KR101033660B1 - Calcium phosphate-silica catalysts for dehydration reaction of lactates, preparation thereof, and Process for the preparation of acrylic compounds from lactates - Google Patents

Abstract

The present invention relates to a calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester and a method for preparing the same, and a method for producing acrylic acid and acrylic acid esters, which are acrylic compounds, by dehydrating the lactic acid ester using the catalyst. Dehydration of the lactic acid ester having an alkyl group having 1 to 4 carbon atoms in the presence of the acrylic acid can be produced in high yield.

The calcium phosphate-silica catalyst of the present invention consists of 50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, wherein the calcium phosphate is Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , Ca ₅ (P At least one selected from the group consisting of ₃ O ₁₀ ) ₂ and Ca ₃ (PO ₃ ) ₆ .

Calcium Phosphate Catalyst, Dehydration Reaction, Lactic Acid Ester, Acrylic Acid, Acrylic Acid Ester

Description

Calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester and method for preparing the same, and method for preparing acrylic compound from lactate ester using the same Calcium phosphate-silica catalysts for dehydration reaction of lactates, preparation according, and Process for the preparation of acrylic compounds from lactates}

The present invention relates to a calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester and a method for preparing the same, and a method for producing acrylic acid and acrylic acid esters, which are acrylic compounds, by dehydrating the lactic acid ester using the catalyst. Dehydration of the lactic acid ester having an alkyl group having 1 to 4 carbon atoms in the presence of the acrylic acid can be produced in high yield.

The calcium phosphate-silica catalyst of the present invention consists of 50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, wherein the calcium phosphate is Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , Ca ₅ (P At least one selected from the group consisting of ₃ O ₁₀ ) ₂ and Ca ₃ (PO ₃ ) ₆ .

Acrylic acid is used as a synthetic raw material for acrylic ester monomers, and is also used as a modifier to impart a hydrophilic group of an acrylate resin or to provide a crosslinking site. Thus, polyacrylic acid water-soluble polymers using acrylic acid are widely used, and are mainly used in dispersants of pigments and paints, scale inhibitors in water treatment, and zeolite co-builders of powder detergents. Acrylate including acrylic ester has excellent properties such as transparency, UV stability, elongation, solvent resistance and water resistance. In particular, acrylic esters having a low glass transition temperature are used in polymers for various applications such as paints, fibers, adhesives, coatings, and inks.

Acrylic acid is currently being industrially synthesized by the two-stage oxidation of propylene, a petrochemical intermediate, but due to the rapid rise in crude oil prices, research and development of new acrylic acid manufacturing processes from alternative raw materials are actively underway worldwide. Among them, lactic acid can be easily synthesized in a large amount by fermentation from starch, which is a natural raw material, and acrylic acid may be prepared by dehydrating the synthesized lactic acid.

A method for preparing acrylic acid by dehydration of lactic acid was first presented in US Pat. No. 2,859,240. The catalyst was prepared by impregnating CaSO ₄ with Na ₂ SO ₄ aqueous solution.In the case of the Na ₂ SO ₄ / CaSO ₄ (4/96 weight ratio) catalyst, 10% lactic acid aqueous solution was used at 400 ° C at atmospheric pressure. Hour Space Velocity) The reaction was supplied at 0.15-0.23 ml / ml cat-hr and the yield of acrylic acid was 68%. In case of Na ₄ P ₂ O ₇ / CaSO ₄ (7/93 weight ratio) catalyst, 50% lactic acid aqueous solution was supplied at 0.26ml / ml cat-hr (LHSV, Liquid Hour Space Velocity) at 425 ℃. As a result, the yield of acrylic acid was 51%. In addition, the Na ₄ P ₂ O ₇ / Ca ₃ (PO ₄ ) ₂ (4/96 weight ratio) catalyst was used to produce a 50% lactic acid aqueous solution at 425 ° C and a liquid hour space velocity (LHSV, 0.48ml / ml cat-). As a result of supplying and reacting in hr, the yield of acrylic acid was 48 to 52%.

A method of lactic acid dehydration using a catalyst prepared by supporting NaH ₂ PO ₄ aqueous solution on a powdery silica (SiO ₂ ) carrier and buffering the pH to 5.9 with an aqueous NaHCO ₃ solution was reported in US Pat. No. 4,729,978. In case of NaH ₂ PO ₄ -NaHCO ₃ / SiO ₂ (1mmol-0.1mmol / g SiO ₂ , 10/90 weight ratio), 20% lactic acid solution at 350 ℃ atmospheric pressure was added to liquid hour space velocity (LHSV) 0.41 As a result of supplying the reaction in ml / ml cat-hr, the conversion of lactic acid was 89%, the selectivity of acrylic acid was 65%, and the yield of acrylic acid was 58%. NaH ₂ PO ₄ , the main catalyst component, has a relatively strong acidity, so NaH ₂ PO ₄ / SiO _{2 has} a pH of 4.4 under the same catalyst production conditions, and the reaction results in 94% conversion of lactic acid, 30% acrylic acid selectivity, and acrylic acid. The yield was 28%, and instead, the selectivity of the oxidative byproduct acetaldehyde was 56%. Therefore, the high activity and high selectivity of the catalyst has been told that the acidity and basicity must be properly balanced.

A method for producing acrylic acid from ammonium lactate using an ammonia treated AlPO ₄ catalyst is reported in US Pat. No. 4,729,978. The reaction of 20% ammonium lactate lactate solution at 0.5 to 0.6ml / ml cat-hr at 340 ° C at atmospheric pressure was conducted.The conversion rate of ammonium lactate was 100%, and acrylic acid selectivity was 61%. The yield of acrylic acid is relatively high, which is 61%, but the product contains nitrogen-containing by-products, making it difficult to separate and purify acrylic acid. Also, when the reactant is made into an aqueous solution of lactic acid under the same catalyst and reaction conditions, the conversion of lactic acid is 100%, Acrylic acid selectivity was as low as 43%, and the selectivity of the oxidation byproduct acetaldehyde was 35%.

In U.S. Pat.Nos. 5,071,754 and 5,250,729, Ca ₃ (PO ₄ ) ₂ / CaSO ₄ prepared by adding Ca ₃ (PO ₄ ) ₂ powder to CaSO ₄ in a 30% hydrous slurry type and mixing and calcining at 340-400 ° C. The reaction was carried out by supplying 100% methyl lactate (LHSV, Liquid Hour Space Velocity) 1.7 ml / ml cat-hr at 350 ° C using a catalyst (15/85 weight ratio). The conversion was 50%, the selectivity of methyl acrylate was 24%, and the selectivity of acrylic acid was 29%. Although the reactant has the advantage of synthesizing acrylic acid ester and acrylic acid using lactic acid ester rather than lactic acid, the conversion rate begins to decrease from 8 hours after the start of the reaction, and the reaction temperature is increased from 350 ° C. to 404 ° C. until 31 hours. Since the conversion rate must be maintained, an improvement in the stability of the catalyst is required.

In order to overcome the drawbacks of the prior art, the present invention uses phosphate precursors, calcium precursors and silica precursors to significantly increase the high dispersion, uniformity and stability of calcium phosphate and silica, thereby increasing the activity, selectivity and reaction stability of the dehydration reaction. To provide a two-component catalyst, the present inventors examine in detail the type of precursor, the precipitate pH and the mixing time when synthesizing calcium phosphate from the phosphate precursor and the calcium precursor, and the type of precursor when synthesizing silica from the silicon precursor. The pH and mixing time of the precipitates were examined in detail, and the mixing and maturing conditions of the synthesized calcium phosphate and silica were investigated. As a result, the microcrystallization, high dispersion, binding and homogeneity of calcium phosphate and silica under specific conditions and methods were investigated. It is confirmed that the activity of the dehydration reaction and the selectivity and reaction stability are greatly increased by increasing the properties, thereby completing the present invention. I became holy.

Accordingly, an object of the present invention is to provide a useful calcium phosphate-silica catalyst for producing an acrylic compound and acrylic acid ester by dehydrating a lactic acid ester having an alkyl group having 1 to 4 carbon atoms, and a method for preparing the same and a lactic acid ester under the catalyst. In providing a method of preparing acrylic acid and acrylic acid ester, which is an acrylic compound that is continuously dehydrated in a reactor, it provides a catalyst and a dehydration method suitable for long-term reactions because the reaction stability is excellent as a high activity and high selectivity dehydration catalyst.

In order to achieve the above object, the present invention is an acrylic compound by continuously dehydrating a calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester, and a method for preparing the same, and a lactate ester having an alkyl group having 1 to 4 carbon atoms using the catalyst. Provided is a process for producing phosphoric acrylic acid and acrylic acid esters in high yield.

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

The calcium phosphate-silica catalyst of the present invention consists of 50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, wherein the calcium phosphate is Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , Ca ₅ (P At least one selected from the group consisting of ₃ O ₁₀ ) ₂ and Ca ₃ (PO ₃ ) ₆ .

In the catalyst, calcium phosphate is included in the range of 50 to 98% by weight, preferably 60 to 95% by weight, and silica is included in the range of 2 to 50% by weight, preferably 5 to 40% by weight. If the calcium phosphate is less than 50% by weight, the activity of the initial reaction is high due to the high dispersibility of the active ingredient calcium phosphate, but the crystal size of calcium phosphate is too fine, the deactivation proceeds soon to decrease the conversion and selectivity. In addition, when the calcium phosphate is more than 98% by weight, the dispersibility of the crystal of calcium phosphate is low and the crystal is too large, the activity is lowered and the conversion rate is reduced, so the reaction temperature must be increased, and in the long term, the reaction stability is reduced.

The calcium phosphate-silica catalyst according to the present invention is prepared through the following steps:

 (1) mixing calcium phosphate solution with calcium salt solution to produce calcium phosphate;

(2) mixing the aqueous silicon salt solution with the aqueous acid solution to produce a silica slurry;

(3) filtering, washing, and drying the mixed slurry obtained by mixing the calcium phosphate with the silica slurry to form a powder; And

(4) calcining the powder at 300 to 700 ° C. in air.

Looking at the manufacturing process of the calcium phosphate-silica catalyst according to the present invention in more detail.

In the method for preparing a calcium phosphate-silica catalyst according to the present invention, in step (1), the phosphate aqueous solution (A) and the calcium salt aqueous solution (B) are mixed and precipitated as calcium phosphate particles, wherein the phosphate aqueous solution concentration is 5 to 20% by weight, the aqueous solution of calcium is adjusted to 10 to 30% by weight. The order of mixing the aqueous phosphate solution (A) and the aqueous calcium salt solution (B) is irrelevant, and the temperature of the mixed solution is kept constant in the range of 15 to 30 ° C. so that the resulting calcium phosphate crystals can be kept in a fine form. To 3 hours is preferred. The resulting calcium phosphate slurry is filtered and recovered with a cake of calcium phosphate.

The precursor of the phosphate component usable in the present invention is not particularly limited as long as the object of the present invention is not impaired. Examples of the water-soluble phosphate precursor that can be used include Li ₆ (PO ₄ ) _2, Li ₄ P ₂ O ₇ , Li ₁₀ ( P ₃ O ₁₀ ) _2, Na ₆ (PO ₄ ) _2, Na ₄ P ₂ O ₇ , Na ₁₀ (P ₃ O ₁₀ ) _2, K ₆ (PO ₄ ) _2, K ₄ P ₂ O ₇ , K ₁₀ ( P ₃ O ₁₀ ) ₂ and the like, among which Na ₆ (PO ₄ ) _2, Na ₄ P ₂ O ₇ or Na ₁₀ (P ₃ O ₁₀ ) ₂ are most preferably used.

Examples of calcium precursors that can be used in the present invention include hydrochloride (CaCl ₂ ), nitrate (Ca (NO ₃ ) ₂ ) or acetate ((CH ₃ COO) ₂ Ca). It is preferably used.

In the step (2), the silicon salt aqueous solution (A) and the acid aqueous solution (B) as a precipitant are mixed and precipitated into silica particles, wherein the silicon salt aqueous solution concentration is 10 to 40% by weight, and the acid aqueous solution is 5 to 25% by weight. Adjust to% range. In the mixing order, an acid aqueous solution (B) is supplied to an aqueous silicon salt solution (A), or a silicon slurry aqueous solution (A) and an acid aqueous solution (B) are simultaneously supplied to produce a silica slurry. The temperature of the mixed solution is kept constant in the range of 15 to 30 ℃ so that the resulting silica crystals can maintain a fine form, the mixing time is preferably 1-5 hours.

The precursor of the silicon component usable in the present invention is not particularly limited as long as the object of the present invention is not impaired. Examples of the water-soluble silicone salt precursor that can be used include Li ₂ SiO _{3 ,} Na ₂ SiO _{3 , and} K ₂ SiO _3. And the like, of which Na ₂ SiO ₃ and K ₂ SiO ₃ are most preferably used. Examples of the acid used as the precipitant include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and the like, among which hydrochloric acid and sulfuric acid are most preferably used.

Subsequently, in step (3), the calcium phosphate cake obtained in step (1) is added to the silica slurry solution obtained in step (2) and heated at 40 to 80 ° C. for 2 to 10 hours while stirring to uniformly disperse calcium phosphate and silica. It is dispersed and stabilized. When heating below 40 ℃, the binding of calcium phosphate and silica is not sufficient, so the uniform dispersion of calcium phosphate and silica and the stability of particles are low. Therefore, the activity is decreased. The interaction between calcium and silica is strong to produce by-products that are converted to calcium silicates, resulting in reduced catalytic activity and reduced selectivity because of side reactions of catalyst poisons and decarbonates.

In addition, the stabilized calcium phosphate-silica mixed slurry is filtered, washed and dried to prepare a powder. In the washing process, it is preferable to control the residual amount of the cationic material such as lithium, sodium or potassium derived from the silicon salt added in step (2) and the anionic material such as hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid derived from the acid precipitant. Importantly, the concentration of the ionic material is below 1,000 ppm relative to the catalyst. The washed precipitate is dried at 100 to 120 ° C. for 5 to 30 hours and ground to a size of 5 to 100 micrometers in a grinder. In addition, the precipitate of stabilized calcium phosphate-silica mixed slurry is dried to a powder in a spray dryer.

In addition, the powder of step (3) may be molded in a tablet press, or 0.5 to 5% by weight of graphite powder used as a lubricant and a pore regulator may be formed into pellets. In addition, in the case of batch reaction, the dried powder of step (3) may not be compressed.

Subsequently, in step (4), the powder of step (3) is calcined at 300 to 700 ° C, preferably 400 to 600 ° C, in air for 3 to 10 hours, and then used as a catalyst. If the calcination temperature is too high above 700 ° C, the calcium phosphate particles are sintered to deteriorate catalytic activity. If the calcination temperature is too low below 300 ° C, calcium phosphate particles are incompletely produced and the conversion rate is lowered.

The present invention also provides a method for producing an acrylic compound and acrylic acid esters by dehydrating the lactic acid ester using the calcium phosphate-silica catalyst prepared as described above.

The lactic acid ester is a lactic acid ester having an alkyl group having 1 to 4 carbon atoms, and may include lactic acid methyl ester, lactic acid ethyl ester, or lactic acid butyl ester.

In the dehydration reaction using the calcium phosphate-silica catalyst of the present invention, a continuous reaction and a batch using a fixed bed reactor may be used. As a reaction method using a fixed reactor, a solid reactor is charged with a solid calcium phosphate-silica catalyst and the reactant lactic acid ester is continuously supplied to the reactor to produce a product.

As the dehydration reaction condition of the lactic acid ester, the reaction temperature is 300 to 500 ° C., preferably 350 to 450 ° C., and the reaction pressure is performed at atmospheric pressure to 5 atmospheres (bar), preferably at atmospheric pressure to 2 atmospheres (bar). The feed rate (LHSV) of the lactic acid ester as a reactant is carried out at 0.05 to 1.0 hr ⁻¹ , preferably 0.10 to 0.50 hr ⁻¹ . If the reaction temperature is higher than 500 ° C., or the reaction pressure is less than normal pressure, and the feed rate of the reactants is less than 0.05 hr ^−1, the activity of the catalyst is excessively increased, so that the hydrocracking side reaction proceeds, thereby reducing the selectivity. And if the reaction temperature is less than 300 ℃, or the reaction pressure is more than 5 atmospheres, the feed rate of the reactants exceeds 1.0hr ^-1 , the conversion rate is lowered, the other reaction conditions must be severely increased and the cost is increased in the separation and recovery stage of the product .

Acrylic acid and acrylic acid esters can be produced in high yield by the calcium phosphate-silica catalyst of the present invention and a method of continuously dehydrating lactic acid esters under the catalyst.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the invention only.

Example 1

(1-1) Calcium Phosphate-Silica Catalyst ( Ca ₂ ( P ₂ O ₇ )) _a ( SiO ₂ ) _b [a = 80 wt %, b = 20 wt %] Preparation

41.9 g of sodium pyrophosphate [Na ₄ (P ₂ O ₇ )] was dissolved in deionized water to prepare a 450 ml aqueous solution of phosphate (A solution). 35.0 g of calcium chloride [CaCl ₂ ] was dissolved in deionized water to prepare a 200 ml aqueous calcium salt solution (B solution). The B solution was added to the A solution at room temperature for 10 minutes, and further stirred for 30 minutes. A white calcium phosphate precipitate was formed in the form of a slurry when the A and B solutions were mixed. After stirring was complete, the slurry solution was filtered, 600 ml of deionized water was added, dispersed, stirred and filtered to obtain a calcium phosphate cake. 42.3 g of sodium silicate [Na ₂ SiO ₃ 9H ₂ O] was dissolved in deionized water to prepare 150 ml of an aqueous silicon salt solution (C solution). 16.5 g of sulfuric acid [H ₂ SO ₄ ] was dissolved in deionized water to prepare an aqueous 100 ml sulfuric acid solution (D solution). D solution was added to C solution for 30 minutes with stirring at room temperature, and upon mixing, a semi-transparent silica slurry was produced. The calcium phosphate cake and deionized water 200 ml were added to the silica slurry solution, and the mixture was heated and stirred at 60 ° C. for 3 hours. The slurry liquid heated and stirred was filtered, 500 ml of deionized water was added, dispersion | stirring, stirring, and filtration were repeated twice. The filtered calcium phosphate-silica cake was dried at 100 ° C. for 6 hours. The dry matter was ground to a size of 20-40 mesh and fired in air at 500 ° C. for 6 hours. As a result of analyzing the calcined catalyst in air by XRD, crystals of calcium phosphate [Ca ₂ (P ₂ O ₇ )] were confirmed, and the silica was fine amorphous (FIG. 1). The BET specific surface area was 130 m 2 / g.

(1-2) Dehydration Reaction

A 6 mm Pyrex glass tubular reactor was filled with 2 ml (1 g) of the catalyst calcined in Example (1-1), and the aqueous solution containing 50 wt% of lactic acid methyl ester at 370 ° C. and atmospheric pressure was used. LHSV (Liquid Hour Space Velocity) was supplied at 0.35 ml / ml cat-hr to start the dehydration reaction. After the start of the reaction, the product was quantitatively analyzed by GC (Gas Chromatography) equipped with DB-WAX column at 50 hours after the product was collected by ice water collector. The reaction product was acrylic acid, acrylic acid methyl ester and acetaldehyde. , Propionic acid and the like are the main products, and a small amount of acetol, methoxy methyl propionate and the like were produced. The reaction results are expressed in mol% and are shown in Table 1.

[Example 2]

Calcium Phosphate-Silica Catalyst ( Ca ₃ ( PO ₄ ) ₂ ) _a ( SiO ₂ ) _b [a = 80 wt %, b = 20 wt %] Produce

In Example 1 A solution was prepared using 42.3 g of sodium phosphate [Na ₃ PO ₄ ] instead of 41.9 g of sodium pyrophosphate [Na ₄ (P ₂ O ₇ )], and 42.9 g of calcium chloride [CaCl ₂ ] was prepared. A catalyst was synthesized in the same manner as in Example 1 (1-1) except that B solution was prepared. The prepared catalyst was dehydrated in the same manner as in Example 1 (1-2), and the results are shown in Table 1 below.

Example 3

Calcium Phosphate-Silica Catalyst ( Ca ₅ ( P ₃ O ₁₀ ) ₂ ) _a ( SiO ₂ ) _b [a = 80 wt %, b = 20 wt %] Produce

In Example 1 A solution was prepared using 41.7 g of sodium triphosphate [Na ₅ P ₃ O ₁₀ ] instead of 41.9 g of sodium pyrophosphate [Na ₄ (P ₂ O ₇ )], and calcium chloride [CaCl ₂ ] was 31.4. A catalyst was synthesized in the same manner as in Example 1 (1-1) except that B solution was prepared using g. The prepared catalyst was dehydrated in the same manner as in Example 1 (1-2), and the results are shown in Table 1 below.

TABLE 1

EXAMPLES 4-5

Calcium phosphate-silica catalyst (Ca ₂ (P ₂ O ₇ )) _a (SiO ₂ ) _{b In the} catalyst composition a is 50 to 98 wt%, b is 2 to 50 wt% as described in Table 2 within the scope of the present invention. A catalyst was synthesized in the same manner as in Example 1 (1-1) except for the change. The prepared catalyst was dehydrated in the same manner as in Example 1 (1-2), and the results are shown in Table 2 below.

[Comparative Examples 1 and 2]

Example 1 (1- except that the composition of the calcium phosphate-silica catalyst (Ca ₂ (P ₂ O ₇ )) _a (SiO ₂ ) _b catalyst was changed as described in Table 2 outside the content range according to the invention. The catalyst was synthesized in the same manner as in 1), and dehydrated in the same manner as in Example 1 (1-2), and the results are shown in Table 2 below.

TABLE 2

Example 6

A catalyst was prepared in the same manner as in Example 1, lactic acid ethyl ester was used in place of lactic acid methyl ester, and dehydration reaction was performed in the same manner as in Example 1 (1-2) except that the reaction temperature was 390 ° C. The results are shown in Table 3 below.

Example 7

A catalyst was prepared in the same manner as in Example 1, lactic acid butyl ester was used in place of lactic acid methyl ester, and dehydration was performed in the same manner as in Example 1 (1-2) except that the reaction temperature was 400 ° C. The results are shown in Table 3 below.

[Table 3]

When the catalyst content is out of the range of the present invention from the results of Examples 1 to 5 and Comparative Examples 1 to 2, acrylic acid and acrylic acid esters cannot be produced in high yield from lactic acid ester, and calcium phosphate-silica according to the present invention. It can be seen that the acrylic acid and the acrylic ester can be produced in high yield by the catalyst and the reaction method.

1 is an X-ray diffraction analysis of the metal oxide powder after firing in Example 1 of the present invention.

Claims (13)

50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, wherein the calcium phosphate comprises Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , Ca ₅ (P ₃ O ₁₀ ) _2, and Ca ₃ ( Calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester, characterized in that at least one selected from the group consisting of PO ₃ ) ₆ . (1) mixing calcium phosphate solution with calcium salt solution to produce calcium phosphate; (2) mixing the aqueous silicon salt solution with the aqueous acid solution to produce a silica slurry; (3) filtering, washing, and drying the mixed slurry obtained by mixing the calcium phosphate with the silica slurry to form a powder; And (4) calcining the powder at 300 to 700 ° C. in air; Method for producing a calcium phosphate-silica catalyst for dehydration reaction of lactic acid ester comprising a. 3. The method of claim 2, The aqueous solution of phosphate of step (1) comprises 2 to 50% by weight of phosphate, the calcium salt aqueous solution comprises 10 to 30% by weight of calcium salt. The method of claim 3, wherein The phosphate is Li ₆ (PO ₄ ) _2, Li ₄ P ₂ O ₇ , Li ₁₀ (P ₃ O ₁₀ ) _2, Na ₆ (PO ₄ ) _2, Na ₄ P ₂ O ₇ , Na ₁₀ (P ₃ O ₁₀ ) _2, K ₆ (PO ₄ ) _2, K ₄ P ₂ O ₇ And K ₁₀ (P ₃ O ₁₀ ) _{2 It} is one or more selected from the group consisting of, the calcium salt is CaCl ₂ , Ca (NO ₃ ) _{It is at} least one selected from the group consisting of ₂ and (CH ₃ COO) ₂ Ca. 3. The method of claim 2, The aqueous silicon salt solution of step (2) comprises 10 to 40% by weight of the silicon salt, the acid aqueous solution comprises a acid 5 to 25% by weight. The method of claim 5, The silicon salt is at least one selected from the group consisting of Li ₂ SiO _{3 ,} Na ₂ SiO ₃ and K ₂ SiO ₃ , The acid is characterized in that at least one selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid. Manufacturing method. 3. The method of claim 2, In the step (3), the production method, characterized in that the washing so that the content of the anionic material derived from the acid and the cationic material derived from the silicon salt added in step (2) to 1000ppm or less. The method according to any one of claims 2 to 7, wherein The calcium phosphate-silica catalyst for the dehydration reaction of the lactic acid ester is composed of 50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, wherein the calcium phosphate is Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , At least one selected from the group consisting of Ca ₅ (P ₃ O ₁₀ ) ₂ and Ca ₃ (PO ₃ ) ₆ . In the presence of calcium phosphate-silica catalyst for dehydration of lactic acid ester composed of 50 to 98% by weight of calcium phosphate and 2 to 50% by weight of silica, dehydration reaction of lactic acid ester having an alkyl group having 1 to 4 carbon atoms to prepare an acrylic compound, The calcium phosphate is at least one selected from the group consisting of Ca ₃ (PO ₄ ) _2, Ca ₂ P ₂ O ₇ , Ca ₅ (P ₃ O ₁₀ ) ₂ and Ca ₃ (PO ₃ ) ₆ Acrylic compound. The method of claim 9, The calcium phosphate-silica catalyst is a method for producing an acrylic compound, characterized in that consisting of 40 to 95% by weight of calcium phosphate and 5 to 40% by weight of silica. The method of claim 9, The lactic acid ester having an alkyl group having 1 to 4 carbon atoms is lactic acid methyl ester, lactic acid ethyl ester or lactic acid butyl ester. The method according to any one of claims 9 to 11, The dehydration reaction is a method for producing an acrylic compound, characterized in that the reaction temperature is carried out at 300 to 500 ℃, reaction pressure normal pressure to 5 atm, the feed rate of the lactic acid ester (LHSV) 0.05 ~ 1.0hr ^-1 . The method of claim 12, The dehydration reaction is a method for producing an acrylic compound, characterized in that the reaction temperature is carried out at 350 to 450 ℃, reaction pressure normal pressure to 2 atm, supply rate of the lactic acid ester (LHSV) 0.10 to 0.50hr ^-1 .

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