KR20210080087A - Manufacturing method of ammoxidation catalyst for propylene, and ammoxidation methode using the same catalyst - Google Patents

Abstract

The present invention relates to a manufacturing method of an ammoxidation catalyst of propylene, and an ammoxidation method of propylene using the method, and specifically, in one embodiment of the present invention, provided is the manufacturing method of the ammoxidation catalyst of the propylene, which increases a conversion rate and selectivity by adding a certain amount of citric acid.

Description

Method for preparing ammoxidation catalyst of propylene and method for ammoxidation of propylene using same {MANUFACTURING METHOD OF AMMOXIDATION CATALYST FOR PROPYLENE, AND AMMOXIDATION METHODE USING THE SAME CATALYST

The present invention relates to a method for preparing a catalyst for ammoxidation of propylene and a method for ammoxidation of propylene using the same.

The ammoxidation process of propylene is based on the reduction reaction of ammonia and propylene and the mechanism of reoxidation by oxygen, the conversion of the reactant (ie propylene), and the selectivity of the reaction product (ie acrylonitrile) And catalysts of various compositions to increase the yield have been studied.

Specifically, since Mo (molybdenum) -Bi (bismuth) oxide catalysts have been proposed, catalysts to which metals having various oxidation states are added have been studied in order to increase their catalytic activity and stability. As a result, depending on the type or amount of added metal, the yield of acrylonitrile is improved compared to the initial study.

However, in recent years, it is difficult to expect a rapid improvement in the performance of the catalyst only by adding a new metal component or changing the composition, so the conversion rate of the reactant (ie propylene) and the selectivity of the reaction product (ie acrylonitrile) during ammoxidation of propylene There was a limit to significantly increasing the

Accordingly, in the present invention, even though the prepared catalyst has a relatively simple composition, it was intended to provide an efficient method for preparing a propylene ammoxidation catalyst in which the conversion rate of reactants and selectivity of the product are improved.

The present invention provides a method for producing a catalyst for ammoxidation of propylene by adding a certain amount of citric acid, by uniformly dispersing the catalyst raw material during the production of the catalyst for ammoxidation of propylene to increase the activity of the catalyst, It is intended to convert propylene at a high rate and to produce acrylonitrile with high selectivity and yield.

The present invention comprises the steps of preparing a precursor solution containing a molybdenum precursor, a cobalt precursor, an iron precursor, a bismuth precursor, potassium nitrate and citric acid (step 1);

spray-drying the precursor solution prepared in step 1 (step 2); and

Including; sintering the dry precursor particles in step 2 (step 3);

Containing 9 to 50 moles of the citric acid relative to 100 moles of the total metal atoms of the precursor solution,

wherein the total metal comprises molybdenum, cobalt, iron, bismuth and potassium;

A method for preparing a propylene ammoxidation catalyst is provided.

In addition, the present invention provides a method for ammoxidation of propylene, comprising the step of reacting propylene and ammonia in a reactor in the presence of the catalyst prepared by the above production method.

The above-described manufacturing method exhibits high activity by uniformly dispersing the catalyst raw material in the preparation of the propylene ammoxidation catalyst, converting propylene at a higher ratio, and producing acrylonitrile with higher selectivity and yield.

Hereinafter, the present invention will be described in detail for each step.

(Step 1)

Step 1 of the present invention is a step of preparing a precursor solution of a propylene ammoxidation catalyst, including a process of mixing a metal precursor and a process of supporting it on a carrier.

The precursor solution may include a molybdenum precursor, a cobalt precursor, an iron precursor, a bismuth precursor, and potassium nitrate as a metal precursor, and the metal molar ratio of the precursor solution may be adjusted by adjusting the content of each precursor. In addition, the precursor of the metal is not particularly limited, and an ammonium salt, nitrate, carbonate, chloride, lactate, hydroxide, organic acid salt, oxide, or mixture thereof of the metal element may be applied in combination.

Meanwhile, in one embodiment of the present invention, the precursor solution contains citric acid. Conventionally, in the development of an ammoxidation catalyst, a method of changing the type of metal or controlling the composition of the metal has been tried, but it is difficult to expect a rapid change in the performance of the catalyst. Accordingly, by using the citric acid, even if the catalyst has a relatively simple composition, dispersion stability of the slurry is increased in the manufacturing process, thereby making it possible to prepare an efficient catalyst in terms of conversion and yield.

The citric acid includes 9 to 50 moles of the citric acid relative to 100 moles of the total metal atoms of the precursor solution, and the total metal includes molybdenum, cobalt, iron, bismuth and potassium. Preferably, the citric acid is 9 to 40 moles, 10 to 35 moles, 15 to 35 moles, 15 to 30 moles, 20 to 30 moles, 25 to 30 moles, relative to 100 moles of the total metal atoms of the precursor solution; or 27 to 30 moles.

When the amount of citric acid is less than 9 moles based on 100 moles of the total metal atoms, silica sol is gelled, making it difficult to mix with the metal solution, and the dispersion stability of the slurry decreases, and the catalyst strength after calcination due to the increase in slurry viscosity is about becomes On the other hand, when citric acid exceeds 50 moles relative to 100 moles of all metal atoms, citric acid is ignited together with nitrate during the calcination process, making it difficult to control the catalyst drying temperature, and the catalyst density decreases and strength after calcination is weakened

Preferably, the propylene ammoxidation catalyst prepared through an embodiment of the present invention may be represented by the following Chemical Formula 1:

[Formula 1]

Mo ₁₂ Bi _a Fe _b A _c B _d C _e O _x

In Formula 1,

A is one or more of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

B is one or more of Li, Na, K, Rb, and Cs,

C is one or more of Cr, W, B, Al, Ca, and V,

Wherein a to e, and x is a fraction of an atom or group, a is 0.1 to 7, b is 0.1 to 10, c is 0.01 to 5, d is 0.1 to 10, e is 0 to 10, x is a numerical value determined according to the oxidation state of each element.

More preferably, the propylene ammoxidation catalyst may be represented by the following Chemical Formula 1-1:

[Formula 1-1]

Mo ₁₂ Bi _a Fe _b Co _c K _d O _x

In Formula 1-1,

a to d and x are as defined in Formula 1 above.

Preferably, the BET specific surface area of the catalyst may be 33 to 35 m ² /g, and the internal pore volume may be 0.22 to 0.27 cm ³ /g.

Preferably, step 1 of preparing the precursor solution may include the following steps:

A supported aqueous solution containing a carrier and citric acid, a first aqueous precursor solution containing a molybdenum precursor, a second aqueous precursor solution containing a cobalt precursor and an iron precursor, and a third aqueous precursor solution containing a bismuth precursor and potassium nitrate preparing (step 1-1);

preparing by mixing the first aqueous precursor solution and the supporting aqueous solution (step 1-2);

preparing by mixing the aqueous solution prepared in step 1-2 with the second aqueous precursor solution (step 1-3); and

A step of preparing by mixing the aqueous solution prepared in step 1-3 and the third aqueous precursor solution (step 1-4).

In step 1 of one embodiment of the present invention, the aqueous precursor solution is not supported on the carrier after all of the aqueous precursor solution is mixed, and as described in step 1-1 above, the first aqueous precursor solution is first loaded on the carrier, and then the second aqueous precursor solution and the third precursor are supported. The aqueous solution is mixed sequentially.

The carrier is, for example, SiO ₂ , Al ₂ O ₃ , MgO, MgCl ₂ , CaCl ₂ , ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ , SiO ₂ -Al ₂ O ₃ , SiO _It may be at least one compound selected from the group consisting of _2- MgO, SiO ₂ -TiO ₂ , SiO ₂ -V ₂ O ₅ , SiO _{2 -CrO 2} O ₃ , SiO ₂ -TiO _{2 -MgO, and zeolite, preferably} For example, it may be silica (SiO ₂ ).

(Step 2)

Step 2 of the present invention is a step of spray-drying the precursor solution prepared in step 1, and there is no particular limitation as long as the conditions are for drying to obtain spherical particles of a size suitable for a fluidized bed reaction from a metal precursor when preparing a catalyst. . On the other hand, the diameter of the catalyst particles is preferably 40 to 200 ㎛.

As a condition for obtaining a catalyst having a desirable particle size, for example, a rotary disk drying device may be used, and spray drying may be performed by maintaining the dryer inlet temperature at 200 to 230°C and the outlet temperature at 120 to 150°C. have.

(Step 3)

Step 3 of the present invention is a step of sintering the precursor particles dried in step 2, and there is no particular limitation as long as it is a condition for sintering the metal precursor during the preparation of the catalyst.

For example, as the firing method in step 3, it is preferable to use a muffle firing furnace, the firing temperature may be preferably 500 to 700° C. or 500 to 600° C., and the firing time may be 1 to 6 hours. Conditions such as calcination temperature and calcination time can be appropriately selected to obtain desired catalyst properties and reaction performance.

Method for ammoxidation of propylene

In another embodiment of the present invention, in a reactor, there is provided a method for ammoxidation of propylene, comprising the step of reacting propylene and ammonia in the presence of the catalyst prepared by the production method of the above-described embodiment.

The catalyst prepared by the preparation method of the one embodiment may be used in the ammoxidation reaction of propylene to increase the conversion rate of propylene, the selectivity and the yield of acrylonitrile.

For matters other than the catalyst prepared by the preparation method of the embodiment, reference may be made to matters generally known in the art.

Hereinafter, it will be described in more detail to help the understanding of the present invention. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

Example 1

200 g of ammonium paramolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O] was dissolved in deionized water, and 607 g of silica sol and an aqueous citric acid solution were mixed. The amount of citric acid in the aqueous solution of citric acid was 0.15 times the number of moles of all metals excluding silica, and dissolved in 115 g of deionized water. _{167 g of cobalt nitrate [Co(NO 3} ) ₂ .6H ₂ O], iron nitrate [Co(NO 3 ) 2 .6H 2 O] dissolved in 120 g of deionized water after adding a silica-citric acid mixture and an aqueous solution of ammonium paramolybdate under stirring in a reactor maintained at 75 ° C. Fe(NO ₃ ) ₃ ·9H ₂ O] 50.9 g was added to prepare solution 1. After adding 44.4 g of bismuth nitrate [Bi(NO ₃ ) ₃ ·5H ₂ O] and 0.57 g of potassium nitrate [KNO ₃ ] to deionized water, 24.85 g of 60 wt% nitric acid was added to the bismuth-potassium aqueous solution for dissolution. Dissolve to make solution 2. Solution 2 was added to solution 1 being stirred at 75° C. to make a catalyst precursor solution, and then the catalyst precursor solution was spray dried. At this time, the air temperature at the inlet of the dryer was 215°C, and the outlet temperature was 140°C. The rotation speed of the disk of the rotary spray dryer was set to 7000 rotations/minute. After drying, the resulting particles were heated to 580 °C at 5 °C/min and calcined for 3 hours.

Example 2

A catalyst was prepared in the same manner as in Example 1, except that citric acid was added 0.25 times based on the total number of moles of metal excluding silica.

Example 3

A catalyst was prepared in the same manner as in Example 1, except that citric acid was added 0.3 times based on the total number of moles of metal excluding silica.

Comparative Example 1

A catalyst was prepared in the same manner as in Example 1, except that citric acid was added 0.08 times based on the total number of moles of metal excluding silica.

Experimental Example 1: Evaluation of Catalyst Properties

The catalyst surface area and pore structure of the catalysts prepared in Examples 1 to 3 and Comparative Example 1 were confirmed through BET analysis results.

(1) BET specific surface area: Using a BET specific surface area measuring instrument (manufacturer: BEL Japan, instrument name: BELSORP-mini X), the specific surface area was evaluated from the amount of nitrogen gas adsorbed under liquid nitrogen temperature (77 K), and the Table 1 shows the evaluation results.

(2) Abrasion loss: Abrasion resistance strength of the catalyst was measured as abrasion loss according to the method described in ASTM D5757-00. The wear loss was calculated by the following equation (1).

[Equation 1]

Wear loss (%)= (m1+m5)/ms×100

In the above formula, m1 is the amount of powder collected in the collector for 1 hour (g), m5 is the amount of powder collected in the collector for 5 hours (g), and ms is the initial catalyst amount (g).

(3) Apparent specific gravity (Bulk density): The apparent specific gravity was calculated by calculating the mass/capacity by filling a 25 ml measuring cylinder with a catalyst volume of 10 ml.

surface area
(m ² /g) pore size
(nm) pore volume
(cm ³ /g) Bulk density
(g/mL) wear loss
(%) Example 1 32.8 27.1 0.226 0.8 8.0 Example 2 33.0 26.9 0.222 0.79 33.9 Example 3 34.0 29.5 0.256 0.62 39.1 Comparative Example 1 33.2 26.4 0.219 0.91 4.7

Experimental Example 2: Evaluation of Catalyst Performance in a Fixed Bed Reactor

The performances of the catalysts prepared in Examples 1 to 3 and Comparative Example 1 were evaluated. Catalyst was introduced into a reactor having an inner diameter of 6.5 mm and a height of 460 mm, and then reactants (C ₃ H ₆ , NH ₃ , Air) were injected from the top of the reactor to evaluate catalyst performance.

For the propylene ammoxidation reaction, 0.2 g of a catalyst having a size of 100 to 150 μm is used, and a mixed gas of propylene/ammonia/air is supplied at a total gas flow rate of 10 ml/min at a reaction temperature of 400° C. and atmospheric pressure to form a fixed bed reaction. carried out. At this time, the molar ratio of propylene/ammonia/air of the mixed gas was 1/1.5/10.

Propylene conversion rate
(%) Acrylonitrile Selectivity
(%) Acrylonitrile yield
(%) Example 1 48.3 73.6 35.5 Example 2 44.6 72.8 32.5 Example 3 70.2 79.7 55.9 Comparative Example 1 42.8 73.1 31.3

As shown in Table 2, when citric acid was used in a certain content range, it was confirmed that the conversion rate of propylene and the yield of acrylonitrile were excellent.

Claims (8)

preparing a precursor solution including a molybdenum precursor, a cobalt precursor, an iron precursor, a bismuth precursor, potassium nitrate and citric acid (step 1);
spray-drying the precursor solution prepared in step 1 (step 2); and
Including; sintering the dry precursor particles in step 2 (step 3);
Containing 9 to 50 moles of the citric acid relative to 100 moles of the total metal atoms of the precursor solution,
wherein the total metal comprises molybdenum, cobalt, iron, bismuth and potassium;
A method for preparing a propylene ammoxidation catalyst.
According to claim 1,
The propylene ammoxidation catalyst is represented by the following formula (1),
Method for preparing propylene ammoxidation catalyst:
[Formula 1]
Mo ₁₂ Bi _a Fe _b A _c B _d C _e O _x
In Formula 1,
A is one or more of Ni, Mn, Co, Zn, Mg, Ca, and Ba,
B is one or more of Li, Na, K, Rb, and Cs,
C is one or more of Cr, W, B, Al, Ca, and V,
Wherein a to e, and x is a fraction of an atom or atomic group, a is 0.1 to 7, b is 0.1 to 10, c is 0.01 to 5, d is 0.1 to 10, e is 0 to 10, x is a numerical value determined according to the oxidation state of each element.
3. The method of claim 2,
The propylene ammoxidation catalyst is represented by the following Chemical Formula 1-1,
Method for preparing propylene ammoxidation catalyst:
[Formula 1-1]
Mo ₁₂ Bi _a Fe _b Co _c K _d O _x
In Formula 1-1,
a to d and x are as defined in claim 2.
According to claim 1,
The BET specific surface area of the catalyst is 33 to 35 m ² /g,
The pore volume in the catalyst is 0.22 to 0.27 cm ³ /g,
A method for preparing a propylene ammoxidation catalyst.
According to claim 1,
The step of preparing the precursor solution (step 1) is
A supported aqueous solution containing a carrier and citric acid, a first aqueous precursor solution containing a molybdenum precursor, a second aqueous precursor solution containing a cobalt precursor and an iron precursor, and a third aqueous precursor solution containing a bismuth precursor and potassium nitrate preparing (step 1-1);
preparing by mixing the first aqueous precursor solution and the supporting aqueous solution (step 1-2);
preparing by mixing the aqueous solution prepared in step 1-2 with the second aqueous precursor solution (step 1-3); and
Including the step of preparing by mixing the aqueous solution prepared in step 1-3 and the third aqueous precursor solution (step 1-4),
A method for preparing a propylene ammoxidation catalyst.
6. The method of claim 5,
The carrier is silica,
A method for preparing propylene ammoxidation catalyst.
According to claim 1,
The step of calcining the dried material,
carried out within a temperature range of 500 to 700 °C,
A method for preparing a propylene ammoxidation catalyst.
In a reactor, comprising the step of reacting propylene and ammonia in the presence of the catalyst prepared by the method of claim 1,
Method for ammoxidation of propylene.