.

In another specific example, the catalytic method of the present invention comprises: 1) preparing a metal precursor aqueous solution by adding trivalent iron (Fe) precursor and divalent cation metal (A) precursor to water; 2) supplying the aqueous solution of the metal precursor through an aqueous solution having a pH adjusted to 6 to 10 or a lower part of a co-bathing vessel prepared with water, and dropping the basic aqueous solution in the co-treatment bath to coprecipitate iron and A metal; And 3) stirring the coprecipitation solution having completed the coprecipitation; Or agitating and aging the mixed coprecipitate, and then firing the coprecipitated coprecipitate, wherein the coprecipitation step and the step of feeding nitrogen or air into the cooperating vessel during the stirring are performed.

In addition, the catalyst according to the production method of the present invention may be characterized by satisfying the following formula (1).

[Equation 1]

0? T2 / T1? 0.80

(Wherein, in the above formula (1), T2 represents an amount of the α-Fe contained in 100 wt% of the total amount of the catalyst prepared according to the catalyst preparation method of the present invention including the step of supplying the metal precursor aqueous solution to the bottom of the co- ₂ O ₃ T1 is the content of the catalyst in 100 wt% of the catalyst prepared by spontaneously coprecipitation with the basic aqueous solution instead of supplying the aqueous solution of the metal precursor to the lower part of the co- α-Fe ₂ O ₃ and the content of crystal structure, α-Fe ₂ O content of ₃ crystal structure of the XRD diffraction patterns of the catalyst α-Fe ₂ O ₃ crystal structure peak: measured by the size (2theta 33 to 34 °) do.)

More preferably, the value of T2 / T1 may be from 0 to 0.75, from 0 to 0.70, or from 0 to 0.68, and the activity of the catalyst is excellent within this range. When this is applied to an oxidative dehydrogenation reaction, the yield and selectivity of butadiene And the like, thereby providing high-quality butadiene at a high productivity and exhibiting high activity at a low hot spot temperature.

The oxidative dehydrogenation reaction catalyst prepared according to the present invention can be used for the reaction for forming butadiene from the oxidative dehydrogenation reaction of butene, and the oxidative dehydrogenation method of the present invention will be described below.

In the oxidative dehydrogenation method of the present invention, for example, an oxidative dehydrogenation reaction is performed while passing a reaction mixture containing a C4 mixture containing normal butene and oxygen in a reactor filled with a catalyst for an oxidative dehydrogenation reaction according to the above- The method comprising the steps of:

The oxidative dehydrogenation may be, for example, a process for preparing butadiene.

As a specific example, the butadiene producing method of the present invention comprises the steps of: i) charging a catalyst for an oxidative dehydrogenation reaction into a reactor; And ii) conducting an oxidative dehydrogenation reaction while continuously passing a reactant containing oxygen and a C4 mixture containing n-butene to the catalyst bed of the reactor packed with the catalyst.

The C4 mixture includes at least one n-butene selected from, for example, 2-butene, 1-butene, 1-butene, -3. ≪ / RTI >

The reactant may further include at least one selected from air, nitrogen, steam, and carbon dioxide.

As a specific example, the reactants may comprise a C4 mixture, oxygen, steam and nitrogen in a molar ratio of 1: 0.01 to 1.5: 1 to 15: 1 to 10 or 1: 0.5 to 1.2: 5 to 15: , The reaction heat is easily controlled within this range, and the yield of butadiene is excellent.

The oxidative dehydrogenation reaction can be performed at a reaction temperature of 250 to 430 ° C, 300 to 425 ° C, or 350 to 425 ° C, and the reaction efficiency is excellent without significantly increasing the energy cost within this range, Can be provided at a high productivity, and the catalyst activity and stability can be maintained at a high level.

The oxidative dehydrogenation is a space velocity of 50, based on the normal butene as an example to 2000h ^-1, from 50 to 1500 h ^-1, or 50 to 1000 h ^-1: can be carried out by (GHSV Gas Hourly Space Velocity), Within this range, the reaction efficiency is excellent and the conversion efficiency, selectivity and yield are excellent.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

[Example]

Example 1

0.122 mol of zinc chloride (ZnCl ₂ ) and 0.243 mol of ferric chloride (FeCl ₃ 6H ₂ O) were dissolved in 12.778 mol of water to prepare a metal precursor aqueous solution. At this time, the molar ratio of the metal components contained in the metal precursor aqueous solution was Fe: Zn = 2: 1.

Next, in the coprecipitation tank prepared with distilled water, the aqueous solution of the metal precursor was dripped with ammonia water having a concentration of 9-10 wt%, and iron and zinc were coprecipitated and nitrogen was supplied. At this time, nitrogen was injected for 80-90 minutes in an amount of 1 L / min per 1 L of the distilled water. After completion of coprecipitation, a coprecipitation solution was stirred for 1 hour so that sufficient coprecipitation was achieved, wherein nitrogen was injected at an amount of 0.5 L / min per liter of the distilled water. After stopping the agitation, the coprecipitate was allowed to stand for one hour at room temperature so that all of the precipitate would sink.

The coprecipitation solution, which had been stirred and aged, was filtered under reduced pressure using a vacuum filter to obtain a coprecipitate. The co-precipitate was washed and dried at 90 DEG C for 24 hours, and the dried co-precipitate was placed in a calcination furnace at 650 DEG C for 5 hours The zinc ferrite catalyst was prepared by heat treatment.

Comparative Example 1

The same procedure as in Example 1 was carried out except that all of the steps of feeding nitrogen into the co-bath in Example 1 were omitted.

[Test Example]

The following test analyzes were carried out using the zinc ferrite catalyst prepared in Example 1 and Comparative Example 1 as follows.

Test Example 1: XRD analysis

XRD analysis was performed to confirm the crystal structure and the ratio of the catalyst prepared in Example 1 and Comparative Example 1, and XRD analysis results are shown in FIG. 1 and Table 1 below.

division	Example 1	Comparative Example 1
ZnFe 2 O 4 crystal structure (% by weight)	96.0	92.4
α-Fe 2 O 3 crystal structure (% by weight)	4.0	7.6

Referring to FIG. 1 and Table 1, the zinc ferrite catalyst prepared in Example 1 and Comparative Example 1 was ZnFe ₂ O ₄ Α-Fe ₂ O ₃ ratio of the crystal structure of the catalyst according to the crystal structure as α-Fe ₂ O ₃ in Example 1 to check the combination of the crystal structure merchant, this was confirmed to be significantly lower. From this, it was found that the nitrogen gas supply in the co-precipitation tank had a favorable effect on the crystal structure of the ferrite-based catalyst.

Test Example 2: Oxidative dehydrogenation reaction

Butadiene was produced by the following oxidative dehydrogenation reaction using the zinc ferrite catalyst synthesized in Example 1 and Comparative Example 1. The results are shown in Table 2 as Examples 1a to 1c and Comparative Examples 1a to 1d Respectively.

As a reactor, the catalyst prepared in Example 1 or Comparative Example 1 was fixed to a metal tubular reactor having a diameter of 1.8 cm at a catalyst bed volume of 30 cc, and 40 wt% of cis-2-butene and 60 wt% of trans- - Butene mixture and oxygen were used and nitrogen and steam were introduced. The reactant ratios were set to the molar ratio of oxygen / butene 1, steam / butene 8 and nitrogen / butene 1, and the steam was vaporized at 340 ° C vaporizer and introduced into the reactor together with the reactants.

The amount of butene mixture was controlled at 0.625 cc / min using a mass flow controller for liquids. The oxygen and nitrogen were controlled using a mass flow controller for gas, and the feed rate was controlled using a liquid pump. The gas hourly space velocity (GHSV) of the reactor was set to 66 h ^-1 and the reaction was carried out at normal pressure (pressure gauge 0) under the temperature conditions shown in Table 2 below.

The reaction product was analyzed by gas chromatography (GC), and the conversion of each butene in the mixture (BE_Conv.), 1,3-butadiene selectivity (S_BD), 1,3-butadiene yield (Y) S_COx), heavy component selectivity (S_heavy) and O ₂ conversion rate (O ₂ _Conv.) Were calculated according to the following equations (2) to (4), and the hot spot temperature was calculated by transferring a thermo-couple After connecting to the apparatus, it was scanned by moving it from the top to the bottom of the reactor at a constant speed.

&Quot; (2) "

Conversion rate (%) = (number of moles of butene or oxygen reacted / mole of supplied butene or oxygen) x 100

&Quot; (3) "

Selectivity (%) = (number of moles of produced 1,3-butadiene or COx or heavy component / mole of reacted butene) x 100

&Quot; (4) "

Butadiene yield (%) = (moles of produced 1,3-butadiene / moles of supplied butene) x 100

division	Reaction temperature (캜)	BE_Conv. (%)	S_BD (%)	Y (%)	S_COx (%)	S_heavy (%)	O 2 _Conv. (%)	Hotspot temperature (℃)
Example 1a	330	83.2	89.5	74.4	9.5	1.0	96.4	475
Example 1b	334	85.4	89.7	76.6	9.2	1.1	99.0	-
Example 1c	335	85.5	89.2	76.3	9.9	1.0	99.6	476
Comparative Example 1a	325	79.7	88.5	70.6	10.5	1.0	95.3	478
Comparative Example 1b	330	82.8	88.8	73.5	10.3	1.0	97.8	484.9
Comparative Example 1c	334	84.1	88.5	74.4	10.5	1.0	99.9	485.8
Comparative Example 1d	335	83.7	89.6	75.0	9.4	1.0	99.2	-
Reaction conditions: GHSV 66 h -1 , oxygen: steam: nitrogen = 1: 8: 1 (based on the number of moles of butene)

Referring to Table 2, the catalysts of Example 1 and Comparative Example 1 exhibited the highest activity under oxygen-rich conditions, and the catalyst of Example 1 synthesized by performing the nitrogen supply process at a specific point of time was comparative Example 1 Butene conversion, butadiene selectivity and yield were increased, and the selectivity of COx as a side reaction was decreased. In addition, it was confirmed that the catalyst of Example 1 exhibited excellent reaction activity at a low hot spot temperature as compared with the catalyst of Comparative Example 1 in an oxidative dehydrogenation reaction. That is, it was found that the nitrogen introduction step performed in the synthesis of the zinc ferrite catalyst contributes both to the reduction of the inactive α-Fe ₂ O ₃ crystal structure and to the increase of the reaction activity.

Example 2

A metal precursor aqueous solution was prepared under the same conditions as in Example 1 except that the aqueous solution was supplied through the lower part of the cooperating vessel and ammonia water was dropped to coprecipitate iron and zinc.

Example 3

Example 2 was carried out in the same manner as in Example 2, except that air was supplied instead of nitrogen (N ₂ ).

Test Example 3: XRD analysis

XRD analysis was performed to confirm the crystal structure and the ratio of the catalysts prepared in Examples 1 to 3, and the results of XRD analysis are shown in FIG. 2 and Table 3 together with the XRD analysis results of Comparative Example 1.

division	Example 2	Example 3	Comparative Example 1
ZnFe 2 O 4 crystal structure (% by weight)	95.3	94.8	92.4
α-Fe 2 O 3 crystal structure (% by weight)	4.7	5.2	7.6

Referring to FIGS. 2 and 3, it can be seen that the zinc ferrite catalyst prepared in Examples 2 and 3 is a mixed phase of a ZnFe ₂ O ₄ crystal structure and an α-Fe ₂ O ₃ crystal structure, supplied through the bottom and the catalyst preparation, including the step of supplying in the ball chimjo nitrogen or oxygen (example 2 or 3) is not, in Comparative catalyst preparation inert crystals of example 1, the structure of α-Fe ₂ O ₃ crystal structure Of the total amount of water. That is, it was found that when the aqueous solution of the metal precursor was supplied through the lower part of the co-precipitation tank and the nitrogen gas or air supply process was performed during the synthesis of the zinc ferrite catalyst by coprecipitation, the crystal structure of the zinc ferrite catalyst was favorably affected .

Test Example 4: Particle size analysis

The results of the particle size analysis of the ferrite-based catalyst precursor slurry prepared in Examples 1 to 3 and Comparative Example 1 are shown in Table 4 and FIG. The particle size distribution of the slurry was measured by Horiba's Laser Particle Size Analyzer-960, and the refractive index required was determined based on Fe as a main component in the slurry.

division	Example 1	Example 2	Example 3	Comparative Example 1
Median size (탆)	6.9	5.8	6.0	8.4
Mode size (탆)	7.2	6.2	6.3	8.3

* Median size: Medium particle size * Mode size: Most widely distributed particle size

As shown in Table 4 and FIG. 3, it can be seen from Examples 1 to 3 that the slurry particles as compared with Comparative Example 1 are relatively small and have a uniform particle size, and Examples 2 and 3 show that the slurry particles Was relatively small and had a uniform particle size. From these results, it was confirmed that the introduction of nitrogen is effective to have a small and uniform particle size of the catalyst precursor, and that the introduction of air and the introduction of the aqueous solution of the metal precursor are effective to have a smaller and uniform particle size.

Test Example 5: Oxidative dehydrogenation reaction

Butadiene was produced through an oxidative dehydrogenation reaction using the zinc ferrite catalyst synthesized according to Examples 2 and 3 under the same conditions and conditions as above, and the results are shown in the following Table 5 in Examples 2a to 2d and Example 3a to 3c, and Comparative Examples 1a to 1d are re-described for comparison.

division	Reaction temperature (캜)	BE_Conv. (%)	S_BD (%)	Y (%)	S_COx (%)	S_heavy (%)	O 2 _Conv. (%)	Hotspot temperature (℃)
Example 2a	340	86.7	89.4	77.5	9.6	1.0	99.8	-
Example 2b	330	86.2	89.5	77.1	9.4	1.1	97.6	474.2
Example 2c	335	86.5	89.3	77.2	9.6	1.1	99.8	486.9
Example 2d	325	81.1	90.0	73.0	9.0	1.0	94.4	468.2
Example 3a	330	85.5	89.2	76.3	9.8	1.0	99.5	-
Example 3b	334	86.6	89.5	77.5	9.4	1.1	97.7	476.0
Example 3c	339	87.1	89.4	77.9	9.6	1.0	99.9	478.8
Comparative Example 1a	325	79.7	88.5	70.6	10.5	1.0	95.3	478
Comparative Example 1b	330	82.8	88.8	73.5	10.3	1.0	97.8	484.9
Comparative Example 1c	334	84.1	88.5	74.4	10.5	1.0	99.9	485.8
Comparative Example 1d	335	83.7	89.6	75.0	9.4	1.0	99.2	-
Reaction conditions: GHSV 66 h -1 , oxygen: steam: nitrogen = 1: 8: 1 (based on the number of moles of butene)

Referring to Table 5, it was confirmed that both of the oxidative dehydrogenation reactions using the catalysts of Examples 2 and 3 and Comparative Example 1 exhibited high activity under oxygen consumption conditions, and the aqueous solution of the metal precursor And the zinc ferrite catalyst prepared by supplying nitrogen or air at a specific time point (Examples 2 and 3) exhibited a higher conversion ratio of butene and a higher butadiene selectivity than the catalyst of Comparative Example 1 And the selectivity of COx, which is a side reaction substance, is low. In addition, when the zinc ferrite catalyst of Examples 2 and 3 according to the present invention was used, it was confirmed that the reaction activity was excellent even at a low hot spot temperature as compared with Comparative Example 1. [

That is, during the synthesis of the zinc ferrite catalyst by the coprecipitation method, the aqueous solution of the metal precursor is supplied through the lower part of the coprecipitator and the nitrogen or air injection process performed at a specific point of time not only reduces the inactive crystal structure of the zinc ferrite catalyst, And also contributes to an increase in the activity of the reaction.

Claims (14)

1. Adding a trivalent iron (Fe) precursor and a divalent cation metal (A) precursor to water to produce an aqueous metal precursor solution; Adding the metal precursor aqueous solution and the basic aqueous solution to an aqueous solution adjusted to a pH of 6 or more or a coprecipitation tank prepared with water to coprecipitate iron and an A metal; And firing the copreciped co-precipitate,

   Upon coprecipitation; After coping; Or from the coping to the coping after the coping; An inert gas or air is supplied to the coprecipitation tank

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
2. The method according to claim 1,

   In the co-precipitation step, the aqueous solution of the metal precursor is supplied through the lower part of the co-

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
3. The method according to claim 1,

   Stirring the coprecipitation solution having completed the coprecipitation; ferment; Or agitating and aging the mixture.

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
4. The method of claim 3,

   And introducing nitrogen (N ₂ ) gas into the coprecipitation solution during the stirring.

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
5. The method according to claim 1,

   The trivalent iron (Fe) precursor and the divalent cation metal (A) precursor are independently at least one selected from the group consisting of nitrate, ammonium salt, sulfate and chloride. Featured

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
6. The method according to claim 1,

   The divalent cation metal (A) may be at least one selected from the group consisting of copper (Cu), radium (Ra), barium (Ba), strontium (Sr), calcium (Ca), beryllium (Be), zinc (Zn) (Mn) and cobalt (Co).

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
7. The method according to claim 1,

   Wherein the pH of the coprecipitation solution in the co-precipitation step is maintained at 7 to 10

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
8. The method according to claim 1,

   The catalyst comprising the AFe ₂ O ₄ crystal structure

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
9. The method according to claim 1,

   Wherein the catalyst is a mixed phase comprising an AFe ₂ O ₄ crystal structure and an α-Fe ₂ O ₃ crystal structure

   A method for preparing a catalyst for an oxidative dehydrogenation reaction.
10. The method according to claim 1,

    The coprecipitates the coprecipitation solution; percolation; Or < RTI ID = 0.0 > drying and filtration < / RTI >

    A method for preparing a catalyst for an oxidative dehydrogenation reaction.
11. The method according to claim 1,

    Characterized in that the catalyst satisfies the following formula (1)

    A method for preparing a catalyst for an oxidative dehydrogenation reaction.

    [Equation 1]

    0? T2 / T1? 0.80

    (In the formula 1, wherein T2 is a second catalyst that contains a total of 100% by weight, produced by the method according to the α-Fe ₂ O ₃ The content of the crystal structure, T1 is the amount of the claim 1 method in an inert gas or air supply step the skip is a contained within the catalyst 100% by weight of manufacturing α-Fe ₂ O ₃ crystal structure, α-Fe ₂ O _{3 The} crystal structure content is measured from the size of the α-Fe ₂ O ₃ crystal structure peak (2theta: 33 to 34 °) of the XRD diffraction analysis of the catalyst.
12. An oxidative dehydrogenation reaction is carried out by passing a C4 mixture containing n-butene and a reactant containing oxygen into a reactor filled with a catalyst for an oxidative dehydrogenation reaction produced by the process of any one of claims 1 to 11 ≪ RTI ID = 0.0 >

    Oxidative dehydrogenation.
13. 13. The method of claim 12,

    Wherein the reactant further comprises at least one selected from air, nitrogen, steam and carbon dioxide

    Oxidative dehydrogenation.
14. 13. The method of claim 12,

    Wherein the oxidative dehydrogenation reaction is carried out at a reaction temperature of 250 to 430 ° C. and a gas hourly space velocity (GHSV) of 50 to 2000 h ^-1 (butene)

    Oxidative dehydrogenation.

Images