JP5180303B2 - Method for producing improved acrylic acid production catalyst - Google Patents

Description

  The present invention relates to a method for producing an oxide catalyst for producing acrylic acid, and more specifically, a catalyst precursor is obtained by adding a complex acid mixture containing a carboxylic acid, a peroxide, and a sulfuric acid compound as additives. It is related with the manufacturing method of the oxide catalyst for acrylic acid manufacture which can obtain acrylic acid with high activity compared with the catalyst for existing acrylic acid manufacture by this.

  Until now, in order to produce acrylic acid by direct oxidation of propane, much research has been conducted on quaternary complex oxide catalysts such as MoVTeNbO catalysts. However, in the state where there is no change in the constituent components of the catalyst, the degree of increase in reaction activity is limited, and the degree of improvement in catalyst activity is still insufficient. Therefore, it was necessary to develop a highly active catalyst having high propane conversion and selectivity to acrylic acid.

  Research has been done on the use of additives as part of research to increase catalyst activity. For example, according to Applied catalysis A: General Vol 257, Issue 1, 67 (2004), the addition of nitric acid increases the activity of the catalyst during the production process of the complex oxide catalyst, and the maximum is around pH 2.0 to 2.5. The results of a study showing the activity of However, the activity of the catalyst according to the above research does not reach the level of commercialization, but has a problem that its active region is very narrow. In Korean Patent Publication 2001-0067257A_P and US Patent 6,642,174B2, MoVTeNbO composite oxide catalyst having the components as in the present invention was manufactured, but no additive was used during the manufacturing process, and the activity of the catalyst was also included in the results of this study. Not reached.

  Accordingly, there is an urgent need for research on a method for producing a catalyst for producing acrylic acid that exhibits higher activity and exhibits increased activity in a wider area.

Korean Patent Publication 2001-0067257A_P US Patent 6,642,174B2

Applied catalysis A: General Vol 257, Issue 1, 67 (2004)

  An object of the present invention is to provide a method for producing a catalyst for producing acrylic acid which is excellent in propane conversion and acrylic acid selectivity during the production of acrylic acid by gas phase oxidation of propane, that is, excellent in catalytic activity.

  The present invention provides a method for producing an oxide catalyst for producing acrylic acid by obtaining a catalyst precursor from a solution containing a molybdenum salt, a vanadium salt, a tellurium salt, and a niobium salt, and then drying and calcining the precursor. . As described above, the present invention further includes a step of adding an additive to the mixed solution of the metal salt, wherein the additive is a complex acid mixture containing a carboxylic acid, a peroxide, and a sulfuric acid compound.

  The oxide catalyst for acrylic acid production of the present invention thus produced is represented by Chemical Formula 1.

<Chemical Formula 1>
Mo _1.0 V _a Te _b Nb _c O _n

  In the above formula, Mo is molybdenum, V is vanadium, Te is tellurium, Nb is niobium, a, b, c, and n are atomic molar ratios of vanadium, tellurium, niobium, and oxygen, respectively, 0.01 ≦ a ≦ 1; 0.01 ≦ b ≦ 1; 0.01 ≦ c ≦ 1; and n is a number determined by the valence and amount of other elements.

  The present invention provides a method for producing an oxide catalyst for producing acrylic acid by obtaining a catalyst precursor from a solution containing a molybdenum salt, a vanadium salt, a tellurium salt, and a niobium salt, and then drying and calcining the precursor. . As described above, the present invention further includes a step of adding an additive to the mixed solution of the metal salt, wherein the additive is a complex acid mixture containing a carboxylic acid, a peroxide, and a sulfuric acid compound.

The present invention first includes a step of preparing a mixed solution by mixing a compound containing molybdenum (Mo) salt, vanadium (V) salt, tellurium (Te) salt, and niobium (Nb) salt in a solvent. The solvent used in the above is preferably selected from the group consisting of distilled water, alcohol, ether, and carboxylate, and the metal counterion is the same or different in each metal salt compound. As a specific example, a mixed solution is prepared by dissolving molybdenum (Mo) salt, vanadium (V) salt, and tellurium (Te) salt in distilled water, and niobium (Nb) salt separately dissolved in distilled water. It is desirable to mix thoroughly after adding the solution. Examples of compounds that can be used at this time include molybdenum (Mo) salt compounds such as ammonium paramolybdate, molybdate, sodium molybdate, and molybdenum trioxide, and vanadium (V) salt compounds include metavanadium Examples thereof include ammonium metavanadate, vanadium halogen compounds such as VCl ₄ , and vanadium alkoxides such as VO (OC ₂ H ₅ ) _3. Tellurium (Te) salt compounds include telluric acid, Examples of the niobium (Nb) salt compound include ammonium niobium oxalate, niobic acid, and niobium oxalate. If a niobium salt solution dissolved in distilled water is added separately, a precipitate is usually formed after a certain time has passed, and if the mixed solution is continuously stirred, the precipitated precipitate Continues to form a precipitate while dispersed in the solution.

  Next, the present invention adds an additive to the mixed solution. The additive used in the present invention is a complex acid mixture containing a carboxylic acid, a peroxide, and a sulfuric acid compound. The sulfuric acid compound is preferably one or more selected from the group consisting of sulfuric acid, particularly concentrated sulfuric acid having a concentration of 95% or more, ammonium sulfate, and sulfur dioxide. The carboxylic acid is not particularly limited as long as one or more carboxylic acid functional groups are present, and preferably a dicarboxylic acid such as oxalic acid, succinic acid, tartaric acid, and glutamic acid. The peroxide is not particularly limited in the form of an organic substance or an inorganic substance as long as it is a peroxide, but is a dialkyl peroxide, an acyl peroxide compound, or the like. desirable.

Further, the content of each component of the composite acid mixture added is what desirably 0.05 to 1.5 mol per molybdenum (Mo) atoms to 1 mole of added in the form of Morubuden salt. If the content of each component, particularly the content of sulfuric acid compound, is less than 0.05 mol per mol of molybdenum atom, the catalyst has low propane conversion and acrylic acid selectivity in the whole reaction temperature interval. . On the other hand, when the amount exceeds 1.5 mol, the catalyst exhibits a certain degree of high acrylic acid selectivity at a low temperature, but the conversion at this time is 10% or less, and the selectivity drops sharply as the temperature increases. Show a trend.

  Such an additive serves not only to improve the activity of the catalyst of the present invention but also to further accelerate the precipitation of the catalyst precursor in the mixed solution of the metal salt. Such catalyst precursor precipitate can be collected by evaporating distilled water, for example, evaporating distilled water using a rotary vacuum dryer. The drying temperature is not particularly limited as long as it can evaporate water effectively, but drying can be performed at a temperature of about 100 ° C. or higher. The catalyst precursor thus dried is pulverized, then compression molded, for example, by a hydraulic press, and then pulverized again. Then, it is desirable that the catalyst precursor particles are sieved and screened with a uniform size, and then the firing process proceeds. At this time, the catalyst precursor particles are preferably in the range of 100 to 300 μm. Although the dried and pulverized catalyst precursor powder can be calcined immediately, it is more desirable to calcine it after compression molding and pulverization. The reason is that in the case of compression molding, the density of the catalyst becomes high, and the conversion rate of propane increases when the catalyst reacts with propane.

  Next, in the present invention, the catalyst precursor is calcined to finally obtain a catalyst. Firing usually consists of two stages. The first stage firing process is performed at a temperature of 150 to 250 ° C. for 1 to 4 hours under a flow of air, and the second stage firing process is performed at a temperature of 500 to 650 ° C. under a flow of nitrogen or an inert gas. It is desirable to bake for 4 hours.

  As described above, the produced oxide catalyst for producing acrylic acid of the present invention is represented by the following chemical formula 1.

<Chemical Formula 1>
Mo _1.0 V _a Te _b Nb _c O _n

  In the above formula, Mo is molybdenum, V is vanadium, Te is tellurium, Nb is niobium, a, b, c, and n are atomic molar ratios of vanadium, tellurium, niobium, and oxygen, respectively, 0.01 ≦ a ≦ 1; 0.01 ≦ b ≦ 1; 0.01 ≦ c ≦ 1; and n is a number determined by the valence and amount of other elements.

  The catalyst of the present invention produced as described above is used for producing acrylic acid from propane by gas phase oxidation reaction, and provides high conversion of propane and high selectivity of acrylic acid.

4 is a graph showing the selectivity of acrylic acid according to the conversion rate of propane when propane is vapor-phase oxidized to obtain acrylic acid using catalysts according to Examples and Comparative Examples of the present invention.

  Hereinafter, examples and comparative examples will be specifically described so that the present invention can be understood. However, these examples are only presented to illustrate the present invention, and the scope of rights of the present invention is as follows. It is not limited to examples.

<Example>

  Example 1

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to obtain a clean solution. Had made. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  0.403 g of an oxalic acid aqueous solution and 0.918 g of an aqueous sulfuric acid solution prepared by diluting in distilled water at a concentration of 1 mol / kg of hydrogen ion (acidic hydrogen functional group) standard in the mixed solution, and hydrogen peroxide concentration standard After adding 6.011 g of an aqueous hydrogen peroxide solution prepared at a concentration of 1 mol / kg, the mixture was further stirred for 60 minutes.

Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere. As a result, when the composition of the produced catalyst by molar ratio of the metal salt used must be a _{Mo 1.0 V 0.3 Te 0.23 Nb 0.12} O n, the melting point of Te metal other at 449.5 ° C. Since it is lower than the element, since the Te metal is volatilized and a considerable amount disappears at the firing temperature, the composition ratio of Te in the composition actually becomes low. This is the same for the following embodiments.

  Example 2

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  Manufactured at a concentration of 1 mol / kg of oxalic acid aqueous solution, 0.75 g of aqueous oxalic acid solution and 0.75 g of sulfuric acid aqueous solution prepared by diluting the above mixed solution with distilled water at a concentration of 1 mol / kg of hydrogen ion. After adding 7.5 g of the aqueous hydrogen peroxide solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Example 3

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  Manufactured at 0.5 mol of oxalic acid aqueous solution, 1.0 g of sulfuric acid aqueous solution and 1 mol / kg concentration based on hydrogen peroxide concentration, prepared by diluting the mixed solution in distilled water at a concentration of 1 mol / kg based on hydrogen ion. After adding 5.0 g of the aqueous hydrogen peroxide solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Example 4

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  Manufactured with 1.0 g of oxalic acid aqueous solution, 1.0 g of sulfuric acid aqueous solution, and 1 mol / kg concentration based on hydrogen peroxide concentration, prepared by diluting distilled water with 1 mol / kg concentration based on hydrogen ions. After adding 0.5 g of the aqueous hydrogen peroxide solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  <Comparative example>

  Comparative Example 1

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 240 minutes to prepare a mixed solution.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 2

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  To the mixed solution was added 0.918 g of an aqueous sulfuric acid solution prepared by diluting in distilled water at a concentration of 1 mol / kg based on hydrogen ions, and the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 3

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  To the mixed solution was added 0.403 g of an oxalic acid aqueous solution prepared by diluting in distilled water at a concentration of 1 mol / kg based on hydrogen ions, and the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 4

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  After adding 6.011 g of an aqueous hydrogen peroxide solution prepared at a concentration of 1 mol / kg based on the hydrogen peroxide concentration to the mixed solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 5

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  0.403 g of an oxalic acid aqueous solution prepared by diluting the mixed solution in distilled water at a concentration of 1 mol / kg based on hydrogen ions, and peroxidation prepared at a concentration of 1 mol / kg based on hydrogen peroxide concentration. After adding 6.011 g of aqueous hydrogen solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 6

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  To the mixed solution, 0.403 g of an oxalic acid aqueous solution prepared by diluting in distilled water at a concentration of 1 mol / kg based on hydrogen ions and 0.918 g of an aqueous sulfuric acid solution were added, followed by further stirring for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  Comparative Example 7

  Dissolve 1.178 g ammonium paramolybdate, 0.234 g ammonium metavanadate, and 0.352 g telluric acid in 50 ml distilled water at room temperature to make a clean solution. It was. A solution prepared by dissolving 0.3626 g of ammonium niobium oxalate in advance in 4 ml of distilled water was added thereto, followed by stirring for 180 minutes to prepare a mixed solution.

  Manufactured with 1.0 g of oxalic acid aqueous solution, 0.5 g of sulfuric acid aqueous solution and 1 mol / kg concentration based on hydrogen peroxide concentration, prepared by diluting the above mixed solution with distilled water at a concentration of 1 mol / kg based on hydrogen ion. After adding 10 g of the aqueous hydrogen peroxide solution, the mixture was further stirred for 60 minutes.

  Next, the distilled water was evaporated using a rotary vacuum dryer and dried completely at 120 ° C. This was pulverized to produce a compression molded body, and then pulverized again to select catalyst particles having a particle size of 180 to 250 μm. The selected catalyst particles were subjected to primary calcination for 2 hours at a temperature of 200 ° C. in an air atmosphere, and secondary calcination was performed for 2 hours at a temperature of 600 ° C. in a nitrogen atmosphere.

  <Experimental example>

  Using the catalysts prepared from Examples 1 to 4 and Comparative Examples 1 to 7, a selective oxidation reaction of propane was performed as follows.

After charging 0.1 g of the catalyst into the fixed bed reactor, the propane: oxygen: nitrogen: water molar ratio was 5.85: 11.69: 58.02: 24. A raw material gas having a raw material mixed gas composition of 44 was introduced onto the catalyst at a space time velocity of 1329 hr ⁻¹ . The result is as shown in FIG. 1, and the comparison of the same conversion rate (25%) relative selectivity is as shown in Table 1 below.

  As shown in FIG. 1, when acrylic acid is produced using the catalyst according to the embodiment of the present invention, the conversion rate of propane is generally high and the selectivity of acrylic acid is high, so that the acrylic acid yield is as a whole. It was found that the rate was excellent.

  As shown in Table 1, Examples 1 to 4 according to the present invention use a mixed acid mixture in which three kinds of compounds are mixed as a precipitant, thereby mixing a single compound or two kinds of compounds. It was confirmed that the yield of acrylic acid was excellent as compared with Comparative Examples 1 to 6 using an acid. And the yield of acrylic acid also compared with the comparative example 7 which used the additive of the complex acid mixture with which the content of the additive exceeded 1.5 times the molybdenum 1 mol reference | standard, and 3 types of compounds were mixed. It was confirmed that it was excellent.

  By producing an oxide catalyst for producing acrylic acid according to the method of the present invention, a catalyst having excellent activity can be obtained.

Claims (6)

In the method for producing an oxide catalyst for producing acrylic acid by obtaining a catalyst precursor from a solution containing molybdenum salt, vanadium salt, tellurium salt, and niobium salt, and drying and calcining the precursor, further comprising the step of adding an additive to the mixed solution, the additive acids, peroxides, and Ri complex acid mixtures der containing sulfuric acid compound,
The concentration of the carboxylic acid, peroxide, and sulfuric acid compound is 0.05 to 1.5 moles per mole of molybdenum atoms added in the form of molybdenum salt . A method for producing an oxide catalyst.   The method for producing an oxide catalyst for producing acrylic acid according to claim 1, wherein the sulfuric acid compound is selected from the group consisting of sulfuric acid, ammonium sulfate, and sulfur dioxide. The method for producing an oxide catalyst for producing acrylic acid according to claim 1 , wherein the carboxylic acid is oxalic acid, the peroxide is hydrogen peroxide, and the sulfuric acid compound is sulfuric acid. The method for producing an oxide catalyst for acrylic acid production according to claim 1, wherein the catalyst is represented by Chemical Formula 1.
<Chemical Formula 1>
Mo _1.0 V _a Te _b Nb _c O _n
In the above formula, Mo is molybdenum, V is vanadium, Te is tellurium, Nb is niobium, a, b, c, and n are atomic molar ratios of vanadium, tellurium, niobium, and oxygen, respectively, 0.01 ≦ a ≦ 1; 0.01 ≦ b ≦ 1; 0.01 ≦ c ≦ 1; and n is a number determined by the valence and amount of other elements.   The catalyst precursor is obtained by removing the solvent by directly evaporating the solvent from the mixed solution of the metal salt to which the additive is added, without any separate separation means, and the solvent is water. The method for producing an oxide catalyst for producing acrylic acid according to claim 1.   The firing is performed at a temperature of 150 to 250 ° C. for 1 to 4 hours under a flow of air, and then for 1 to 4 hours at a temperature of 500 to 650 ° C. under a flow of nitrogen or an inert gas. The manufacturing method of the oxide catalyst for acrylic acid manufacture of Claim 1 characterized by the above-mentioned.