KR20220076217A - Manufacturing method for phosphate-calcium catalyst composition for manufacturing phosphate-calcium catalyst and manufacturing method for acrylic acid - Google Patents

Abstract

The present specification comprises the steps of preparing a phosphate solution having a pH of 9.55 to 9.8; preparing a mixed solution by mixing the phosphate solution and the calcium salt solution; preparing a calcium phosphate cake by stirring the mixed solution; and calcining the calcium phosphate cake. A method for preparing a calcium phosphate catalyst, a composition for preparing a calcium phosphate catalyst, and a method for preparing acrylic acid

Description

A method for producing a calcium phosphate catalyst, a composition for producing a calcium phosphate catalyst, and a method for producing acrylic acid

The present invention relates to a method for preparing a calcium phosphate catalyst, a composition for preparing a calcium phosphate catalyst, and a method for preparing acrylic acid.

Acrylic acid, which is used as a raw material for superabsorbent polymers, paints, and coatings, is synthesized through a two-step oxidation reaction of propylene, a petrochemical raw material. With the recent development of industrial biotechnology, lactic acid can be mass-produced by fermentation from biomass raw materials, and acrylic acid (ester) can be produced by dehydrating the synthesized lactic acid (ester) in one step.

Various acid catalysts and base catalysts can be used as catalysts for the dehydration reaction of lactic acid. However, due to the nature of the reactant lactic acid and the product acrylic acid, side reactions such as decarboxylation and oxidation and hydrocracking reactions are more likely to occur than dehydration reactions. Catalysts and processes with high stability are required.

Currently, catalysts having a mixed phase of hydroxyapatite (HAPP) and calcium pyrophosphate (CaPP) are known as catalysts with high activity. little.

KR 10-2012-0025888 A

The present invention relates to a method for preparing a calcium phosphate catalyst and a method for preparing acrylic acid.

An exemplary embodiment of the present invention comprises the steps of preparing a phosphate solution having a pH of 9.55 to 9.8;

preparing a mixed solution by mixing the phosphate solution and the calcium salt solution;

preparing a calcium phosphate cake by stirring the mixed solution; and

It provides a method for producing a calcium phosphate catalyst comprising the step of calcining the calcium phosphate cake.

In addition, an exemplary embodiment of the present invention provides a method for producing acrylic acid comprising the step of dehydrating a lactic acid ester using the calcium phosphate catalyst.

According to the method for preparing a catalyst according to an exemplary embodiment of the present invention, there is no need for a mixing process of mixing after preparing a catalyst including each phase of hydroxyapatite (HAPP) and calcium pyrophosphate (CaPP) in one step It is possible to prepare a catalyst including both phases.

The prepared catalyst has the effect of exhibiting a high yield when used in the production of acrylic acid.

1 is an XRD analysis data of the calcium phosphate catalyst prepared in Examples and Comparative Examples.

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

When the calcium phosphate catalyst has a single phase of hydroxyapatite (HAPP) or calcium pyrophosphate (CaPP), there is a problem in that the yield decreases in the dehydration reaction and the processability is deteriorated due to the short lifespan. On the other hand, a catalyst having a mixed phase of hydroxyapatite (HAPP) and calcium pyrophosphate (CaPP) has advantages in that the yield of the dehydration reaction is improved and processability is improved due to a long lifespan.

However, since a catalyst having a mixed phase of hydroxyapatite (HAPP) and calcium pyrophosphate (CaPP) requires separately preparing a slurry or cake including each phase, a process of mixing them again is essential. There was an upper limit.

The present inventors found that when the pH of the phosphate solution used in preparing the mixed solution is adjusted to 9.55 to 9.8, there is no need to separately prepare a cake having different phases, and the preparation of a catalyst having a mixed phase in one pot is possible. Found possible and completed the present invention.

The presence or absence of the mixed phase can be confirmed using XRD analysis of the prepared catalyst. Specifically, it is confirmed that a mixed phase exists when a hydroxyapatite (HAP) phase and a calcium pyrophosphate (CaPP) phase at 26.7 and 30.5 degrees simultaneously appear at 2-theta angles of 25.9 degrees and 31.7 degrees. At this time, XRD analysis can use Bruker's D4 endeavor X-ray diffractometer, CuKα lamp, 40kV voltage, 40mA current, 0.8 deg/min scan speed, 0.015 scan step condition, and 2-theta range from 10 to 60 degrees can be measured in

When the hydroxyapatite (HAP) and calcium pyrophosphate (CaPP) are included, it may be defined as having a mixed phase of hydroxyapatite (HAP) and calcium pyrophosphate (CaPP). The mixed phase means that hydroxyapatite (HAP) and calcium pyrophosphate (CaPP) are simply mixed.

Specifically, one embodiment of the present invention comprises the steps of preparing a phosphate solution having a pH of 9.55 to 9.8;

preparing a mixed solution by mixing the phosphate solution and the calcium salt solution;

preparing a calcium phosphate cake by stirring the mixed solution; and

It provides a method for producing a calcium phosphate catalyst comprising the step of calcining the calcium phosphate cake.

The method for preparing a calcium phosphate catalyst according to an exemplary embodiment of the present invention includes preparing a phosphate solution having a pH of 9.55 to 9.8. The phosphate solution may be prepared by purchasing a commercial product whose pH has been adjusted in advance, or by adjusting the pH of a phosphate solution whose pH is not adjusted.

In the step of preparing a mixed solution by mixing the phosphate solution and the calcium salt solution, when the phosphate solution and the calcium salt solution are mixed to precipitate the phosphate and calcium salt, the solution is acidified and a single phase of calcium pyrophosphate (CaPP) is formed . On the other hand, when the acidified solution is adjusted with a strong base, a single phase of hydroxyapatite (HAP) is formed, so when the pH of the phosphate solution is adjusted to the above range, A complex phase may be formed.

In one embodiment of the present invention, the step of preparing the phosphate solution having a pH of 9.55 to 9.8 may include adding a basic material to the phosphate solution. Through this, the pH of the phosphate solution can be adjusted to 9.55 to 9.8. The step of adding the basic material to the phosphate solution may be repeated while measuring the pH of the phosphate solution until a desired pH is reached. In this case, the concentration or volume ratio of the basic material may be adjusted. For example, when the basic material is sodium hydroxide (NaOH), 1M sodium hydroxide solution may be added in an amount of 1 vol% to 6 vol%, or 2 vol% to 5 vol% relative to the volume of the phosphate solution.

In an exemplary embodiment of the present invention, the pH of the phosphate solution may be 9.55 to 9.8, 9.6 to 9.8, or 9.6 to 9.7.

In an exemplary embodiment of the present invention, the pH of the mixed solution may be 9.55 to 9.8, 9.6 to 9.8, or 9.6 to 9.7.

In an exemplary embodiment of the present invention, the basic material may be at least one selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH) ₂ ). Especially, it is preferable to use sodium hydroxide. When a calcium phosphate catalyst is prepared by using sodium hydroxide as a basic material, catalytic activity is improved, and there is an advantage in that the conversion rate of lactic acid and the selectivity of acrylic acid to be produced are improved during the lactic acid dehydration reaction.

In one embodiment of the present invention, it may include adding a second basic material to the calcium salt solution or the mixed solution. The second basic material may be the same as or different from the basic material added to the phosphate solution, and the type of the second basic material is the same as the basic material described above.

The phosphate solution is (NH ₄ ) ₂ HPO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , K ₂ HPO ₄ , KH ₂ PO ₄ , Li ₃ PO ₄ , Na ₃ PO ₄ , K ₃ PO ₄ , pyrophosphoric acid ( H ₄ P ₂ O ₇ ), Li ₄ P ₂ O _{7 ,} Na ₄ P ₂ O ₇ and K ₄ P ₂ O ₇ may include at least one selected from the group consisting of, or a phosphate of a hydrate thereof. At this time, it is preferable to use (NH ₄ ) ₂ HPO ₄ that is easy to obtain and handle.

The calcium salt solution may include one or more calcium salts selected from the group consisting of calcium chloride, calcium nitrate, calcium sulfate and calcium acetate. At this time, it is preferable to use calcium chloride or calcium nitrate, which is easy to obtain and handle.

The phosphate concentration of the phosphate solution may be 0.1M or more and 5.0M or less, preferably 0.3M or more and 2.0M or less, and more preferably 0.5M or more and 1.0M or less. If it exceeds the above range, there is a problem in that the particles are hardened during stirring due to gelation of the phosphate, and when it is less than the above range, there is a problem in that catalyst productivity is low. The phosphate concentration means the number of moles of phosphate relative to the total volume (L) of the phosphate and solvent in the phosphate solution.

The calcium salt concentration of the calcium salt solution may be 0.1M or more and 5.0M or less, preferably 0.5M or more and 3M or less, and more preferably 1.0M or more and 2.0M or less. When it exceeds the above range, there is a problem in that the particles are hardened during stirring due to gelation of the calcium salt, and when it is less than the above range, there is a problem in that catalyst productivity is low. The calcium salt concentration refers to the number of moles of calcium salt relative to the total volume (L) of the sum of all the calcium salts and the solvent in the calcium salt solution.

The step of preparing a mixed solution by mixing the phosphate solution and the calcium salt solution may include dripping the calcium salt solution into the phosphate solution. This is to drop the calcium salt solution using the phosphate solution as the mother liquid, and when the phosphate solution is dripped using the calcium salt solution as the mother liquid as in the prior art, Na ₂ CaP ₂ O ₇ hydrate is generated and the calcium pyrophosphate (CaPP) phase is different. It was not well formed, so there was a problem in that the mixed phase of hydroxyapatite (HAP) and calcium pyrophosphate (CaPP) was not well formed. On the other hand, in the method for preparing a calcium phosphate catalyst according to an exemplary embodiment of the present invention, by dripping the calcium salt solution into the phosphate solution, Na ₂ CaP ₂ O ₇ hydrate is prevented from being generated, so that hydroxyapatite (HAP) and A mixed phase of calcium pyrophosphate (CaPP) can be easily formed.

The step of dripping the calcium salt solution to the phosphate solution may be performed for a time period of 1 minute or more and 10 hours or less. The above step may be preferably performed for a period of 10 minutes or more and 5 hours or less, or 30 minutes or more and 2 hours or less. In the above time range, the calcium salt solution is sufficiently dripped into the phosphate solution, so that the size and shape of the prepared calcium phosphate catalyst can appear uniformly.

In the step of adding the calcium salt solution to the phosphate solution, the dropping rate of the calcium salt solution may be 0.1 mL/min or more and 10 mL/min or less, or 1 mL/min or more and 10 mL/min or less. If it is less than the above range, the reaction is slow and fairness is deteriorated, and if the rate is exceeded, the reaction may occur rapidly and precipitates may occur, so it is preferable to adjust the reaction within the above range.

The step of preparing the calcium phosphate cake by stirring the mixed solution includes preparing a calcium phosphate slurry by stirring the mixed solution; and filtering, washing and drying the calcium phosphate slurry.

The stirring may be performed at a temperature of 20°C to 60°C for 1 hour to 48 hours. In the above temperature and time range, the calcium phosphate slurry can be sufficiently stirred without being damaged.

The stirring may be performed through a separate stirrer, in which case the stirring speed may be 50 rpm to 200 rpm. In the stirring speed range, the reaction can be prevented from occurring rapidly and sufficient fairness can be ensured.

The drying may be performed at 80 °C to 150 °C. The drying is a process for evaporating moisture in the calcium phosphate slurry to prevent side reactions caused by moisture in the sintering step, and moisture can be sufficiently evaporated within the above temperature and time range. In addition, the drying may be performed for 5 to 48 hours.

In an exemplary embodiment of the present specification, the calcining of the calcium phosphate cake may be performed at a temperature of 300°C to 700°C. The temperature condition may be adjusted to 400°C to 650°C, or 450°C to 600°C so that the firing can be sufficiently performed.

In an exemplary embodiment of the present specification, the calcining of the calcium phosphate cake may be performed for 1 to 24 hours, 1 to 12 hours, or 2 to 6 hours.

In an exemplary embodiment of the present specification, the method may further include grinding the calcium phosphate cake.

The grinding of the calcium phosphate cake may include grinding the calcium phosphate cake into a powder having an average particle size of 5 μm to 100 μm (D50). The average particle size D50 means a particle size when the cumulative percentage in the average particle size distribution reaches 50%. For the average particle size (D50), Horiba's Laser Particle Size Analyzer LA-950 equipment can be used, and a solution containing the calcium phosphate powder is diluted with water to prepare a dispersion, and 15~ It can measure in the temperature range of 35 degreeC.

In an exemplary embodiment of the present specification, the method may further include molding the calcium phosphate cake or calcium phosphate powder into calcium phosphate pellets.

An exemplary embodiment of the present invention is a phosphate solution having a pH of 9.55 to 9.8; And it provides a composition for preparing a calcium phosphate catalyst comprising a calcium salt solution. The composition for preparing the calcium phosphate catalyst is a composition used for the preparation of the above-described calcium phosphate catalyst, and the above contents may be applied in the same manner.

An exemplary embodiment of the present invention provides a method for producing acrylic acid comprising the step of dehydrating a lactic acid ester using the catalyst prepared by the above-described method. In this case, it may proceed in a fixed-bed reactor or a batch reactor in which the catalyst is filled, and when a fixed-bed reactor is used, the product may be continuously manufactured by filling the reactor with the extruded catalyst.

In an exemplary embodiment of the present invention, the dehydration reaction may be performed at a reaction temperature of 300° C. to 500° C., atmospheric pressure to 5 bar, and a feed rate (LHSV) of the reactant, lactic acid ester, of 0.05 to 1.0 hr ^-1 .

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are means for explaining the present invention, and the scope of the present invention is not limited to the matters described in the examples.

<Production of catalyst>

1. Example 1

After dissolving 14.5 g of phosphate {(NH ₄ ) ₂ HPO ₄ } in 150 ml of distilled water, NaOH solution (1M 6cc: 4 vol% compared to distilled water) was added to adjust the pH to 9.6 to obtain Solution A (phosphate molar concentration: 0.73M) prepared.

Calcium salt {Ca(NO3) ₂ } 4H ₂ O 54 g was dissolved in 150 ml of distilled water to prepare solution B (calcium salt molar concentration: 1.52 M), and the solution B was added dropwise to the solution A for 30 minutes, and at 25° C. Stirred for 18 hours.

A cake obtained by filtering, filtering, and washing the slurry formed by mixing the solution A and the solution B was dried in an oven at 120°C.

A catalyst was prepared by calcining the dried material in a calcination furnace at 600° C. under air conditions for 4 hours.

As a result of XRD analysis, a complex crystalline phase of hydroxyapatite (HAP) and calcium acid pyrophosphate (CAPP) was revealed.

2. Comparative Example 1

A catalyst was prepared in the same manner as in Example 1, except that NaOH was not added and the pH was adjusted to 8.

XRD analysis revealed a single crystalline phase of calcium pyrophosphate (CAPP).

3. Comparative Example 2

A catalyst was prepared in the same manner as in Example 1 except that the pH was adjusted to 9.9 by adding a larger amount of NaOH solution (1M 10cc: 6.7 vol% compared to distilled water) than in Example 1.

XRD analysis revealed a single crystalline phase of hydroxyapatite (HAP).

<XRD analysis method>

The catalysts prepared in each Example and Comparative Example were set to CuKα lamp, voltage 40kV, current 40mA, scan speed 0.8 deg/min, and scan step 0.015 using a D4 Endeavor X-ray diffractometer from Bruker, and 2-theta angle 10~ It was measured under the condition of 60 degrees.

The HAP phase can be confirmed from the peaks observed at 25.9 degrees and 31.7 degrees, and the γ-CAPP phase can be confirmed from the peaks observed at 26.7 degrees and 30.5 degrees.

The catalyst of Example 1 showed a complex phase of HAP and γ-CAPP, the catalyst of Comparative Example 2 had a single phase of γ-CAPP, and the catalyst of Comparative Example 3 had a single phase of HAP ( FIG. 1 ).

<Dehydration reaction of lactic acid>

6ml (3.9g) of the catalyst prepared in Examples and Comparative Examples was charged in a fixed bed reactor, and an aqueous solution containing 20wt% of lactic acid methyl ester at a reaction temperature of 370°C and atmospheric pressure was supplied as WHSV 0.45 h ^-1 for dehydration reaction. started

During the initial 4 hours of the reaction, the reactants were received and removed as a reaction stabilization time, and the liquid product obtained for 8 to 16 hours was recovered as a liquid sample using a cooling collector at 4° C., and then liquid chromatography (High Performance Liquid Chromatography: HPLC) was used for quantitative analysis.

As a result of the analysis, acrylic acid, acrylic acid methyl ester, acetaldehyde, and acetyl propionyl were mainly produced as reaction products, and in addition, trace amounts of acetol and methoxymethyl propionate were produced (others). The reaction results were calculated using the following formula, and are shown in Table 1 below.

[Equation 1]

Conversion of lactic acid (%) = 100 Х (moles of lactic acid before reaction - moles of lactic acid after reaction)/(moles of lactic acid before reaction)

[Equation 2]

Acrylic acid selectivity (%) = 100 Х (moles of acrylic acid produced)/(moles of reacted lactic acid)

[Equation 3]

Acetaldehyde selectivity (%) = 100 Х (moles of acetaldehyde produced)/(moles of reacted lactic acid)

[Equation 4]

Acetyl propionyl selectivity (%) = 100 Х (number of moles of acetyl propionyl produced)/(number of moles of reacted lactic acid)

pH of phosphate solution Conversion rate of lactic acid (%) Acrylic acid selectivity (%) Acetaldehyde Selectivity (%) Acetyl propionyl selectivity (%) Etc (%) Example 1 9.6 100 52 9.8 0 39 Comparative Example 1 8 83 30.4 30.6 0 21.9 Comparative Example 2 9.9 100 39.1 14.1 0 46.8

From the above results, when the pH of the phosphate solution was adjusted to 9.55 to 9.8, a catalyst having a complex crystal phase of hydroxyapatite (HAP) and calcium pyrophosphate (CAPP) was prepared, and it was confirmed that acrylic acid can be obtained with high selectivity. did.

On the other hand, when the pH of the phosphate solution was less than 9.55 or exceeded 9.8, a catalyst having a single phase of hydroxyapatite (HAP) and calcium pyrophosphate (CAP) was prepared, and it was confirmed that the selectivity of acrylic acid was low.

Claims (16)

preparing a phosphate solution having a pH of 9.55 to 9.8;
preparing a mixed solution by mixing the phosphate solution and the calcium salt solution;
preparing a calcium phosphate cake by stirring the mixed solution; and
Method for producing a calcium phosphate catalyst comprising the step of calcining the calcium phosphate cake. The method according to claim 1,
The step of preparing a phosphate solution having a pH of 9.55 to 9.8
A method for producing a calcium phosphate catalyst comprising the step of adding a basic material to the phosphate solution. 3. The method according to claim 2,
The basic material is sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH) ₂ ) Method for producing a calcium phosphate catalyst at least one selected from the group consisting of. The method according to claim 1,
The phosphate solution is (NH ₄ ) ₂ HPO _{4 ,} Na ₂ HPO ₄ , NaH ₂ PO ₄ , K ₂ HPO ₄ , KH ₂ PO ₄ , Li ₃ PO ₄ , Na ₃ PO ₄ , K ₃ PO ₄ , pyrophosphoric acid ( H ₄ P ₂ O ₇ ), Li ₄ P ₂ O _{7 ,} Na ₄ P ₂ O ₇ and K ₄ P ₂ O ₇ Preparation of a calcium phosphate catalyst comprising a phosphate of at least one selected from the group consisting of or a hydrate thereof Way. The method according to claim 1,
The calcium salt solution is a method for producing a calcium phosphate catalyst comprising at least one calcium salt selected from the group consisting of calcium chloride, calcium nitrate, calcium sulfate and calcium acetate. The method according to claim 1,
A method for producing a calcium phosphate catalyst wherein the phosphate concentration of the phosphate solution is 0.1M or more and 5M or less. The method according to claim 1,
A method for producing a calcium phosphate catalyst wherein the calcium salt concentration of the calcium salt solution is 1M or more and 5M or less. The method according to claim 1,
The step of preparing a mixed solution by mixing the phosphate solution and the calcium salt solution
The method for producing a calcium phosphate catalyst comprising the step of dripping the calcium salt solution to the phosphate solution. 9. The method of claim 8,
The step of dripping the calcium salt solution to the phosphate solution is a method for producing a calcium phosphate catalyst is performed for a time period of 1 minute or more and 10 hours or less. The method according to claim 1,
The step of preparing a calcium phosphate cake by stirring the mixed solution is
preparing a calcium phosphate slurry by stirring the mixed solution; and
A method for producing a calcium phosphate catalyst comprising the steps of filtering, washing and drying the calcium phosphate slurry. 11. The method of claim 10,
The stirring is a method for producing a calcium phosphate catalyst that is carried out at a temperature of 20 ℃ to 60 ℃ for 1 hour to 48 hours. 11. The method of claim 10,
The drying method for producing a calcium phosphate catalyst is carried out at 80 ℃ to 150 ℃. The method according to claim 1,
The method for producing a calcium phosphate catalyst wherein the calcination is carried out at a temperature condition of 300 ℃ to 700 ℃. a phosphate solution having a pH of 9.55 to 9.8; and
A composition for preparing a calcium phosphate catalyst comprising a calcium salt solution. A method for producing acrylic acid comprising the step of dehydrating a lactic acid ester using the catalyst prepared by the method according to any one of claims 1 to 13. 16. The method of claim 15,
The dehydration reaction is a method for producing acrylic acid, characterized in that it is carried out at a reaction temperature of 300 ° C to 500 ° C, atmospheric pressure to 5 bar, and a feed rate (LHSV) of the reactant lactic acid ester (LHSV) of 0.05 to 1.0 hr ^-1 .

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