JP2010536552A - Method for producing catalyst for acrylic acid production using reactive ball mill - Google Patents

Abstract

  The present invention provides a method for producing an oxide catalyst for producing acrylic acid. The present invention includes the steps of preparing 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. The invention is characterized by removing impurities from the prepared catalyst by ball milling in the presence of a polar solvent. Therefore, according to the method of the present invention, an oxidation catalyst for producing acrylsan having a very high catalytic activity can be prepared.

Description

  The present invention relates to a method for producing an oxide catalyst for producing acrylic acid, and more particularly, for producing an existing acrylic acid by ball milling the produced catalyst in the presence of a polar solvent to remove impurities. The present invention relates to a method for producing an oxide catalyst for producing acrylic acid, which can obtain acrylic acid with higher activity than the catalyst.

  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 catalyst. US Pat. No. 5,380,933 reports that acrylic acid was synthesized with a high selectivity of 60.5% using a four-component catalyst in the form of MoVTeNbO. After that, research was continued to add additional components to the four basic components to increase the activity of the catalyst and change the synthesis method of the catalyst. However, depending on the method of using a co-catalyst or changing the synthesis method of the catalyst, the degree of activity increase is limited, and the degree of improvement in catalyst activity is insufficient. Therefore, it was necessary to develop a highly active catalyst having high propane conversion and selectivity to acrylic acid through a new method different from the conventional technology.

  However, it is impossible to produce a catalyst composed only of active components by a generally known existing synthesis method, and since the impurity components generated in the synthesis process do not react with the reactants, the conversion rate is low. Not maximized, causing a complete oxidation reaction with the intermediate or product to reduce selectivity.

  Therefore, in order to synthesize a catalyst having higher activity and selectivity, it is required to establish a method capable of producing a catalyst having a minimum content of impurity components generated during the synthesis.

U.S. Pat.No. 5,380,933

  In order to improve the problems of low activity and low selectivity of a quaternary catalyst as a catalyst for producing acrylic acid, the present inventors removed the impurities generated during the synthesis or calcination process of the catalyst, thereby improving the activity of the catalyst. I tried to find a way to improve it. The present invention has been obtained as a result of such efforts.

  Therefore, 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, acrylic acid selectivity, and catalytic activity during the production of acrylic acid by gas phase oxidation of propane. is there.

  More specifically, the present invention relates to an oxidation process for producing acrylic acid by preparing a catalyst precursor from a solution containing molybdenum, vanadium, tellurium and niobium salts, and then drying and calcining the precursor. A method for producing a product catalyst is provided. The method of the present invention is characterized in that impurities are removed by ball milling the catalyst thus prepared in the presence of a polar solvent.

前記式中、Moはモリブデン、Vはバナジウム、Teはテルル、Nbはニオブであり、ａ、ｂ、ｃおよびｎは、それぞれバナジウム、テルル、ニオブおよび酸素の原子モル比であり、０.０１≦ａ≦１；０.０１≦ｂ≦１；０.０１≦ｃ≦１であり；ｎは他元素の原子価と量によって決められる数である The oxide catalyst for producing acrylic acid of the present invention is represented by the following chemical formula 1.

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

  The present invention relates to a method for producing an oxide catalyst for producing acrylic acid by a method in which a catalyst precursor is prepared from a solution containing molybdenum salt, vanadium salt, tellurium salt, and niobium salt, and then the precursor is dried and calcined. I will provide a. The present invention is characterized in that impurities are removed by ball milling the catalyst thus prepared in the presence of a polar solvent.

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 here is preferably selected from the group consisting of distilled water, alcohol, ether, and carboxylic acid ester, and in each metal salt compound, the metal counter ion may be the same or different. Good. 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) separately dissolved in distilled water. It is desirable to mix well after adding the salt solution. In this case, examples of compounds that can be used include molybdenum (Mo) salt compounds such as ammonium paramolybdate, molybdic acid, sodium molybdate, and molybdenum trioxide. Examples of vanadium (V) salt compounds include: Examples include ammonium metavanadate, vanadium halogen compounds (such as VCl ₄ ), and vanadium alkoxides (such as VO (OC ₂ H ₅ ) ₃ ). Telluric acid (Te) salt compounds include telluric acid. (Telluric acid) and tellurium dioxide are exemplified, and niobium (Nb) salt compounds include ammonium niobium oxalate, niobic acid and niobium oxalate. In general, when a niobium salt solution dissolved in distilled water is added separately, a precipitate is formed and sinks after a certain period of time. By continuously stirring the mixed solution, the formation of the precipitate is continued while the precipitated precipitate is dispersed in the solution.

  Next, the present invention adds an additive to the mixed solution. The additive is desirably one or more sulfuric acid compounds selected from the group consisting of concentrated sulfuric acid (particularly concentrated sulfuric acid having a concentration of 95% or more), ammonium sulfate, and sulfur dioxide. This additive is added to increase the activity of the catalyst and also has the effect of accelerating the precipitation of the catalyst precursor. Such a sulfuric acid compound is desirably 0.05 to 0.5 mol with respect to 1 mol of molybdenum (Mo) atom added. The catalyst precursor precipitate can be collected, preferably by evaporating the distilled water, for example by evaporating the distilled water using a rotary evaporator. The drying temperature is not particularly limited as long as it is a temperature capable of effectively evaporating water, but drying can be performed at a temperature of about 100 ° C. or higher. The dried catalyst precursor is pulverized, then compression molded by, for example, a hydraulic press, and then pulverized again. It is desirable to screen the catalyst precursor particles so as to be uniform in size by sieving with a sieve and proceed with the subsequent calcination process. The size of the catalyst precursor particles is desirably 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 it is compression-molded and pulverized. This is because, when compression molding is performed before firing, the density of the catalyst is increased, and this also increases the conversion rate of propane when the catalyst reacts with propane.

  Next, in the method of the present invention, the prepared catalyst precursor is calcined to obtain a final catalyst. Firing usually consists of two steps. In the first step of the firing process, firing is performed at a temperature of 150 to 250 ° C. for 1 to 4 hours in an air stream. In the second step of the firing process, 500 to 650 ° C. is performed under a stream of nitrogen or an inert gas. It is desirable to bake at temperature for 1-4 hours.

前記式中、Moはモリブデン、Vはバナジウム、Teはテルル、Nbはニオブであり、ａ、ｂ、ｃおよびｎは、それぞれ、バナジウム、テルル、ニオブ、および酸素の原子モル比であり、０.０１≦ａ≦１；０.０１≦ｂ≦１；０.０１≦ｃ≦１であり；ｎは他元素の原子価と量によって決められる数である。 The prepared oxide catalyst for producing acrylic acid of the present invention is represented by the following chemical formula 1.

In the above formula, Mo is molybdenum, V is vanadium, Te is tellurium, Nb is niobium, and a, b, c, and n are atomic molar ratios of vanadium, tellurium, niobium, and oxygen, respectively. 01 ≦ a ≦ 1; 0.01 ≦ b ≦ 1; 0.01 ≦ c ≦ 1; n is a number determined by the valence and amount of other elements.

  A catalyst may not be able to exhibit sufficient catalytic activity due to impurities contained in the catalyst production process. Therefore, the present invention can remarkably improve the catalytic activity, that is, the conversion rate of propane and the selectivity of acrylic acid by removing impurities from the catalyst formed by calcination.

  The present invention is characterized in that impurities are removed by ball milling the produced catalyst in the presence of a polar solvent. The ball mill is desirably performed using zirconia balls to which yttrium is added. The amount of the solvent used in the ball mill is preferably 2 to 100 times the amount of the catalyst volume, and more preferably 5 to 20 times. The solvent used for the ball mill is not particularly limited as long as it is a polar solvent. For example, water, methanol, ethanol, 1-propanol, 2-propanol, butanol, 1,2-ethanediol, acetone, acetic acid, and the like. Can be used.

  The present invention achieves both removal of impurities from the catalyst by the ball mill and improvement of the catalyst activity, but it is not clear why the improvement of the catalyst activity can be achieved. However, in view of the fact that the catalyst obtained by stirring the calcined catalyst for several hours in the presence of a polar solvent and then washing and drying did not change much in its activity, Improvement is an unexpected and unexpected result. Thus, the role of the ball mill in the present invention is to improve the catalytic activity by causing structural changes in the catalyst due to the high energy of the ball mill in the presence of a polar solvent, rather than by simple catalyst grinding and impurity purification. Is presumed to be achieved. Accordingly, the ball mill in the present invention is worthy of being called “reactive ball mill”.

  The catalyst produced by the method of the present invention can be used for the production of acrylic acid by the gas phase oxidation reaction of propane, providing high conversion of propane and high selectivity of acrylic acid.

  Hereinafter, practical and preferable embodiments of the present invention will be illustrated in the following examples. However, those skilled in the art can make various modifications or improvements within the spirit and scope of the present invention based on the present disclosure. It should be considered what can be done.

[Example]
[Comparative Example 1]
A solution was prepared by dissolving 0.234 g of ammonium metavanadate, 0.352 g of telluric acid, and 1.178 g of ammonium paramolybdate in 50 ml of distilled water at room temperature. . To this, 0.3626 g of ammonium niobium oxalate previously dissolved in 4 ml of distilled water was added and stirred for 180 minutes to prepare a mixed solution.

  A 1 mol / kg concentration solution was prepared by diluting 5.2 g of 95% concentrated sulfuric acid solution in distilled water. After adding 1.2 g of this concentrated sulfuric acid solution to the mixed solution, the mixture was further stirred for 60 minutes.

  The distilled water was then evaporated using a rotary evaporator and dried completely at 120 ° C. The dried catalyst was filled in a tube having an inner diameter of 4 mm and a length of 12.5 cm, and calcined in an atmosphere furnace. Primary firing was performed at a temperature of 210 ° C. for 2 hours in an air atmosphere, and secondary firing was performed at a temperature of 640 ° C. for 2 hours in a nitrogen atmosphere.

[Example 1]
1 g of the catalyst of Comparative Example 1 was placed in a 60 ml volume single container, 15 zirconia balls with a diameter of 10 mm and 80 zirconia balls with a diameter of 5 mm were added, 15 ml of water was added, and then ball milled at a speed of 150 rpm for 15 hours. Went.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be tan. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Example 2]
1 g of the catalyst of Comparative Example 1 is put into a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm are added, 15 ml of ethanol is added, and then ball milling is performed at a speed of 150 rpm for 15 hours. went.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be tan. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Example 3]
1 g of the catalyst of Comparative Example 1 was put into a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm were added, 15 ml of 1-propanol was added, and then 15 hours at a speed of 150 rpm. A ball mill was performed.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be tan. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Example 4]
1 g of the catalyst of Comparative Example 1 was put into a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm were added, 15 ml of 2-propanol was added, and then 15 hours at a speed of 150 rpm. A ball mill was performed.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be blue. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Example 5]
1 g of the catalyst of Comparative Example 1 is placed in a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm are added, 15 ml of butanol is added, and then ball milling is performed at a speed of 150 rpm for 15 hours. went.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be tan. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Example 6]
1 g of the catalyst of Comparative Example 1 is placed in a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm are added, 15 ml of 1,2-ethanediol is added, and then the speed is 150 rpm. And then ball milled for 15 hours.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. In order to confirm that the impurities of the catalyst were dissolved, the solution after centrifugation was collected and confirmed to be tan. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Comparative Example 2]
1 g of the catalyst of Comparative Example 1 is put into a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm are added, 15 ml of heptane is added, and then the ball mill is run at a speed of 150 rpm for 15 hours. went.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. The solution after centrifugation was collected and confirmed to be colorless, and it was confirmed that catalyst impurities were dissolved. ICP analysis was performed to confirm that the catalyst component was not eluted. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Comparative Example 3]
1 g of the catalyst of Comparative Example 1 is put into a 60 ml volume single container, 15 zirconia balls having a diameter of 10 mm and 80 zirconia balls having a diameter of 5 mm are added, 15 ml of hexane is added, and then ball milling is performed at a speed of 150 rpm for 15 hours. went.

  After the ball mill, the catalyst and solvent were recovered. An additional 30 cc of solvent was added thereto and centrifuged. Centrifugation is performed at 4000 rpm for 2 hours. The solution after centrifugation was collected and confirmed to be colorless, and it was confirmed that the impurities of the catalyst were dissolved. ICP analysis was performed to confirm that the catalyst component was not eluted. The catalyst that had settled to the bottom was collected, dried at 80 ° C. for 4 hours, and then ground by an agate to complete the catalyst.

[Comparative Example 4]
1 g of the catalyst of Comparative Example 1 was placed in a reactor equipped with a stirrer, 50 ml of water was added, and the mixture was stirred for 4 hours at a speed of 300 rpm. The color of the solution was transparent, and it was confirmed that impurities were not dissolved. Thereafter, the catalyst was finally filtered after washing, drying and drying.

[Comparative Example 5]
1 g of the catalyst of Comparative Example 1 was placed in a reactor equipped with a stirrer, 50 ml of 2-propanol was added, and the mixture was stirred at a speed of 300 rpm for 4 hours. The color of the solution was transparent, and it was confirmed that impurities were not dissolved. Thereafter, the catalyst was finally filtered after washing, drying and drying.

[Experimental example]
The selective oxidation reaction of propane was performed as follows using the catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 5.
After 0.1 g of catalyst was charged into a fixed bed reactor, a raw material gas having a propane: oxygen: nitrogen: water molar ratio of 8.3: 11.8: 42.3: 37.6 was spatiotemporal. The catalyst was introduced onto the catalyst at a rate of 1100 hr ⁻¹ , and the reaction temperature and the selectivity of acrylic acid were measured under the condition that the propane conversion was 40%. The results are shown in Table 1 below.

  As shown in Table 1, the catalysts of Examples 1 to 6 according to the present invention are characterized in that a ball mill was performed using a polar solvent, but the ball mill was not performed or the polar solvent was not used. It was demonstrated that the reaction temperature was lower and the selectivity of acrylic acid and the yield of acrylic acid were better when compared with the catalysts of Comparative Examples 1 to 3 that performed ball milling at the same conversion rate. On the other hand, the catalysts according to Comparative Examples 4 and 5 in which the catalyst purification process in which the catalyst is stirred in the presence of the polar solvent are changed in their activity as compared with the catalyst in Comparative Example 1 in which such a purification process is not performed. There was almost no.

  In the present invention, a catalyst having excellent activity can be obtained by producing a catalyst by calcination from a catalyst precursor and then removing the impurities contained in the production process of the catalyst by ball milling in the presence of a polar solvent. .

  Hereinafter, preferred examples are presented to help understanding of the present invention. However, the following examples illustrate the present invention, and various changes and modifications can be made within the scope and technical idea of the present invention. It will be apparent to those skilled in the art that such variations and modifications are also encompassed by the appended claims.

Claims (7)

Preparing a catalyst precursor from a solution containing molybdenum, vanadium, tellurium, and niobium salts;
A method for producing an oxide catalyst for producing acrylic acid, comprising: drying and calcining the catalyst precursor; and ball milling a pre-catalyst produced by calcination in the presence of a polar solvent.   The method for producing an oxide catalyst for producing acrylic acid according to claim 1, wherein the amount of the polar solvent used is 2 to 100 times the volume of the catalyst.   The said polar solvent is selected from the group consisting of water, methanol, ethanol, 1-propanol, 2-propanol, butanol, 1,2-ethanediol, acetone, and acetic acid. Of producing an oxide catalyst for producing acrylic acid. The catalyst is represented by the chemical formula 1:

[In the above formula, Mo is molybdenum, V is vanadium, Te is tellurium, Nb is niobium, and 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]
It is represented by these, The manufacturing method of the oxide catalyst for acrylic acid manufacture of Claim 1 characterized by the above-mentioned.   The method further includes adding an additive to the mixed solution containing the molybdenum salt, vanadium salt, tellurium salt, and niobium salt, and the additive is selected from the group consisting of concentrated sulfuric acid, ammonium sulfate, and sulfur dioxide. The method for producing an oxide catalyst for producing acrylic acid according to claim 1, wherein the method is one or more sulfuric acid compounds.   The method for producing an oxide catalyst for producing acrylic acid according to claim 5, wherein the content of the additive is 0.05 to 0.5 mol per mol of the molybdenum atom.   The calcination is first performed at a temperature of 150 to 250 ° C. for 1 to 4 hours under a stream of air, and then performed at a temperature of 500 to 650 ° C. for 1 to 4 hours under a stream of nitrogen or an inert gas. The method for producing an oxide catalyst for producing acrylic acid according to claim 1, wherein