KR20170075638A - Preparing method of catalyst for dehydration of glycerin, and preparing method of acrolein - Google Patents

Abstract

The present invention relates to a process for preparing a catalyst for dehydration of glycerol, a catalyst for the dehydration reaction of glycerol and a process for preparing acrolein by the process, and the production of acrolein can be improved by minimizing the production of byproducts In addition, since it has sufficient mechanical strength, it is possible to produce a catalyst for dehydration reaction of glycerol which can be applied in actual process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for dehydration reaction of glycerin and a method for producing acrolein,

The present invention relates to a process for producing a catalyst for dehydration of glycerol, a catalyst for dehydration of glycerol and a process for preparing acrolein, and more particularly, to a process for producing acrolein by minimizing the production of by- The present invention also relates to a process for producing a catalyst for dehydration reaction of glycerol, which has an adequate mechanical strength and can be applied to an actual process.

Acrolein is a simple unsaturated aldehyde compound, has high reactivity, including incomplete reactors, and is used as a key intermediate for the synthesis of various compounds. In particular, acrolein has been widely used as an intermediate for the synthesis of acrylic acid, acrylic esters, superabsorbent resins, animal feed supplements, or food supplements.

These acrolein were prepared from propylene synthesized mainly from petroleum process through atmospheric oxygen and selective gas phase oxidation reaction. However, as environmental problems such as the reduction of fossil fuels and the greenhouse effect have been increasing, many studies have been conducted on the synthesis of acrolein using renewable raw materials that are not based on fossil fuels.

Accordingly, glycerin, which can be obtained as a by-product of the step of synthesizing biodiesel as a natural product, has attracted much attention as a raw material for producing acrolein. In particular, the market size of glycerin is increasing with the production of biodiesel, and due to the decrease in the price of glycerin, a method of industrial application thereof has been studied.

As an example, it is known to obtain glycerine in the form of a mixture of acrolein and acrylic acid by dehydration in the presence of a catalyst. The dehydration reaction of the glycerin proceeds in a gas phase oxidation reaction in the presence of a catalyst, and the use of a catalyst is essential.

However, previous catalysts used to prepare acrolein have been found to produce byproducts such as hydroxpropane, propanaldehyde, acetaldehyde, acetone, polycondensation product of glycerin, and cyclic glycerin ether to produce high purity acrolein There has been a limit to use, and there is a limit to generate phenol or polyaromatic compound as a by-product to form a coke on the catalyst, thereby causing inactivation of the catalyst.

In addition, the previously used catalysts have a low mechanical strength and thus have limited application to practical processes such as generating internal pressure during the reaction experiment.

Therefore, the development of a catalytic system which can be applied in actual process can be achieved by minimizing the formation of by-products causing the above problems, improving the selectivity of acrolein, improving the conversion of glycerin and reaction yield, Is required.

The present invention is to provide a catalyst for glycerin dehydration reaction which can minimize the production of byproducts to improve the selectivity of acrolein and has a sufficient mechanical strength so that it can be applied in actual processes.

The present invention also provides a catalyst for dehydration reaction of glycerin prepared according to the above process.

The present invention also relates to a method for producing acrolein using the catalyst for dehydration reaction of glycerin.

The present invention relates to a composite metal oxide comprising zirconium (Zr), tungsten (W) and phosphorus (P)

5 to 20% by weight of at least one inorganic metal sol selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol; And a residual amount of at least one alcohol selected from the group consisting of glycerin, isopropyl alcohol, diacetone alcohol, methanol, ethanol and propanol; And

And extruding the mixture. The present invention also provides a method for preparing a catalyst for dehydration reaction of glycerin.

The present invention also provides a catalyst for dehydration reaction of glycerin prepared according to the process for preparing a catalyst for dehydration reaction of glycerol.

The present invention also provides a process for producing acrolein comprising the step of reacting glycerin in the presence of the catalyst for dehydration of glycerol.

Hereinafter, a method for preparing a catalyst for dehydration reaction of glycerol, a catalyst for dehydration reaction of glycerol, and a method for producing acrolein according to a specific embodiment of the present invention will be described in detail.

As used herein, the term " glycerin dehydration reaction "means a whole process in which water is separated in the molecule of glycerin or between molecules of glycerin.

According to an embodiment of the present invention, there is provided a process for producing a composite metal oxide, which comprises reacting a composite metal oxide containing zirconium (Zr), tungsten (W) and phosphorus (P) with at least one inorganic metal sol selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol 5 to 20% by weight; And a residual amount of at least one alcohol selected from the group consisting of glycerin, isopropyl alcohol, diacetone alcohol, methanol, ethanol and propanol; And a step of extruding the mixture. A method for producing a catalyst for dehydration reaction of glycerin can be provided.

The present inventors have found that the prior catalysts used for producing acrolein have a limited ability to be used in a process for synthesizing acrolein of high purity by producing a large amount of byproducts and have a low mechanical strength, The present inventors have recognized that it is difficult to apply the present invention and that the selectivity of acrolein can be improved by minimizing the formation of byproducts and a method of preparing a catalyst having sufficient mechanical strength has been studied. As a result, it has been found that a catalyst for a glycerin dehydration reaction prepared by mixing a composite metal oxide containing zirconium (Zr), tungsten (W) and phosphorus (P) with a coagulant of a specific composition, And it was confirmed through experiments that acrolein was produced at a high yield and a high conversion rate when it was used in a glycerin dehydration reaction, and completed the invention.

In particular, the catalyst for the dehydration reaction of glycerin can significantly reduce the production of byproducts compared to the conventional catalyst for the dehydration of glycerol or the catalyst for acrolein such as zeolite, sulfate and phosphate, thereby increasing the yield of acrolein.

In addition, since the conventional catalysts have low mechanical strength, they cause various problems such as generation of internal pressure when they are applied to an actual process. However, according to the method for preparing a catalyst for dehydration reaction of glycerin, inorganic metal sols and alcohols And a catalyst having sufficient mechanical strength can be produced by extrusion.

The composite metal oxide used in the method for preparing a catalyst for dehydration reaction of glycerol includes zirconium (Zr), tungsten (W), and phosphorus (P). In the composite metal oxide, each of the components is strongly bonded to each other to serve as an acid site to receive a proton or a non-covalent electron pair. Thus, acrolein can be produced by dehydration reaction of glycerin with higher selectivity, conversion and yield.

Particularly, the composite metal oxide essentially contains zirconium (Zr), and zirconium forms zirconium phosphate together with phosphorus to prevent the phosphorus component from disappearing in the course of the reaction. Thus, the conventional metal oxide does not contain zirconium The catalyst activity is higher than that of the conventional catalyst, and stable catalytic activity can be shown for a long time.

In addition, in the composite metal oxide, phosphorus binds to oxygen and binds in an oxide form of phosphoric acid (PO ₄ ) to increase acid sites such as Bronsted acid sites or Lewis acid sites, thereby more efficiently carrying out dehydration reaction of glycerin .

The composite metal oxide may further include at least one transition metal selected from the group consisting of Zn, V, Fe, Mo, Ce and Cu in addition to zirconium (Zr), tungsten (W) .

The transition metal may be in a state in which oxygen is shared with zirconium (Zr), tungsten (W), and phosphorus (P) in the composite metal oxide. The composite metal oxide further improves the selectivity of acrolein by containing the transition metal, and can inhibit the production of hydroxyacetone, which is a by-product.

Meanwhile, the composite metal oxide may be represented by the following formula (1).

[Chemical Formula 1]

Zr (M ₁ ) _p (M ₂ ) _q W _r P _s H _x O _y

In Formula 1,

M ₁ and M ₂ are each independently a transition metal selected from the group consisting of Zn, V, Fe, Mo, Ce and Cu,

p is a real number of more than 0 and not more than 1,

q is a real number of 0 or more and 1 or less,

r is a real number greater than 0 and less than or equal to 1,

s is a real number greater than 0 and less than or equal to 10,

x and y each independently represent a real number of 0.1 to 20 inclusive.

The content of hydrogen and oxygen in the composite metal oxide, that is, the x and y values in the formula (1) can be appropriately controlled according to the content and the ratio of the zirconium, tungsten, phosphorus and transition metal which may be additionally contained, And may be a real number of 0.1 to 20.

In Formula 1, one of M ₁ and M ₂ may be Zn and the other may be V. As described above, the composite metal oxide containing zinc and vanadium in addition to zirconium, tungsten, and phosphorus is a metal oxide of zinc and vanadium, which can remove the coke or provide a Bststed acid point, thereby enhancing the activity of the catalyst. The catalyst activity can be maintained.

Also, such a composite metal oxide may be prepared by mixing a zirconium precursor, a tungsten precursor, and a phosphorus precursor; And drying and firing the mixed solution.

The zirconium precursor, the tungsten precursor and the phosphorus precursor are collectively referred to as zirconium, tungsten, and phosphorus, which are contained in the catalyst for the dehydration reaction of glycerin, respectively. The zirconium precursor, the tungsten precursor and the phosphorus precursor are, for example, zirconium, tungsten, Or in the form of an oxide or salt containing one. More specifically, the tungsten precursor may be ammonium metatungstate hydrate, the phosphorus precursor may be ammonium phosphate, and the zirconium precursor may be zirconium oxychloride.

In the step of mixing the zirconium precursor, tungsten precursor and phosphorus precursor, at least one transition metal selected from the group consisting of Zn, V Fe, Mo, Ce and Cu as well as the zirconium precursor, tungsten precursor and phosphorus precursor The precursor may be further mixed and mixed. As the precursor of the transition metal, a nitrate of each transition metal can be used.

Next, the mixed solution prepared by mixing the zirconium precursor, tungsten precursor and phosphorus precursor is dried and fired.

More specifically, in the drying step, the mixed solution may be dried at a temperature of 80 to 150 ° C. for 10 minutes to 24 hours to remove the solvent from the mixed solution. In this drying process, a drying method and a drying device known to be commonly used can be used. For example, drying can be performed using a heat source such as a hot air fan, an oven, or a hot plate.

The firing step is a series of steps of heating the reactants at a high temperature to produce a curable material. The firing step may be performed at a temperature ranging from 300 to 900 ° C, preferably 500 to 750 ° C. If the temperature is lower than the above range, the structure and crystallinity of the catalyst may change during the reaction, and if the temperature is higher than the above range, the interatomic interaction may be too strong to increase the particle size or cause unnecessary side reactions.

In addition, the firing step may be performed for 10 minutes to 10 hours each. If the calcination time is too short, the catalyst may not be completely calcined. If the calcination time is too long, various side reactions such as carbonization of the catalyst may occur.

On the other hand, in the method for producing a catalyst for a glycerin dehydration reaction according to the embodiment, the composite metal oxide is mixed with a flocculant containing an inorganic metal sol and an alcohol.

The coagulant is a material mixed for improving the mechanical strength of the composite metal oxide having a low mechanical strength and comprises 5 to 20% by weight of at least one inorganic metal sol selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol; And residual amounts of at least one alcohol selected from the group consisting of glycerin, isopropyl alcohol, diacetone alcohol, methanol, ethanol and propanol, and the like.

The inorganic metal sol may impart an effect of increasing physical strength to the catalyst, and may contain 5 to 20% by weight. If the amount of the inorganic metal sol is less than 5% by weight, the physical strength is insufficient for use as a catalyst. On the other hand, when the content of the inorganic metal sol is more than 20% by weight, The strength can be weakened. Therefore, the inorganic metal sol is preferably used in an amount of 5 to 20% by weight.

As the inorganic metal sol, it is preferable to use silica sol or alumina sol.

The alcohol may serve to uniformly mix the catalyst and the molding solution uniformly and to control the viscosity of the catalyst. More specifically, in the alcohol, glycerin serves as a lubricant in the process of forming the catalyst. And isopropyl alcohol can control the viscosity of the catalyst. Therefore, when a mixture of isopropyl alcohol and glycerin is used for the coagulant, a catalyst for a glycerin dehydration reaction having an improved mechanical strength can be produced.

The coagulant may further include at least one additive selected from the group consisting of bentonite, kaolin, kaolin, boehmite, and montmorillinite. The additives such as bentonite, kaolin and the like can significantly increase the physical strength even when added in a small amount. At this time, the additive is preferably used in an amount of 20 wt% or less, preferably 15 wt% or less.

The composite metal oxide and the flocculant may be mixed in a weight ratio of 1: 1 to 1: 5, preferably 1: 1 to 1: 3. If the coagulant is contained too much in comparison with the composite metal oxide, the activity of the catalyst may be deteriorated. When the coagulant is included in an excessively small amount, the effect of increasing the physical strength of the catalyst is insignificant. It is preferable to mix them.

Next, a mixture of the composite metal oxide and the flocculant is extruded. In the method for preparing a catalyst for dehydration of glycerin according to one embodiment of the present invention, a catalyst may be formed by extruding a mixture of a composite metal oxide and a coagulant to have better mechanical strength. The catalyst can be maintained in the reaction activity for 140 hours or longer without generating internal pressure even when applied to an actual pilot process, as compared with the case where the catalyst is used directly or supported on a carrier.

At this time, the extrusion temperature is preferably 25 to 70 DEG C and the screw rotation speed is preferably 200 rpm or more. If the extrusion temperature is less than 25 캜, kneading may not be performed properly, and if it exceeds 70 캜, the alcohol component may evaporate and catalyst formation may be difficult. If the screw rotating speed is less than 200 rpm, smooth kneading does not occur.

Then, after the step of extruding the mixture, the step of drying and firing the extrudate may be further included. The step of drying and firing the extrudate can be applied without limitation to the reaction conditions of the step of drying in the step of producing the composite metal oxide, the step of firing, the reaction device, and the like.

According to another embodiment of the present invention, there is provided a method for producing acrolein, comprising the step of reacting glycerin dehydration reaction catalyst and glycerin in the presence of glycerin dehydration reaction produced according to the above- have.

As described above, the catalyst for the dehydration reaction of glycerin prepared by mixing a composite metal oxide containing zirconium (Zr), tungsten (W) and phosphorus (P) with a coagulant of a specific composition and extruding the coagulant has high compressive strength Exhibits sufficient mechanical strength, and when used in a glycerin dehydration reaction, acrolein can be produced with high yield and high conversion.

The amount of the catalyst for the dehydration reaction of glycerin can be appropriately adjusted according to the amount and concentration of glycerin. For example, it may be used in an amount of 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, per 100 parts by weight of glycerin per hour.

In addition, the dehydration reaction may be performed at a temperature of 200 to 400 ° C. The dehydration reaction is an endothermic reaction. In order to produce acrolein with high conversion and selectivity, the reaction is preferably carried out at a temperature within the above range.

According to the present invention, the selectivity of acrolein can be minimized by minimizing the formation of byproducts, and the catalyst can be provided with a catalyst for dehydration reaction of glycerol which can be applied in actual process because of having sufficient mechanical strength.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[Preparation Example 1]: Preparation of composite metal oxide

_{ZrZn 0 .02 V 0.1 W 0. 1} H x (PO 4) 2 catalyst to 1 mole ratio of Zr, V and Zn molar ratio of the transition metal is from 0.02 and 0.1, respectively, in a molar ratio of P 2, W molar ratio was adjusted to 0.1. To this end, 183.11 g of zirconium oxychloride, 3.414 g of zinc precursor (Zn (NO ₃ ) 6H ₂ O), 6.464 g of ammonium vanadate and 13.93 g of ammonium metatungstate hydrate were mixed in 2250 ml of distilled water And 132.05 g of ammonium phosphate (NH ₄ H ₂ PO ₄ ) was added thereto.

When precipitates were formed after mixing, the mixture was stirred at a temperature of 90 ° C for 3 days or more, and the precipitates were separated by filtration and washed with ethanol three to five times. Cake-type precipitate obtained after the washing process was dried in an oven at 100 ° C. for 12 hours. The dried Cake was calcined in air at 700 ℃ for 6 hr to produce composite metal oxide.

[Examples 1 to 5 and Comparative Examples 1 to 3]

30 g of the composite metal oxide prepared in Preparation Example 1 and 30-40 g of the coagulant of the following Table 1 were mixed and extruded under extreme conditions using an extruder (SPG) at a normal temperature and a screw rotation speed of 200 rpm or more. The extrudate was dried in an oven at 100 ° C for a day, molded into a cylindrical shape having a length of 5 mm, and calcined at 700 ° C for 6 hours to prepare a catalyst.

Silica sol
(wt%) Alumina sol
(wt%) glycerin
(wt%) IPA
(wt%) water
(wt%) Bentonite
(wt%) kaoline
(wt%) Example 1 15 17 68 Example 2 13 15 59 13 Example 3 13 15 59 13 Example 4 15 85 Example 5 22 16 62 Comparative Example 1 40 12 48 Comparative Example 2 30 14 56 Comparative Example 3 15 17 68

[ Comparative Example  4]

remind The ZrZn ₀ produced in Production Example _{1 .02 V 0.1 W 0. 1 H} x (PO 4) 2 The composite metal oxide itself was used as a catalyst without forming process.

[Comparative Example 5]

remind ZrZn _{0 .02} in the same manner as in Production Example _{1 V 0.1 W 0. 1 H x} (PO 4) 2 The composite metal oxide was prepared and the vanadium precursor (ammonium vanadate) was sufficiently dissolved in distilled water to sufficiently carry 2.5 wt% of V, followed by thorough drying using an evaporator to prepare a catalyst by impregnation. The fully dried catalyst was calcined in air at 700 ℃ for 6 hr to prepare 2.5 wt% V / ZrZn _0.02 V _0.1 W _0.1 H _x (PO ₄ ) ₂ composite metal oxide.

[Experimental Example 1]: Compressive strength of catalyst for dehydration reaction of glycerin

In order to measure the compressive strength of the catalyst for dehydration reaction of glycerin prepared in Examples 1 to 5 and Comparative Examples 1 to 3, the analysis was commissioned by PDIS. Using a Bose 5500 apparatus, a specimen having a length of 0.5 mm and a diameter of 0.5 mm The pressure at which the cracks were generated by this pressure was measured, and the average value of the data obtained through three repeated experiments was summarized in Table 2 below.

Compressive strength (N) Example 1 29.05 Example 2 29.73 Example 3 55.74 Example 4 41.89 Example 5 41.55 Comparative Example 1 - Comparative Example 2 - Comparative Example 3 46.64

As shown in Table 2, the catalysts for the dehydration reaction of glycerin of Examples 1 to 5 prepared by mixing the composite metal oxide prepared in Production Example with a coagulant of a specific composition and extruding exhibited a compressive strength of 25 N or more, However, in Comparative Examples 1 and 2 prepared by mixing a large amount of silica sol with 30 wt% and 40 wt%, it was found that the physical strength was not sufficient and the impact strength was low enough that the impact strength could not be measured And various problems such as internal pressure occurred in actual experiments.

In addition, in Comparative Example 3, water is added to the flocculant. Since the catalyst is easily squeezed or dried, it is difficult to form the catalyst.

[Experimental Example 2]: Conversion of glycerin, yield and selectivity of acrolein

Using the catalysts prepared in Example 1 and Comparative Examples 4 to 5, a high-throughput screening (HTS) apparatus was prepared so as to evaluate the performance with a small amount of catalyst in a short time under the conditions shown in Table 3 below Acrolein was produced from glycerin and the conversion, selectivity and yield were calculated by GC analysis of the product in situ.

More specifically, the HTS apparatus has 16 reactors (9 mm in outer diameter, 25 cm in length) to perform a large amount of catalyst experiments in the shortest time. In order to inject the liquid reaction product at a constant rate, a pump Was sent to the evaporator heater, and the vaporized reactant was fed to the reactor at a constant rate along with the carrier gas, nitrogen. The sampling operation was performed in a chiller set at a temperature of 0 ° C for condensation and distilled water was added to the glass bottle to allow the reaction to condense. Reactions were analyzed using on-line gas chromatography (HP 6890N). Flame ionization detector (FID) was used and HP-FFAP (25m X 0.32mm X 0.52mm) was used for the column.

The conversion of glycerin, acrolein selectivity, hydroxyl acetone selectivity, acetic acid selectivity and residual byproduct selectivity are shown in Table 4 below.

Here, the conversion rate represents the rate at which glycerin is converted to another compound, and the selectivity represents the ratio of each substance in the converted compound. In addition, hydroxyl acetone and acetic acid are major by-products of the glycerin dehydration reaction, and the remaining by-products are hydroxyl acetone and other by-products other than acetic acid.

Glycerin dehydration reaction conditions Example 1 Comparative Examples 4 to 5 Reaction temperature 285 ℃ 280 ℃ Reaction pressure 0 barg Atmospheric pressure Glycerin concentration 50 wt% 50 wt% Amount of catalyst 250 g 250 g Feed rate 4-7.5 g / min 4-7.5 g / min GHSV 660-1642 h ^-1 11321 h ^-1 WHSV 3-6.4 h ^-1 45.8 h ^-1

Reaction time
(h) Glycerin conversion (%) Acrolein selectivity (%) Selectivity of hydroxyl acetone (%) Acetic acid selectivity (%) Residual by-product selectivity (%) Example 1 80 100 69.0 0 8.0 18.7 100 100 62.0 0 7.3 18.4 120 100 60.7 0 5.7 29.3 140 100 67.0 One 3.9 25.8 Comparative Example 4 69.38 75.66 4.36 15.38 Comparative Example 5 23.32 51.08 7.73 37.34

As shown in Table 3, the catalyst prepared in the condition of Example 1 was subjected to actual pilot process steps, and it was confirmed that the catalyst was applicable to actual experiments.

As a result, when glycerin was reacted with the catalyst of Example 1, acrolein could be produced from glycerin with high selectivity and high purity, and production of by-products such as hydroxyl acetone and acetic acid could be inhibited Table 4 shows the results.

In addition, it was confirmed that the catalyst for the dehydration reaction of glycerin of Example 1 maintained the activity for 140 hours or more and maintained the cylindrical pellet shape of the catalyst after the reaction.

Claims (9)

A composite metal oxide containing zirconium (Zr), tungsten (W) and phosphorus (P)
5 to 20% by weight of at least one inorganic metal sol selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol; And a residual amount of at least one alcohol selected from the group consisting of glycerin, isopropyl alcohol, diacetone alcohol, methanol, ethanol and propanol; And
And then extruding the mixture. ≪ RTI ID = 0.0 > 8. < / RTI >
The method according to claim 1,
Wherein the composite metal oxide further comprises at least one transition metal selected from the group consisting of Zn, V, Fe, Mo, Ce and Cu.
The method according to claim 1,
Wherein the composite metal oxide is represented by the following Formula 1:
[Chemical Formula 1]
Zr (M ₁ ) _p (M ₂ ) _q W _r P _s H _x O _y
In Formula 1,
M ₁ and M ₂ are each independently a transition metal selected from the group consisting of Zn, V, Fe, Mo, Ce and Cu,
p is a real number of more than 0 and not more than 1,
q is a real number of 0 or more and 1 or less,
r is a real number greater than 0 and less than or equal to 1,
s is a real number greater than 0 and less than or equal to 10,
x and y each independently represent a real number of 0.1 to 20 inclusive.
The method according to claim 1,
The composite metal oxide
A zirconium precursor, a tungsten precursor, and a phosphorus precursor; And
And drying and firing the mixed solution. ≪ Desc / Clms Page number 20 >
The method according to claim 1,
Wherein the coagulant further comprises at least one additive selected from the group consisting of bentonite, kaolin, kaolin, boehmite and montmorillinite.
The method according to claim 1,
Wherein the composite metal oxide and the flocculant are mixed in a weight ratio of 1: 1 to 1: 5.
The method according to claim 1,
Further comprising the step of drying and firing the extrudate.
A catalyst for the dehydration reaction of glycerin prepared by the process of any one of claims 1 to 7.
A process for producing acrolein, comprising the step of reacting glycerin in the presence of the catalyst for dehydration reaction of glycerin of claim 8.