KR20220046966A - Manufacturing method for zinc-ferrite catalyst and manufacturing method for butadien using zinc-ferrite catalyst - Google Patents

Abstract

The present specification relates to a method for preparing a zinc ferrite catalyst and a method for preparing butadiene using the zinc ferrite catalyst prepared thereby. The method for preparing a zinc ferrite catalyst includes: a step of preparing zinc ferrite powder using a co-precipitation method; a step of adding a crystal control material including molybdenum oxide (MoO_3) to the zinc ferrite powder; and a step of sintering the zinc ferrite powder. The zinc ferrite catalyst of the present invention can reduce generation of by-products such as CO_x when applied to preparation of butadiene.

Description

A method for producing a zinc ferrite catalyst and a method for producing butadiene using the zinc ferrite catalyst prepared thereby

The present specification relates to a method for producing a zinc ferrite catalyst and a method for producing butadiene using the zinc ferrite catalyst prepared thereby.

1,3-butadiene (1,3-butadiene) is an intermediate in petrochemical products, and its demand and value are gradually increasing worldwide. The 1,3-butadiene is produced using naphtha cracking, direct dehydrogenation of butene, oxidative dehydrogenation of butene, and the like.

However, the naphtha cracking process not only consumes a lot of energy due to a high reaction temperature, but is not a single process only for the production of 1,3-butadiene, so there is a problem that other basic oils other than 1,3-butadiene are produced in excess. . In addition, the direct dehydrogenation reaction of n-butene is not only thermodynamically disadvantageous, but also high temperature and low pressure conditions are required to produce 1,3-butadiene in high yield as an endothermic reaction, so commercialization of 1,3-butadiene is produced. The process is not suitable.

On the other hand, the oxidative dehydrogenation of butene is a reaction in which butene and oxygen react to produce 1,3-butadiene and water in the presence of a metal oxide catalyst, and since stable water is produced, it has a thermodynamically very advantageous advantage. In addition, since it is an exothermic reaction unlike the direct dehydrogenation reaction of butene, a high yield of 1,3-butadiene can be obtained even at a lower reaction temperature compared to the direct dehydrogenation reaction, and 1,3-butadiene does not require additional heat supply. It can be an effective standalone production process that can meet the demand.

On the other hand, a ferrite-based catalyst widely known as a catalyst for the oxidative dehydrogenation of butene is generally synthesized by a co-precipitation method. It is known that ₂ O ₃ crystal structures coexist. Therefore, it was necessary to study a technique for reducing the inactive α-Fe ₂ O ₃ crystal structure during catalyst synthesis or for preparing a catalyst with excellent activity even if the inactive crystal structure exists at a certain level or more.

In addition, in the case of synthesizing the catalyst using the co-precipitation method, the production at one time is small due to technological and spatial limitations, so in order to meet the target amount, the same process must be repeated several times to prepare the catalyst, so it is difficult to improve productivity. It is preferable to synthesize the catalyst, but in this case, the content of the inactive crystal structure increases, which causes a problem in that activity or stability is deteriorated.

US 8513479 B2

The present invention relates to a method for producing a zinc ferrite catalyst capable of reducing the production of by-products such as COx when applied to the production of butadiene while using a co-precipitation method, and to a method for producing butadiene using the zinc ferrite catalyst prepared thereby.

One embodiment of the present invention comprises the steps of preparing a zinc ferrite powder using a co-precipitation method; adding a crystal control material including molybdenum oxide (MoO ₃ ) to the zinc ferrite powder; and calcining the zinc ferrite powder.

In addition, an exemplary embodiment of the present invention comprises the steps of forming a catalyst layer by filling a reactor with the zinc ferrite catalyst prepared by the above method; and inducing an oxidative dehydrogenation reaction while continuously passing a reactant containing a C4 fraction and oxygen through the catalyst layer.

The zinc ferrite catalyst prepared according to the method for producing a zinc ferrite catalyst according to an exemplary embodiment of the present specification can reduce the production of by-products such as COx when applied to the production of butadiene.

Accordingly, it is possible to obtain a higher yield of 1,3-butadiene compared to the conventional zinc ferrite catalyst used for the oxidative dehydrogenation of butenes.

1 is an XRD diagram of Experimental Example 1.
2 is a photograph showing that the molybdenum oxide of Comparative Example 4 was precipitated without being dissolved.

Hereinafter, the present specification will be described in more detail.

As used herein, the term “impurity” refers to a halogen component such as chlorine ions (Cl ⁻ ) excluding a metal component of a zinc precursor or an iron precursor, or α-Fe ₂ O ₃ phase formed in the co-precipitation process. If the “impurity” is a halogen substance such as chlorine, the presence and content can be determined by a combination method of sample combustion and titration, a combination method of sample combustion and ion chromatography, and inductively coupled plasma emission spectroscopy (ICP-AES/OES). can be calculated On the other hand, ICP-AES/OES is preferable.

In this specification, "water" may be distilled water (DI water).

In the present specification, 'yield (%)' is defined as a value obtained by dividing the number of moles of 1,3-butadiene, which is a product of the oxidative dehydrogenation reaction, by the number of moles of butene, a raw material. For example, the yield may be expressed by the following formula.

Yield (%) = [(number of moles of 1,3-butadiene produced)/(number of moles of butene supplied)] × 100

In the present specification, 'conversion (%)' refers to the rate at which a reactant is converted into a product, for example, the conversion rate of butene may be defined by the following formula.

Conversion (%) = [(number of moles of butene reacted)/(number of moles of butene supplied)] × 100

In the present specification, 'selectivity (%)' is defined as a value obtained by dividing the amount of change in butadiene (BD) by the amount of change in butene (BE). For example, selectivity can be expressed by the following formula.

Selectivity (%) = [(number of moles of 1,3-butadiene or COx produced)/(number of moles of butene reacted)] × 100

It is known that a ferritic catalyst having a spinel structure (AFe ₂ O ₄ ) has good activity as a catalyst for a process for producing 1,3-butadiene through the oxidative dehydrogenation of butene. In this case, A may be a divalent metal, specifically Cu, Ra, Ba, Sr, Ca, Cu, Be, Zn, Mg, Mn, Co or Ni.

On the other hand, in the case of a ferritic catalyst, it is known that the reactivity to 2-butene, especially trans-2-butene, is superior to that of the bismuth-molybdenum catalyst (Mo-Bi catalyst). there is. Therefore, even if the Mo-Bi catalyst is applied to the oxidative dehydrogenation of 2-butene, the same effect as in the present invention, that is, the results such as butene conversion or butadiene selectivity are not obtained.

At this time, the ZnFe ₂ O ₄ catalyst used for the oxidative dehydrogenation of butene is generally prepared by a co-precipitation method. The co-precipitation method is prepared through precipitation, stirring, aging and washing, drying, and calcination processes. The problem is that during the synthesis of a zinc ferrite catalyst using the conventional co-precipitation method, an α-Fe ₂ O ₃ phase is formed. The α-Fe ₂ O ₃ phase shows a low butadiene selectivity in the oxidative dehydrogenation of butene, whereas a high butadiene selectivity in the ZnFe ₂ O ₄ phase.

In addition, when a zinc ferrite catalyst is applied to the production of butadiene, a large amount of by-products such as COx is generated, and the present inventors have proposed a method for minimizing the α-Fe ₂ O ₃ phase or reducing the generation of COx searched for As a result, when a zinc ferrite catalyst is prepared by adding a crystal control material to the zinc ferrite powder prepared using the co-precipitation method, the α-Fe ₂ O ₃ phase is reduced, and heavy substances generated during butadiene production are removed. and it was confirmed that the hot spot in the reactor could be kept low.

One embodiment of the present invention comprises the steps of preparing a zinc ferrite powder using a co-precipitation method; adding a crystal control material including molybdenum oxide (MoO ₃ ) to the zinc ferrite powder; and calcining the zinc ferrite powder.

The method for producing a zinc ferrite catalyst according to an exemplary embodiment of the present invention includes adding a crystal control material to the prepared zinc ferrite powder, thereby allowing the crystal control material to remain in the prepared co-precipitate of the prepared zinc ferrite catalyst. α-Fe ₂ O ₃ It is possible to reduce the phase (phase), and effectively remove the heavy material when using the catalyst in the reaction process to improve the reaction yield.

In one embodiment of the present invention, the method of adding the crystal control material to the zinc ferrite powder is not particularly limited, and the crystal control material may be added to a solution containing the zinc ferrite powder.

In one embodiment of the present invention, the crystal control material is any one selected from the group consisting of Mn, V, Bi, Sb, Cr, Ce, La, Sm, Ca, Mg, Co, Sn, Al, Ba and Sr It may be an oxide of the above elements. The crystal control material is a material that can replace iron or zinc element of the zinc ferrite catalyst or can be attached to the zinc ferrite catalyst, and are elements suitable for removing heavy materials.

In an exemplary embodiment of the present invention, the crystal control material may further include an alkali metal. The alkali metal may be K, Na or Ca. In this case, the crystal control material may include a hydroxide or nitride form of an alkali metal.

In an exemplary embodiment of the present invention, the crystal control material is added to the zinc ferrite powder. In this case, the zinc ferrite powder refers to a zinc ferrite powder prepared from a catalyst precursor material, and refers to a state in which the co-precipitate is calcined.

In one embodiment of the present invention, the content of the crystal control material is 0.01 wt% or more and 1 wt% or less, 0.02 wt% or more and 0.5 wt% or less, or 0.02 wt% or more and 0.1 wt% based on the total weight of the zinc ferrite powder. may be below. When the content of the crystal control material is too small, the effect of the crystal control material is difficult to appear, and when the content of the crystal control material exceeds the above range, there is a problem in that the activity of the prepared catalyst is deteriorated.

In an exemplary embodiment of the present invention, the method for preparing the zinc ferrite catalyst includes calcining the zinc ferrite powder. In this case, the step of calcining the zinc ferrite powder is different from the step of calcining the coprecipitate to be described later because the calcination target is different. However, the firing conditions such as the firing temperature may be the same.

In an exemplary embodiment of the present invention, the preparing of zinc ferrite powder by using the co-precipitation method includes preparing an aqueous solution of a metal precursor including a zinc precursor and an iron precursor; contacting the aqueous metal precursor solution with a basic aqueous solution to obtain a co-precipitate; and calcining the co-precipitate.

The zinc precursor and the iron precursor may each independently be at least one selected from the group consisting of nitrate, ammonium salt, sulfate, and chloride. Among them, it may be preferably selected from nitrate or chloride in consideration of the cost of preparing a catalyst for mass production as it is inexpensive and readily available.

The zinc precursor may be a divalent zinc precursor, specifically zinc chloride (ZnCl ₂ ). In this case, the formation of the zinc ferrite catalyst is easy.

The iron precursor may be a trivalent iron precursor, specifically ferric chloride hydrate (FeCl ₃ ·6H ₂ O). In this case, the formation of the zinc ferrite catalyst is excellent.

The zinc precursor and the iron precursor are mixed in water to prepare an aqueous metal precursor solution, and when the metal precursor is dissolved in water and exists in a liquid phase, ion exchange between zinc and iron is easy, which makes it easy to prepare a desired co-precipitate. can

A mixing ratio (molar ratio) of the zinc precursor and the iron precursor in the aqueous metal precursor solution may be 1:1.5 to 1:10, preferably 1:1.6 to 1:5, more preferably 1:1.8 to 1:3. . In the above range, it is easy to form a crystal structure active in the oxidative dehydrogenation reaction, so that the catalyst activity is excellent.

The metal precursor aqueous solution may be an acidic solution, and a specific pH may be, for example, 0 to 4, 1 to 3, or 1 to 2, and within this range, the desired active ingredient is stably formed.

After the metal precursor aqueous solution is prepared, the metal precursor aqueous solution and the basic aqueous solution may be added to a coprecipitation tank to coprecipitate iron and zinc.

The basic aqueous solution may be one selected from the group consisting of potassium hydroxide, ammonium carbonate, ammonium hydrogen carbonate, sodium hydroxide aqueous solution, sodium carbonate aqueous solution, and aqueous ammonia, or a mixed solution thereof. Preferably, the basic aqueous solution may be aqueous ammonia. In this case, in the process of preparing a zinc ferrite catalyst synthesized by changing the precipitation sequence, precipitation is easy, thereby improving the formation of catalyst particles.

The concentration of the basic aqueous solution may be 5 wt% to 20 wt% based on the total aqueous solution in the coprecipitation tank. Preferably, it may be 5 wt% to 10 wt%.

The pH of the aqueous metal precursor solution in the step of obtaining a co-precipitate by contacting the aqueous metal precursor solution with a basic aqueous solution may be adjusted to 6 or more, preferably 6 or more and 10 or less, and more preferably 7 or more and 8 or less. In this case, the catalyst can be stably co-precipitated by preventing an excessively sudden change in pH immediately after the input due to the input of the aqueous metal precursor solution. Before adding the metal precursor aqueous solution and the basic aqueous solution to the coprecipitation tank, the pH environment of the coprecipitation tank may be adjusted by first introducing the basic aqueous solution into the coprecipitation tank.

The method for preparing the zinc ferrite catalyst includes stirring; ferment; or further comprising stirring and aging. Specifically, the stirring and aging steps may be sequentially included.

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

The step of removing impurities by adding a material for removing impurities to the coprecipitation solution may be performed before the aging step. Specifically, the method for preparing the zinc ferrite catalyst includes a stirring step and an aging step, and the step of removing impurities by adding a material for removing impurities to the co-precipitation solution may be performed between the stirring step and the aging step.

As used herein, the term “coprecipitate” may refer to a material existing in a slurry state in the coprecipitation tank.

The maximum particle diameter of the co-precipitate may be 10 μm or less, preferably 8 μm or less, more preferably 7 μm or less, and the lower limit may be 1 μm or more.

The step of obtaining a co-precipitate from the co-precipitation solution includes: filtration; dry; or filtration and drying. Through the filtration or drying process, more sufficient co-precipitation can be achieved before calcining the co-precipitate.

The drying and filtration are not particularly limited as long as each of the methods are conventionally carried out in the art, and the filtration may be, for example, reduced pressure filtration, and may further include a process of washing after filtration if necessary.

The reduced pressure filtration may be a method of filtering under reduced pressure using a vacuum pump, and in this case, there is an effect of washing and separating moisture from the catalyst.

The drying may be performed using a conventional dryer, for example, at 60 to 100 ℃, 70 to 100 ℃, or 80 to 100 ℃ to be dried for 12 to 48 hours, 14 to 30 hours, or 14 to 26 hours. can In this case, the dryer may be an oven, and the oven may be in an air or vacuum state.

Through the step of calcining the co-precipitate, it is possible to obtain a catalyst including a ZnFe ₂ O ₄ crystal structure.

The sintering may be performed by raising the temperature at 80° C. at a rate of 1° C./min and maintaining the temperature at 600° C. to 800° C. for 5 to 10 hours. In the firing, specifically, the firing may be performed at 600°C to 700°C, and more specifically, at 600°C to 650°C. The calcination may be specifically calcined for 5 hours to 8 hours, more specifically, calcination for 5 hours to 6 hours.

After the firing, it may be cooled to a temperature of 30° C. or less.

The crystal size of the ZnFe ₂ O ₄ structure of the catalyst is controlled according to the temperature range, and the crystal size tends to increase as the temperature increases. Adsorption and desorption of oxygen are very important in the dehydrogenation reaction of the present invention, and the higher the crystallinity, the less desorption is performed, so reactivity may decrease. For example, commercial ZnFe ₂ O ₄ shows very high crystallinity, but has very low activity in this reaction. For this reason, it is very important to make a catalyst with appropriate crystallinity, and it can be said that the calcination temperature is the key.

Although it is generally known that the above time range has the same tendency as temperature, the effect may be less than raising the temperature, and if the time is maintained too long, it is a factor that takes too much production time when producing several tons of catalyst in the later commercialization stage In general, in the lab, the firing time is adjusted to around 6 hours.

When out of the above temperature and time range, for example, if the temperature is too less than 600 ℃, crystal formation may be weak and structural stability may be deteriorated. Conversely, when the temperature exceeds 800° C., the crystallinity is very high, and a catalyst with low activity may be produced. In conclusion, appropriate crystallinity in consideration of feed characteristics and reaction characteristics is important, and this can be controlled by the temperature and time of the calcination of the second precipitate.

The zinc ferrite catalyst may include a ZnFe ₂ O ₄ crystal structure.

In addition, the zinc ferrite catalyst may have a ZnFe ₂ O ₄ crystal structure and a mixed phase of α-Fe ₂ O ₃ .

The presence and content ratio of the ZnFe ₂ O ₄ crystal structure and the α-Fe ₂ O ₃ crystal structure of the zinc ferrite catalyst may be calculated through the area ratio of peaks corresponding to each phase of XRD diffraction analysis.

The diffraction peaks corresponding to the ZnFe ₂ O ₄ crystal structure are (220), (311), (222), (400), (422), (511), (440) plane positions, the α-Fe ₂ O ₃ The diffraction peaks corresponding to the 2θ angles corresponding to the in-plane positions of (104), (110), (113), (024), (116) and (018) are 24.16°, 33.12°, 35.63°, 40.64°, It can be a diffraction peak that is 49.47°, 54.08° or 57.42°.

The content of the crystal structure of α-Fe ₂ O ₃ in the zinc ferrite catalyst is 12 wt%, preferably 11.8 wt%, more preferably based on the ZnFe ₂ O ₄ crystal structure and the α-Fe ₂ O ₃ crystal structure as a whole. may be 11.6 wt% or less. When the above range is satisfied, the ratio of the crystal structure of the impurity α-Fe ₂ O ₃ is reduced, thereby increasing the activity of the catalyst. On the other hand, the lower limit of the content of the crystal structure of α-Fe ₂ O ₃ is not particularly limited, but 1 wt% or more, preferably 5, based on the ZnFe ₂ O ₄ crystal structure and the α-Fe ₂ O ₃ crystal structure as a whole wt% or more, more preferably 8 wt% or more.

The above-described method for preparing the zinc ferrite catalyst may satisfy Equation 1 below. In addition, A2/A1 of Equation 1 below may be preferably 0.88 or less, more preferably 0.87 or less.

[Equation 1]

A2/A1 ≤ 0.9

In Equation 1,

A2 is the content of the crystal structure of α-Fe ₂ O ₃ based on the total of the zinc ferrite catalyst prepared by the method for producing the zinc ferrite catalyst,

The A1 is based on the total of the zinc ferrite catalyst prepared by the method for producing a zinc ferrite catalyst when it does not include the step of preparing zinc ferrite powder by using the co-precipitation method of α-Fe ₂ O ₃ Crystal structure of is the content

The above-described method for preparing the zinc ferrite catalyst may satisfy Equation 2 below. In addition, B2/B1 of Equation 2 below may be preferably 0.3 or less, more preferably 0.1 or less.

[Equation 2]

B2/B1 ≤ 0.5

In Equation 2,

Wherein B2 is the content of anions derived from the metal precursor based on the whole of the zinc ferrite catalyst prepared by the method for preparing the zinc ferrite catalyst,

B1 is the content of anions derived from the metal precursor based on the total of the zinc ferrite catalyst prepared by the method for producing a zinc ferrite catalyst when it does not include the step of preparing zinc ferrite powder using the co-precipitation method. .

Since the anion means an anion component included in the metal precursor of the iron precursor or the zinc precursor, when the metal precursor is a chloride, the anion may be chlorine (Cl ⁻ ).

The content of the anion can be measured using C-IC analysis and EDS analysis of the prepared catalyst, and in this case, HITACHI's S4800 product can be used.

The zinc ferrite catalyst prepared by the method for producing a zinc ferrite catalyst of the present invention may be used in a method for producing butadiene through the oxidative dehydrogenation of butene.

The zinc ferrite catalyst prepared according to the method for preparing the zinc ferrite catalyst described above may have a molar ratio of ferrite and zinc (ferrite/zinc (Fe/Zn ^a )) of 1 to 2.5. Preferably, it may be 2 to 2.5. More preferably, it may be 2 to 2.4. When the molar ratio of ferrite and zinc is within the above range, it helps to increase the crystal structure and activity of the zinc ferrite catalyst, and by controlling the α-Fe ₂ O ₃ phase to a certain range, the zinc ferrite phase is predominantly formed, resulting in oxidative dehydrogenation There is an excellent effect of the selectivity and yield of butadiene according to the reaction. The molar ratio of ferrite and zinc (ferrite/zinc (Fe/Zn ^a )) is measured through EDS (Energy Dispersive X-ray Spectrometer) characteristic analysis to determine how dispersed the ratio of Fe/Zn on the actual catalyst surface is. is the value

The oxidative dehydrogenation of butene according to the present invention may be referred to as a method for producing butadiene. The method for producing butadiene may include performing an oxidative dehydrogenation reaction while passing a reactant containing a C4 fraction and oxygen through a reactor filled with a zinc ferrite catalyst prepared by the above-described method.

The manufacturing method of butadiene includes the steps of forming a catalyst layer by filling a reactor with the zinc ferrite catalyst prepared by the above-mentioned manufacturing method; and inducing an oxidative dehydrogenation reaction while continuously passing a reactant including a C4 fraction and oxygen through the catalyst layer.

The C4 fraction may refer to C4 raffinate-1, 2, and 3 remaining after separating useful compounds from the C4 mixture produced by naphtha cracking, and refers to C4 that can be obtained through ethylene dimerization may be doing Specifically, the C4 fraction is n-butane, trans-2-butene, cis-2-butene, and 1-butene. ) may be one or a mixture of two or more selected from the group consisting of.

The reactant may include steam or nitrogen (N ₂ ) in addition to the C4 fraction and oxygen. The steam or nitrogen (N ₂ ) is a diluent gas that is input for the purpose of reducing the risk of explosion of the reactants, preventing coking of the catalyst, and removing the heat of reaction.

The oxygen (O ₂ ) reacts with the C4 fraction as an oxidant to cause a dehydrogenation reaction.

The oxidative dehydrogenation reaction may be carried out according to Scheme 1 or Scheme 2 below.

[Scheme 1]

C ₄ H ₈ + 1/2O ₂ → C ₄ H ₆ + H ₂ O

[Scheme 2]

C ₄ H ₁₀ + O ₂ → C ₄ H ₆ + 2H ₂ O

The oxidative dehydrogenation reaction removes hydrogen from butane or butene, thereby producing butadiene. On the other hand, in the oxidative dehydrogenation reaction, in addition to the main reaction shown in Schemes 1 or 2, side reaction products including carbon monoxide (CO) or carbon dioxide (CO ₂ ) may be produced. The side reaction product may include a process of being separated and discharged to the outside of the system so that continuous accumulation does not occur in the process.

In the method for producing butadiene, the conversion rate of butene may be 40% or more, preferably 45% or more, and more preferably 50% or more.

In the method for producing butadiene, the selectivity of butadiene may be 40% or more, preferably 45% or more, and more preferably 50% or more.

The oxidative dehydrogenation reaction may be performed at a reaction temperature of 200° C. to 600° C., a pressure condition of 0.1 bar to 10 bar, and a gas Hourly Space Velocity (GHSV) 100h ^-1 to 400h ^-1 condition.

Hereinafter, examples will be given to describe the present specification in detail. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present specification to those of ordinary skill in the art.

<Example 1>

A metal precursor aqueous solution was prepared by dissolving zinc chloride (ZnCl ₂ ) and ferric chloride (FeCl ₃ ) in pure water (DI water) in a molar ratio of 2:1.

Ammonia aqueous solution was added dropwise so that the pH of the metal precursor aqueous solution was 7, and the solution was stirred for 1 hour to co-precipitate. Thereafter, the co-precipitation solution was washed with distilled water, dried at 90° C. for 24 hours, and then heated from 80° C. to 650° C. at a temperature increase rate of 1° C./min in an air atmosphere, and maintained for 6 hours to form a spinel structure A zinc-iron oxide (ZnFe ₂ O ₄ ) powder having a was prepared.

Molybdenum oxide (MoO ₃ ) as a crystal control material was added to the zinc-iron oxide (ZnFe ₂ O ₄ ) powder at 0.03 wt% based on the total weight of the zinc-iron oxide (ZnFe ₂ O ₄ ) powder, and then pure ( DI water).

Thereafter, the temperature was raised from 80° C. to 650° C. at a temperature increase rate of 1° C./min, and then maintained for 6 hours to prepare a final zinc ferrite catalyst.

<Example 2>

A zinc-iron oxide (ZnFe ₂ O ₄ ) catalyst was prepared in the same manner as in Example 1 except that the content of the crystal control material was increased to 0.05 wt%.

<Comparative Example 1>

As a crystal control material, a zinc-iron oxide (ZnFe ₂ O ₄ ) catalyst was prepared in the same manner as in Example 1, except that 0.01 wt% of potassium nitrate was used instead of molybdenum oxide.

<Comparative Example 2>

As a crystal control material, a zinc-iron oxide (ZnFe ₂ O ₄ ) catalyst was prepared in the same manner as in Example 1, except that 0.1 wt% of potassium nitrate was used instead of molybdenum oxide.

<Comparative Example 3>

A zinc-iron oxide (ZnFe ₂ O ₄ ) catalyst was prepared in the same manner as in Example 1 except that a crystal control material was not added.

<Comparative Example 4>

As a crystal control material, molybdenum oxide (MoO ₃ ) was added to the preparation step of the aqueous metal precursor solution, but it was confirmed that the molybdenum oxide did not dissolve in the co-precipitation solution and appeared as a white precipitate ( FIG. 2 ).

<Experimental Example 1>

XRD (X-Ray Diffraction, Endeavor X-ray Diffraction) of the zinc ferrite catalysts prepared in Comparative Examples and Examples in order to compare the formation rates of ZnFe ₂ O ₄ and α-Fe ₂ O ₃ as a target phase system) was analyzed.

At this time, it was measured in the range of 20 to 80 degrees based on 2q, and a Cu target was used.

The area of the diffraction peak {(220), (311), (222), (400), (422), (511), (440) plane position} corresponding to ZnFe ₂ O ₄ and α-Fe ₂ O ₃ The in-plane positions of the corresponding diffraction peaks {(104), (110), (113), (024), (116) and (018), the 2θ angles are 24.16°, 33.12°, 35.63°, 40.64°, 49.47°, 54.08° or 57.42°} corresponds to the weight ratio of each phase.

The results of Experimental Example 1 are shown in Table 1 and FIG. 1, and it was confirmed that the ratio of the α-Fe ₂ O ₃ phase was reduced in the catalyst prepared by the preparation method according to the Example compared to the Comparative Example.

division Experimental Example 1 ZnFe ₂ O ₄ (wt%) α-Fe ₂ O ₃ (wt%) Example 1 89.5 10.5 Example 2 89.9 10.1 Comparative Example 1 89.3 10.7 Comparative Example 2 89.5 10.5 Comparative Example 3 88.7 11.3

<Experimental Example 2> Preparation of butadiene

1,3-butadiene by oxidative dehydrogenation using the zinc ferritic catalyst prepared in Examples and Comparative Examples under the conditions of 420° C., GHSV=250h ^-1 , OBR=1, SBR=1, NBR=8 After preparing the product, the product was analyzed by gas chromatography (GC) to calculate the selectivity and yield, and is shown in Table 2 below.

OBR = Oxygen/total 2-butene ratio

SBR = Steam/total 2-butene ratio

NBR = Nitrogen/total 2-butene ratio

catalyst COx
Selectivity (%) butene
Conversion rate (%) butadiene
Selectivity (%) Butadiene yield (%) Hot spot temperature (℃) Example 1 11.75 82.19 87.61 72 565 Example 2 12.23 80 86.56 69.25 530 Comparative Example 1 14.2 76.4 84.8 64.6 552 Comparative Example 2 16.8 71 82.1 58.4 565 Comparative Example 3 13.75 81.36 85.69 69.72 550 Butene conversion (%) = [(number of moles of butene reacted)/(number of moles of butene supplied)] × 100
Butadiene selectivity (%) = [(number of moles of 1,3-butadiene produced)/(number of moles of butene reacted)] × 100
Butadiene yield (%) = [(number of moles of 1,3-butadiene produced)/(number of moles of butene supplied)] × 100
COx selectivity (%) = [(number of moles of COx produced)/(number of moles of butene reacted)] × 100

From the above results, it was confirmed that the catalyst of Examples prepared by adding molybdenum oxide as a crystal control material had a small amount of COx generated when applied to the production of butadiene, compared to Comparative Examples. The above results are because molybdenum oxide, which is a crystal control material, suppressed the generation of COx.

On the other hand, it was confirmed that the catalyst of Example maintained excellent selectivity and yield of butadiene, and that the temperature of the hot spot was not maintained high.

From the above results, it was confirmed that the catalyst prepared by adding molybdenum oxide as a crystal control material maintained excellent catalytic activity when applied to butadiene production, and generated less by-products (COx).

Claims (14)

preparing zinc ferrite powder using a co-precipitation method;
adding a crystal control material including molybdenum oxide (MoO ₃ ) to the zinc ferrite powder; and
sintering the zinc ferrite powder
A method for producing a zinc ferrite catalyst. The method according to claim 1,
The crystal control material further comprises an oxide of any one or more elements selected from the group consisting of Mn, V, Bi, Sb, Cr, Ce, La, Sm, Ca, Mg, Co, Sn, Al, Ba, and Sr A method for preparing a phosphorus zinc ferrite catalyst. The method according to claim 1,
The method for producing a zinc ferrite catalyst, wherein the crystal control material further comprises an alkali metal. The method according to claim 1,
The method for producing a zinc ferrite catalyst wherein the content of the crystal control material is 0.01 wt% or more and 1 wt% or less based on the total weight of the zinc ferrite powder. The method according to claim 1,
The step of preparing zinc ferrite powder by using the co-precipitation method is
preparing an aqueous solution of a metal precursor including a zinc precursor and an iron precursor;
contacting the aqueous metal precursor solution with a basic aqueous solution to obtain a co-precipitate; and
Which comprises the step of calcining the co-precipitate
A method for producing a zinc ferrite catalyst. 6. The method of claim 5,
The zinc precursor and the iron precursor are each independently at least one selected from the group consisting of nitrate, ammonium salt, sulfate and chloride. 6. The method of claim 5,
In the step of contacting the aqueous metal precursor aqueous solution with a basic aqueous solution to obtain a co-precipitate, the pH of the metal precursor aqueous solution is maintained at 6 or higher. 6. The method of claim 5,
filtering the coprecipitate; dry; Or a method for producing a zinc ferrite catalyst comprising the steps of filtering and drying. The method according to claim 1,
The zinc ferrite catalyst is a method for producing a zinc ferrite catalyst comprising a ZnFe ₂ O ₄ crystal structure. The method according to claim 1,
The zinc ferrite catalyst has a ZnFe ₂ O ₄ crystal structure and a mixed phase of α-Fe ₂ O ₃ A method for producing a zinc ferrite catalyst. The method according to claim 1,
A method for producing a zinc ferrite catalyst that satisfies the following Equation 1:
[Equation 1]
A2/A1 ≤ 0.9
In Equation 1,
A2 is the content of the crystal structure of α-Fe ₂ O ₃ based on the total of the zinc ferrite catalyst prepared by the method for producing the zinc ferrite catalyst,
The A1 is based on the total of the zinc ferrite catalyst prepared by the method for producing a zinc ferrite catalyst when it does not include the step of preparing zinc ferrite powder by using the co-precipitation method of α-Fe ₂ O ₃ Crystal structure of is the content The method according to claim 1,
A method for producing a zinc ferrite catalyst that satisfies the following Equation 2:
[Equation 2]
B2/B1 ≤ 0.5
In Equation 2,
Wherein B2 is the content of anions derived from the metal precursor based on the whole of the zinc ferrite catalyst prepared by the method for preparing the zinc ferrite catalyst,
B1 is the content of anions derived from the metal precursor based on the total of the zinc ferrite catalyst prepared by the method for producing a zinc ferrite catalyst when it does not include the step of preparing zinc ferrite powder using the co-precipitation method. . Forming a catalyst layer by filling a reactor with a zinc ferrite catalyst prepared by the method according to any one of claims 1 to 12; and
A method for producing butadiene, comprising the step of inducing an oxidative dehydrogenation reaction while continuously passing a reactant containing C4 fraction and oxygen through the catalyst layer. 14. The method of claim 13,
The oxidative dehydrogenation reaction is a reaction temperature of 200 ° C. to 600 ° C., a pressure condition of 0.1 bar to 10 bar, and GHSV (Gas Hourly Space Velocity) 100h ^-1 to 400h ^-1 Method of producing butadiene .

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