KR101309259B1 - Single crystalline catalyst of gamma-bismuth molybdate and process for preparing 1,3-butadiene using the catalyst - Google Patents

Abstract

The present invention relates to a method for producing 1,3-butadiene by oxidative dehydrogenation of gamma-bismuth molybdate single phase catalyst, a method for preparing the same, and C ₄ residue oil-III discharged from naphtha cracking using the catalyst. It is about.

Description

Single crystalline catalyst of gamma-bismuth molybdate and process for preparing 1,3-butadiene using the catalyst

The present invention relates to a method for producing 1,3-butadiene by oxidative dehydrogenation of gamma-bismuth molybdate single phase catalyst, a method for preparing the same, and C ₄ residue oil-III discharged from naphtha cracking using the catalyst. It is about.

1,3-Butadiene is a colorless, odorless, flammable gas that is a very important base oil that is a raw material for synthetic rubber. Industrial methods for obtaining 1,3-butadiene using petrochemical base oil as a raw material include a method of extracting butadiene from C ₄ oil produced by steam cracking naphtha, and dehydrogenating butane or butene. For example, there is a method of oxidative dehydrogenation of butene.

Oxide dehydrogenation of butenes is a method of dehydrogenation by reacting butene with oxygen (air) to produce water. The catalysts used in the oxidative dehydrogenation process are ferrite catalysts having a spinel structure of AB ₄ O ₄ , such as CoFe ₂ O ₄ and CuFe ₂ O _4, and Sb / Sn or Sn / P. Sn-based catalysts, and bismuth-molybdate-based catalysts based on Bi-Mo. Dual ferrite-based catalysts have the disadvantage of inducing complete oxidation, and the conversion obtained at optimum conditions is around 70% [J. Mol. Catal. A. Volume 125, 53 (1997)]. It is known that Sn-based catalysts exhibit different catalytic activities depending on the Sn content, and the conversion obtained under optimum conditions is about 55% [Petroleum Chemistry USSR Vol. 7, pp. 177 (1967)]. On the other hand, U.S. Patent No. 3,764,632 shows a bismuth-molybdate-based catalyst, although catalytic activity varies depending on the type and amount of metal added, but at least 90% butene conversion under optimum reaction conditions. It has been shown to exhibit 1,3-butadiene selectivity and is known to be the most efficient catalyst developed to date.

Bismuth-molybdate-based catalysts can be divided into pure bismuth molybdate made only of bismuth and molybdenum oxides, and multicomponent bismuth molybdate catalysts based on bismuth and molybdenum added with various metal components. Pure bismuth molybdate has several phases, including alpha-bismuth molybdate (Bi ₂ Mo ₃ O ₁₂ ), beta-bismuth molybdate (Bi ₂ Mo ₂ O ₉ ) and gamma-bismuth molybdate ( Bi ₂ MoO ₆ ) is divided into three phases [B. Grzybowska, J. Haber, J. Komorek, J. Catal., 25, 25 (1972)]. Among them, beta and gamma phases are known to be more effective catalysts for oxidative dehydrogenation of normal-butene than bismuth molybdate of alpha phase [APV Soares, LK Kimitrov, MCA Oliveira, L. Hilaire, MF Portela, RK Grasselli , Appl. Catal., Vol. 253, 191 (2003)].

In addition, as a method for increasing the activity of oxidative dehydrogenation of normal-butene, multi-component bismuth molybdate catalysts in which various metal components are added in addition to bismuth and molybdate have been reported. Specifically, it was reported that oxidative dehydrogenation of 1-butene was carried out at 520 ° C. using a complex oxide catalyst consisting of nickel, cesium, bismuth, and molybdenum to obtain 69% 1,3-butadiene yield [J. Catal., 32, 25 (1974)]. U.S. Patent No. 3,998,867 (1976) discloses an oxidative dehydrogenation reaction of a C ₄ mixture containing normal-butane and normal-butene at 470 ° C. using a complex oxide catalyst consisting of cobalt, iron, bismuth, magnesium, potassium, and molybdenum. It was reported that 1,3-butadiene yield of up to 62% was obtained by performing the following. US Patent No. 3,764,632 (1973) discloses 1-butene oxidative dehydrogenation at 320 ° C. using a complex oxide catalyst consisting of nickel, cobalt, iron, bismuth, phosphorus, potassium, and molybdenum to yield up to 96% It was reported that 1,3-butadiene yield was obtained.

Using the multicomponent bismuth molybdate catalysts described in the literature, very high yields of 1,3-butadiene can be obtained. However, these catalysts have a very complicated synthesis process, and various metal precursors are used to prepare the catalyst. It is difficult to maintain uniformity due to difficulty in mixing between metals, and it is difficult to commercialize catalyst production because it is not easy to secure reproducibility of catalyst production.

As described above, methods for producing 1,3-butadiene from butenes with high efficiency are well known.However, a method for preparing 1,3-butadiene from C ₄ residue oil-III produced in naphtha cracking process has only recently been published. have.

According to Applide Catalysis A: General 317, 244 (2007), the C ₄ mixture was reacted at 440 ° C on a gamma-Bi ₂ MoO ₆ catalyst, resulting in a conversion of normal-butene up to 66% and selectivity of 1,3-butadiene. Is reported to be 60%. Korean Patent Laid-Open Publication No. 2007-0103219 discloses a method for preparing 1,3-butadiene from a C ₄ mixture comprising normal-butane and normal-butene, wherein alpha-bismuth molybdate (Bi ₂ Mo ₃ O ₁₂ ) And gamma-bismuly molybdate (Bi ₂ MoO ₆ ) using a mixed bismuth-molybdate catalyst yielded about 60% 1,3-butadiene yield from normal-butene with no inactivation for 48 hours Yin was presented.

In general, single phase pure bismuth molybdate catalysts are prepared by coprecipitation, which is a traditional catalyst preparation. When bismuth molybdate single phase catalysts are prepared by coprecipitation, the catalyst components are not easily mixed uniformly, pH control must be precisely formed to form a precipitate, and the loss of metal during the filtration of the catalyst after precipitation This may cause a problem of poor reproducibility of catalyst production. In addition, the bismuth molybdate single phase catalyst prepared by the coprecipitation method has a disadvantage that the specific surface area is so low that the number of active sites on the surface of the catalyst is small, resulting in poor economic efficiency in the process of producing 1,3-butadiene from the C ₄ mixture. .

As described above, the literature or patents relating to the catalytic process for producing 1,3-butadiene from normal-butene with high efficiency and the catalytic process for producing 1,3-butadiene from C ₄ residue oil-III produced in naphtha cracking process are described. It is a common technique to prepare pure bismuth molybdate or very complex multicomponent bismuth molybdate by coprecipitation method.

However, the present invention proposes a new method for preparing a single-phase gamma-bismuth molybdate catalyst consisting of bismuth and molybdenum by the sol-gel method, and in particular, incorporating citric acid in the sol-gel reaction to ensure reproducibility of catalyst production. Of course, by increasing the pore volume, pore size, and specific surface area of the prepared catalyst, experiments confirmed that high catalytic activity can be obtained in oxidative dehydrogenation of C ₄ residue-III.

It is an object of the present invention to provide a gamma-bismuth molybdate single phase catalyst having controlled pore volume, pore size and specific surface area.

An object of the present invention is to provide a method for preparing a gamma-bismuth molybdate single phase catalyst by a sol-gel production process using citric acid.

An object of the present invention is to provide a method for producing 1,3-butadiene from C ₄ residue oil-III using the gamma-bismuth molybdate single phase catalyst described above.

In order to solve the above problems, the present invention has a specific surface area of 5 to 30 m 2 / g, an average pore volume of 0.05 to 0.1 cm 3 / g, and an average pore diameter of 200 to 500 kPa. It features a date single phase catalyst.

In addition, the present invention is a) molybdenum precursor aqueous solution, bismuth precursor aqueous solution and citric acid aqueous solution so that the atomic ratio of bismuth (Bi) / molybdenum (Mo) is in the range of 1 to 3, and the molar ratio of citric acid / bismuth is in the range of 0.1 to 5. Each manufacturing process; b) preparing a mixed solution in which the molybdenum precursor aqueous solution and the citric acid aqueous solution are mixed; c) adding the bismuth precursor aqueous solution while stirring the mixed solution, adding nitric acid aqueous solution to finally adjust the pH of the solution to a range of 0.1 to 3 to prepare a transparent sol (Sol) solution; d) aging the solution in the form of a sol to obtain a mixture in the form of a gel; And e) drying and firing the mixture in gel form. Characterized by a method for producing a gamma-bismuth molybdate single-phase catalyst for oxidative dehydrogenation reaction for the production of 1,3-butadiene comprising a.

In addition, the present invention is characterized in that the method for producing 1,3-butadiene by oxidative dehydrogenation of C ₄ residue oil-III discharged from the naphtha cracking process in the presence of the gamma-bismuth molybdate single-phase catalyst described above. do.

Unlike complex multicomponent metal oxides, the gamma-bismuth molybdate single phase catalyst of the present invention has a simple constituent and is easy to synthesize, which is advantageous to secure reproducibility of the catalyst production, and reacts to oxidative dehydrogenation of C ₄ residue-III. It has a useful effect as a catalyst.

Gamma-bismuth molybdate single phase catalyst of the present invention is prepared by the sol-gel method, including citric acid during the sol-gel process to increase the uniformity of the catalyst to increase the reproducibility of the catalyst production and easy mass production of the catalyst There is.

Gamma-bismuth molybdate single phase catalyst of the present invention has the effect of increasing the specific surface area, pore volume and pore diameter of the catalyst compared to the catalyst prepared by the conventional coprecipitation method to increase the catalytic activity.

The gamma bismuth molybdate single phase catalyst of the present invention exhibits high catalytic activity in the reaction of converting C ₄ residue oil-III to 1,3-butadiene by oxidative dehydrogenation reaction, thereby inexpensive C ₄ residue oil- It is very effective in terms of achieving high value added to III.

In addition, the present invention is an invention to obtain industrially useful 1,3-butadiene by recycling C ₄ residue oil-III burned away as waste fuel, it is effective to prevent environmental pollution.

1 is a schematic diagram of a process for preparing a gamma-bismuth molybdate single phase catalyst by the sol-gel method according to the present invention.
2 is a schematic diagram of a process for preparing gamma-bismuth molybdate single phase catalyst by a conventional coprecipitation method.
Figure 3 is a graph comparing the results of X-ray diffraction analysis of the gamma-bismuth molybdate single phase catalyst prepared by the sol-gel method or a conventional coprecipitation method according to the present invention.

The present invention provides a high yield of 1,3-butadiene by using a gamma-bismuth molybdate single phase catalyst and a method for preparing the catalyst, and the oxidative dehydrogenation of C4 residue oil-III discharged from the naphtha cracking process. It is characterized by a method of manufacturing.

Particularly, in the present invention, citric acid is used in the sol-gel process for preparing the catalyst, and the citric acid prevents disproportionation occurring in the process of mixing the active metals, thereby improving the uniformity of the catalyst and thus improving the reproducibility of the catalyst production. This is a breakthrough result when compared to a catalyst prepared by a general coprecipitation method. In addition, citric acid is burned during the firing process as an organic material to generate additional pores in the catalyst. As the pore is generated due to the combustion of citric acid, the specific surface area of the catalyst is remarkably increased, and it is possible to control the diameter and volume of the pore and the catalyst specific surface area by controlling the amount of citric acid used. Increasing the specific surface of the catalyst increases the number of catalytically active sites, allowing the reactant normal-butene to adsorb more, and the wider surface facilitates the transfer of lattice oxygen participating in the reaction. As a result, compared with the catalyst prepared by the coprecipitation method, which is well known as a method for preparing a gamma-bismuth molybdate single phase catalyst, the conversion rate of the normal-butene was shown to be higher in the oxidative dehydrogenation reaction of the normal-butene. The selectivity of 1,3-butadiene is increased.

The method for preparing the gamma-bismuth molybdate single phase catalyst of the present invention having the advanced characteristics as described above will be described in detail according to the preparation process.

First, in the process a), bismuth precursor aqueous solution, molybdenum precursor aqueous solution, and citric acid aqueous solution are prepared, respectively.

The bismuth precursor and the molybdenum precursor are metal salts generally used in the field of catalyst production, and may be appropriately selected from nitrate, acetate, sulfate, ammonium, chloride, oxide, and the like. Although the bismuth nitrate is used as the bismuth precursor and ammonium molybdate as the molybdenum precursor in the embodiment of the present invention, the present invention does not particularly limit the selection of such precursor compounds. Citric acid monohydrate can be used typically as a citric acid compound, and this invention does not have a restriction | limiting in particular about selection of a citric acid compound. In the preparation of the aqueous solution, in order to improve the solubility, the temperature of the distilled water may be raised to 30 ° C. to 90 ° C., preferably 40 ° C. to 60 ° C., or, if necessary, to nitric acid in a range of 0.01 to 5 wt%. Solution may also be added.

The use ratio of the bismuth precursor, molybdenum precursor and the citric acid compound can be controlled in various ways, but in order to meet the purpose of the catalyst production of the present invention, and to improve the catalytic activity, the ratio of bismuth / molybdenum and citric acid / bismuth The molar ratio is preferably limited to a specific range. In the present invention, in preparing a bismuth precursor aqueous solution and molybdenum precursor aqueous solution ratio in step a), the bismuth / molybdenum atomic ratio is adjusted to a range of 1 to 3, preferably 1.5 to 2.2, particularly preferably 2 To form a daily routine. In preparing the citric acid aqueous solution, the specific surface area, pore volume and pore diameter of the catalyst are adjusted by adjusting the molar ratio of citric acid / bismuth to 0.5 to 30, preferably 1 to 10, particularly preferably 1 to 3 Adjusted.

In the process b), the molybdenum precursor aqueous solution prepared above and the aqueous citric acid solution are mixed first to prepare a mixed solution.

Since the precipitation may occur in the process b), it is recommended to proceed by slowly dropping the molybdenum precursor aqueous solution to the citric acid aqueous solution, and adding a nitric acid solution in the mixing process to prevent the precipitation from forming a transparent sol solution. It is also possible to manufacture. When the sol form solution is finally adjusted to a pH range of 0.1 to 3, preferably 0.5 to 2, a clear sol solution can be obtained. When mixing is complete, the mixture is sufficiently stirred for 1 to 6 hours, preferably 2 to 4 hours.

In the step c), a bismuth precursor aqueous solution is added to the mixed solution to prepare a transparent sol (Sol) solution.

Since cation may occur in the process c), it is preferable to proceed slowly by dropwise addition of bismuth precursor aqueous solution, and nitric acid solution is added in a mixing process to prevent precipitation, thereby preparing a transparent sol (Sol) solution. When the sol form solution is finally adjusted to a pH range of 0.1 to 3, preferably 0.5 to 2, a clear sol solution can be obtained. When mixing is complete, the mixture is sufficiently stirred for 1 to 6 hours, preferably 2 to 4 hours.

In the step d), a solution in the form of a sol form is prepared by aging to prepare a mixture in the form of a gel.

When the sol-type solution prepared above is stored without stirring, it is stored at a temperature of 40 ° C. to 120 ° C., preferably 60 ° C. to 80 ° C., for 12 to 60 hours, preferably 24 to 48 hours, A mixture of forms can be obtained.

In the e) process, the mixture of the gel form is dried and calcined to prepare a gamma-bismuth molybdate single phase catalyst.

The gel-form mixture prepared above is dried at 80 ° C. to 250 ° C., preferably at 110 ° C. to 150 ° C. for 10 to 24 hours. Then, the dried solid component is placed in an electric furnace and calcined at 200 ° C to 700 ° C, preferably 350 ° C to 550 ° C, thereby obtaining a gamma bismuth molybdate single phase catalyst according to the present invention.

The gamma-bismuth molybdate single phase catalyst prepared by the sol-gel method as described above has a specific surface area of 5 to 30 m 2 / g, an average pore volume of 0.05 to 0.1 cm 3 / g, and an average pore diameter of 200 to 500 kPa. to be. This is a markedly improved result when compared to a catalyst prepared by conventional coprecipitation.

On the other hand, the present invention is also characterized by a method for producing 1,3-butadiene by carrying out the oxidative dehydrogenation of C ₄ residue-III using the gamma-bismuth molybdate single-phase catalyst.

C ₄ residue oil-III, which is used as a raw material in the production method of 1,3-butadiene according to the present invention, is a by-product in the steam cracking process of naphtha and is mainly used as a fuel. Looking at the constituents of C ₄ residue-III, n-butene accounts for 40% by weight or more, about 40% by weight of butanes including isobutane and the remainder of isobutene and other impurities (e.g. C ₅ Hydrocarbon, methyl tertiary butyl ether, dimethyl ether, ethylene). That is, the general composition of C ₄ residue oil-III consists of 40 to 65 wt% of n-butene, 30 to 50 wt% of butanes, 0 to 10 wt% of isobutene and 0.5 to 5 wt% of other impurities.

Hereinafter, the method for preparing 1,3-butadiene according to the present invention will be described in more detail with reference to the reaction conditions.

The reaction temperature of the oxidative dehydrogenation reaction of C ₄ residue-III is maintained in the range of 250 ° C. to 550 ° C., preferably in the range of 350 ° C. to 450 ° C. Here, as for a reason why only the reaction temperature in the above range to optimize the activity of the catalyst, the conversion of emergency reaction temperature is C ₄ residue due to an increase in the increase of unreacted by-product naejineun fall outside of the above range and -Ⅲ This is because it causes a big problem in the selectivity of 1,3-butadiene. In addition, since the reaction pressure is 0 to 10 atm, if it is out of the range, there is a problem that the selectivity of 1,3-butadiene decreases rapidly, which is not preferable. In the oxidative dehydrogenation reaction, the volume ratio of the reactants is C ₄ residue oil-III / air / steam = 1/1 1-20 / 1-30. The reason for limiting the range is the degree of reaction progress and selectivity. Because there is a big change. Finally, the oxidative dehydrogenation reaction is carried out with a contact time of 0.01 to 100 seconds (sec), as described above, because it significantly affects the degree of reaction progress and the selectivity change.

As described above, the gamma-bismuth molybdate single phase catalyst of the present invention significantly increased the catalytic activity compared to the catalyst prepared by the co-precipitation method, and was increased by the oxidative dehydration reaction of C ₄ residue-III. Yield 1,3-butadiene can be obtained, and the effect of reducing the amount of carbon dioxide generated as a by-product can be obtained.

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

[Example]

Example 1 Preparation of Gamma-bismuth Molybdate Single Phase Catalysts (Citrate / Bismuth Molar Ratio = 0.5)

2.89 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O) was sufficiently stirred to dissolve well in 60 ml of distilled water at 60 ° C. In the same manner, 15.91 g of bismuth nitrate pentahydrate (Bi (NO ₃ ) ₃ .5H ₂ O) was added to 20 ml of 10% HNO ₃ and dissolved with stirring. In addition, the aqueous citric acid solution was prepared by stirring 3.45 g of citric acid monohydrate into 35 ml of distilled water. The citric acid of the prepared citric acid aqueous solution was 0.5 molar ratio with respect to bismuth (citric acid / bismuth molar ratio = 0.5). It was confirmed that all prepared solutions were completely dissolved.

Then, an aqueous citric acid solution was added to the aqueous ammonium molybdate solution and sufficiently stirred to prepare a mixed solution. The bismuth nitrate aqueous solution prepared in advance was slowly added to the mixed solution, and a separate nitric acid solution was added to keep the solution in sol form and no precipitation was formed during the addition of the bismuth precursor solution. After all the solutions were added the pH was finally set to 1 using nitric acid solution. And it was stirred for 2 hours at 60 ℃ using a hot plate.

The reaction solution was completely stopped stirring and aged for 48 hours at a temperature of 80 ℃ to obtain a mixture in the form of a gel. The resulting mixture was dried in an oven at 140 ° C. and calcined at 475 ° C. to prepare the desired gamma-bismuly molybdate single phase catalyst.

A schematic diagram of a process for preparing a gamma-bismuth molybdate single phase catalyst according to Example 1 is shown in FIG. 1.

Example 2. Preparation of Gamma-bismuth molybdate single phase catalyst (citric acid / bismuth molar ratio = 1.0)

A gamma-bismuth molybdate single phase catalyst was prepared by the sol-gel method illustrated in Example 1, except that 6.89 g of citric acid monohydrate was dissolved in 70 ml of distilled water to prepare an aqueous citric acid solution (citric acid / bismuth molar ratio = 1.0). Used.

Example 3. Preparation of Gamma-bismuth molybdate single phase catalyst (citric acid / bismuth molar ratio = 2.0)

A gamma-bismuth molybdate single phase catalyst was prepared by the sol-gel method illustrated in Example 1, except that 13.78 g of citric acid monohydrate was dissolved in 140 ml of distilled water to prepare an aqueous citric acid solution (citric acid / bismuth molar ratio = 2.0). Used.

Example 4 Preparation of Gamma-bismuth Molybdate Single Phase Catalysts (Citrate / Bismuth Molar Ratio = 3.0)

A gamma-bismuth molybdate single phase catalyst was prepared by the sol-gel method illustrated in Example 1, except that 20.67 g of citric acid monohydrate was dissolved in 210 ml of distilled water to prepare an aqueous citric acid solution (citric acid / bismuth molar ratio = 3.0). Used.

Comparative Example 1. Preparation of gamma-bismuth molybdate single phase catalyst by coprecipitation

Gamma-bismuth molybdate single phase catalysts were prepared using coprecipitation methods widely used in the art.

2.89 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O) was sufficiently stirred to dissolve well in 60 ml of distilled water at 60 ° C. In the same manner, 15.91 g of bismuth nitrate pentahydrate (Bi (NO ₃ ) ₃ .5H ₂ O) was added to 20 ml of 10% HNO ₃ and dissolved with stirring. Bismuth nitrate aqueous solution was slowly added dropwise to the ammonium molybdate solution. The pH was adjusted to 3 while dropwise adding ammonia water for pH adjustment. This mixed solution was stirred at room temperature for 1 hour using a stirrer. After stopping the stirring, the precipitated solution was obtained using a vacuum filter to obtain a solid sample. The solid sample was dried in an oven at 140 ° C. and calcined at 475 ° C. to prepare a gamma-bismuth molybdate single phase catalyst.

A schematic diagram of a process for preparing a gamma-bismuth molybdate single phase catalyst according to Comparative Example 1 is shown in FIG. 2.

[Chemical Property Check]

1. Structural Analysis of Catalysts

1) Elemental Analysis (ICP-AES) and Surface Area (BET) Analysis

Table 1 shows the results of elemental analysis (ICP-AES) and surface area (BET) analysis of the gamma-bismuth molybdate single phase catalyst prepared in Example 2 and Comparative Example 1.

catalyst Bi / Mo atomic ratio (ICP-AES) Surface area (m ² / g) Bi ₂ MoO ₆ -sol gel method (Example 2) 1.9 8.0 Bi ₂ MoO ₆ -Coprecipitation Method (Comparative Example 1) 1.8 2.0

Table 1 shows the Bi / Mo atomic number ratio and the surface area (BET) obtained by the elemental component analysis (ICP-AES) of the catalysts prepared in Example 2 and Comparative Example 1. As a result of elemental analysis (ICP-AES), it was confirmed that both catalysts consisted of a desired phase in the metal content ratio, and both catalysts were bismuth molybdate catalysts having a gamma phase. In addition, it was confirmed through BET analysis that the catalyst prepared by the sol-gel method including citric acid has a large specific surface area increased by four times compared to the catalyst prepared by the coprecipitation method. From these results, it was found that the sol-gel method including citric acid in the preparation of the gamma-bismuth molybdate single phase catalyst was a method for preparing a catalyst having a much wider specific surface area than the coprecipitation method. The catalytic activity point is increased by the specific surface area, which is a very effective catalyst showing excellent activity in the oxidative dehydrogenation reaction.

2) pore volume and pore diameter analysis

Nitrogen adsorption and desorption experiments (N ₂ Ads./Des.) And scanning electron microscopy of pore volume and average pore diameter for the gamma-bismuth molybdate single phase catalyst prepared in Examples 1 to 4 and Comparative Example 1 SEM) results are shown in Table 2 below.

division catalyst Catalyst Preparation Citric Acid /
Bismuth molar Pore volume (cm 3 / g) Pore diameter Example 1 Bi ₂ MoO ₆ Sol-gel method 0.5 0.02 120 Example 2 Bi ₂ MoO ₆ Sol-gel method One 0.08 250 Example 3 Bi ₂ MoO ₆ Sol-gel method 2 0.09 320 Example 4 Bi ₂ MoO ₆ Sol-gel method 3 0.05 200 Comparative Example 1 Bi ₂ MoO ₆ Coprecipitation method - 0.01 95

3) X-ray diffraction analysis

X-ray diffraction analysis results of the gamma-bismuth molybdate single phase catalyst prepared in Example 2 and Comparative Example 1 are shown in FIG. 3.

According to FIG. 3, the two catalysts showed almost identical analysis results, and it was found that the bismuth molybdate single phase having a gamma phase reported in the literature.

2. Catalytic Activity Evaluation

1,3-butadiene was prepared by oxidative dehydrogenation of C ₄ residue oil-III using the respective solid catalysts prepared in Examples 1 to 4 and Comparative Example 1.

C ₄ residue oil-III used in the present experimental example is discharged from the naphtha cracking process, the composition of n-butene 58% by weight, butanes 40% by weight, isobutene 0.1% by weight and other impurities (C ₅ or more hydrocarbons) , Methyl tertiary butyl ether, dimethyl ether, ethylene).

The oxidative dehydrogenation reaction was carried out with a reaction temperature of 420 ° C., a reaction pressure of 1 atmosphere, a volume ratio of C ₄ residue oil-III / air / steam = 1/2 / 7.5, and a contact time of 5 seconds (sec).

The conversion of n-butene and the yield of 1,3-butadiene were calculated by the following equations (1) and (2) as a reaction result under each solid catalyst. In addition, carbon dioxide, furan and other substances were generated as reaction byproducts. The results are shown in Table 3 below.

division catalyst Catalyst Preparation Citric acid / bismuth molar ratio % conversion of n-butene Selectivity of 1,3-butadiene (%) 1,3-butadiene yield (%) Example 1 Bi ₂ MoO ₆ Sol-gel method 0.5 40.0 94.7 38.0 Example 2 Bi ₂ MoO ₆ Sol-gel method One 71.1 95.0 67.5 Example 3 Bi ₂ MoO ₆ Sol-gel method 2 63.7 94.0 59.8 Example 4 Bi ₂ MoO ₆ Sol-gel method 3 60.8 95.9 58.3 Comparative Example 1 Bi ₂ MoO ₆ Coprecipitation method - 52.1 90.5 47.1

According to the above results, the catalysts of Examples 1 to 4 according to the present invention are bismuth molybdate catalysts prepared by the sol-gel method using citric acid, and in particular, are prepared by adjusting the molar ratio of citric acid / bismuth to 1 to 3 range. Compared to the catalyst prepared by the conventional coprecipitation method, the conversion of n-butene and the selectivity of 1,3-butadiene are simultaneously improved in oxidative dehydrogenation of C ₄ residue oil-III. This effect is obtained as a result of catalyst structure change such as pore volume, pore diameter, specific surface area, etc. of the catalyst by citric acid.

Accordingly, the gamma-bismuth molybdate single phase catalyst prepared by the production method characterized by the present invention is useful as a catalyst in the process for producing 1,3-butadiene by oxidative dehydrogenation of C ₄ residue oil-III. .

Claims (10)

delete delete delete delete delete delete 1,3-butadiene was prepared by oxidative dehydrogenation of C ₄ residue oil-III discharged from the naphtha cracking process in the presence of a gamma-bismuth molybdate single phase catalyst prepared by carrying out the steps a) to e). Method for producing 1,3-butadiene, characterized in that:
a) a process of preparing an aqueous molybdenum precursor solution, an aqueous bismuth precursor solution and an aqueous citric acid solution such that the atomic ratio of bismuth (Bi) / molybdenum (Mo) is in the range of 1 to 3 and the molar ratio of citric acid / bismuth is in the range of 0.1 to 5;
b) preparing a mixed solution in which the molybdenum precursor aqueous solution and the citric acid aqueous solution are mixed;
c) adding the bismuth precursor aqueous solution while stirring the mixed solution, adding nitric acid aqueous solution to finally adjust the pH of the solution to a range of 0.1 to 3 to prepare a transparent sol (Sol) solution,
d) aging the solution in the form of a sol (Sol) at a temperature of 40 ℃ to 120 ℃ for 12 to 60 hours to obtain a gel (gel) mixture, and
e) The gel-like mixture is dried at a temperature of 80 ° C to 250 ° C, calcined at a temperature of 200 ° C to 700 ° C, and has a specific surface area of 5 to 30 m 2 / g and an average pore volume of 0.05 to 0.1 cm 3. / g and a process for producing a gamma-bismuth molybdate single phase catalyst having an average pore diameter of 200 to 500 microns.
The method of claim 7,
In the oxidative dehydrogenation reaction, the reaction temperature is 250 ° C to 550 ° C, the reaction pressure is 0 to 10 atm, and the volume ratio of the reactants is C ₄ residue-III / air / steam = 1/1 to 20 to 1 to 30. And And a method for producing 1,3-butadiene, characterized in that carried out under the condition that the contact time is 0.01 to 100 seconds (sec). delete delete

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